Commit Graph

417 Commits

Author SHA1 Message Date
Christian Brauner
c1632a0f11
fs: port ->setattr() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:02 +01:00
Linus Torvalds
c76ff350bd lsm/stable-6.2 PR 20221212
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Merge tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull lsm updates from Paul Moore:

 - Improve the error handling in the device cgroup such that memory
   allocation failures when updating the access policy do not
   potentially alter the policy.

 - Some minor fixes to reiserfs to ensure that it properly releases
   LSM-related xattr values.

 - Update the security_socket_getpeersec_stream() LSM hook to take
   sockptr_t values.

   Previously the net/BPF folks updated the getsockopt code in the
   network stack to leverage the sockptr_t type to make it easier to
   pass both kernel and __user pointers, but unfortunately when they did
   so they didn't convert the LSM hook.

   While there was/is no immediate risk by not converting the LSM hook,
   it seems like this is a mistake waiting to happen so this patch
   proactively does the LSM hook conversion.

 - Convert vfs_getxattr_alloc() to return an int instead of a ssize_t
   and cleanup the callers. Internally the function was never going to
   return anything larger than an int and the callers were doing some
   very odd things casting the return value; this patch fixes all that
   and helps bring a bit of sanity to vfs_getxattr_alloc() and its
   callers.

 - More verbose, and helpful, LSM debug output when the system is booted
   with "lsm.debug" on the command line. There are examples in the
   commit description, but the quick summary is that this patch provides
   better information about which LSMs are enabled and the ordering in
   which they are processed.

 - General comment and kernel-doc fixes and cleanups.

* tag 'lsm-pr-20221212' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: Fix description of fs_context_parse_param
  lsm: Add/fix return values in lsm_hooks.h and fix formatting
  lsm: Clarify documentation of vm_enough_memory hook
  reiserfs: Add missing calls to reiserfs_security_free()
  lsm,fs: fix vfs_getxattr_alloc() return type and caller error paths
  device_cgroup: Roll back to original exceptions after copy failure
  LSM: Better reporting of actual LSMs at boot
  lsm: make security_socket_getpeersec_stream() sockptr_t safe
  audit: Fix some kernel-doc warnings
  lsm: remove obsoleted comments for security hooks
  fs: edit a comment made in bad taste
2022-12-13 09:47:48 -08:00
Linus Torvalds
299e2b1967 Landlock updates for v6.2-rc1
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Merge tag 'landlock-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull landlock updates from Mickaël Salaün:
 "This adds file truncation support to Landlock, contributed by Günther
  Noack. As described by Günther [1], the goal of these patches is to
  work towards a more complete coverage of file system operations that
  are restrictable with Landlock.

  The known set of currently unsupported file system operations in
  Landlock is described at [2]. Out of the operations listed there,
  truncate is the only one that modifies file contents, so these patches
  should make it possible to prevent the direct modification of file
  contents with Landlock.

  The new LANDLOCK_ACCESS_FS_TRUNCATE access right covers both the
  truncate(2) and ftruncate(2) families of syscalls, as well as open(2)
  with the O_TRUNC flag. This includes usages of creat() in the case
  where existing regular files are overwritten.

  Additionally, this introduces a new Landlock security blob associated
  with opened files, to track the available Landlock access rights at
  the time of opening the file. This is in line with Unix's general
  approach of checking the read and write permissions during open(), and
  associating this previously checked authorization with the opened
  file. An ongoing patch documents this use case [3].

  In order to treat truncate(2) and ftruncate(2) calls differently in an
  LSM hook, we split apart the existing security_path_truncate hook into
  security_path_truncate (for truncation by path) and
  security_file_truncate (for truncation of previously opened files)"

Link: https://lore.kernel.org/r/20221018182216.301684-1-gnoack3000@gmail.com [1]
Link: https://www.kernel.org/doc/html/v6.1/userspace-api/landlock.html#filesystem-flags [2]
Link: https://lore.kernel.org/r/20221209193813.972012-1-mic@digikod.net [3]

* tag 'landlock-6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux:
  samples/landlock: Document best-effort approach for LANDLOCK_ACCESS_FS_REFER
  landlock: Document Landlock's file truncation support
  samples/landlock: Extend sample tool to support LANDLOCK_ACCESS_FS_TRUNCATE
  selftests/landlock: Test ftruncate on FDs created by memfd_create(2)
  selftests/landlock: Test FD passing from restricted to unrestricted processes
  selftests/landlock: Locally define __maybe_unused
  selftests/landlock: Test open() and ftruncate() in multiple scenarios
  selftests/landlock: Test file truncation support
  landlock: Support file truncation
  landlock: Document init_layer_masks() helper
  landlock: Refactor check_access_path_dual() into is_access_to_paths_allowed()
  security: Create file_truncate hook from path_truncate hook
2022-12-13 09:14:50 -08:00
Kees Cook
86ef3c735e LSM: Better reporting of actual LSMs at boot
Enhance the details reported by "lsm.debug" in several ways:

- report contents of "security="
- report contents of "CONFIG_LSM"
- report contents of "lsm="
- report any early LSM details
- whitespace-align the output of similar phases for easier visual parsing
- change "disabled" to more accurate "skipped"
- explain what "skipped" and "ignored" mean in a parenthetical

Upgrade the "security= is ignored" warning from pr_info to pr_warn,
and include full arguments list to make the cause even more clear.

Replace static "Security Framework initializing" pr_info with specific
list of the resulting order of enabled LSMs.

For example, if the kernel is built with:

CONFIG_SECURITY_SELINUX=y
CONFIG_SECURITY_APPARMOR=y
CONFIG_SECURITY_LOADPIN=y
CONFIG_SECURITY_YAMA=y
CONFIG_SECURITY_SAFESETID=y
CONFIG_SECURITY_LOCKDOWN_LSM=y
CONFIG_SECURITY_LANDLOCK=y
CONFIG_INTEGRITY=y
CONFIG_BPF_LSM=y
CONFIG_DEFAULT_SECURITY_APPARMOR=y
CONFIG_LSM="landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,
            smack,tomoyo,apparmor,bpf"

Booting without options will show:

LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,
     safesetid,integrity,selinux,bpf
landlock: Up and running.
Yama: becoming mindful.
LoadPin: ready to pin (currently not enforcing)
SELinux:  Initializing.
LSM support for eBPF active

Boot with "lsm.debug" will show:

LSM: legacy security= *unspecified*
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,
                selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm= *unspecified*
LSM:   early started: lockdown (enabled)
LSM:   first ordered: capability (enabled)
LSM: builtin ordered: landlock (enabled)
LSM: builtin ignored: lockdown (not built into kernel)
LSM: builtin ordered: yama (enabled)
LSM: builtin ordered: loadpin (enabled)
LSM: builtin ordered: safesetid (enabled)
LSM: builtin ordered: integrity (enabled)
LSM: builtin ordered: selinux (enabled)
LSM: builtin ignored: smack (not built into kernel)
LSM: builtin ignored: tomoyo (not built into kernel)
LSM: builtin ordered: apparmor (enabled)
LSM: builtin ordered: bpf (enabled)
LSM: exclusive chosen:   selinux
LSM: exclusive disabled: apparmor
LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,
                      safesetid,integrity,selinux,bpf
LSM: cred blob size       = 32
LSM: file blob size       = 16
LSM: inode blob size      = 72
LSM: ipc blob size        = 8
LSM: msg_msg blob size    = 4
LSM: superblock blob size = 80
LSM: task blob size       = 8
LSM: initializing capability
LSM: initializing landlock
landlock: Up and running.
LSM: initializing yama
Yama: becoming mindful.
LSM: initializing loadpin
LoadPin: ready to pin (currently not enforcing)
LSM: initializing safesetid
LSM: initializing integrity
LSM: initializing selinux
SELinux:  Initializing.
LSM: initializing bpf
LSM support for eBPF active

And some examples of how the lsm.debug ordering report changes...

With "lsm.debug security=selinux":

LSM: legacy security=selinux
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,
                selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm= *unspecified*
LSM:   early started: lockdown (enabled)
LSM:   first ordered: capability (enabled)
LSM: security=selinux disabled: apparmor (only one legacy major LSM)
LSM: builtin ordered: landlock (enabled)
LSM: builtin ignored: lockdown (not built into kernel)
LSM: builtin ordered: yama (enabled)
LSM: builtin ordered: loadpin (enabled)
LSM: builtin ordered: safesetid (enabled)
LSM: builtin ordered: integrity (enabled)
LSM: builtin ordered: selinux (enabled)
LSM: builtin ignored: smack (not built into kernel)
LSM: builtin ignored: tomoyo (not built into kernel)
LSM: builtin ordered: apparmor (disabled)
LSM: builtin ordered: bpf (enabled)
LSM: exclusive chosen:   selinux
LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,
		      safesetid,integrity,selinux,bpf

With "lsm.debug lsm=integrity,selinux,loadpin,crabability,bpf,
                    loadpin,loadpin":

LSM: legacy security= *unspecified*
LSM: CONFIG_LSM=landlock,lockdown,yama,loadpin,safesetid,integrity,
                selinux,smack,tomoyo,apparmor,bpf
LSM: boot arg lsm=integrity,selinux,loadpin,capability,bpf,loadpin,
		  loadpin
LSM:   early started: lockdown (enabled)
LSM:   first ordered: capability (enabled)
LSM: cmdline ordered: integrity (enabled)
LSM: cmdline ordered: selinux (enabled)
LSM: cmdline ordered: loadpin (enabled)
LSM: cmdline ignored: crabability (not built into kernel)
LSM: cmdline ordered: bpf (enabled)
LSM: cmdline skipped: apparmor (not in requested order)
LSM: cmdline skipped: yama (not in requested order)
LSM: cmdline skipped: safesetid (not in requested order)
LSM: cmdline skipped: landlock (not in requested order)
LSM: exclusive chosen:   selinux
LSM: initializing lsm=lockdown,capability,integrity,selinux,loadpin,bpf

Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-security-module@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Mickaël Salaün <mic@digikod.net>
[PM: line wrapped commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-11-16 17:50:09 -05:00
Paul Moore
b10b9c342f lsm: make security_socket_getpeersec_stream() sockptr_t safe
Commit 4ff09db1b7 ("bpf: net: Change sk_getsockopt() to take the
sockptr_t argument") made it possible to call sk_getsockopt()
with both user and kernel address space buffers through the use of
the sockptr_t type.  Unfortunately at the time of conversion the
security_socket_getpeersec_stream() LSM hook was written to only
accept userspace buffers, and in a desire to avoid having to change
the LSM hook the commit author simply passed the sockptr_t's
userspace buffer pointer.  Since the only sk_getsockopt() callers
at the time of conversion which used kernel sockptr_t buffers did
not allow SO_PEERSEC, and hence the
security_socket_getpeersec_stream() hook, this was acceptable but
also very fragile as future changes presented the possibility of
silently passing kernel space pointers to the LSM hook.

There are several ways to protect against this, including careful
code review of future commits, but since relying on code review to
catch bugs is a recipe for disaster and the upstream eBPF maintainer
is "strongly against defensive programming", this patch updates the
LSM hook, and all of the implementations to support sockptr_t and
safely handle both user and kernel space buffers.

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-11-04 23:25:30 -04:00
Christian Brauner
e61b135f7b
integrity: implement get and set acl hook
The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].

So far posix acls were passed as a void blob to the security and
integrity modules. Some of them like evm then proceed to interpret the
void pointer and convert it into the kernel internal struct posix acl
representation to perform their integrity checking magic. This is
obviously pretty problematic as that requires knowledge that only the
vfs is guaranteed to have and has lead to various bugs. Add a proper
security hook for setting posix acls and pass down the posix acls in
their appropriate vfs format instead of hacking it through a void
pointer stored in the uapi format.

I spent considerate time in the security module and integrity
infrastructure and audited all codepaths. EVM is the only part that
really has restrictions based on the actual posix acl values passed
through it (e.g., i_mode). Before this dedicated hook EVM used to translate
from the uapi posix acl format sent to it in the form of a void pointer
into the vfs format. This is not a good thing. Instead of hacking around in
the uapi struct give EVM the posix acls in the appropriate vfs format and
perform sane permissions checks that mirror what it used to to in the
generic xattr hook.

IMA doesn't have any restrictions on posix acls. When posix acls are
changed it just wants to update its appraisal status to trigger an EVM
revalidation.

The removal of posix acls is equivalent to passing NULL to the posix set
acl hooks. This is the same as before through the generic xattr api.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-10-20 10:13:29 +02:00
Christian Brauner
72b3897e78
security: add get, remove and set acl hook
The current way of setting and getting posix acls through the generic
xattr interface is error prone and type unsafe. The vfs needs to
interpret and fixup posix acls before storing or reporting it to
userspace. Various hacks exist to make this work. The code is hard to
understand and difficult to maintain in it's current form. Instead of
making this work by hacking posix acls through xattr handlers we are
building a dedicated posix acl api around the get and set inode
operations. This removes a lot of hackiness and makes the codepaths
easier to maintain. A lot of background can be found in [1].

So far posix acls were passed as a void blob to the security and
integrity modules. Some of them like evm then proceed to interpret the
void pointer and convert it into the kernel internal struct posix acl
representation to perform their integrity checking magic. This is
obviously pretty problematic as that requires knowledge that only the
vfs is guaranteed to have and has lead to various bugs. Add a proper
security hook for setting posix acls and pass down the posix acls in
their appropriate vfs format instead of hacking it through a void
pointer stored in the uapi format.

In the next patches we implement the hooks for the few security modules
that do actually have restrictions on posix acls.

Link: https://lore.kernel.org/all/20220801145520.1532837-1-brauner@kernel.org [1]
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-10-20 10:13:28 +02:00
Günther Noack
b9f5ce27c8
landlock: Support file truncation
Introduce the LANDLOCK_ACCESS_FS_TRUNCATE flag for file truncation.

This flag hooks into the path_truncate, file_truncate and
file_alloc_security LSM hooks and covers file truncation using
truncate(2), ftruncate(2), open(2) with O_TRUNC, as well as creat().

This change also increments the Landlock ABI version, updates
corresponding selftests, and updates code documentation to document
the flag.

In security/security.c, allocate security blobs at pointer-aligned
offsets. This fixes the problem where one LSM's security blob can
shift another LSM's security blob to an unaligned address (reported
by Nathan Chancellor).

The following operations are restricted:

open(2): requires the LANDLOCK_ACCESS_FS_TRUNCATE right if a file gets
implicitly truncated as part of the open() (e.g. using O_TRUNC).

Notable special cases:
* open(..., O_RDONLY|O_TRUNC) can truncate files as well in Linux
* open() with O_TRUNC does *not* need the TRUNCATE right when it
  creates a new file.

truncate(2) (on a path): requires the LANDLOCK_ACCESS_FS_TRUNCATE
right.

ftruncate(2) (on a file): requires that the file had the TRUNCATE
right when it was previously opened. File descriptors acquired by
other means than open(2) (e.g. memfd_create(2)) continue to support
truncation with ftruncate(2).

Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
Link: https://lore.kernel.org/r/20221018182216.301684-5-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19 09:01:44 +02:00
Günther Noack
3350607dc5
security: Create file_truncate hook from path_truncate hook
Like path_truncate, the file_truncate hook also restricts file
truncation, but is called in the cases where truncation is attempted
on an already-opened file.

This is required in a subsequent commit to handle ftruncate()
operations differently to truncate() operations.

Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20221018182216.301684-2-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>
2022-10-19 09:01:40 +02:00
Linus Torvalds
4899a36f91 powerpc updates for 6.1
- Remove our now never-true definitions for pgd_huge() and p4d_leaf().
 
  - Add pte_needs_flush() and huge_pmd_needs_flush() for 64-bit.
 
  - Add support for syscall wrappers.
 
  - Add support for KFENCE on 64-bit.
 
  - Update 64-bit HV KVM to use the new guest state entry/exit accounting API.
 
  - Support execute-only memory when using the Radix MMU (P9 or later).
 
  - Implement CONFIG_PARAVIRT_TIME_ACCOUNTING for pseries guests.
 
  - Updates to our linker script to move more data into read-only sections.
 
  - Allow the VDSO to be randomised on 32-bit.
 
  - Many other small features and fixes.
 
 Thanks to: Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira Rajeev, Christophe
 Leroy, David Hildenbrand, Disha Goel, Fabiano Rosas, Gaosheng Cui, Gustavo A. R. Silva,
 Haren Myneni, Hari Bathini, Jilin Yuan, Joel Stanley, Kajol Jain, Kees Cook, Krzysztof
 Kozlowski, Laurent Dufour, Liang He, Li Huafei, Lukas Bulwahn, Madhavan Srinivasan, Nathan
 Chancellor, Nathan Lynch, Nicholas Miehlbradt, Nicholas Piggin, Pali Rohár, Rohan McLure,
 Russell Currey, Sachin Sant, Segher Boessenkool, Shrikanth Hegde, Tyrel Datwyler, Wolfram
 Sang, ye xingchen, Zheng Yongjun.
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Merge tag 'powerpc-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

 - Remove our now never-true definitions for pgd_huge() and p4d_leaf().

 - Add pte_needs_flush() and huge_pmd_needs_flush() for 64-bit.

 - Add support for syscall wrappers.

 - Add support for KFENCE on 64-bit.

 - Update 64-bit HV KVM to use the new guest state entry/exit accounting
   API.

 - Support execute-only memory when using the Radix MMU (P9 or later).

 - Implement CONFIG_PARAVIRT_TIME_ACCOUNTING for pseries guests.

 - Updates to our linker script to move more data into read-only
   sections.

 - Allow the VDSO to be randomised on 32-bit.

 - Many other small features and fixes.

Thanks to Andrew Donnellan, Aneesh Kumar K.V, Arnd Bergmann, Athira
Rajeev, Christophe Leroy, David Hildenbrand, Disha Goel, Fabiano Rosas,
Gaosheng Cui, Gustavo A. R. Silva, Haren Myneni, Hari Bathini, Jilin
Yuan, Joel Stanley, Kajol Jain, Kees Cook, Krzysztof Kozlowski, Laurent
Dufour, Liang He, Li Huafei, Lukas Bulwahn, Madhavan Srinivasan, Nathan
Chancellor, Nathan Lynch, Nicholas Miehlbradt, Nicholas Piggin, Pali
Rohár, Rohan McLure, Russell Currey, Sachin Sant, Segher Boessenkool,
Shrikanth Hegde, Tyrel Datwyler, Wolfram Sang, ye xingchen, and Zheng
Yongjun.

* tag 'powerpc-6.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (214 commits)
  KVM: PPC: Book3S HV: Fix stack frame regs marker
  powerpc: Don't add __powerpc_ prefix to syscall entry points
  powerpc/64s/interrupt: Fix stack frame regs marker
  powerpc/64: Fix msr_check_and_set/clear MSR[EE] race
  powerpc/64s/interrupt: Change must-hard-mask interrupt check from BUG to WARN
  powerpc/pseries: Add firmware details to the hardware description
  powerpc/powernv: Add opal details to the hardware description
  powerpc: Add device-tree model to the hardware description
  powerpc/64: Add logical PVR to the hardware description
  powerpc: Add PVR & CPU name to hardware description
  powerpc: Add hardware description string
  powerpc/configs: Enable PPC_UV in powernv_defconfig
  powerpc/configs: Update config files for removed/renamed symbols
  powerpc/mm: Fix UBSAN warning reported on hugetlb
  powerpc/mm: Always update max/min_low_pfn in mem_topology_setup()
  powerpc/mm/book3s/hash: Rename flush_tlb_pmd_range
  powerpc: Drops STABS_DEBUG from linker scripts
  powerpc/64s: Remove lost/old comment
  powerpc/64s: Remove old STAB comment
  powerpc: remove orphan systbl_chk.sh
  ...
2022-10-09 14:05:15 -07:00
Linus Torvalds
4c0ed7d8d6 whack-a-mole: constifying struct path *
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Merge tag 'pull-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull vfs constification updates from Al Viro:
 "whack-a-mole: constifying struct path *"

* tag 'pull-path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ecryptfs: constify path
  spufs: constify path
  nd_jump_link(): constify path
  audit_init_parent(): constify path
  __io_setxattr(): constify path
  do_proc_readlink(): constify path
  overlayfs: constify path
  fs/notify: constify path
  may_linkat(): constify path
  do_sys_name_to_handle(): constify path
  ->getprocattr(): attribute name is const char *, TYVM...
2022-10-06 17:31:02 -07:00
Linus Torvalds
26b84401da lsm/stable-6.1 PR 20221003
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Merge tag 'lsm-pr-20221003' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull LSM updates from Paul Moore:
 "Seven patches for the LSM layer and we've got a mix of trivial and
  significant patches. Highlights below, starting with the smaller bits
  first so they don't get lost in the discussion of the larger items:

   - Remove some redundant NULL pointer checks in the common LSM audit
     code.

   - Ratelimit the lockdown LSM's access denial messages.

     With this change there is a chance that the last visible lockdown
     message on the console is outdated/old, but it does help preserve
     the initial series of lockdown denials that started the denial
     message flood and my gut feeling is that these might be the more
     valuable messages.

   - Open userfaultfds as readonly instead of read/write.

     While this code obviously lives outside the LSM, it does have a
     noticeable impact on the LSMs with Ondrej explaining the situation
     in the commit description. It is worth noting that this patch
     languished on the VFS list for over a year without any comments
     (objections or otherwise) so I took the liberty of pulling it into
     the LSM tree after giving fair notice. It has been in linux-next
     since the end of August without any noticeable problems.

   - Add a LSM hook for user namespace creation, with implementations
     for both the BPF LSM and SELinux.

     Even though the changes are fairly small, this is the bulk of the
     diffstat as we are also including BPF LSM selftests for the new
     hook.

     It's also the most contentious of the changes in this pull request
     with Eric Biederman NACK'ing the LSM hook multiple times during its
     development and discussion upstream. While I've never taken NACK's
     lightly, I'm sending these patches to you because it is my belief
     that they are of good quality, satisfy a long-standing need of
     users and distros, and are in keeping with the existing nature of
     the LSM layer and the Linux Kernel as a whole.

     The patches in implement a LSM hook for user namespace creation
     that allows for a granular approach, configurable at runtime, which
     enables both monitoring and control of user namespaces. The general
     consensus has been that this is far preferable to the other
     solutions that have been adopted downstream including outright
     removal from the kernel, disabling via system wide sysctls, or
     various other out-of-tree mechanisms that users have been forced to
     adopt since we haven't been able to provide them an upstream
     solution for their requests. Eric has been steadfast in his
     objections to this LSM hook, explaining that any restrictions on
     the user namespace could have significant impact on userspace.
     While there is the possibility of impacting userspace, it is
     important to note that this solution only impacts userspace when it
     is requested based on the runtime configuration supplied by the
     distro/admin/user. Frederick (the pathset author), the LSM/security
     community, and myself have tried to work with Eric during
     development of this patchset to find a mutually acceptable
     solution, but Eric's approach and unwillingness to engage in a
     meaningful way have made this impossible. I have CC'd Eric directly
     on this pull request so he has a chance to provide his side of the
     story; there have been no objections outside of Eric's"

* tag 'lsm-pr-20221003' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lockdown: ratelimit denial messages
  userfaultfd: open userfaultfds with O_RDONLY
  selinux: Implement userns_create hook
  selftests/bpf: Add tests verifying bpf lsm userns_create hook
  bpf-lsm: Make bpf_lsm_userns_create() sleepable
  security, lsm: Introduce security_create_user_ns()
  lsm: clean up redundant NULL pointer check
2022-10-03 17:51:52 -07:00
Nathan Lynch
b8f3e48834 powerpc/rtas: block error injection when locked down
The error injection facility on pseries VMs allows corruption of
arbitrary guest memory, potentially enabling a sufficiently privileged
user to disable lockdown or perform other modifications of the running
kernel via the rtas syscall.

Block the PAPR error injection facility from being opened or called
when locked down.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926131643.146502-3-nathanl@linux.ibm.com
2022-09-28 19:22:14 +10:00
Nathan Lynch
99df7a2810 powerpc/pseries: block untrusted device tree changes when locked down
The /proc/powerpc/ofdt interface allows the root user to freely alter
the in-kernel device tree, enabling arbitrary physical address writes
via drivers that could bind to malicious device nodes, thus making it
possible to disable lockdown.

Historically this interface has been used on the pseries platform to
facilitate the runtime addition and removal of processor, memory, and
device resources (aka Dynamic Logical Partitioning or DLPAR). Years
ago, the processor and memory use cases were migrated to designs that
happen to be lockdown-friendly: device tree updates are communicated
directly to the kernel from firmware without passing through untrusted
user space. I/O device DLPAR via the "drmgr" command in powerpc-utils
remains the sole legitimate user of /proc/powerpc/ofdt, but it is
already broken in lockdown since it uses /dev/mem to allocate argument
buffers for the rtas syscall. So only illegitimate uses of the
interface should see a behavior change when running on a locked down
kernel.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM)
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926131643.146502-2-nathanl@linux.ibm.com
2022-09-28 19:22:14 +10:00
Al Viro
c8e477c649 ->getprocattr(): attribute name is const char *, TYVM...
cast of ->d_name.name to char * is completely wrong - nothing is
allowed to modify its contents.

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2022-09-01 17:34:39 -04:00
Luis Chamberlain
2a58401240 lsm,io_uring: add LSM hooks for the new uring_cmd file op
io-uring cmd support was added through ee692a21e9 ("fs,io_uring:
add infrastructure for uring-cmd"), this extended the struct
file_operations to allow a new command which each subsystem can use
to enable command passthrough. Add an LSM specific for the command
passthrough which enables LSMs to inspect the command details.

This was discussed long ago without no clear pointer for something
conclusive, so this enables LSMs to at least reject this new file
operation.

[0] https://lkml.kernel.org/r/8adf55db-7bab-f59d-d612-ed906b948d19@schaufler-ca.com

Cc: stable@vger.kernel.org
Fixes: ee692a21e9 ("fs,io_uring: add infrastructure for uring-cmd")
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-08-26 11:19:43 -04:00
Frederick Lawler
7cd4c5c210 security, lsm: Introduce security_create_user_ns()
User namespaces are an effective tool to allow programs to run with
permission without requiring the need for a program to run as root. User
namespaces may also be used as a sandboxing technique. However, attackers
sometimes leverage user namespaces as an initial attack vector to perform
some exploit. [1,2,3]

While it is not the unprivileged user namespace functionality, which
causes the kernel to be exploitable, users/administrators might want to
more granularly limit or at least monitor how various processes use this
functionality, while vulnerable kernel subsystems are being patched.

Preventing user namespace already creation comes in a few of forms in
order of granularity:

        1. /proc/sys/user/max_user_namespaces sysctl
        2. Distro specific patch(es)
        3. CONFIG_USER_NS

To block a task based on its attributes, the LSM hook cred_prepare is a
decent candidate for use because it provides more granular control, and
it is called before create_user_ns():

        cred = prepare_creds()
                security_prepare_creds()
                        call_int_hook(cred_prepare, ...
        if (cred)
                create_user_ns(cred)

Since security_prepare_creds() is meant for LSMs to copy and prepare
credentials, access control is an unintended use of the hook. [4]
Further, security_prepare_creds() will always return a ENOMEM if the
hook returns any non-zero error code.

This hook also does not handle the clone3 case which requires us to
access a user space pointer to know if we're in the CLONE_NEW_USER
call path which may be subject to a TOCTTOU attack.

Lastly, cred_prepare is called in many call paths, and a targeted hook
further limits the frequency of calls which is a beneficial outcome.
Therefore introduce a new function security_create_user_ns() with an
accompanying userns_create LSM hook.

With the new userns_create hook, users will have more control over the
observability and access control over user namespace creation. Users
should expect that normal operation of user namespaces will behave as
usual, and only be impacted when controls are implemented by users or
administrators.

This hook takes the prepared creds for LSM authors to write policy
against. On success, the new namespace is applied to credentials,
otherwise an error is returned.

Links:
1. https://nvd.nist.gov/vuln/detail/CVE-2022-0492
2. https://nvd.nist.gov/vuln/detail/CVE-2022-25636
3. https://nvd.nist.gov/vuln/detail/CVE-2022-34918
4. https://lore.kernel.org/all/1c4b1c0d-12f6-6e9e-a6a3-cdce7418110c@schaufler-ca.com/

Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: KP Singh <kpsingh@kernel.org>
Signed-off-by: Frederick Lawler <fred@cloudflare.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-08-16 17:32:46 -04:00
Linus Torvalds
87fe1adb66 SafeSetID changes for Linux 6.0
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Merge tag 'safesetid-6.0' of https://github.com/micah-morton/linux

Pull SafeSetID updates from Micah Morton:
 "This contains one commit that touches common kernel code, one that
  adds functionality internal to the SafeSetID LSM code, and a few other
  commits that only modify the SafeSetID LSM selftest.

  The commit that touches common kernel code simply adds an LSM hook in
  the setgroups() syscall that mirrors what is done for the existing LSM
  hooks in the setuid() and setgid() syscalls. This commit combined with
  the SafeSetID-specific one allow the LSM to filter setgroups() calls
  according to configured rule sets in the same way that is already done
  for setuid() and setgid()"

* tag 'safesetid-6.0' of https://github.com/micah-morton/linux:
  LSM: SafeSetID: add setgroups() testing to selftest
  LSM: SafeSetID: Add setgroups() security policy handling
  security: Add LSM hook to setgroups() syscall
  LSM: SafeSetID: add GID testing to selftest
  LSM: SafeSetID: selftest cleanup and prepare for GIDs
  LSM: SafeSetID: fix userns bug in selftest
2022-08-02 15:12:13 -07:00
Micah Morton
fcfe0ac2fc security: Add LSM hook to setgroups() syscall
Give the LSM framework the ability to filter setgroups() syscalls. There
are already analagous hooks for the set*uid() and set*gid() syscalls.
The SafeSetID LSM will use this new hook to ensure setgroups() calls are
allowed by the installed security policy. Tested by putting print
statement in security_task_fix_setgroups() hook and confirming that it
gets hit when userspace does a setgroups() syscall.

Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
2022-07-15 18:21:49 +00:00
Christian Brauner
0e363cf3fa
security: pass down mount idmapping to setattr hook
Before this change we used to take a shortcut and place the actual
values that would be written to inode->i_{g,u}id into struct iattr. This
had the advantage that we moved idmappings mostly out of the picture
early on but it made reasoning about changes more difficult than it
should be.

The filesystem was never explicitly told that it dealt with an idmapped
mount. The transition to the value that needed to be stored in
inode->i_{g,u}id appeared way too early and increased the probability of
bugs in various codepaths.

We know place the same value in struct iattr no matter if this is an
idmapped mount or not. The vfs will only deal with type safe
vfs{g,u}id_t. This makes it massively safer to perform permission checks
as the type will tell us what checks we need to perform and what helpers
we need to use.

Adapt the security_inode_setattr() helper to pass down the mount's
idmapping to account for that change.

Link: https://lore.kernel.org/r/20220621141454.2914719-8-brauner@kernel.org
Cc: Seth Forshee <sforshee@digitalocean.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
CC: linux-fsdevel@vger.kernel.org
Reviewed-by: Seth Forshee <sforshee@digitalocean.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2022-06-26 18:18:56 +02:00
Linus Torvalds
cb44e4f061 Landlock updates for v5.19-rc1
Important changes:
 * improve the path_rename LSM hook implementations for RENAME_EXCHANGE;
 * fix a too-restrictive filesystem control for a rare corner case;
 * set the nested sandbox limitation to 16 layers;
 * add a new LANDLOCK_ACCESS_FS_REFER access right to properly handle
   file reparenting (i.e. full rename and link support);
 * add new tests and documentation;
 * format code with clang-format to make it easier to maintain and
   contribute.
 
 Related patch series:
 * [PATCH v1 0/7] Landlock: Clean up coding style with clang-format
   https://lore.kernel.org/r/20220506160513.523257-1-mic@digikod.net
 * [PATCH v2 00/10] Minor Landlock fixes and new tests
   https://lore.kernel.org/r/20220506160820.524344-1-mic@digikod.net
 * [PATCH v3 00/12] Landlock: file linking and renaming support
   https://lore.kernel.org/r/20220506161102.525323-1-mic@digikod.net
 * [PATCH v2] landlock: Explain how to support Landlock
   https://lore.kernel.org/r/20220513112743.156414-1-mic@digikod.net
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Merge tag 'landlock-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux

Pull Landlock updates from Mickaël Salaün:

 - improve the path_rename LSM hook implementations for RENAME_EXCHANGE;

 - fix a too-restrictive filesystem control for a rare corner case;

 - set the nested sandbox limitation to 16 layers;

 - add a new LANDLOCK_ACCESS_FS_REFER access right to properly handle
   file reparenting (i.e. full rename and link support);

 - add new tests and documentation;

 - format code with clang-format to make it easier to maintain and
   contribute.

* tag 'landlock-5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mic/linux: (30 commits)
  landlock: Explain how to support Landlock
  landlock: Add design choices documentation for filesystem access rights
  landlock: Document good practices about filesystem policies
  landlock: Document LANDLOCK_ACCESS_FS_REFER and ABI versioning
  samples/landlock: Add support for file reparenting
  selftests/landlock: Add 11 new test suites dedicated to file reparenting
  landlock: Add support for file reparenting with LANDLOCK_ACCESS_FS_REFER
  LSM: Remove double path_rename hook calls for RENAME_EXCHANGE
  landlock: Move filesystem helpers and add a new one
  landlock: Fix same-layer rule unions
  landlock: Create find_rule() from unmask_layers()
  landlock: Reduce the maximum number of layers to 16
  landlock: Define access_mask_t to enforce a consistent access mask size
  selftests/landlock: Test landlock_create_ruleset(2) argument check ordering
  landlock: Change landlock_restrict_self(2) check ordering
  landlock: Change landlock_add_rule(2) argument check ordering
  selftests/landlock: Add tests for O_PATH
  selftests/landlock: Fully test file rename with "remove" access
  selftests/landlock: Extend access right tests to directories
  selftests/landlock: Add tests for unknown access rights
  ...
2022-05-24 13:09:13 -07:00
Linus Torvalds
efd1df1982 selinux/stable-5.19 PR 20220523
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Merge tag 'selinux-pr-20220523' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got twelve patches queued for v5.19, with most being fairly
  minor. The highlights are below:

   - The checkreqprot and runtime disable knobs have been deprecated for
     some time with no active users that we can find. In an effort to
     move things along we are adding a pause when the knobs are used to
     help make the deprecation more noticeable in case anyone is still
     using these hacks in the shadows.

   - We've added the anonymous inode class name to the AVC audit records
     when anonymous inodes are involved. This should make writing policy
     easier when anonymous inodes are involved.

   - More constification work. This is fairly straightforward and the
     source of most of the diffstat.

   - The usual minor cleanups: remove unnecessary assignments, assorted
     style/checkpatch fixes, kdoc fixes, macro while-loop
     encapsulations, #include tweaks, etc"

* tag 'selinux-pr-20220523' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  security: declare member holding string literal const
  selinux: log anon inode class name
  selinux: declare data arrays const
  selinux: fix indentation level of mls_ops block
  selinux: include necessary headers in headers
  selinux: avoid extra semicolon
  selinux: update parameter documentation
  selinux: resolve checkpatch errors
  selinux: don't sleep when CONFIG_SECURITY_SELINUX_CHECKREQPROT_VALUE is true
  selinux: checkreqprot is deprecated, add some ssleep() discomfort
  selinux: runtime disable is deprecated, add some ssleep() discomfort
  selinux: Remove redundant assignments
2022-05-24 13:06:32 -07:00
Linus Torvalds
0bf13a8436 kernel-hardening updates for v5.19-rc1
- usercopy hardening expanded to check other allocation types
   (Matthew Wilcox, Yuanzheng Song)
 
 - arm64 stackleak behavioral improvements (Mark Rutland)
 
 - arm64 CFI code gen improvement (Sami Tolvanen)
 
 - LoadPin LSM block dev API adjustment (Christoph Hellwig)
 
 - Clang randstruct support (Bill Wendling, Kees Cook)
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Merge tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - usercopy hardening expanded to check other allocation types (Matthew
   Wilcox, Yuanzheng Song)

 - arm64 stackleak behavioral improvements (Mark Rutland)

 - arm64 CFI code gen improvement (Sami Tolvanen)

 - LoadPin LSM block dev API adjustment (Christoph Hellwig)

 - Clang randstruct support (Bill Wendling, Kees Cook)

* tag 'kernel-hardening-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (34 commits)
  loadpin: stop using bdevname
  mm: usercopy: move the virt_addr_valid() below the is_vmalloc_addr()
  gcc-plugins: randstruct: Remove cast exception handling
  af_unix: Silence randstruct GCC plugin warning
  niu: Silence randstruct warnings
  big_keys: Use struct for internal payload
  gcc-plugins: Change all version strings match kernel
  randomize_kstack: Improve docs on requirements/rationale
  lkdtm/stackleak: fix CONFIG_GCC_PLUGIN_STACKLEAK=n
  arm64: entry: use stackleak_erase_on_task_stack()
  stackleak: add on/off stack variants
  lkdtm/stackleak: check stack boundaries
  lkdtm/stackleak: prevent unexpected stack usage
  lkdtm/stackleak: rework boundary management
  lkdtm/stackleak: avoid spurious failure
  stackleak: rework poison scanning
  stackleak: rework stack high bound handling
  stackleak: clarify variable names
  stackleak: rework stack low bound handling
  stackleak: remove redundant check
  ...
2022-05-24 12:27:09 -07:00
Daniel Thompson
eadb2f47a3 lockdown: also lock down previous kgdb use
KGDB and KDB allow read and write access to kernel memory, and thus
should be restricted during lockdown.  An attacker with access to a
serial port (for example, via a hypervisor console, which some cloud
vendors provide over the network) could trigger the debugger so it is
important that the debugger respect the lockdown mode when/if it is
triggered.

Fix this by integrating lockdown into kdb's existing permissions
mechanism.  Unfortunately kgdb does not have any permissions mechanism
(although it certainly could be added later) so, for now, kgdb is simply
and brutally disabled by immediately exiting the gdb stub without taking
any action.

For lockdowns established early in the boot (e.g. the normal case) then
this should be fine but on systems where kgdb has set breakpoints before
the lockdown is enacted than "bad things" will happen.

CVE: CVE-2022-21499
Co-developed-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-05-24 11:29:34 -07:00
Mickaël Salaün
100f59d964
LSM: Remove double path_rename hook calls for RENAME_EXCHANGE
In order to be able to identify a file exchange with renameat2(2) and
RENAME_EXCHANGE, which will be useful for Landlock [1], propagate the
rename flags to LSMs.  This may also improve performance because of the
switch from two set of LSM hook calls to only one, and because LSMs
using this hook may optimize the double check (e.g. only one lock,
reduce the number of path walks).

AppArmor, Landlock and Tomoyo are updated to leverage this change.  This
should not change the current behavior (same check order), except
(different level of) speed boosts.

[1] https://lore.kernel.org/r/20220221212522.320243-1-mic@digikod.net

Cc: James Morris <jmorris@namei.org>
Cc: Kentaro Takeda <takedakn@nttdata.co.jp>
Cc: Serge E. Hallyn <serge@hallyn.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20220506161102.525323-7-mic@digikod.net
2022-05-23 13:27:58 +02:00
Christian Göttsche
1af0e4a023 security: declare member holding string literal const
The struct security_hook_list member lsm is assigned in
security_add_hooks() with string literals passed from the individual
security modules.  Declare the function parameter and the struct member
const to signal their immutability.

Reported by Clang [-Wwrite-strings]:

    security/selinux/hooks.c:7388:63: error: passing 'const char [8]'
      to parameter of type 'char *' discards qualifiers
      [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
            security_add_hooks(selinux_hooks,
                               ARRAY_SIZE(selinux_hooks), selinux);
                                                          ^~~~~~~~~
    ./include/linux/lsm_hooks.h:1629:11: note: passing argument to
      parameter 'lsm' here
                                    char *lsm);
                                          ^

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Paul Moore <paul@paul-moore.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-05-13 14:51:06 -04:00
Bill Wendling
75c1182e18 security: don't treat structure as an array of struct hlist_head
The initialization of "security_hook_heads" is done by casting it to
another structure pointer type, and treating it as an array of "struct
hlist_head" objects. This requires an exception be made in "randstruct",
because otherwise it will emit an error, reducing the effectiveness of
the hardening technique.

Instead of using a cast, initialize the individual struct hlist_head
elements in security_hook_heads explicitly. This removes the need for
the cast and randstruct exception.

Signed-off-by: Bill Wendling <morbo@google.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220407175930.471870-1-morbo@google.com
2022-04-13 12:15:53 -07:00
Linus Torvalds
c269497d24 selinux/stable-5.18 PR 20220321
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Merge tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a number of SELinux patches queued up, the highlights are:

   - Fixup the security_fs_context_parse_param() LSM hook so it executes
     all of the LSM hook implementations unless a serious error occurs.

     We also correct the SELinux hook implementation so that it returns
     zero on success.

   - In addition to a few SELinux mount option parsing fixes, we
     simplified the parsing by moving it earlier in the process.

     The logic was that it was unlikely an admin/user would use the new
     mount API and not have the policy loaded before passing the SELinux
     options.

   - Properly fixed the LSM/SELinux/SCTP hooks with the addition of the
     security_sctp_assoc_established() hook.

     This work was done in conjunction with the netdev folks and should
     complete the move of the SCTP labeling from the endpoints to the
     associations.

   - Fixed a variety of sparse warnings caused by changes in the "__rcu"
     markings of some core kernel structures.

   - Ensure we access the superblock's LSM security blob using the
     stacking-safe accessors.

   - Added the ability for the kernel to always allow FIOCLEX and
     FIONCLEX if the "ioctl_skip_cloexec" policy capability is
     specified.

   - Various constifications improvements, type casting improvements,
     additional return value checks, and dead code/parameter removal.

   - Documentation fixes"

* tag 'selinux-pr-20220321' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux: (23 commits)
  selinux: shorten the policy capability enum names
  docs: fix 'make htmldocs' warning in SCTP.rst
  selinux: allow FIOCLEX and FIONCLEX with policy capability
  selinux: use correct type for context length
  selinux: drop return statement at end of void functions
  security: implement sctp_assoc_established hook in selinux
  security: add sctp_assoc_established hook
  selinux: parse contexts for mount options early
  selinux: various sparse fixes
  selinux: try to use preparsed sid before calling parse_sid()
  selinux: Fix selinux_sb_mnt_opts_compat()
  LSM: general protection fault in legacy_parse_param
  selinux: fix a type cast problem in cred_init_security()
  selinux: drop unused macro
  selinux: simplify cred_init_security
  selinux: do not discard const qualifier in cast
  selinux: drop unused parameter of avtab_insert_node
  selinux: drop cast to same type
  selinux: enclose macro arguments in parenthesis
  selinux: declare name parameter of hash_eval const
  ...
2022-03-21 20:47:54 -07:00
Ondrej Mosnacek
5e50f5d4ff security: add sctp_assoc_established hook
security_sctp_assoc_established() is added to replace
security_inet_conn_established() called in
sctp_sf_do_5_1E_ca(), so that asoc can be accessed in security
subsystem and save the peer secid to asoc->peer_secid.

Fixes: 72e89f5008 ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Based-on-patch-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-02-15 15:03:38 -05:00
Linus Torvalds
d1e7f0919e Fix NULL pointer crash in LSM via Ceph, from Vivek Goyal <vgoyal@redhat.com>.
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Merge tag 'fixes-v5.17-lsm-ceph-null' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull security sybsystem fix from James Morris:
 "Fix NULL pointer crash in LSM via Ceph, from Vivek Goyal"

* tag 'fixes-v5.17-lsm-ceph-null' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  security, lsm: dentry_init_security() Handle multi LSM registration
2022-01-29 08:52:27 +02:00
Vivek Goyal
7f5056b9e7 security, lsm: dentry_init_security() Handle multi LSM registration
A ceph user has reported that ceph is crashing with kernel NULL pointer
dereference. Following is the backtrace.

/proc/version: Linux version 5.16.2-arch1-1 (linux@archlinux) (gcc (GCC)
11.1.0, GNU ld (GNU Binutils) 2.36.1) #1 SMP PREEMPT Thu, 20 Jan 2022
16:18:29 +0000
distro / arch: Arch Linux / x86_64
SELinux is not enabled
ceph cluster version: 16.2.7 (dd0603118f56ab514f133c8d2e3adfc983942503)

relevant dmesg output:
[   30.947129] BUG: kernel NULL pointer dereference, address:
0000000000000000
[   30.947206] #PF: supervisor read access in kernel mode
[   30.947258] #PF: error_code(0x0000) - not-present page
[   30.947310] PGD 0 P4D 0
[   30.947342] Oops: 0000 [#1] PREEMPT SMP PTI
[   30.947388] CPU: 5 PID: 778 Comm: touch Not tainted 5.16.2-arch1-1 #1
86fbf2c313cc37a553d65deb81d98e9dcc2a3659
[   30.947486] Hardware name: Gigabyte Technology Co., Ltd. B365M
DS3H/B365M DS3H, BIOS F5 08/13/2019
[   30.947569] RIP: 0010:strlen+0x0/0x20
[   30.947616] Code: b6 07 38 d0 74 16 48 83 c7 01 84 c0 74 05 48 39 f7 75
ec 31 c0 31 d2 89 d6 89 d7 c3 48 89 f8 31 d2 89 d6 89 d7 c3 0
f 1f 40 00 <80> 3f 00 74 12 48 89 f8 48 83 c0 01 80 38 00 75 f7 48 29 f8 31
ff
[   30.947782] RSP: 0018:ffffa4ed80ffbbb8 EFLAGS: 00010246
[   30.947836] RAX: 0000000000000000 RBX: ffffa4ed80ffbc60 RCX:
0000000000000000
[   30.947904] RDX: 0000000000000000 RSI: 0000000000000000 RDI:
0000000000000000
[   30.947971] RBP: ffff94b0d15c0ae0 R08: 0000000000000000 R09:
0000000000000000
[   30.948040] R10: 0000000000000000 R11: 0000000000000000 R12:
0000000000000000
[   30.948106] R13: 0000000000000001 R14: ffffa4ed80ffbc60 R15:
0000000000000000
[   30.948174] FS:  00007fc7520f0740(0000) GS:ffff94b7ced40000(0000)
knlGS:0000000000000000
[   30.948252] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   30.948308] CR2: 0000000000000000 CR3: 0000000104a40001 CR4:
00000000003706e0
[   30.948376] Call Trace:
[   30.948404]  <TASK>
[   30.948431]  ceph_security_init_secctx+0x7b/0x240 [ceph
49f9c4b9bf5be8760f19f1747e26da33920bce4b]
[   30.948582]  ceph_atomic_open+0x51e/0x8a0 [ceph
49f9c4b9bf5be8760f19f1747e26da33920bce4b]
[   30.948708]  ? get_cached_acl+0x4d/0xa0
[   30.948759]  path_openat+0x60d/0x1030
[   30.948809]  do_filp_open+0xa5/0x150
[   30.948859]  do_sys_openat2+0xc4/0x190
[   30.948904]  __x64_sys_openat+0x53/0xa0
[   30.948948]  do_syscall_64+0x5c/0x90
[   30.948989]  ? exc_page_fault+0x72/0x180
[   30.949034]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[   30.949091] RIP: 0033:0x7fc7521e25bb
[   30.950849] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18 00
00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 0
0 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 54 24 28 64 48 2b 14
25

Core of the problem is that ceph checks for return code from
security_dentry_init_security() and if return code is 0, it assumes
everything is fine and continues to call strlen(name), which crashes.

Typically SELinux LSM returns 0 and sets name to "security.selinux" and
it is not a problem. Or if selinux is not compiled in or disabled, it
returns -EOPNOTSUP and ceph deals with it.

But somehow in this configuration, 0 is being returned and "name" is
not being initialized and that's creating the problem.

Our suspicion is that BPF LSM is registering a hook for
dentry_init_security() and returns hook default of 0.

LSM_HOOK(int, 0, dentry_init_security, struct dentry *dentry,...)

I have not been able to reproduce it just by doing CONFIG_BPF_LSM=y.
Stephen has tested the patch though and confirms it solves the problem
for him.

dentry_init_security() is written in such a way that it expects only one
LSM to register the hook. Atleast that's the expectation with current code.

If another LSM returns a hook and returns default, it will simply return
0 as of now and that will break ceph.

Hence, suggestion is that change semantics of this hook a bit. If there
are no LSMs or no LSM is taking ownership and initializing security context,
then return -EOPNOTSUP. Also allow at max one LSM to initialize security
context. This hook can't deal with multiple LSMs trying to init security
context. This patch implements this new behavior.

Reported-by: Stephen Muth <smuth4@gmail.com>
Tested-by: Stephen Muth <smuth4@gmail.com>
Suggested-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Paul Moore <paul@paul-moore.com>
Cc: <stable@vger.kernel.org> # 5.16.0
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: James Morris <jmorris@namei.org>
2022-01-28 10:53:26 -08:00
Casey Schaufler
ecff30575b LSM: general protection fault in legacy_parse_param
The usual LSM hook "bail on fail" scheme doesn't work for cases where
a security module may return an error code indicating that it does not
recognize an input.  In this particular case Smack sees a mount option
that it recognizes, and returns 0. A call to a BPF hook follows, which
returns -ENOPARAM, which confuses the caller because Smack has processed
its data.

The SELinux hook incorrectly returns 1 on success. There was a time
when this was correct, however the current expectation is that it
return 0 on success. This is repaired.

Reported-by: syzbot+d1e3b1d92d25abf97943@syzkaller.appspotmail.com
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2022-01-27 20:43:02 -05:00
Ondrej Mosnacek
52f982f00b security,selinux: remove security_add_mnt_opt()
Its last user has been removed in commit f2aedb713c ("NFS: Add
fs_context support.").

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-12-06 13:46:24 -05:00
Paul Moore
6326948f94 lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()
The security_task_getsecid_subj() LSM hook invites misuse by allowing
callers to specify a task even though the hook is only safe when the
current task is referenced.  Fix this by removing the task_struct
argument to the hook, requiring LSM implementations to use the
current task.  While we are changing the hook declaration we also
rename the function to security_current_getsecid_subj() in an effort
to reinforce that the hook captures the subjective credentials of the
current task and not an arbitrary task on the system.

Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-11-22 17:52:47 -05:00
Paul Moore
32a370abf1 net,lsm,selinux: revert the security_sctp_assoc_established() hook
This patch reverts two prior patches, e7310c9402
("security: implement sctp_assoc_established hook in selinux") and
7c2ef0240e ("security: add sctp_assoc_established hook"), which
create the security_sctp_assoc_established() LSM hook and provide a
SELinux implementation.  Unfortunately these two patches were merged
without proper review (the Reviewed-by and Tested-by tags from
Richard Haines were for previous revisions of these patches that
were significantly different) and there are outstanding objections
from the SELinux maintainers regarding these patches.

Work is currently ongoing to correct the problems identified in the
reverted patches, as well as others that have come up during review,
but it is unclear at this point in time when that work will be ready
for inclusion in the mainline kernel.  In the interest of not keeping
objectionable code in the kernel for multiple weeks, and potentially
a kernel release, we are reverting the two problematic patches.

Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-11-12 12:07:02 -05:00
Xin Long
7c2ef0240e security: add sctp_assoc_established hook
security_sctp_assoc_established() is added to replace
security_inet_conn_established() called in
sctp_sf_do_5_1E_ca(), so that asoc can be accessed in security
subsystem and save the peer secid to asoc->peer_secid.

v1->v2:
  - fix the return value of security_sctp_assoc_established() in
    security.h, found by kernel test robot and Ondrej.

Fixes: 72e89f5008 ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Reviewed-by: Richard Haines <richard_c_haines@btinternet.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-03 11:09:20 +00:00
Xin Long
c081d53f97 security: pass asoc to sctp_assoc_request and sctp_sk_clone
This patch is to move secid and peer_secid from endpoint to association,
and pass asoc to sctp_assoc_request and sctp_sk_clone instead of ep. As
ep is the local endpoint and asoc represents a connection, and in SCTP
one sk/ep could have multiple asoc/connection, saving secid/peer_secid
for new asoc will overwrite the old asoc's.

Note that since asoc can be passed as NULL, security_sctp_assoc_request()
is moved to the place right after the new_asoc is created in
sctp_sf_do_5_1B_init() and sctp_sf_do_unexpected_init().

v1->v2:
  - fix the description of selinux_netlbl_skbuff_setsid(), as Jakub noticed.
  - fix the annotation in selinux_sctp_assoc_request(), as Richard Noticed.

Fixes: 72e89f5008 ("security: Add support for SCTP security hooks")
Reported-by: Prashanth Prahlad <pprahlad@redhat.com>
Reviewed-by: Richard Haines <richard_c_haines@btinternet.com>
Tested-by: Richard Haines <richard_c_haines@btinternet.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2021-11-03 11:09:20 +00:00
Vivek Goyal
15bf32398a security: Return xattr name from security_dentry_init_security()
Right now security_dentry_init_security() only supports single security
label and is used by SELinux only. There are two users of this hook,
namely ceph and nfs.

NFS does not care about xattr name. Ceph hardcodes the xattr name to
security.selinux (XATTR_NAME_SELINUX).

I am making changes to fuse/virtiofs to send security label to virtiofsd
and I need to send xattr name as well. I also hardcoded the name of
xattr to security.selinux.

Stephen Smalley suggested that it probably is a good idea to modify
security_dentry_init_security() to also return name of xattr so that
we can avoid this hardcoding in the callers.

This patch adds a new parameter "const char **xattr_name" to
security_dentry_init_security() and LSM puts the name of xattr
too if caller asked for it (xattr_name != NULL).

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Acked-by: James Morris <jamorris@linux.microsoft.com>
[PM: fixed typos in the commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-20 08:17:08 -04:00
Todd Kjos
52f8869337 binder: use cred instead of task for selinux checks
Since binder was integrated with selinux, it has passed
'struct task_struct' associated with the binder_proc
to represent the source and target of transactions.
The conversion of task to SID was then done in the hook
implementations. It turns out that there are race conditions
which can result in an incorrect security context being used.

Fix by using the 'struct cred' saved during binder_open and pass
it to the selinux subsystem.

Cc: stable@vger.kernel.org # 5.14 (need backport for earlier stables)
Fixes: 79af73079d ("Add security hooks to binder and implement the hooks for SELinux.")
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Todd Kjos <tkjos@google.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-14 20:48:04 -04:00
Kees Cook
86dd9fd52e LSM: Avoid warnings about potentially unused hook variables
Building with W=1 shows many unused const variable warnings. These can
be silenced, as we're well aware of their being potentially unused:

./include/linux/lsm_hook_defs.h:36:18: error: 'ptrace_access_check_default' defined but not used [-Werror=unused-const-variable=]
   36 | LSM_HOOK(int, 0, ptrace_access_check, struct task_struct *child,
      |                  ^~~~~~~~~~~~~~~~~~~
security/security.c:706:32: note: in definition of macro 'LSM_RET_DEFAULT'
  706 | #define LSM_RET_DEFAULT(NAME) (NAME##_default)
      |                                ^~~~
security/security.c:711:9: note: in expansion of macro 'DECLARE_LSM_RET_DEFAULT_int'
  711 |         DECLARE_LSM_RET_DEFAULT_##RET(DEFAULT, NAME)
      |         ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/lsm_hook_defs.h:36:1: note: in expansion of macro 'LSM_HOOK'
   36 | LSM_HOOK(int, 0, ptrace_access_check, struct task_struct *child,
      | ^~~~~~~~

Cc: James Morris <jmorris@namei.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: linux-security-module@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/linux-mm/202110131608.zms53FPR-lkp@intel.com/
Fixes: 98e828a065 ("security: Refactor declaration of LSM hooks")
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-10-14 16:07:53 -04:00
Paul Moore
cdc1404a40 lsm,io_uring: add LSM hooks to io_uring
A full expalantion of io_uring is beyond the scope of this commit
description, but in summary it is an asynchronous I/O mechanism
which allows for I/O requests and the resulting data to be queued
in memory mapped "rings" which are shared between the kernel and
userspace.  Optionally, io_uring offers the ability for applications
to spawn kernel threads to dequeue I/O requests from the ring and
submit the requests in the kernel, helping to minimize the syscall
overhead.  Rings are accessed in userspace by memory mapping a file
descriptor provided by the io_uring_setup(2), and can be shared
between applications as one might do with any open file descriptor.
Finally, process credentials can be registered with a given ring
and any process with access to that ring can submit I/O requests
using any of the registered credentials.

While the io_uring functionality is widely recognized as offering a
vastly improved, and high performing asynchronous I/O mechanism, its
ability to allow processes to submit I/O requests with credentials
other than its own presents a challenge to LSMs.  When a process
creates a new io_uring ring the ring's credentials are inhertied
from the calling process; if this ring is shared with another
process operating with different credentials there is the potential
to bypass the LSMs security policy.  Similarly, registering
credentials with a given ring allows any process with access to that
ring to submit I/O requests with those credentials.

In an effort to allow LSMs to apply security policy to io_uring I/O
operations, this patch adds two new LSM hooks.  These hooks, in
conjunction with the LSM anonymous inode support previously
submitted, allow an LSM to apply access control policy to the
sharing of io_uring rings as well as any io_uring credential changes
requested by a process.

The new LSM hooks are described below:

 * int security_uring_override_creds(cred)
   Controls if the current task, executing an io_uring operation,
   is allowed to override it's credentials with @cred.  In cases
   where the current task is a user application, the current
   credentials will be those of the user application.  In cases
   where the current task is a kernel thread servicing io_uring
   requests the current credentials will be those of the io_uring
   ring (inherited from the process that created the ring).

 * int security_uring_sqpoll(void)
   Controls if the current task is allowed to create an io_uring
   polling thread (IORING_SETUP_SQPOLL).  Without a SQPOLL thread
   in the kernel processes must submit I/O requests via
   io_uring_enter(2) which allows us to compare any requested
   credential changes against the application making the request.
   With a SQPOLL thread, we can no longer compare requested
   credential changes against the application making the request,
   the comparison is made against the ring's credentials.

Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-09-19 22:37:21 -04:00
Daniel Borkmann
51e1bb9eea bpf: Add lockdown check for probe_write_user helper
Back then, commit 96ae522795 ("bpf: Add bpf_probe_write_user BPF helper
to be called in tracers") added the bpf_probe_write_user() helper in order
to allow to override user space memory. Its original goal was to have a
facility to "debug, divert, and manipulate execution of semi-cooperative
processes" under CAP_SYS_ADMIN. Write to kernel was explicitly disallowed
since it would otherwise tamper with its integrity.

One use case was shown in cf9b1199de ("samples/bpf: Add test/example of
using bpf_probe_write_user bpf helper") where the program DNATs traffic
at the time of connect(2) syscall, meaning, it rewrites the arguments to
a syscall while they're still in userspace, and before the syscall has a
chance to copy the argument into kernel space. These days we have better
mechanisms in BPF for achieving the same (e.g. for load-balancers), but
without having to write to userspace memory.

Of course the bpf_probe_write_user() helper can also be used to abuse
many other things for both good or bad purpose. Outside of BPF, there is
a similar mechanism for ptrace(2) such as PTRACE_PEEK{TEXT,DATA} and
PTRACE_POKE{TEXT,DATA}, but would likely require some more effort.
Commit 96ae522795 explicitly dedicated the helper for experimentation
purpose only. Thus, move the helper's availability behind a newly added
LOCKDOWN_BPF_WRITE_USER lockdown knob so that the helper is disabled under
the "integrity" mode. More fine-grained control can be implemented also
from LSM side with this change.

Fixes: 96ae522795 ("bpf: Add bpf_probe_write_user BPF helper to be called in tracers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
2021-08-10 10:10:10 +02:00
Daniel Borkmann
71330842ff bpf: Add _kernel suffix to internal lockdown_bpf_read
Rename LOCKDOWN_BPF_READ into LOCKDOWN_BPF_READ_KERNEL so we have naming
more consistent with a LOCKDOWN_BPF_WRITE_USER option that we are adding.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
2021-08-09 21:50:41 +02:00
Linus Torvalds
6bd344e55f selinux/stable-5.14 PR 20210629
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Merge tag 'selinux-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull SELinux updates from Paul Moore:

 - The slow_avc_audit() function is now non-blocking so we can remove
   the AVC_NONBLOCKING tricks; this also includes the 'flags' variant of
   avc_has_perm().

 - Use kmemdup() instead of kcalloc()+copy when copying parts of the
   SELinux policydb.

 - The InfiniBand device name is now passed by reference when possible
   in the SELinux code, removing a strncpy().

 - Minor cleanups including: constification of avtab function args,
   removal of useless LSM/XFRM function args, SELinux kdoc fixes, and
   removal of redundant assignments.

* tag 'selinux-pr-20210629' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  selinux: kill 'flags' argument in avc_has_perm_flags() and avc_audit()
  selinux: slow_avc_audit has become non-blocking
  selinux: Fix kernel-doc
  selinux: use __GFP_NOWARN with GFP_NOWAIT in the AVC
  lsm_audit,selinux: pass IB device name by reference
  selinux: Remove redundant assignment to rc
  selinux: Corrected comment to match kernel-doc comment
  selinux: delete selinux_xfrm_policy_lookup() useless argument
  selinux: constify some avtab function arguments
  selinux: simplify duplicate_policydb_cond_list() by using kmemdup()
2021-06-30 14:55:42 -07:00
Roberto Sassu
7e135dc725 evm: Pass user namespace to set/remove xattr hooks
In preparation for 'evm: Allow setxattr() and setattr() for unmodified
metadata', this patch passes mnt_userns to the inode set/remove xattr hooks
so that the GID of the inode on an idmapped mount is correctly determined
by posix_acl_update_mode().

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Reviewed-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
2021-05-21 12:57:52 -04:00
Zhongjun Tan
8a922805fb selinux: delete selinux_xfrm_policy_lookup() useless argument
seliunx_xfrm_policy_lookup() is hooks of security_xfrm_policy_lookup().
The dir argument is uselss in security_xfrm_policy_lookup(). So
remove the dir argument from selinux_xfrm_policy_lookup() and
security_xfrm_policy_lookup().

Signed-off-by: Zhongjun Tan <tanzhongjun@yulong.com>
[PM: reformat the subject line]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-05-10 21:38:31 -04:00
Linus Torvalds
17ae69aba8 Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com>
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Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull Landlock LSM from James Morris:
 "Add Landlock, a new LSM from Mickaël Salaün.

  Briefly, Landlock provides for unprivileged application sandboxing.

  From Mickaël's cover letter:
    "The goal of Landlock is to enable to restrict ambient rights (e.g.
     global filesystem access) for a set of processes. Because Landlock
     is a stackable LSM [1], it makes possible to create safe security
     sandboxes as new security layers in addition to the existing
     system-wide access-controls. This kind of sandbox is expected to
     help mitigate the security impact of bugs or unexpected/malicious
     behaviors in user-space applications. Landlock empowers any
     process, including unprivileged ones, to securely restrict
     themselves.

     Landlock is inspired by seccomp-bpf but instead of filtering
     syscalls and their raw arguments, a Landlock rule can restrict the
     use of kernel objects like file hierarchies, according to the
     kernel semantic. Landlock also takes inspiration from other OS
     sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
     Pledge/Unveil.

     In this current form, Landlock misses some access-control features.
     This enables to minimize this patch series and ease review. This
     series still addresses multiple use cases, especially with the
     combined use of seccomp-bpf: applications with built-in sandboxing,
     init systems, security sandbox tools and security-oriented APIs [2]"

  The cover letter and v34 posting is here:

      https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/

  See also:

      https://landlock.io/

  This code has had extensive design discussion and review over several
  years"

Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]

* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  landlock: Enable user space to infer supported features
  landlock: Add user and kernel documentation
  samples/landlock: Add a sandbox manager example
  selftests/landlock: Add user space tests
  landlock: Add syscall implementations
  arch: Wire up Landlock syscalls
  fs,security: Add sb_delete hook
  landlock: Support filesystem access-control
  LSM: Infrastructure management of the superblock
  landlock: Add ptrace restrictions
  landlock: Set up the security framework and manage credentials
  landlock: Add ruleset and domain management
  landlock: Add object management
2021-05-01 18:50:44 -07:00
Mickaël Salaün
83e804f0bf fs,security: Add sb_delete hook
The sb_delete security hook is called when shutting down a superblock,
which may be useful to release kernel objects tied to the superblock's
lifetime (e.g. inodes).

This new hook is needed by Landlock to release (ephemerally) tagged
struct inodes.  This comes from the unprivileged nature of Landlock
described in the next commit.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Jann Horn <jannh@google.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-7-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 12:22:11 -07:00
Casey Schaufler
1aea780837 LSM: Infrastructure management of the superblock
Move management of the superblock->sb_security blob out of the
individual security modules and into the security infrastructure.
Instead of allocating the blobs from within the modules, the modules
tell the infrastructure how much space is required, and the space is
allocated there.

Cc: John Johansen <john.johansen@canonical.com>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-6-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 12:22:10 -07:00
Paul Moore
4ebd7651bf lsm: separate security_task_getsecid() into subjective and objective variants
Of the three LSMs that implement the security_task_getsecid() LSM
hook, all three LSMs provide the task's objective security
credentials.  This turns out to be unfortunate as most of the hook's
callers seem to expect the task's subjective credentials, although
a small handful of callers do correctly expect the objective
credentials.

This patch is the first step towards fixing the problem: it splits
the existing security_task_getsecid() hook into two variants, one
for the subjective creds, one for the objective creds.

  void security_task_getsecid_subj(struct task_struct *p,
				   u32 *secid);
  void security_task_getsecid_obj(struct task_struct *p,
				  u32 *secid);

While this patch does fix all of the callers to use the correct
variant, in order to keep this patch focused on the callers and to
ease review, the LSMs continue to use the same implementation for
both hooks.  The net effect is that this patch should not change
the behavior of the kernel in any way, it will be up to the latter
LSM specific patches in this series to change the hook
implementations and return the correct credentials.

Acked-by: Mimi Zohar <zohar@linux.ibm.com> (IMA)
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2021-03-22 15:23:32 -04:00