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Use list_splice_tail_init_rcu() to extend the existing custom IMA policy
with additional IMA policy rules.
Signed-off-by: Petko Manolov <petko.manolov@konsulko.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
match_string() returns the index of an array for a matching string,
which can be used intead of open coded variant.
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
As IMA policy rules are added, a mask of the type of rule (eg. kernel
modules, firmware, IMA policy) is updated. Unlike custom IMA policy
rules, which replace the original builtin policy rules and update the
mask, the builtin "secure_boot" policy rules were loaded, but did not
update the mask.
This patch refactors the code to load custom policies, defining a new
function named ima_appraise_flag(). The new function is called either
when loading the builtin "secure_boot" or custom policies.
Fixes: 503ceaef8e2e ("ima: define a set of appraisal rules requiring file signatures")
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Don't differentiate, for now, between kernel_read_file_id READING_FIRMWARE
and READING_FIRMWARE_PREALLOC_BUFFER enumerations.
Fixes: a098ecd firmware: support loading into a pre-allocated buffer (since 4.8)
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
If/when file data signatures are distributed with the file data, this
patch will not be needed. In the current environment where only some
files are signed, the ability to differentiate between file systems is
needed. Some file systems consider the file system magic number
internal to the file system.
This patch defines a new IMA policy condition named "fsname", based on
the superblock's file_system_type (sb->s_type) name. This allows policy
rules to be expressed in terms of the filesystem name.
The following sample rules require file signatures on rootfs files
executed or mmap'ed.
appraise func=BPRM_CHECK fsname=rootfs appraise_type=imasig
appraise func=FILE_MMAP fsname=rootfs appraise_type=imasig
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Sites may wish to provide additional metadata alongside files in order
to make more fine-grained security decisions[1]. The security of this is
enhanced if this metadata is protected, something that EVM makes
possible. However, the kernel cannot know about the set of extended
attributes that local admins may wish to protect, and hardcoding this
policy in the kernel makes it difficult to change over time and less
convenient for distributions to enable.
This patch adds a new /sys/kernel/security/integrity/evm/evm_xattrs node,
which can be read to obtain the current set of EVM-protected extended
attributes or written to in order to add new entries. Extending this list
will not change the validity of any existing signatures provided that the
file in question does not have any of the additional extended attributes -
missing xattrs are skipped when calculating the EVM hash.
[1] For instance, a package manager could install information about the
package uploader in an additional extended attribute. Local LSM policy
could then be associated with that extended attribute in order to
restrict the privileges available to packages from less trusted
uploaders.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Use a list of xattrs rather than an array - this makes it easier to
extend the list at runtime.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
We want to add additional evm control nodes, and it'd be preferable not
to clutter up the securityfs root directory any further. Create a new
integrity directory, move the ima directory into it, create an evm
directory for the evm attribute and add compatibility symlinks.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Commit a756024 ("ima: added ima_policy_flag variable") replaced
ima_initialized with ima_policy_flag, but didn't remove ima_initialized.
This patch removes it.
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Reviewed-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Define pr_fmt everywhere.
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> (powerpc build error)
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Changelog:
Previous pr_fmt definition was too late and caused problems in powerpc
allyesconfg build.
Kernel configured as CONFIG_IMA_READ_POLICY=y && CONFIG_IMA_WRITE_POLICY=n
keeps 0600 mode after loading policy. Remove write permission to state
that policy file no longer be written.
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Recognizing that the audit context is an internal audit value, use an
access function to retrieve the audit context pointer for the task
rather than reaching directly into the task struct to get it.
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[PM: merge fuzz in auditsc.c and selinuxfs.c, checkpatch.pl fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
The kernel should not calculate new hmacs for mounts done by
non-root users. Update evm_calc_hmac_or_hash() to refuse to
calculate new hmacs for mounts for non-init user namespaces.
Cc: linux-integrity@vger.kernel.org
Cc: linux-security-module@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: James Morris <james.l.morris@oracle.com>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Dongsu Park <dongsu@kinvolk.io>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This is required to use SMACK and IMA/EVM together. Add it to the
default nomeasure/noappraise list like other pseudo filesystems.
Signed-off-by: Martin Townsend <mtownsend1973@gmail.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
EVM might update the evm xattr while the VFS performs a remount to
readonly mode. This is not properly checked for, additionally check
the s_readonly_remount superblock flag before writing.
The bug can for example be observed with UBIFS. UBIFS checks the free
space on the device before and after a remount. With EVM enabled the
free space sometimes differs between both checks.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Replace nested ifs in the EVM xattr verification logic with a switch
statement, making the code easier to understand.
Also, add comments to the if statements in the out section and constify the
cause variable.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
The "goto out" statement doesn't have any purpose since there's no cleanup
to be done when returning early, so remove it. This also makes the rc
variable unnecessary so remove it as well.
Also, the xattr_len and fmt variables are redundant so remove them as well.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This macro isn't used anymore since commit 0d73a55208e9 ("ima: re-introduce
own integrity cache lock"), so remove it.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
In keeping with the directive to get rid of VLAs [1], let's drop the VLA
from ima_audit_measurement(). We need to adjust the return type of
ima_audit_measurement, because now this function can fail if an allocation
fails.
[1]: https://lkml.org/lkml/2018/3/7/621
v2: just use audit_log_format instead of doing a second allocation
v3: ignore failures in ima_audit_measurement()
Signed-off-by: Tycho Andersen <tycho@tycho.ws>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
TPM_CRB driver provides TPM CRB 2.0 support. If it is built as a
module, the TPM chip is registered after IMA init. tpm_pcr_read() in
IMA fails and displays the following message even though eventually
there is a TPM chip on the system.
ima: No TPM chip found, activating TPM-bypass! (rc=-19)
Fix IMA Kconfig to select TPM_CRB so TPM_CRB driver is built in the kernel
and initializes before IMA.
Signed-off-by: Jiandi An <anjiandi@codeaurora.org>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
There is no gain from doing this except for some self-documenting.
Signed-off-by: Hernán Gonzalez <hernan@vanguardiasur.com.ar>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
These variables are not used where they are was defined. There is no
point in declaring them there as extern. Move and constify them, saving
2 bytes.
Function old new delta
init_desc 273 271 -2
Total: Before=2112094, After=2112092, chg -0.00%
Signed-off-by: Hernán Gonzalez <hernan@vanguardiasur.com.ar>
Tested-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This patch addresses the fuse privileged mounted filesystems in
environments which are unwilling to accept the risk of trusting the
signature verification and want to always fail safe, but are for example
using a pre-built kernel.
This patch defines a new builtin policy named "fail_securely", which can
be specified on the boot command line as an argument to "ima_policy=".
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Dongsu Park <dongsu@kinvolk.io>
Cc: Alban Crequy <alban@kinvolk.io>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
The IMA_APPRAISE and IMA_HASH policies overlap. Clear IMA_HASH properly.
Fixes: da1b0029f527 ("ima: support new "hash" and "dont_hash" policy actions")
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This patch addresses the fuse privileged mounted filesystems in a "secure"
environment, with a correctly enforced security policy, which is willing
to assume the inherent risk of specific fuse filesystems that are well
defined and properly implemented.
As there is no way for the kernel to detect file changes, the kernel
ignores the cached file integrity results and re-measures, re-appraises,
and re-audits the file.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Dongsu Park <dongsu@kinvolk.io>
Cc: Alban Crequy <alban@kinvolk.io>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
FUSE can be mounted by unprivileged users either today with fusermount
installed with setuid, or soon with the upcoming patches to allow FUSE
mounts in a non-init user namespace.
This patch addresses the new unprivileged non-init mounted filesystems,
which are untrusted, by failing the signature verification.
This patch defines two new flags SB_I_IMA_UNVERIFIABLE_SIGNATURE and
SB_I_UNTRUSTED_MOUNTER.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Seth Forshee <seth.forshee@canonical.com>
Cc: Dongsu Park <dongsu@kinvolk.io>
Cc: Alban Crequy <alban@kinvolk.io>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
The existing BPRM_CHECK functionality in IMA validates against the
credentials of the existing process, not any new credentials that the
child process may transition to. Add an additional CREDS_CHECK target
and refactor IMA to pass the appropriate creds structure. In
ima_bprm_check(), check with both the existing process credentials and
the credentials that will be committed when the new process is started.
This will not change behaviour unless the system policy is extended to
include CREDS_CHECK targets - BPRM_CHECK will continue to check the same
credentials that it did previously.
After this patch, an IMA policy rule along the lines of:
measure func=CREDS_CHECK subj_type=unconfined_t
will trigger if a process is executed and runs as unconfined_t, ignoring
the context of the parent process. This is in contrast to:
measure func=BPRM_CHECK subj_type=unconfined_t
which will trigger if the process that calls exec() is already executing
in unconfined_t, ignoring the context that the child process executes
into.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Changelog:
- initialize ima_creds_status
security/integrity/digsig.c has build errors on some $ARCH due to a
missing header file, so add it.
security/integrity/digsig.c:146:2: error: implicit declaration of function 'vfree' [-Werror=implicit-function-declaration]
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-integrity@vger.kernel.org
Link: http://kisskb.ellerman.id.au/kisskb/head/13396/
Signed-off-by: James Morris <james.morris@microsoft.com>
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Merge tag 'iversion-v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull inode->i_version cleanup from Jeff Layton:
"Goffredo went ahead and sent a patch to rename this function, and
reverse its sense, as we discussed last week.
The patch is very straightforward and I figure it's probably best to
go ahead and merge this to get the API as settled as possible"
* tag 'iversion-v4.16-2' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
iversion: Rename make inode_cmp_iversion{+raw} to inode_eq_iversion{+raw}
Intermittently security.ima is not being written for new files. This
patch re-initializes the new slab iint->atomic_flags field before
freeing it.
Fixes: commit 0d73a55208e9 ("ima: re-introduce own integrity cache lock")
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
The function inode_cmp_iversion{+raw} is counter-intuitive, because it
returns true when the counters are different and false when these are equal.
Rename it to inode_eq_iversion{+raw}, which will returns true when
the counters are equal and false otherwise.
Signed-off-by: Goffredo Baroncelli <kreijack@inwind.it>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Pull tpm updates from James Morris:
- reduce polling delays in tpm_tis
- support retrieving TPM 2.0 Event Log through EFI before
ExitBootServices
- replace tpm-rng.c with a hwrng device managed by the driver for each
TPM device
- TPM resource manager synthesizes TPM_RC_COMMAND_CODE response instead
of returning -EINVAL for unknown TPM commands. This makes user space
more sound.
- CLKRUN fixes:
* Keep #CLKRUN disable through the entier TPM command/response flow
* Check whether #CLKRUN is enabled before disabling and enabling it
again because enabling it breaks PS/2 devices on a system where it
is disabled
* 'next-tpm' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
tpm: remove unused variables
tpm: remove unused data fields from I2C and OF device ID tables
tpm: only attempt to disable the LPC CLKRUN if is already enabled
tpm: follow coding style for variable declaration in tpm_tis_core_init()
tpm: delete the TPM_TIS_CLK_ENABLE flag
tpm: Update MAINTAINERS for Jason Gunthorpe
tpm: Keep CLKRUN enabled throughout the duration of transmit_cmd()
tpm_tis: Move ilb_base_addr to tpm_tis_data
tpm2-cmd: allow more attempts for selftest execution
tpm: return a TPM_RC_COMMAND_CODE response if command is not implemented
tpm: Move Linux RNG connection to hwrng
tpm: use struct tpm_chip for tpm_chip_find_get()
tpm: parse TPM event logs based on EFI table
efi: call get_event_log before ExitBootServices
tpm: add event log format version
tpm: rename event log provider files
tpm: move tpm_eventlog.h outside of drivers folder
tpm: use tpm_msleep() value as max delay
tpm: reduce tpm polling delay in tpm_tis_core
tpm: move wait_for_tpm_stat() to respective driver files
Pull integrity updates from James Morris:
"This contains a mixture of bug fixes, code cleanup, and new
functionality. Of note is the integrity cache locking fix, file change
detection, and support for a new EVM portable and immutable signature
type.
The re-introduction of the integrity cache lock (iint) fixes the
problem of attempting to take the i_rwsem shared a second time, when
it was previously taken exclusively. Defining atomic flags resolves
the original iint/i_rwsem circular locking - accessing the file data
vs. modifying the file metadata. Although it fixes the O_DIRECT
problem as well, a subsequent patch is needed to remove the explicit
O_DIRECT prevention.
For performance reasons, detecting when a file has changed and needs
to be re-measured, re-appraised, and/or re-audited, was limited to
after the last writer has closed, and only if the file data has
changed. Detecting file change is based on i_version. For filesystems
that do not support i_version, remote filesystems, or userspace
filesystems, the file was measured, appraised and/or audited once and
never re-evaluated. Now local filesystems, which do not support
i_version or are not mounted with the i_version option, assume the
file has changed and are required to re-evaluate the file. This change
does not address detecting file change on remote or userspace
filesystems.
Unlike file data signatures, which can be included and distributed in
software packages (eg. rpm, deb), the existing EVM signature, which
protects the file metadata, could not be included in software
packages, as it includes file system specific information (eg. i_ino,
possibly the UUID). This pull request defines a new EVM portable and
immutable file metadata signature format, which can be included in
software packages"
* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
ima/policy: fix parsing of fsuuid
ima: Use i_version only when filesystem supports it
integrity: remove unneeded initializations in integrity_iint_cache entries
ima: log message to module appraisal error
ima: pass filename to ima_rdwr_violation_check()
ima: Fix line continuation format
ima: support new "hash" and "dont_hash" policy actions
ima: re-introduce own integrity cache lock
EVM: Add support for portable signature format
EVM: Allow userland to permit modification of EVM-protected metadata
ima: relax requiring a file signature for new files with zero length
The switch to uuid_t invereted the logic of verfication that &entry->fsuuid
is zero during parsing of "fsuuid=" rule. Instead of making sure the
&entry->fsuuid field is not attempted to be overwritten, we bail out for
perfectly correct rule.
Fixes: 787d8c530af7 ("ima/policy: switch to use uuid_t")
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Device number (the character device index) is not a stable identifier
for a TPM chip. That is the reason why every call site passes
TPM_ANY_NUM to tpm_chip_find_get().
This commit changes the API in a way that instead a struct tpm_chip
instance is given and NULL means the default chip. In addition, this
commit refines the documentation to be up to date with the
implementation.
Suggested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com> (@chip_num -> @chip part)
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@ziepe.ca>
Tested-by: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
i_version is only supported by a filesystem when the SB_I_VERSION
flag is set. This patch tests for the SB_I_VERSION flag before using
i_version. If we can't use i_version to detect a file change then we
must assume the file has changed in the last_writer path and remeasure
it.
On filesystems without i_version support IMA used to measure a file
only once and didn't detect any changes to a file. With this patch
IMA now works properly on these filesystems.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
The init_once routine memsets the whole object to 0, and then
explicitly sets some of the fields to 0 again. Just remove the explicit
initializations.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Simple but useful message log to the user in case of module appraise is
forced and fails due to the lack of file descriptor, that might be
caused by kmod calls to compressed modules.
Signed-off-by: Bruno E. O. Meneguele <brdeoliv@redhat.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
ima_rdwr_violation_check() retrieves the full path of a measured file by
calling ima_d_path(). If process_measurement() calls this function, it
reuses the pointer and passes it to the functions to measure/appraise/audit
an accessed file.
After commit bc15ed663e7e ("ima: fix ima_d_path() possible race with
rename"), ima_d_path() first tries to retrieve the full path by calling
d_absolute_path() and, if there is an error, copies the dentry name to the
buffer passed as argument.
However, ima_rdwr_violation_check() passes to ima_d_path() the pointer of a
local variable. process_measurement() might be reusing the pointer to an
area in the stack which may have been already overwritten after
ima_rdwr_violation_check() returned.
Correct this issue by passing to ima_rdwr_violation_check() the pointer of
a buffer declared in process_measurement().
Fixes: bc15ed663e7e ("ima: fix ima_d_path() possible race with rename")
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Line continuations with excess spacing causes unexpected output.
Based on commit 6f76b6fcaa60 ("CodingStyle: Document the exception of
not splitting user-visible strings, for grepping") recommendation.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
The builtin ima_appraise_tcb policy, which is specified on the boot
command line, can be replaced with a custom policy, normally early in
the boot process. Custom policies can be more restrictive in some ways,
like requiring file signatures, but can be less restrictive in other
ways, like not appraising mutable files. With a less restrictive policy
in place, files in the builtin policy might not be hashed and labeled
with a security.ima hash. On reboot, files which should be labeled in
the ima_appraise_tcb are not labeled, possibly preventing the system
from booting properly.
To resolve this problem, this patch extends the existing IMA policy
actions "measure", "dont_measure", "appraise", "dont_appraise", and
"audit" with "hash" and "dont_hash". The new "hash" action will write
the file hash as security.ima, but without requiring the file to be
appraised as well.
For example, the builtin ima_appraise_tcb policy includes the rule,
"appraise fowner=0". Adding the "hash fowner=0" rule to a custom
policy, will cause the needed file hashes to be calculated and written
as security.ima xattrs.
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
i_version is only supported by a filesystem when the SB_I_VERSION
flag is set. This patch tests for the SB_I_VERSION flag before using
i_version. If we can't use i_version to detect a file change then we
must assume the file has changed in the last_writer path and remeasure
it.
On filesystems without i_version support IMA used to measure a file
only once and didn't detect any changes to a file. With this patch
IMA now works properly on these filesystems.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Before IMA appraisal was introduced, IMA was using own integrity cache
lock along with i_mutex. process_measurement and ima_file_free took
the iint->mutex first and then the i_mutex, while setxattr, chmod and
chown took the locks in reverse order. To resolve the potential deadlock,
i_mutex was moved to protect entire IMA functionality and the redundant
iint->mutex was eliminated.
Solution was based on the assumption that filesystem code does not take
i_mutex further. But when file is opened with O_DIRECT flag, direct-io
implementation takes i_mutex and produces deadlock. Furthermore, certain
other filesystem operations, such as llseek, also take i_mutex.
More recently some filesystems have replaced their filesystem specific
lock with the global i_rwsem to read a file. As a result, when IMA
attempts to calculate the file hash, reading the file attempts to take
the i_rwsem again.
To resolve O_DIRECT related deadlock problem, this patch re-introduces
iint->mutex. But to eliminate the original chmod() related deadlock
problem, this patch eliminates the requirement for chmod hooks to take
the iint->mutex by introducing additional atomic iint->attr_flags to
indicate calling of the hooks. The allowed locking order is to take
the iint->mutex first and then the i_rwsem.
Original flags were cleared in chmod(), setxattr() or removwxattr()
hooks and tested when file was closed or opened again. New atomic flags
are set or cleared in those hooks and tested to clear iint->flags on
close or on open.
Atomic flags are following:
* IMA_CHANGE_ATTR - indicates that chATTR() was called (chmod, chown,
chgrp) and file attributes have changed. On file open, it causes IMA
to clear iint->flags to re-evaluate policy and perform IMA functions
again.
* IMA_CHANGE_XATTR - indicates that setxattr or removexattr was called
and extended attributes have changed. On file open, it causes IMA to
clear iint->flags IMA_DONE_MASK to re-appraise.
* IMA_UPDATE_XATTR - indicates that security.ima needs to be updated.
It is cleared if file policy changes and no update is needed.
* IMA_DIGSIG - indicates that file security.ima has signature and file
security.ima must not update to file has on file close.
* IMA_MUST_MEASURE - indicates the file is in the measurement policy.
Fixes: Commit 6552321831dc ("xfs: remove i_iolock and use i_rwsem in
the VFS inode instead")
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
The EVM signature includes the inode number and (optionally) the
filesystem UUID, making it impractical to ship EVM signatures in
packages. This patch adds a new portable format intended to allow
distributions to include EVM signatures. It is identical to the existing
format but hardcodes the inode and generation numbers to 0 and does not
include the filesystem UUID even if the kernel is configured to do so.
Removing the inode means that the metadata and signature from one file
could be copied to another file without invalidating it. This is avoided
by ensuring that an IMA xattr is present during EVM validation.
Portable signatures are intended to be immutable - ie, they will never
be transformed into HMACs.
Based on earlier work by Dmitry Kasatkin and Mikhail Kurinnoi.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@huawei.com>
Cc: Mikhail Kurinnoi <viewizard@viewizard.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
When EVM is enabled it forbids modification of metadata protected by
EVM unless there is already a valid EVM signature. If any modification
is made, the kernel will then generate a new EVM HMAC. However, this
does not map well on use cases which use only asymmetric EVM signatures,
as in this scenario the kernel is unable to generate new signatures.
This patch extends the /sys/kernel/security/evm interface to allow
userland to request that modification of these xattrs be permitted. This
is only permitted if no keys have already been loaded. In this
configuration, modifying the metadata will invalidate the EVM appraisal
on the file in question. This allows packaging systems to write out new
files, set the relevant extended attributes and then move them into
place.
There's also some refactoring of the use of evm_initialized in order to
avoid heading down codepaths that assume there's a key available.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Custom policies can require file signatures based on LSM labels. These
files are normally created and only afterwards labeled, requiring them
to be signed.
Instead of requiring file signatures based on LSM labels, entire
filesystems could require file signatures. In this case, we need the
ability of writing new files without requiring file signatures.
The definition of a "new" file was originally defined as any file with
a length of zero. Subsequent patches redefined a "new" file to be based
on the FILE_CREATE open flag. By combining the open flag with a file
size of zero, this patch relaxes the file signature requirement.
Fixes: 1ac202e978e1 ima: accept previously set IMA_NEW_FILE
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Commit b65a9cfc2c38 ("Untangling ima mess, part 2: deal with counters")
moved the call of ima_file_check() from may_open() to do_filp_open() at a
point where the file descriptor is already opened.
This breaks the assumption made by IMA that file descriptors being closed
belong to files whose access was granted by ima_file_check(). The
consequence is that security.ima and security.evm are updated with good
values, regardless of the current appraisal status.
For example, if a file does not have security.ima, IMA will create it after
opening the file for writing, even if access is denied. Access to the file
will be allowed afterwards.
Avoid this issue by checking the appraisal status before updating
security.ima.
Cc: stable@vger.kernel.org
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Pull crypto updates from Herbert Xu:
"Here is the crypto update for 4.15:
API:
- Disambiguate EBUSY when queueing crypto request by adding ENOSPC.
This change touches code outside the crypto API.
- Reset settings when empty string is written to rng_current.
Algorithms:
- Add OSCCA SM3 secure hash.
Drivers:
- Remove old mv_cesa driver (replaced by marvell/cesa).
- Enable rfc3686/ecb/cfb/ofb AES in crypto4xx.
- Add ccm/gcm AES in crypto4xx.
- Add support for BCM7278 in iproc-rng200.
- Add hash support on Exynos in s5p-sss.
- Fix fallback-induced error in vmx.
- Fix output IV in atmel-aes.
- Fix empty GCM hash in mediatek.
Others:
- Fix DoS potential in lib/mpi.
- Fix potential out-of-order issues with padata"
* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (162 commits)
lib/mpi: call cond_resched() from mpi_powm() loop
crypto: stm32/hash - Fix return issue on update
crypto: dh - Remove pointless checks for NULL 'p' and 'g'
crypto: qat - Clean up error handling in qat_dh_set_secret()
crypto: dh - Don't permit 'key' or 'g' size longer than 'p'
crypto: dh - Don't permit 'p' to be 0
crypto: dh - Fix double free of ctx->p
hwrng: iproc-rng200 - Add support for BCM7278
dt-bindings: rng: Document BCM7278 RNG200 compatible
crypto: chcr - Replace _manual_ swap with swap macro
crypto: marvell - Add a NULL entry at the end of mv_cesa_plat_id_table[]
hwrng: virtio - Virtio RNG devices need to be re-registered after suspend/resume
crypto: atmel - remove empty functions
crypto: ecdh - remove empty exit()
MAINTAINERS: update maintainer for qat
crypto: caam - remove unused param of ctx_map_to_sec4_sg()
crypto: caam - remove unneeded edesc zeroization
crypto: atmel-aes - Reset the controller before each use
crypto: atmel-aes - properly set IV after {en,de}crypt
hwrng: core - Reset user selected rng by writing "" to rng_current
...
