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handling. Collecting per-thread register values is the
only thing that needs to be ifdefed there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull elf coredumping updates from Al Viro:
"Unification of regset and non-regset sides of ELF coredump handling.
Collecting per-thread register values is the only thing that needs to
be ifdefed there..."
* tag 'pull-elfcore' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
[elf] get rid of get_note_info_size()
[elf] unify regset and non-regset cases
[elf][non-regset] use elf_core_copy_task_regs() for dumper as well
[elf][non-regset] uninline elf_core_copy_task_fpregs() (and lose pt_regs argument)
elf_core_copy_task_regs(): task_pt_regs is defined everywhere
[elf][regset] simplify thread list handling in fill_note_info()
[elf][regset] clean fill_note_info() a bit
kill extern of vsyscall32_sysctl
kill coredump_params->regs
kill signal_pt_regs()
The only real difference is in filling per-thread notes - getting
the values of registers. And this is the only part that is worth
an ifdef - we don't need to duplicate the logics regarding gathering
threads, filling other notes, etc.
It would've been hard to do back when regset-based variant had been
introduced, mostly due to sharing bits and pieces of helpers with
aout coredumps. As the result, too much had been duplicated and
the copies had drifted away since then. Now it can be done cleanly...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't bother with pointless macros - we are not sharing it with aout coredumps
anymore. Just convert the underlying functions to the same arguments (nobody
uses regs, actually) and call them elf_core_copy_task_fpregs(). And unexport
the entire bunch, while we are at it.
[added missing includes in arch/{csky,m68k,um}/kernel/process.c to avoid extra
warnings about the lack of externs getting added to huge piles for those
files. Pointless, but...]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The err variable was the same like retval, but capped to <= 0. This is the
same as retval as elf_read() never returns positive values.
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/4137126.7Qn9TF0dmF@mobilepool36.emlix.com
This function has never returned anything but a plain NULL.
Fixes: 6a8d38945c ("binfmt_elf: Hoist ELF program header loading to a function")
Signed-off-by: Rolf Eike Beer <eb@emlix.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/2359389.EDbqzprbEW@mobilepool36.emlix.com
fill_note_info() iterates through the list of threads collected in
mm->core_state->dumper, allocating a struct elf_thread_core_info
instance for each and linking those into a list.
We need the entry corresponding to current to be first in the
resulting list, so the logics for list insertion is
if it's for current or list is empty
insert in the head
else
insert after the first element
However, in mm->core_state->dumper the entry for current is guaranteed
to be the first one. Which means that both parts of condition will
be true on the first iteration and neither will be true on all subsequent
ones.
Taking the first iteration out of the loop simplifies things nicely...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit 925346c129 ("fs/binfmt_elf: fix PT_LOAD p_align values for
loaders") was an attempt to fix regressions due to 9630f0d60f
("fs/binfmt_elf: use PT_LOAD p_align values for static PIE").
But regressionss continue to be reported:
https://lore.kernel.org/lkml/cb5b81bd-9882-e5dc-cd22-54bdbaaefbbc@leemhuis.info/https://bugzilla.kernel.org/show_bug.cgi?id=215720https://lkml.kernel.org/r/b685f3d0-da34-531d-1aa9-479accd3e21b@leemhuis.info
This patch reverts the fix, so the original can also be reverted.
Fixes: 925346c129 ("fs/binfmt_elf: fix PT_LOAD p_align values for loaders")
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thorsten Leemhuis <regressions@leemhuis.info>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Handle unusual AT_PHDR offsets (Akira Kawata)
- Fix initial mapping size when PT_LOADs are not ordered (Alexey Dobriyan)
- Move more code under CONFIG_COREDUMP (Alexey Dobriyan)
- Fix missing mmap_lock in file_files_note (Eric W. Biederman)
- Remove a.out support for alpha and m68k (Eric W. Biederman)
- Include first pages of non-exec ELF libraries in coredump (Jann Horn)
- Don't write past end of notes for regset gap in coredump (Rick Edgecombe)
- Comment clean-ups (Tom Rix)
- Force single empty string when argv is empty (Kees Cook)
- Add NULL argv selftest (Kees Cook)
- Properly redefine PT_GNU_* in terms of PT_LOOS (Kees Cook)
- MAINTAINERS: Update execve entry with tree (Kees Cook)
- Introduce initial KUnit testing for binfmt_elf (Kees Cook)
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Merge tag 'execve-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull execve updates from Kees Cook:
"Execve and binfmt updates.
Eric and I have stepped up to be the active maintainers of this area,
so here's our first collection. The bulk of the work was in coredump
handling fixes; additional details are noted below:
- Handle unusual AT_PHDR offsets (Akira Kawata)
- Fix initial mapping size when PT_LOADs are not ordered (Alexey
Dobriyan)
- Move more code under CONFIG_COREDUMP (Alexey Dobriyan)
- Fix missing mmap_lock in file_files_note (Eric W. Biederman)
- Remove a.out support for alpha and m68k (Eric W. Biederman)
- Include first pages of non-exec ELF libraries in coredump (Jann
Horn)
- Don't write past end of notes for regset gap in coredump (Rick
Edgecombe)
- Comment clean-ups (Tom Rix)
- Force single empty string when argv is empty (Kees Cook)
- Add NULL argv selftest (Kees Cook)
- Properly redefine PT_GNU_* in terms of PT_LOOS (Kees Cook)
- MAINTAINERS: Update execve entry with tree (Kees Cook)
- Introduce initial KUnit testing for binfmt_elf (Kees Cook)"
* tag 'execve-v5.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
binfmt_elf: Don't write past end of notes for regset gap
a.out: Stop building a.out/osf1 support on alpha and m68k
coredump: Don't compile flat_core_dump when coredumps are disabled
coredump: Use the vma snapshot in fill_files_note
coredump/elf: Pass coredump_params into fill_note_info
coredump: Remove the WARN_ON in dump_vma_snapshot
coredump: Snapshot the vmas in do_coredump
coredump: Move definition of struct coredump_params into coredump.h
binfmt_elf: Introduce KUnit test
ELF: Properly redefine PT_GNU_* in terms of PT_LOOS
MAINTAINERS: Update execve entry with more details
exec: cleanup comments
fs/binfmt_elf: Refactor load_elf_binary function
fs/binfmt_elf: Fix AT_PHDR for unusual ELF files
binfmt: move more stuff undef CONFIG_COREDUMP
selftests/exec: Test for empty string on NULL argv
exec: Force single empty string when argv is empty
coredump: Also dump first pages of non-executable ELF libraries
ELF: fix overflow in total mapping size calculation
In fill_thread_core_info() the ptrace accessible registers are collected
to be written out as notes in a core file. The note array is allocated
from a size calculated by iterating the user regset view, and counting the
regsets that have a non-zero core_note_type. However, this only allows for
there to be non-zero core_note_type at the end of the regset view. If
there are any gaps in the middle, fill_thread_core_info() will overflow the
note allocation, as it iterates over the size of the view and the
allocation would be smaller than that.
There doesn't appear to be any arch that has gaps such that they exceed
the notes allocation, but the code is brittle and tries to support
something it doesn't. It could be fixed by increasing the allocation size,
but instead just have the note collecting code utilize the array better.
This way the allocation can stay smaller.
Even in the case of no arch's that have gaps in their regset views, this
introduces a change in the resulting indicies of t->notes. It does not
introduce any changes to the core file itself, because any blank notes are
skipped in write_note_info().
In case, the allocation logic between fill_note_info() and
fill_thread_core_info() ever diverges from the usage logic, warn and skip
writing any notes that would overflow the array.
This fix is derrived from an earlier one[0] by Yu-cheng Yu.
[0] https://lore.kernel.org/lkml/20180717162502.32274-1-yu-cheng.yu@intel.com/
Co-developed-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220317192013.13655-4-rick.p.edgecombe@intel.com
Matthew Wilcox reported that there is a missing mmap_lock in
file_files_note that could possibly lead to a user after free.
Solve this by using the existing vma snapshot for consistency
and to avoid the need to take the mmap_lock anywhere in the
coredump code except for dump_vma_snapshot.
Update the dump_vma_snapshot to capture vm_pgoff and vm_file
that are neeeded by fill_files_note.
Add free_vma_snapshot to free the captured values of vm_file.
Reported-by: Matthew Wilcox <willy@infradead.org>
Link: https://lkml.kernel.org/r/20220131153740.2396974-1-willy@infradead.org
Cc: stable@vger.kernel.org
Fixes: a07279c9a8 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: 2aa362c49c ("coredump: extend core dump note section to contain file names of mapped files")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Instead of individually passing cprm->siginfo and cprm->regs
into fill_note_info pass all of struct coredump_params.
This is preparation to allow fill_files_note to use the existing
vma snapshot.
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Move the call of dump_vma_snapshot and kvfree(vma_meta) out of the
individual coredump routines into do_coredump itself. This makes
the code less error prone and easier to maintain.
Make the vma snapshot available to the coredump routines
in struct coredump_params. This makes it easier to
change and update what is captures in the vma snapshot
and will be needed for fixing fill_file_notes.
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
I delete load_addr because it is not used anymore. And I rename
load_addr_set to first_pt_load because it is used only to capture the
first iteration of the loop.
Signed-off-by: Akira Kawata <akirakawata1@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220127124014.338760-3-akirakawata1@gmail.com
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=197921
As pointed out in the discussion of buglink, we cannot calculate AT_PHDR
as the sum of load_addr and exec->e_phoff.
: The AT_PHDR of ELF auxiliary vectors should point to the memory address
: of program header. But binfmt_elf.c calculates this address as follows:
:
: NEW_AUX_ENT(AT_PHDR, load_addr + exec->e_phoff);
:
: which is wrong since e_phoff is the file offset of program header and
: load_addr is the memory base address from PT_LOAD entry.
:
: The ld.so uses AT_PHDR as the memory address of program header. In normal
: case, since the e_phoff is usually 64 and in the first PT_LOAD region, it
: is the correct program header address.
:
: But if the address of program header isn't equal to the first PT_LOAD
: address + e_phoff (e.g. Put the program header in other non-consecutive
: PT_LOAD region), ld.so will try to read program header from wrong address
: then crash or use incorrect program header.
This is because exec->e_phoff
is the offset of PHDRs in the file and the address of PHDRs in the
memory may differ from it. This patch fixes the bug by calculating the
address of program headers from PT_LOADs directly.
Signed-off-by: Akira Kawata <akirakawata1@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220127124014.338760-2-akirakawata1@gmail.com
struct linux_binfmt::core_dump and struct min_coredump::min_coredump
are used under CONFIG_COREDUMP only. Shrink those embedded configs
a bit.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/YglbIFyN+OtwVyjW@localhost.localdomain
Kernel assumes that ELF program headers are ordered by mapping address,
but doesn't enforce it. It is possible to make mapping size extremely huge
by simply shuffling first and last PT_LOAD segments.
As long as PT_LOAD segments do not overlap, it is silly to require
sorting by v_addr anyway because mmap() doesn't care.
Don't assume PT_LOAD segments are sorted and calculate min and max
addresses correctly.
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Tested-by: "Magnus Groß" <magnus.gross@rwth-aachen.de>
Link: https://lore.kernel.org/all/Yfqm7HbucDjPbES+@fractal.localdomain/
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/lkml/YVmd7D0M6G%2FDcP4O@localhost.localdomain
Partially revert commit 5f501d5556 ("binfmt_elf: reintroduce using
MAP_FIXED_NOREPLACE"), which applied the ET_DYN "total_mapping_size"
logic also to ET_EXEC.
At least ia64 has ET_EXEC PT_LOAD segments that are not virtual-address
contiguous (but _are_ file-offset contiguous). This would result in a
giant mapping attempting to cover the entire span, including the virtual
address range hole, and well beyond the size of the ELF file itself,
causing the kernel to refuse to load it. For example:
$ readelf -lW /usr/bin/gcc
...
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz ...
...
LOAD 0x000000 0x4000000000000000 0x4000000000000000 0x00b5a0 0x00b5a0 ...
LOAD 0x00b5a0 0x600000000000b5a0 0x600000000000b5a0 0x0005ac 0x000710 ...
...
^^^^^^^^ ^^^^^^^^^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^
File offset range : 0x000000-0x00bb4c
0x00bb4c bytes
Virtual address range : 0x4000000000000000-0x600000000000bcb0
0x200000000000bcb0 bytes
Remove the total_mapping_size logic for ET_EXEC, which reduces the
ET_EXEC MAP_FIXED_NOREPLACE coverage to only the first PT_LOAD (better
than nothing), and retains it for ET_DYN.
Ironically, this is the reverse of the problem that originally caused
problems with MAP_FIXED_NOREPLACE: overlapping PT_LOAD segments. Future
work could restore full coverage if load_elf_binary() were to perform
mappings in a separate phase from the loading (where it could resolve
both overlaps and holes).
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
Reported-by: matoro <matoro_bugzilla_kernel@matoro.tk>
Fixes: 5f501d5556 ("binfmt_elf: reintroduce using MAP_FIXED_NOREPLACE")
Link: https://lore.kernel.org/r/a3edd529-c42d-3b09-135c-7e98a15b150f@leemhuis.info
Tested-by: matoro <matoro_mailinglist_kernel@matoro.tk>
Link: https://lore.kernel.org/lkml/ce8af9c13bcea9230c7689f3c1e0e2cd@matoro.tk
Tested-By: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/lkml/49182d0d-708b-4029-da5f-bc18603440a6@physik.fu-berlin.de
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Rui Salvaterra reported that Aisleroit solitaire crashes with "Wrong
__data_start/_end pair" assertion from libgc after update to v5.17-rc1.
Bisection pointed to commit 9630f0d60f ("fs/binfmt_elf: use PT_LOAD
p_align values for static PIE") that fixed handling of static PIEs, but
made the condition that guards load_bias calculation to exclude loader
binaries.
Restoring the check for presence of interpreter fixes the problem.
Link: https://lkml.kernel.org/r/20220202121433.3697146-1-rppt@kernel.org
Fixes: 9630f0d60f ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reported-by: Rui Salvaterra <rsalvaterra@gmail.com>
Tested-by: Rui Salvaterra <rsalvaterra@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Extend commit ce81bb256a ("fs/binfmt_elf: use PT_LOAD p_align values
for suitable start address") which fixed PIE binaries built with
-Wl,-z,max-page-size=0x200000, to cover static PIE binaries. This
fixes:
https://bugzilla.kernel.org/show_bug.cgi?id=215275
Tested by verifying static PIE binaries with -Wl,-z,max-page-size=0x200000 loading.
Link: https://lkml.kernel.org/r/20211209174052.370537-1-hjl.tools@gmail.com
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Fangrui Song <maskray@google.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge more updates from Andrew Morton:
"87 patches.
Subsystems affected by this patch series: mm (pagecache and hugetlb),
procfs, misc, MAINTAINERS, lib, checkpatch, binfmt, kallsyms, ramfs,
init, codafs, nilfs2, hfs, crash_dump, signals, seq_file, fork,
sysvfs, kcov, gdb, resource, selftests, and ipc"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (87 commits)
ipc/ipc_sysctl.c: remove fallback for !CONFIG_PROC_SYSCTL
ipc: check checkpoint_restore_ns_capable() to modify C/R proc files
selftests/kselftest/runner/run_one(): allow running non-executable files
virtio-mem: disallow mapping virtio-mem memory via /dev/mem
kernel/resource: disallow access to exclusive system RAM regions
kernel/resource: clean up and optimize iomem_is_exclusive()
scripts/gdb: handle split debug for vmlinux
kcov: replace local_irq_save() with a local_lock_t
kcov: avoid enable+disable interrupts if !in_task()
kcov: allocate per-CPU memory on the relevant node
Documentation/kcov: define `ip' in the example
Documentation/kcov: include types.h in the example
sysv: use BUILD_BUG_ON instead of runtime check
kernel/fork.c: unshare(): use swap() to make code cleaner
seq_file: fix passing wrong private data
seq_file: move seq_escape() to a header
signal: remove duplicate include in signal.h
crash_dump: remove duplicate include in crash_dump.h
crash_dump: fix boolreturn.cocci warning
hfs/hfsplus: use WARN_ON for sanity check
...
"A -= B; A" is equivalent to "A -= B".
Link: https://lkml.kernel.org/r/YVmcP256fRMqCwgK@localhost.localdomain
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit b212921b13 ("elf: don't use MAP_FIXED_NOREPLACE for elf
executable mappings") reverted back to using MAP_FIXED to map ELF LOAD
segments because it was found that the segments in some binaries overlap
and can cause MAP_FIXED_NOREPLACE to fail.
The original intent of MAP_FIXED_NOREPLACE in the ELF loader was to
prevent the silent clobbering of an existing mapping (e.g. stack) by
the ELF image, which could lead to exploitable conditions. Quoting
commit 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map"),
which originally introduced the use of MAP_FIXED_NOREPLACE in the
loader:
Both load_elf_interp and load_elf_binary rely on elf_map to map
segments [to a specific] address and they use MAP_FIXED to enforce
that. This is however [a] dangerous thing prone to silent data
corruption which can be even exploitable.
...
Let's take CVE-2017-1000253 as an example ... we could end up mapping
[the executable] over the existing stack ... The [stack layout] issue
has been fixed since then ... So we should be safe and any [similar]
attack should be impractical. On the other hand this is just too
subtle [an] assumption ... it can break quite easily and [be] hard to
spot.
...
Address this [weakness] by changing MAP_FIXED to the newly added
MAP_FIXED_NOREPLACE. This will mean that mmap will fail if there is
an existing mapping clashing with the requested one [instead of
silently] clobbering it.
Then processing ET_DYN binaries the loader already calculates a total
size for the image when the first segment is mapped, maps the entire
image, and then unmaps the remainder before the remaining segments are
then individually mapped.
To avoid the earlier problems (legitimate overlapping LOAD segments
specified in the ELF), apply the same logic to ET_EXEC binaries as well.
For both ET_EXEC and ET_DYN+INTERP use MAP_FIXED_NOREPLACE for the
initial total size mapping and then use MAP_FIXED to build the final
(possibly legitimately overlapping) mappings. For ET_DYN w/out INTERP,
continue to map at a system-selected address in the mmap region.
Link: https://lkml.kernel.org/r/20210916215947.3993776-1-keescook@chromium.org
Link: https://lore.kernel.org/lkml/1595869887-23307-2-git-send-email-anthony.yznaga@oracle.com
Co-developed-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Chen Jingwen <chenjingwen6@huawei.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrei Vagin <avagin@openvz.org>
Cc: Khalid Aziz <khalid.aziz@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull per signal_struct coredumps from Eric Biederman:
"Current coredumps are mixed up with the exit code, the signal handling
code, and the ptrace code making coredumps much more complicated than
necessary and difficult to follow.
This series of changes starts with ptrace_stop and cleans it up,
making it easier to follow what is happening in ptrace_stop. Then
cleans up the exec interactions with coredumps. Then cleans up the
coredump interactions with exit. Finally the coredump interactions
with the signal handling code is cleaned up.
The first and last changes are bug fixes for minor bugs.
I believe the fact that vfork followed by execve can kill the process
the called vfork if exec fails is sufficient justification to change
the userspace visible behavior.
In previous discussions some of these changes were organized
differently and individually appeared to make the code base worse. As
currently written I believe they all stand on their own as cleanups
and bug fixes.
Which means that even if the worst should happen and the last change
needs to be reverted for some unimaginable reason, the code base will
still be improved.
If the worst does not happen there are a more cleanups that can be
made. Signals that generate coredumps can easily become eligible for
short circuit delivery in complete_signal. The entire rendezvous for
generating a coredump can move into get_signal. The function
force_sig_info_to_task be written in a way that does not modify the
signal handling state of the target task (because coredumps are
eligible for short circuit delivery). Many of these future cleanups
can be done another way but nothing so cleanly as if coredumps become
per signal_struct"
* 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
coredump: Limit coredumps to a single thread group
coredump: Don't perform any cleanups before dumping core
exit: Factor coredump_exit_mm out of exit_mm
exec: Check for a pending fatal signal instead of core_state
ptrace: Remove the unnecessary arguments from arch_ptrace_stop
signal: Remove the bogus sigkill_pending in ptrace_stop
Today when a signal is delivered with a handler of SIG_DFL whose
default behavior is to generate a core dump not only that process but
every process that shares the mm is killed.
In the case of vfork this looks like a real world problem. Consider
the following well defined sequence.
if (vfork() == 0) {
execve(...);
_exit(EXIT_FAILURE);
}
If a signal that generates a core dump is received after vfork but
before the execve changes the mm the process that called vfork will
also be killed (as the mm is shared).
Similarly if the execve fails after the point of no return the kernel
delivers SIGSEGV which will kill both the exec'ing process and because
the mm is shared the process that called vfork as well.
As far as I can tell this behavior is a violation of people's
reasonable expectations, POSIX, and is unnecessarily fragile when the
system is low on memory.
Solve this by making a userspace visible change to only kill a single
process/thread group. This is possible because Jann Horn recently
modified[1] the coredump code so that the mm can safely be modified
while the coredump is happening. With LinuxThreads long gone I don't
expect anyone to have a notice this behavior change in practice.
To accomplish this move the core_state pointer from mm_struct to
signal_struct, which allows different thread groups to coredump
simultatenously.
In zap_threads remove the work to kill anything except for the current
thread group.
v2: Remove core_state from the VM_BUG_ON_MM print to fix
compile failure when CONFIG_DEBUG_VM is enabled.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
[1] a07279c9a8 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Link: https://lkml.kernel.org/r/87y27mvnke.fsf@disp2133
Link: https://lkml.kernel.org/r/20211007144701.67592574@canb.auug.org.au
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
In commit b212921b13 ("elf: don't use MAP_FIXED_NOREPLACE for elf
executable mappings") we still leave MAP_FIXED_NOREPLACE in place for
load_elf_interp.
Unfortunately, this will cause kernel to fail to start with:
1 (init): Uhuuh, elf segment at 00003ffff7ffd000 requested but the memory is mapped already
Failed to execute /init (error -17)
The reason is that the elf interpreter (ld.so) has overlapping segments.
readelf -l ld-2.31.so
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x000000000002c94c 0x000000000002c94c R E 0x10000
LOAD 0x000000000002dae0 0x000000000003dae0 0x000000000003dae0
0x00000000000021e8 0x0000000000002320 RW 0x10000
LOAD 0x000000000002fe00 0x000000000003fe00 0x000000000003fe00
0x00000000000011ac 0x0000000000001328 RW 0x10000
The reason for this problem is the same as described in commit
ad55eac74f ("elf: enforce MAP_FIXED on overlaying elf segments").
Not only executable binaries, elf interpreters (e.g. ld.so) can have
overlapping elf segments, so we better drop MAP_FIXED_NOREPLACE and go
back to MAP_FIXED in load_elf_interp.
Fixes: 4ed2863951 ("fs, elf: drop MAP_FIXED usage from elf_map")
Cc: <stable@vger.kernel.org> # v4.19
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Chen Jingwen <chenjingwen6@huawei.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At exec time when we mmap the new executable via MAP_DENYWRITE we have it
opened via do_open_execat() and already deny_write_access()'ed the file
successfully. Once exec completes, we allow_write_acces(); however,
we set mm->exe_file in begin_new_exec() via set_mm_exe_file() and
also deny_write_access() as long as mm->exe_file remains set. We'll
effectively deny write access to our executable via mm->exe_file
until mm->exe_file is changed -- when the process is removed, on new
exec, or via sys_prctl(PR_SET_MM_MAP/EXE_FILE).
Let's remove all usage of MAP_DENYWRITE, it's no longer necessary for
mm->exe_file.
In case of an elf interpreter, we'll now only deny write access to the file
during exec. This is somewhat okay, because the interpreter behaves
(and sometime is) a shared library; all shared libraries, especially the
ones loaded directly in user space like via dlopen() won't ever be mapped
via MAP_DENYWRITE, because we ignore that from user space completely;
these shared libraries can always be modified while mapped and executed.
Let's only special-case the main executable, denying write access while
being executed by a process. This can be considered a minor user space
visible change.
While this is a cleanup, it also fixes part of a problem reported with
VM_DENYWRITE on overlayfs, as VM_DENYWRITE is effectively unused with
this patch and will be removed next:
"Overlayfs did not honor positive i_writecount on realfile for
VM_DENYWRITE mappings." [1]
[1] https://lore.kernel.org/r/YNHXzBgzRrZu1MrD@miu.piliscsaba.redhat.com/
Reported-by: Chengguang Xu <cgxu519@mykernel.net>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
uselib() is the legacy systemcall for loading shared libraries.
Nowadays, applications use dlopen() to load shared libraries, completely
implemented in user space via mmap().
For example, glibc uses MAP_COPY to mmap shared libraries. While this
maps to MAP_PRIVATE | MAP_DENYWRITE on Linux, Linux ignores any
MAP_DENYWRITE specification from user space in mmap.
With this change, all remaining in-tree users of MAP_DENYWRITE use it
to map an executable. We will be able to open shared libraries loaded
via uselib() writable, just as we already can via dlopen() from user
space.
This is one step into the direction of removing MAP_DENYWRITE from the
kernel. This can be considered a minor user space visible change.
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Merge misc updates from Andrew Morton:
"191 patches.
Subsystems affected by this patch series: kthread, ia64, scripts,
ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab,
slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap,
mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization,
pagealloc, and memory-failure)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (191 commits)
mm,hwpoison: make get_hwpoison_page() call get_any_page()
mm,hwpoison: send SIGBUS with error virutal address
mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes
mm/page_alloc: allow high-order pages to be stored on the per-cpu lists
mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM
mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA
docs: remove description of DISCONTIGMEM
arch, mm: remove stale mentions of DISCONIGMEM
mm: remove CONFIG_DISCONTIGMEM
m68k: remove support for DISCONTIGMEM
arc: remove support for DISCONTIGMEM
arc: update comment about HIGHMEM implementation
alpha: remove DISCONTIGMEM and NUMA
mm/page_alloc: move free_the_page
mm/page_alloc: fix counting of managed_pages
mm/page_alloc: improve memmap_pages dbg msg
mm: drop SECTION_SHIFT in code comments
mm/page_alloc: introduce vm.percpu_pagelist_high_fraction
mm/page_alloc: limit the number of pages on PCP lists when reclaim is active
mm/page_alloc: scale the number of pages that are batch freed
...
Change the type and name of task_struct::state. Drop the volatile and
shrink it to an 'unsigned int'. Rename it in order to find all uses
such that we can use READ_ONCE/WRITE_ONCE as appropriate.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Link: https://lore.kernel.org/r/20210611082838.550736351@infradead.org
have dump_skip() just remember how much needs to be skipped,
leave actual seeks/writing zeroes to the next dump_emit()
or the end of coredump output, whichever comes first.
And instead of playing with do_truncate() in the end, just
write one NUL at the end of the last gap (if any).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull parisc updates from Helge Deller:
- Optimize parisc page table locks by using the existing
page_table_lock
- Export argv0-preserve flag in binfmt_misc for usage in qemu-user
- Fix interrupt table (IVT) checksum so firmware will call crash
handler (HPMC)
- Increase IRQ stack to 64kb on 64-bit kernel
- Switch to common devmem_is_allowed() implementation
- Minor fix to get_whan()
* 'parisc-5.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
binfmt_misc: pass binfmt_misc flags to the interpreter
parisc: Optimize per-pagetable spinlocks
parisc: Replace test_ti_thread_flag() with test_tsk_thread_flag()
parisc: Bump 64-bit IRQ stack size to 64 KB
parisc: Fix IVT checksum calculation wrt HPMC
parisc: Use the generic devmem_is_allowed()
parisc: Drop out of get_whan() if task is running again
It can be useful to the interpreter to know which flags are in use.
For instance, knowing if the preserve-argv[0] is in use would
allow to skip the pathname argument.
This patch uses an unused auxiliary vector, AT_FLAGS, to add a
flag to inform interpreter if the preserve-argv[0] is enabled.
Note by Helge Deller:
The real-world user of this patch is qemu-user, which needs to know
if it has to preserve the argv[0]. See Debian bug #970460.
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: YunQiang Su <ysu@wavecomp.com>
URL: http://bugs.debian.org/970460
Signed-off-by: Helge Deller <deller@gmx.de>
Preparations to doing i386 compat elf_prstatus sanely - rather than duplicating
the beginning of compat_elf_prstatus, take these fields into a separate
structure (compat_elf_prstatus_common), so that it could be reused. Due to
the incestous relationship between binfmt_elf.c and compat_binfmt_elf.c we
need the same shape change done to native struct elf_prstatus, gathering the
fields prior to pr_reg into a new structure (struct elf_prstatus_common).
Fortunately, offset of pr_reg is always a multiple of 16 with no padding
right before it, so it's possible to turn all the stuff prior to it into
a single member without disturbing the layout.
[build fix from Geert Uytterhoeven folded in]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
On 64bit architectures that support 32bit processes there are
two possible layouts for NT_PRSTATUS note in ELF coredumps.
For one thing, several fields are 64bit for native processes
and 32bit for compat ones (pr_sigpend, etc.). For another,
the register dump is obviously different - the size and number
of registers are not going to be the same for 32bit and 64bit
variants of processor.
Usually that's handled by having two structures - elf_prstatus
for native layout and compat_elf_prstatus for 32bit one.
32bit processes are handled by fs/compat_binfmt_elf.c, which
defines a macro called 'elf_prstatus' that expands to compat_elf_prstatus.
Then it includes fs/binfmt_elf.c, which makes all references to
struct elf_prstatus to be textually replaced with struct
compat_elf_prstatus. Ugly and somewhat brittle, but it works.
However, amd64 is worse - there are _three_ possible layouts.
One for native 64bit processes, another for i386 (32bit) processes
and yet another for x32 (32bit address space with full 64bit
registers).
Both i386 and x32 processes are handled by fs/compat_binfmt_elf.c,
with usual compat_binfmt_elf.c trickery. However, the layouts
for i386 and x32 are not identical - they have the common beginning,
but the register dump part (pr_reg) is bigger on x32. Worse, pr_reg
is not the last field - it's followed by int pr_fpvalid, so that
field ends up at different offsets for i386 and x32 layouts.
Fortunately, there's not much code that cares about any of that -
it's all encapsulated in fill_thread_core_info(). Since x32
variant is bigger, we define compat_elf_prstatus to match that
layout. That way i386 processes have enough space to fit
their layout into.
Moreover, since these layouts are identical prior to pr_reg,
we don't need to distinguish x32 and i386 cases when we are
setting the fields prior to pr_reg.
Filling pr_reg itself is done by calling ->get() method of
appropriate regset, and that method knows what layout (and size)
to use.
We do need to distinguish x32 and i386 cases only for two
things: setting ->pr_fpvalid (offset differs for x32 and
i386) and choosing the right size for our note.
The way it's done is Not Nice, for the lack of more accurate
printable description. There are two macros (PRSTATUS_SIZE and
SET_PR_FPVALID), that default essentially to sizeof(struct elf_prstatus)
and (S)->pr_fpvalid = 1. On x86 asm/compat.h provides its own
variants.
Unfortunately, quite a few things go wrong there:
* PRSTATUS_SIZE doesn't use the normal test for process
being an x32 one; it compares the size reported by regset with
the size of pr_reg.
* it hardcodes the sizes of x32 and i386 variants (296 and 144
resp.), so if some change in includes leads to asm/compat.h pulled
in by fs/binfmt_elf.c we are in trouble - it will end up using
the size of x32 variant for 64bit processes.
* it's in the wrong place; asm/compat.h couldn't define
the structure for i386 layout, since it lacks quite a few types
needed for it. Hardcoded sizes are largely due to that.
The proper fix would be to have an explicitly defined i386 variant
of structure and have PRSTATUS_SIZE/SET_PR_FPVALID check for
TIF_X32 to choose the variant that should be used. Unfortunately,
that requires some manipulations of headers; we'll do that later
in the series, but for now let's go with the minimal variant -
rename PRSTATUS_SIZE in asm/compat.h to COMPAT_PRSTATUS_SIZE,
have fs/compat_binfmt_elf.c define PRSTATUS_SIZE to COMPAT_PRSTATUS_SIZE
and use the normal TIF_X32 check in that macro. The size of i386 variant
is kept hardcoded for now. Similar story for SET_PR_FPVALID.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull execve updates from Eric Biederman:
"This set of changes ultimately fixes the interaction of posix file
lock and exec. Fundamentally most of the change is just moving where
unshare_files is called during exec, and tweaking the users of
files_struct so that the count of files_struct is not unnecessarily
played with.
Along the way fcheck and related helpers were renamed to more
accurately reflect what they do.
There were also many other small changes that fell out, as this is the
first time in a long time much of this code has been touched.
Benchmarks haven't turned up any practical issues but Al Viro has
observed a possibility for a lot of pounding on task_lock. So I have
some changes in progress to convert put_files_struct to always rcu
free files_struct. That wasn't ready for the merge window so that will
have to wait until next time"
* 'exec-for-v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
exec: Move io_uring_task_cancel after the point of no return
coredump: Document coredump code exclusively used by cell spufs
file: Remove get_files_struct
file: Rename __close_fd_get_file close_fd_get_file
file: Replace ksys_close with close_fd
file: Rename __close_fd to close_fd and remove the files parameter
file: Merge __alloc_fd into alloc_fd
file: In f_dupfd read RLIMIT_NOFILE once.
file: Merge __fd_install into fd_install
proc/fd: In fdinfo seq_show don't use get_files_struct
bpf/task_iter: In task_file_seq_get_next use task_lookup_next_fd_rcu
proc/fd: In proc_readfd_common use task_lookup_next_fd_rcu
file: Implement task_lookup_next_fd_rcu
kcmp: In get_file_raw_ptr use task_lookup_fd_rcu
proc/fd: In tid_fd_mode use task_lookup_fd_rcu
file: Implement task_lookup_fd_rcu
file: Rename fcheck lookup_fd_rcu
file: Replace fcheck_files with files_lookup_fd_rcu
file: Factor files_lookup_fd_locked out of fcheck_files
file: Rename __fcheck_files to files_lookup_fd_raw
...
(Gabriel Krisman Bertazi)
- All kinds of minor cleanups all over the tree.
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Merge tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cleanups from Borislav Petkov:
"Another branch with a nicely negative diffstat, just the way I
like 'em:
- Remove all uses of TIF_IA32 and TIF_X32 and reclaim the two bits in
the end (Gabriel Krisman Bertazi)
- All kinds of minor cleanups all over the tree"
* tag 'x86_cleanups_for_v5.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
x86/ia32_signal: Propagate __user annotation properly
x86/alternative: Update text_poke_bp() kernel-doc comment
x86/PCI: Make a kernel-doc comment a normal one
x86/asm: Drop unused RDPID macro
x86/boot/compressed/64: Use TEST %reg,%reg instead of CMP $0,%reg
x86/head64: Remove duplicate include
x86/mm: Declare 'start' variable where it is used
x86/head/64: Remove unused GET_CR2_INTO() macro
x86/boot: Remove unused finalize_identity_maps()
x86/uaccess: Document copy_from_user_nmi()
x86/dumpstack: Make show_trace_log_lvl() static
x86/mtrr: Fix a kernel-doc markup
x86/setup: Remove unused MCA variables
x86, libnvdimm/test: Remove COPY_MC_TEST
x86: Reclaim TIF_IA32 and TIF_X32
x86/mm: Convert mmu context ia32_compat into a proper flags field
x86/elf: Use e_machine to check for x32/ia32 in setup_additional_pages()
elf: Expose ELF header on arch_setup_additional_pages()
x86/elf: Use e_machine to select start_thread for x32
elf: Expose ELF header in compat_start_thread()
...
Oleg Nesterov recently asked[1] why is there an unshare_files in
do_coredump. After digging through all of the callers of lookup_fd it
turns out that it is
arch/powerpc/platforms/cell/spufs/coredump.c:coredump_next_context
that needs the unshare_files in do_coredump.
Looking at the history[2] this code was also the only piece of coredump code
that required the unshare_files when the unshare_files was added.
Looking at that code it turns out that cell is also the only
architecture that implements elf_coredump_extra_notes_size and
elf_coredump_extra_notes_write.
I looked at the gdb repo[3] support for cell has been removed[4] in binutils
2.34. Geoff Levand reports he is still getting questions on how to
run modern kernels on the PS3, from people using 3rd party firmware so
this code is not dead. According to Wikipedia the last PS3 shipped in
Japan sometime in 2017. So it will probably be a little while before
everyone's hardware dies.
Add some comments briefly documenting the coredump code that exists
only to support cell spufs to make it easier to understand the
coredump code. Eventually the hardware will be dead, or their won't
be userspace tools, or the coredump code will be refactored and it
will be too difficult to update a dead architecture and these comments
make it easy to tell where to pull to remove cell spufs support.
[1] https://lkml.kernel.org/r/20201123175052.GA20279@redhat.com
[2] 179e037fc1 ("do_coredump(): make sure that descriptor table isn't shared")
[3] git://sourceware.org/git/binutils-gdb.git
[4] abf516c6931a ("Remove Cell Broadband Engine debugging support").
Link: https://lkml.kernel.org/r/87h7pdnlzv.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
