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[ Upstream commit 5e088248375d171b80c643051e77ade6b97bc386 ]
In the setup_arg_pages(), ret is declared as an unsigned long.
The ret might take a negative value. Therefore, its type should
be changed to int.
Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20250825073609.219855-1-zhao.xichao@vivo.com
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 0d196e7589cefe207d5d41f37a0a28a1fdeeb7c6 ]
Both i_mode and noexec checks wrapped in WARN_ON stem from an artifact
of the previous implementation. They used to legitimately check for the
condition, but that got moved up in two commits:
633fb6ac3980 ("exec: move S_ISREG() check earlier")
0fd338b2d2cd ("exec: move path_noexec() check earlier")
Instead of being removed said checks are WARN_ON'ed instead, which
has some debug value.
However, the spurious path_noexec check is racy, resulting in
unwarranted warnings should someone race with setting the noexec flag.
One can note there is more to perm-checking whether execve is allowed
and none of the conditions are guaranteed to still hold after they were
tested for.
Additionally this does not validate whether the code path did any perm
checking to begin with -- it will pass if the inode happens to be
regular.
Keep the redundant path_noexec() check even though it's mindless
nonsense checking for guarantee that isn't given so drop the WARN.
Reword the commentary and do small tidy ups while here.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240805131721.765484-1-mjguzik@gmail.com
[brauner: keep redundant path_noexec() check]
Signed-off-by: Christian Brauner <brauner@kernel.org>
[cascardo: keep exit label and use it]
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit f31b256994acec6929306dfa86ac29716e7503d6 upstream.
Fix the stack start address calculation for the parisc architecture in
setup_arg_pages() when address randomization is disabled. When the
ADDR_NO_RANDOMIZE process personality is disabled there is no need to add
additional space for the stack.
Note that this patch touches code inside an #ifdef CONFIG_STACK_GROWSUP hunk,
which is why only the parisc architecture is affected since it's the
only Linux architecture where the stack grows upwards.
Without this patch you will find the stack in the middle of some
mapped libaries and suddenly limited to 6MB instead of 8MB:
root@parisc:~# setarch -R /bin/bash -c "cat /proc/self/maps"
00010000-00019000 r-xp 00000000 08:05 1182034 /usr/bin/cat
00019000-0001a000 rwxp 00009000 08:05 1182034 /usr/bin/cat
0001a000-0003b000 rwxp 00000000 00:00 0 [heap]
f90c4000-f9283000 r-xp 00000000 08:05 1573004 /usr/lib/hppa-linux-gnu/libc.so.6
f9283000-f9285000 r--p 001bf000 08:05 1573004 /usr/lib/hppa-linux-gnu/libc.so.6
f9285000-f928a000 rwxp 001c1000 08:05 1573004 /usr/lib/hppa-linux-gnu/libc.so.6
f928a000-f9294000 rwxp 00000000 00:00 0
f9301000-f9323000 rwxp 00000000 00:00 0 [stack]
f98b4000-f98e4000 r-xp 00000000 08:05 1572869 /usr/lib/hppa-linux-gnu/ld.so.1
f98e4000-f98e5000 r--p 00030000 08:05 1572869 /usr/lib/hppa-linux-gnu/ld.so.1
f98e5000-f98e9000 rwxp 00031000 08:05 1572869 /usr/lib/hppa-linux-gnu/ld.so.1
f9ad8000-f9b00000 rw-p 00000000 00:00 0
f9b00000-f9b01000 r-xp 00000000 00:00 0 [vdso]
With the patch the stack gets correctly mapped at the end
of the process memory map:
root@panama:~# setarch -R /bin/bash -c "cat /proc/self/maps"
00010000-00019000 r-xp 00000000 08:13 16385582 /usr/bin/cat
00019000-0001a000 rwxp 00009000 08:13 16385582 /usr/bin/cat
0001a000-0003b000 rwxp 00000000 00:00 0 [heap]
fef29000-ff0eb000 r-xp 00000000 08:13 16122400 /usr/lib/hppa-linux-gnu/libc.so.6
ff0eb000-ff0ed000 r--p 001c2000 08:13 16122400 /usr/lib/hppa-linux-gnu/libc.so.6
ff0ed000-ff0f2000 rwxp 001c4000 08:13 16122400 /usr/lib/hppa-linux-gnu/libc.so.6
ff0f2000-ff0fc000 rwxp 00000000 00:00 0
ff4b4000-ff4e4000 r-xp 00000000 08:13 16121913 /usr/lib/hppa-linux-gnu/ld.so.1
ff4e4000-ff4e6000 r--p 00030000 08:13 16121913 /usr/lib/hppa-linux-gnu/ld.so.1
ff4e6000-ff4ea000 rwxp 00032000 08:13 16121913 /usr/lib/hppa-linux-gnu/ld.so.1
ff6d7000-ff6ff000 rw-p 00000000 00:00 0
ff6ff000-ff700000 r-xp 00000000 00:00 0 [vdso]
ff700000-ff722000 rwxp 00000000 00:00 0 [stack]
Reported-by: Camm Maguire <camm@maguirefamily.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: d045c77c1a69 ("parisc,metag: Fix crashes due to stack randomization on stack-grows-upwards architectures")
Fixes: 17d9822d4b4c ("parisc: Consider stack randomization for mmap base only when necessary")
Cc: stable@vger.kernel.org # v5.2+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f50733b45d865f91db90919f8311e2127ce5a0cb upstream.
When opening a file for exec via do_filp_open(), permission checking is
done against the file's metadata at that moment, and on success, a file
pointer is passed back. Much later in the execve() code path, the file
metadata (specifically mode, uid, and gid) is used to determine if/how
to set the uid and gid. However, those values may have changed since the
permissions check, meaning the execution may gain unintended privileges.
For example, if a file could change permissions from executable and not
set-id:
---------x 1 root root 16048 Aug 7 13:16 target
to set-id and non-executable:
---S------ 1 root root 16048 Aug 7 13:16 target
it is possible to gain root privileges when execution should have been
disallowed.
While this race condition is rare in real-world scenarios, it has been
observed (and proven exploitable) when package managers are updating
the setuid bits of installed programs. Such files start with being
world-executable but then are adjusted to be group-exec with a set-uid
bit. For example, "chmod o-x,u+s target" makes "target" executable only
by uid "root" and gid "cdrom", while also becoming setuid-root:
-rwxr-xr-x 1 root cdrom 16048 Aug 7 13:16 target
becomes:
-rwsr-xr-- 1 root cdrom 16048 Aug 7 13:16 target
But racing the chmod means users without group "cdrom" membership can
get the permission to execute "target" just before the chmod, and when
the chmod finishes, the exec reaches brpm_fill_uid(), and performs the
setuid to root, violating the expressed authorization of "only cdrom
group members can setuid to root".
Re-check that we still have execute permissions in case the metadata
has changed. It would be better to keep a copy from the perm-check time,
but until we can do that refactoring, the least-bad option is to do a
full inode_permission() call (under inode lock). It is understood that
this is safe against dead-locks, but hardly optimal.
Reported-by: Marco Vanotti <mvanotti@google.com>
Tested-by: Marco Vanotti <mvanotti@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 1f702603e7125a390b5cdf5ce00539781cfcc86a ]
Now that exec no longer needs to return the unshared files to their
previous value there is no reason to return displaced.
Instead when unshare_fd creates a copy of the file table, call
put_files_struct before returning from unshare_files.
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-2-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-2-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit b6043501289ebf169ae19b810a882d517377302f ]
Many moons ago the binfmts were doing some very questionable things
with file descriptors and an unsharing of the file descriptor table
was added to make things better[1][2]. The helper steal_lockss was
added to avoid breaking the userspace programs[3][4][6].
Unfortunately it turned out that steal_locks did not work for network
file systems[5], so it was removed to see if anyone would
complain[7][8]. It was thought at the time that NPTL would not be
affected as the unshare_files happened after the other threads were
killed[8]. Unfortunately because there was an unshare_files in
binfmt_elf.c before the threads were killed this analysis was
incorrect.
This unshare_files in binfmt_elf.c resulted in the unshares_files
happening whenever threads were present. Which led to unshare_files
being moved to the start of do_execve[9].
Later the problems were rediscovered and the suggested approach was to
readd steal_locks under a different name[10]. I happened to be
reviewing patches and I noticed that this approach was a step
backwards[11].
I proposed simply moving unshare_files[12] and it was pointed
out that moving unshare_files without auditing the code was
also unsafe[13].
There were then several attempts to solve this[14][15][16] and I even
posted this set of changes[17]. Unfortunately because auditing all of
execve is time consuming this change did not make it in at the time.
Well now that I am cleaning up exec I have made the time to read
through all of the binfmts and the only playing with file descriptors
is either the security modules closing them in
security_bprm_committing_creds or is in the generic code in fs/exec.c.
None of it happens before begin_new_exec is called.
So move unshare_files into begin_new_exec, after the point of no
return. If memory is very very very low and the application calling
exec is sharing file descriptor tables between processes we might fail
past the point of no return. Which is unfortunate but no different
than any of the other places where we allocate memory after the point
of no return.
This movement allows another process that shares the file table, or
another thread of the same process and that closes files or changes
their close on exec behavior and races with execve to cause some
unexpected things to happen. There is only one time of check to time
of use race and it is just there so that execve fails instead of
an interpreter failing when it tries to open the file it is supposed
to be interpreting. Failing later if userspace is being silly is
not a problem.
With this change it the following discription from the removal
of steal_locks[8] finally becomes true.
Apps using NPTL are not affected, since all other threads are killed before
execve.
Apps using LinuxThreads are only affected if they
- have multiple threads during exec (LinuxThreads doesn't kill other
threads, the app may do it with pthread_kill_other_threads_np())
- rely on POSIX locks being inherited across exec
Both conditions are documented, but not their interaction.
Apps using clone() natively are affected if they
- use clone(CLONE_FILES)
- rely on POSIX locks being inherited across exec
I have investigated some paths to make it possible to solve this
without moving unshare_files but they all look more complicated[18].
Reported-by: Daniel P. Berrangé <berrange@redhat.com>
Reported-by: Jeff Layton <jlayton@redhat.com>
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
[1] 02cda956de0b ("[PATCH] unshare_files"
[2] 04e9bcb4d106 ("[PATCH] use new unshare_files helper")
[3] 088f5d7244de ("[PATCH] add steal_locks helper")
[4] 02c541ec8ffa ("[PATCH] use new steal_locks helper")
[5] https://lkml.kernel.org/r/E1FLIlF-0007zR-00@dorka.pomaz.szeredi.hu
[6] https://lkml.kernel.org/r/0060321191605.GB15997@sorel.sous-sol.org
[7] https://lkml.kernel.org/r/E1FLwjC-0000kJ-00@dorka.pomaz.szeredi.hu
[8] c89681ed7d0e ("[PATCH] remove steal_locks()")
[9] fd8328be874f ("[PATCH] sanitize handling of shared descriptor tables in failing execve()")
[10] https://lkml.kernel.org/r/20180317142520.30520-1-jlayton@kernel.org
[11] https://lkml.kernel.org/r/87r2nwqk73.fsf@xmission.com
[12] https://lkml.kernel.org/r/87bmfgvg8w.fsf@xmission.com
[13] https://lkml.kernel.org/r/20180322111424.GE30522@ZenIV.linux.org.uk
[14] https://lkml.kernel.org/r/20180827174722.3723-1-jlayton@kernel.org
[15] https://lkml.kernel.org/r/20180830172423.21964-1-jlayton@kernel.org
[16] https://lkml.kernel.org/r/20180914105310.6454-1-jlayton@kernel.org
[17] https://lkml.kernel.org/r/87a7ohs5ow.fsf@xmission.com
[18] https://lkml.kernel.org/r/87pn8c1uj6.fsf_-_@x220.int.ebiederm.org
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
v1: https://lkml.kernel.org/r/20200817220425.9389-1-ebiederm@xmission.com
Link: https://lkml.kernel.org/r/20201120231441.29911-1-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 878f12dbb8f514799d126544d59be4d2675caac3 ]
Al Viro pointed out that using the phrase "close_on_exec(fd,
rcu_dereference_raw(current->files->fdt))" instead of wrapping it in
rcu_read_lock(), rcu_read_unlock() is a very questionable
optimization[1].
Once wrapped with rcu_read_lock()/rcu_read_unlock() that phrase
becomes equivalent the helper function get_close_on_exec so
simplify the code and make it more robust by simply using
get_close_on_exec.
[1] https://lkml.kernel.org/r/20201207222214.GA4115853@ZenIV.linux.org.uk
Suggested-by: Al Viro <viro@ftp.linux.org.uk>
Link: https://lkml.kernel.org/r/87k0tqr6zi.fsf_-_@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 2aea94ac14d1e0a8ae9e34febebe208213ba72f7 upstream.
In NOMMU kernel the value of linux_binprm::p is the offset inside the
temporary program arguments array maintained in separate pages in the
linux_binprm::page. linux_binprm::exec being a copy of linux_binprm::p
thus must be adjusted when that array is copied to the user stack.
Without that adjustment the value passed by the NOMMU kernel to the ELF
program in the AT_EXECFN entry of the aux array doesn't make any sense
and it may break programs that try to access memory pointed to by that
entry.
Adjust linux_binprm::exec before the successful return from the
transfer_args_to_stack().
Cc: <stable@vger.kernel.org>
Fixes: b6a2fea39318 ("mm: variable length argument support")
Fixes: 5edc2a5123a7 ("binfmt_elf_fdpic: wire up AT_EXECFD, AT_EXECFN, AT_SECURE")
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Link: https://lore.kernel.org/r/20240320182607.1472887-1-jcmvbkbc@gmail.com
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 84c39ec57d409e803a9bb6e4e85daf1243e0e80b upstream.
If get_unused_fd_flags() fails, the error handling is incomplete because
bprm->cred is already set to NULL, and therefore free_bprm will not
unlock the cred_guard_mutex. Note there are two error conditions which
end up here, one before and one after bprm->cred is cleared.
Fixes: b8a61c9e7b4a ("exec: Generic execfd support")
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Acked-by: Eric W. Biederman <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/AS8P193MB128517ADB5EFF29E04389EDAE4752@AS8P193MB1285.EURP193.PROD.OUTLOOK.COM
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 5bf2fedca8f59379025b0d52f917b9ddb9bfe17e upstream.
unshare_sighand should only access oldsighand->action
while holding oldsighand->siglock, to make sure that
newsighand->action is in a consistent state.
Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: stable@vger.kernel.org
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/AM8PR10MB470871DEBD1DED081F9CC391E4389@AM8PR10MB4708.EURPRD10.PROD.OUTLOOK.COM
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit e362359ace6f87c201531872486ff295df306d13 upstream.
Commit 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a
task") started looking up tasks by PID when deleting a CPU timer.
When a non-leader thread calls execve, it will switch PIDs with the leader
process. Then, as it calls exit_itimers, posix_cpu_timer_del cannot find
the task because the timer still points out to the old PID.
That means that armed timers won't be disarmed, that is, they won't be
removed from the timerqueue_list. exit_itimers will still release their
memory, and when that list is later processed, it leads to a
use-after-free.
Clean up the timers from the de-threaded task before freeing them. This
prevents a reported use-after-free.
Fixes: 55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220809170751.164716-1-cascardo@canonical.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d5b36a4dbd06c5e8e36ca8ccc552f679069e2946 upstream.
As Chris explains, the comment above exit_itimers() is not correct,
we can race with proc_timers_seq_ops. Change exit_itimers() to clear
signal->posix_timers with ->siglock held.
Cc: <stable@vger.kernel.org>
Reported-by: chris@accessvector.net
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit dcd46d897adb70d63e025f175a00a89797d31a43 upstream.
Quoting[1] Ariadne Conill:
"In several other operating systems, it is a hard requirement that the
second argument to execve(2) be the name of a program, thus prohibiting
a scenario where argc < 1. POSIX 2017 also recommends this behaviour,
but it is not an explicit requirement[2]:
The argument arg0 should point to a filename string that is
associated with the process being started by one of the exec
functions.
...
Interestingly, Michael Kerrisk opened an issue about this in 2008[3],
but there was no consensus to support fixing this issue then.
Hopefully now that CVE-2021-4034 shows practical exploitative use[4]
of this bug in a shellcode, we can reconsider.
This issue is being tracked in the KSPP issue tracker[5]."
While the initial code searches[6][7] turned up what appeared to be
mostly corner case tests, trying to that just reject argv == NULL
(or an immediately terminated pointer list) quickly started tripping[8]
existing userspace programs.
The next best approach is forcing a single empty string into argv and
adjusting argc to match. The number of programs depending on argc == 0
seems a smaller set than those calling execve with a NULL argv.
Account for the additional stack space in bprm_stack_limits(). Inject an
empty string when argc == 0 (and set argc = 1). Warn about the case so
userspace has some notice about the change:
process './argc0' launched './argc0' with NULL argv: empty string added
Additionally WARN() and reject NULL argv usage for kernel threads.
[1] https://lore.kernel.org/lkml/20220127000724.15106-1-ariadne@dereferenced.org/
[2] https://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
[3] https://bugzilla.kernel.org/show_bug.cgi?id=8408
[4] https://www.qualys.com/2022/01/25/cve-2021-4034/pwnkit.txt
[5] https://github.com/KSPP/linux/issues/176
[6] https://codesearch.debian.net/search?q=execve%5C+*%5C%28%5B%5E%2C%5D%2B%2C+*NULL&literal=0
[7] https://codesearch.debian.net/search?q=execlp%3F%5Cs*%5C%28%5B%5E%2C%5D%2B%2C%5Cs*NULL&literal=0
[8] https://lore.kernel.org/lkml/20220131144352.GE16385@xsang-OptiPlex-9020/
Reported-by: Ariadne Conill <ariadne@dereferenced.org>
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Ariadne Conill <ariadne@dereferenced.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lore.kernel.org/r/20220201000947.2453721-1-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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This reverts commit b2c4d9a33cc2dec7466f97eba2c4dd571ad798a5 which is
commit 905ae01c4ae2ae3df05bb141801b1db4b7d83c61 upstream.
This commit should not have been applied to the 5.10.y stable tree, so
revert it.
Reported-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lore.kernel.org/r/87v93k4bl6.fsf@disp2133
Cc: Alexey Gladkov <legion@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 905ae01c4ae2ae3df05bb141801b1db4b7d83c61 ]
For RLIMIT_NPROC and some other rlimits the user_struct that holds the
global limit is kept alive for the lifetime of a process by keeping it
in struct cred. Adding a pointer to ucounts in the struct cred will
allow to track RLIMIT_NPROC not only for user in the system, but for
user in the user_namespace.
Updating ucounts may require memory allocation which may fail. So, we
cannot change cred.ucounts in the commit_creds() because this function
cannot fail and it should always return 0. For this reason, we modify
cred.ucounts before calling the commit_creds().
Changelog
v6:
* Fix null-ptr-deref in is_ucounts_overlimit() detected by trinity. This
error was caused by the fact that cred_alloc_blank() left the ucounts
pointer empty.
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/b37aaef28d8b9b0d757e07ba6dd27281bbe39259.1619094428.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f7cfd871ae0c5008d94b6f66834e7845caa93c15 ]
Recently syzbot reported[0] that there is a deadlock amongst the users
of exec_update_mutex. The problematic lock ordering found by lockdep
was:
perf_event_open (exec_update_mutex -> ovl_i_mutex)
chown (ovl_i_mutex -> sb_writes)
sendfile (sb_writes -> p->lock)
by reading from a proc file and writing to overlayfs
proc_pid_syscall (p->lock -> exec_update_mutex)
While looking at possible solutions it occured to me that all of the
users and possible users involved only wanted to state of the given
process to remain the same. They are all readers. The only writer is
exec.
There is no reason for readers to block on each other. So fix
this deadlock by transforming exec_update_mutex into a rw_semaphore
named exec_update_lock that only exec takes for writing.
Cc: Jann Horn <jannh@google.com>
Cc: Vasiliy Kulikov <segoon@openwall.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Christopher Yeoh <cyeoh@au1.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Sargun Dhillon <sargun@sargun.me>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Fixes: eea9673250db ("exec: Add exec_update_mutex to replace cred_guard_mutex")
[0] https://lkml.kernel.org/r/00000000000063640c05ade8e3de@google.com
Reported-by: syzbot+db9cdf3dd1f64252c6ef@syzkaller.appspotmail.com
Link: https://lkml.kernel.org/r/87ft4mbqen.fsf@x220.int.ebiederm.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- A series from Nick adding ARCH_WANT_IRQS_OFF_ACTIVATE_MM & selecting
it for powerpc, as well as a related fix for sparc.
- Remove support for PowerPC 601.
- Some fixes for watchpoints & addition of a new ptrace flag for
detecting ISA v3.1 (Power10) watchpoint features.
- A fix for kernels using 4K pages and the hash MMU on bare metal
Power9 systems with > 16TB of RAM, or RAM on the 2nd node.
- A basic idle driver for shallow stop states on Power10.
- Tweaks to our sched domains code to better inform the scheduler about
the hardware topology on Power9/10, where two SMT4 cores can be
presented by firmware as an SMT8 core.
- A series doing further reworks & cleanups of our EEH code.
- Addition of a filter for RTAS (firmware) calls done via sys_rtas(),
to prevent root from overwriting kernel memory.
- Other smaller features, fixes & cleanups.
Thanks to: Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V,
Athira Rajeev, Biwen Li, Cameron Berkenpas, Cédric Le Goater, Christophe
Leroy, Christoph Hellwig, Colin Ian King, Daniel Axtens, David Dai, Finn
Thain, Frederic Barrat, Gautham R. Shenoy, Greg Kurz, Gustavo Romero,
Ira Weiny, Jason Yan, Joel Stanley, Jordan Niethe, Kajol Jain, Konrad
Rzeszutek Wilk, Laurent Dufour, Leonardo Bras, Liu Shixin, Luca
Ceresoli, Madhavan Srinivasan, Mahesh Salgaonkar, Nathan Lynch, Nicholas
Mc Guire, Nicholas Piggin, Nick Desaulniers, Oliver O'Halloran, Pedro
Miraglia Franco de Carvalho, Pratik Rajesh Sampat, Qian Cai, Qinglang
Miao, Ravi Bangoria, Russell Currey, Satheesh Rajendran, Scott Cheloha,
Segher Boessenkool, Srikar Dronamraju, Stan Johnson, Stephen Kitt,
Stephen Rothwell, Thiago Jung Bauermann, Tyrel Datwyler, Vaibhav Jain,
Vaidyanathan Srinivasan, Vasant Hegde, Wang Wensheng, Wolfram Sang, Yang
Yingliang, zhengbin.
* tag 'powerpc-5.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (228 commits)
Revert "powerpc/pci: unmap legacy INTx interrupts when a PHB is removed"
selftests/powerpc: Fix eeh-basic.sh exit codes
cpufreq: powernv: Fix frame-size-overflow in powernv_cpufreq_reboot_notifier
powerpc/time: Make get_tb() common to PPC32 and PPC64
powerpc/time: Make get_tbl() common to PPC32 and PPC64
powerpc/time: Remove get_tbu()
powerpc/time: Avoid using get_tbl() and get_tbu() internally
powerpc/time: Make mftb() common to PPC32 and PPC64
powerpc/time: Rename mftbl() to mftb()
powerpc/32s: Remove #ifdef CONFIG_PPC_BOOK3S_32 in head_book3s_32.S
powerpc/32s: Rename head_32.S to head_book3s_32.S
powerpc/32s: Setup the early hash table at all time.
powerpc/time: Remove ifdef in get_dec() and set_dec()
powerpc: Remove get_tb_or_rtc()
powerpc: Remove __USE_RTC()
powerpc: Tidy up a bit after removal of PowerPC 601.
powerpc: Remove support for PowerPC 601
powerpc: Remove PowerPC 601
powerpc: Drop SYNC_601() ISYNC_601() and SYNC()
powerpc: Remove CONFIG_PPC601_SYNC_FIX
...
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc driver updates from Greg KH:
"Here is the big set of char, misc, and other assorted driver subsystem
patches for 5.10-rc1.
There's a lot of different things in here, all over the drivers/
directory. Some summaries:
- soundwire driver updates
- habanalabs driver updates
- extcon driver updates
- nitro_enclaves new driver
- fsl-mc driver and core updates
- mhi core and bus updates
- nvmem driver updates
- eeprom driver updates
- binder driver updates and fixes
- vbox minor bugfixes
- fsi driver updates
- w1 driver updates
- coresight driver updates
- interconnect driver updates
- misc driver updates
- other minor driver updates
All of these have been in linux-next for a while with no reported
issues"
* tag 'char-misc-5.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (396 commits)
binder: fix UAF when releasing todo list
docs: w1: w1_therm: Fix broken xref, mistakes, clarify text
misc: Kconfig: fix a HISI_HIKEY_USB dependency
LSM: Fix type of id parameter in kernel_post_load_data prototype
misc: Kconfig: add a new dependency for HISI_HIKEY_USB
firmware_loader: fix a kernel-doc markup
w1: w1_therm: make w1_poll_completion static
binder: simplify the return expression of binder_mmap
test_firmware: Test partial read support
firmware: Add request_partial_firmware_into_buf()
firmware: Store opt_flags in fw_priv
fs/kernel_file_read: Add "offset" arg for partial reads
IMA: Add support for file reads without contents
LSM: Add "contents" flag to kernel_read_file hook
module: Call security_kernel_post_load_data()
firmware_loader: Use security_post_load_data()
LSM: Introduce kernel_post_load_data() hook
fs/kernel_read_file: Add file_size output argument
fs/kernel_read_file: Switch buffer size arg to size_t
fs/kernel_read_file: Remove redundant size argument
...
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|
These routines are used in places outside of exec(2), so in preparation
for refactoring them, move them into a separate source file,
fs/kernel_read_file.c.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20201002173828.2099543-5-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Move kernel_read_file* out of linux/fs.h to its own linux/kernel_read_file.h
include file. That header gets pulled in just about everywhere
and doesn't really need functions not related to the general fs interface.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/r/20200706232309.12010-2-scott.branden@broadcom.com
Link: https://lore.kernel.org/r/20201002173828.2099543-4-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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FIRMWARE_PREALLOC_BUFFER is a "how", not a "what", and confuses the LSMs
that are interested in filtering between types of things. The "how"
should be an internal detail made uninteresting to the LSMs.
Fixes: a098ecd2fa7d ("firmware: support loading into a pre-allocated buffer")
Fixes: fd90bc559bfb ("ima: based on policy verify firmware signatures (pre-allocated buffer)")
Fixes: 4f0496d8ffa3 ("ima: based on policy warn about loading firmware (pre-allocated buffer)")
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201002173828.2099543-2-keescook@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Grab actual references to the files_struct. To avoid circular references
issues due to this, we add a per-task note that keeps track of what
io_uring contexts a task has used. When the tasks execs or exits its
assigned files, we cancel requests based on this tracking.
With that, we can grab proper references to the files table, and no
longer need to rely on stashing away ring_fd and ring_file to check
if the ring_fd may have been closed.
Cc: stable@vger.kernel.org # v5.5+
Reviewed-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Reading and modifying current->mm and current->active_mm and switching
mm should be done with irqs off, to prevent races seeing an intermediate
state.
This is similar to commit 38cf307c1f20 ("mm: fix kthread_use_mm() vs TLB
invalidate"). At exec-time when the new mm is activated, the old one
should usually be single-threaded and no longer used, unless something
else is holding an mm_users reference (which may be possible).
Absent other mm_users, there is also a race with preemption and lazy tlb
switching. Consider the kernel_execve case where the current thread is
using a lazy tlb active mm:
call_usermodehelper()
kernel_execve()
old_mm = current->mm;
active_mm = current->active_mm;
*** preempt *** --------------------> schedule()
prev->active_mm = NULL;
mmdrop(prev active_mm);
...
<-------------------- schedule()
current->mm = mm;
current->active_mm = mm;
if (!old_mm)
mmdrop(active_mm);
If we switch back to the kernel thread from a different mm, there is a
double free of the old active_mm, and a missing free of the new one.
Closing this race only requires interrupts to be disabled while ->mm
and ->active_mm are being switched, but the TLB problem requires also
holding interrupts off over activate_mm. Unfortunately not all archs
can do that yet, e.g., arm defers the switch if irqs are disabled and
expects finish_arch_post_lock_switch() to be called to complete the
flush; um takes a blocking lock in activate_mm().
So as a first step, disable interrupts across the mm/active_mm updates
to close the lazy tlb preempt race, and provide an arch option to
extend that to activate_mm which allows architectures doing IPI based
TLB shootdowns to close the second race.
This is a bit ugly, but in the interest of fixing the bug and backporting
before all architectures are converted this is a compromise.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-2-npiggin@gmail.com
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After the cleanup of page fault accounting, gup does not need to pass
task_struct around any more. Remove that parameter in the whole gup
stack.
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The path_noexec() check, like the regular file check, was happening too
late, letting LSMs see impossible execve()s. Check it earlier as well in
may_open() and collect the redundant fs/exec.c path_noexec() test under
the same robustness comment as the S_ISREG() check.
My notes on the call path, and related arguments, checks, etc:
do_open_execat()
struct open_flags open_exec_flags = {
.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
.acc_mode = MAY_EXEC,
...
do_filp_open(dfd, filename, open_flags)
path_openat(nameidata, open_flags, flags)
file = alloc_empty_file(open_flags, current_cred());
do_open(nameidata, file, open_flags)
may_open(path, acc_mode, open_flag)
/* new location of MAY_EXEC vs path_noexec() test */
inode_permission(inode, MAY_OPEN | acc_mode)
security_inode_permission(inode, acc_mode)
vfs_open(path, file)
do_dentry_open(file, path->dentry->d_inode, open)
security_file_open(f)
open()
/* old location of path_noexec() test */
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200605160013.3954297-4-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The execve(2)/uselib(2) syscalls have always rejected non-regular files.
Recently, it was noticed that a deadlock was introduced when trying to
execute pipes, as the S_ISREG() test was happening too late. This was
fixed in commit 73601ea5b7b1 ("fs/open.c: allow opening only regular files
during execve()"), but it was added after inode_permission() had already
run, which meant LSMs could see bogus attempts to execute non-regular
files.
Move the test into the other inode type checks (which already look for
other pathological conditions[1]). Since there is no need to use
FMODE_EXEC while we still have access to "acc_mode", also switch the test
to MAY_EXEC.
Also include a comment with the redundant S_ISREG() checks at the end of
execve(2)/uselib(2) to note that they are present to avoid any mistakes.
My notes on the call path, and related arguments, checks, etc:
do_open_execat()
struct open_flags open_exec_flags = {
.open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
.acc_mode = MAY_EXEC,
...
do_filp_open(dfd, filename, open_flags)
path_openat(nameidata, open_flags, flags)
file = alloc_empty_file(open_flags, current_cred());
do_open(nameidata, file, open_flags)
may_open(path, acc_mode, open_flag)
/* new location of MAY_EXEC vs S_ISREG() test */
inode_permission(inode, MAY_OPEN | acc_mode)
security_inode_permission(inode, acc_mode)
vfs_open(path, file)
do_dentry_open(file, path->dentry->d_inode, open)
/* old location of FMODE_EXEC vs S_ISREG() test */
security_file_open(f)
open()
[1] https://lore.kernel.org/lkml/202006041910.9EF0C602@keescook/
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200605160013.3954297-3-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
|
|
Patch series "Relocate execve() sanity checks", v2.
While looking at the code paths for the proposed O_MAYEXEC flag, I saw
some things that looked like they should be fixed up.
exec: Change uselib(2) IS_SREG() failure to EACCES
This just regularizes the return code on uselib(2).
exec: Move S_ISREG() check earlier
This moves the S_ISREG() check even earlier than it was already.
exec: Move path_noexec() check earlier
This adds the path_noexec() check to the same place as the
S_ISREG() check.
This patch (of 3):
Change uselib(2)' S_ISREG() error return to EACCES instead of EINVAL so
the behavior matches execve(2), and the seemingly documented value. The
"not a regular file" failure mode of execve(2) is explicitly
documented[1], but it is not mentioned in uselib(2)[2] which does,
however, say that open(2) and mmap(2) errors may apply. The documentation
for open(2) does not include a "not a regular file" error[3], but mmap(2)
does[4], and it is EACCES.
[1] http://man7.org/linux/man-pages/man2/execve.2.html#ERRORS
[2] http://man7.org/linux/man-pages/man2/uselib.2.html#ERRORS
[3] http://man7.org/linux/man-pages/man2/open.2.html#ERRORS
[4] http://man7.org/linux/man-pages/man2/mmap.2.html#ERRORS
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200605160013.3954297-1-keescook@chromium.org
Link: http://lkml.kernel.org/r/20200605160013.3954297-2-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Both exec and exit want to ensure that the uaccess routines actually do
access user pointers. Use the newly added force_uaccess_begin helper
instead of an open coded set_fs for that to prepare for kernel builds
where set_fs() does not exist.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Link: http://lkml.kernel.org/r/20200710135706.537715-7-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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To allow the kernel not to play games with set_fs to call exec
implement kernel_execve. The function kernel_execve takes pointers
into kernel memory and copies the values pointed to onto the new
userspace stack.
The calls with arguments from kernel space of do_execve are replaced
with calls to kernel_execve.
The calls do_execve and do_execveat are made static as there are now
no callers outside of exec.
The comments that mention do_execve are updated to refer to
kernel_execve or execve depending on the circumstances. In addition
to correcting the comments, this makes it easy to grep for do_execve
and verify it is not used.
Inspired-by: https://lkml.kernel.org/r/20200627072704.2447163-1-hch@lst.de
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/87wo365ikj.fsf@x220.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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In preparation for implementiong kernel_execve (which will take kernel
pointers not userspace pointers) factor out bprm_stack_limits out of
prepare_arg_pages. This separates the counting which depends upon the
getting data from userspace from the calculations of the stack limits
which is usable in kernel_execve.
The remove prepare_args_pages and compute bprm->argc and bprm->envc
directly in do_execveat_common, before bprm_stack_limits is called.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/87365u6x60.fsf@x220.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Currently it is necessary for the usermode helper code and the code
that launches init to use set_fs so that pages coming from the kernel
look like they are coming from userspace.
To allow that usage of set_fs to be removed cleanly the argument
copying from userspace needs to happen earlier. Factor bprm_execve
out of do_execve_common to separate out the copying of arguments
to the newe stack, and the rest of exec.
In separating bprm_execve from do_execve_common the copying
of the arguments onto the new stack happens earlier.
As the copying of the arguments does not depend any security hooks,
files, the file table, current->in_execve, current->fs->in_exec,
bprm->unsafe, or creds this is safe.
Likewise the security hook security_creds_for_exec does not depend upon
preventing the argument copying from happening.
In addition to making it possible to implement kernel_execve that
performs the copying differently, this separation of bprm_execve from
do_execve_common makes for a nice separation of responsibilities making
the exec code easier to navigate.
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/878sfm6x6x.fsf@x220.int.ebiederm.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Currently it is necessary for the usermode helper code and the code that
launches init to use set_fs so that pages coming from the kernel look like
they are coming from userspace.
To allow that usage of set_fs to be removed cleanly the argument copying
from userspace needs to happen earlier. Move the allocation and
initialization of bprm->mm into alloc_bprm so that the bprm->mm is
available early to store the new user stack into. This is a prerequisite
for copying argv and envp into the new user stack early before ther rest of
exec.
To keep the things consistent the cleanup of bprm->mm is moved into
free_bprm. So that bprm->mm will be cleaned up whenever bprm->mm is
allocated a |
