linux-stable.git/fs/proc, branch v5.2.6

/proc//cmdline: add back the setproctitle() special case

2019-08-04T07:29:40+00:00

commit d26d0cd97c88eb1a5704b42e41ab443406807810 upstream.

This makes the setproctitle() special case very explicit indeed, and
handles it with a separate helper function entirely.  In the process, it
re-instates the original semantics of simply stopping at the first NUL
character when the original last NUL character is no longer there.

[ The original semantics can still be seen in mm/util.c: get_cmdline()
  that is limited to a fixed-size buffer ]

This makes the logic about when we use the string lengths etc much more
obvious, and makes it easier to see what we do and what the two very
different cases are.

Note that even when we allow walking past the end of the argument array
(because the setproctitle() might have overwritten and overflowed the
original argv[] strings), we only allow it when it overflows into the
environment region if it is immediately adjacent.

[ Fixed for missing 'count' checks noted by Alexey Izbyshev ]

Link: https://lore.kernel.org/lkml/alpine.LNX.2.21.1904052326230.3249@kich.toxcorp.com/
Fixes: 5ab827189965 ("fs/proc: simplify and clarify get_mm_cmdline() function")
Cc: Jakub Jankowski 
Cc: Alexey Dobriyan 
Cc: Alexey Izbyshev 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

/proc//cmdline: remove all the special cases

2019-08-04T07:29:40+00:00

commit 3d712546d8ba9f25cdf080d79f90482aa4231ed4 upstream.

Start off with a clean slate that only reads exactly from arg_start to
arg_end, without any oddities.  This simplifies the code and in the
process removes the case that caused us to potentially leak an
uninitialized byte from the temporary kernel buffer.

Note that in order to start from scratch with an understandable base,
this simplifies things _too_ much, and removes all the legacy logic to
handle setproctitle() having changed the argument strings.

We'll add back those special cases very differently in the next commit.

Link: https://lore.kernel.org/lkml/20190712160913.17727-1-izbyshev@ispras.ru/
Fixes: f5b65348fd77 ("proc: fix missing final NUL in get_mm_cmdline() rewrite")
Cc: Alexey Izbyshev 
Cc: Alexey Dobriyan 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

proc: use down_read_killable mmap_sem for /proc/pid/maps

2019-07-31T05:24:55+00:00

[ Upstream commit 8a713e7df3352b8d9392476e9cf29e4e185dac32 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

This function is also used for /proc/pid/smaps.

Link: http://lkml.kernel.org/r/156007493160.3335.14447544314127417266.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/map_files

2019-07-31T05:24:54+00:00

[ Upstream commit cd9e2bb8271c971d9f37c722be2616c7f8ba0664 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

It seems ->d_revalidate() could return any error (except ECHILD) to abort
validation and pass error as result of lookup sequence.

[akpm@linux-foundation.org: fix proc_map_files_lookup() return value, per Andrei]
Link: http://lkml.kernel.org/r/156007493995.3335.9595044802115356911.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/clear_refs

2019-07-31T05:24:54+00:00

[ Upstream commit c46038017fbdcac627b670c9d4176f1d0c2f5fa3 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Replace the only unkillable mmap_sem lock in clear_refs_write().

Link: http://lkml.kernel.org/r/156007493826.3335.5424884725467456239.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/pagemap

2019-07-31T05:24:54+00:00

[ Upstream commit ad80b932c57d85fd6377f97f359b025baf179a87 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493638.3335.4872164955523928492.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

proc: use down_read_killable mmap_sem for /proc/pid/smaps_rollup

2019-07-31T05:24:54+00:00

[ Upstream commit a26a97815548574213fd37f29b4b78ccc6d9ed20 ]

Do not remain stuck forever if something goes wrong.  Using a killable
lock permits cleanup of stuck tasks and simplifies investigation.

Link: http://lkml.kernel.org/r/156007493429.3335.14666825072272692455.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Roman Gushchin 
Reviewed-by: Cyrill Gorcunov 
Reviewed-by: Kirill Tkhai 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Al Viro 
Cc: Matthew Wilcox 
Cc: Michal Koutný 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

fs/proc/proc_sysctl.c: fix the default values of i_uid/i_gid on /proc/sys inodes.

2019-07-26T07:11:01+00:00

commit 5ec27ec735ba0477d48c80561cc5e856f0c5dfaf upstream.

Normally, the inode's i_uid/i_gid are translated relative to s_user_ns,
but this is not a correct behavior for proc.  Since sysctl permission
check in test_perm is done against GLOBAL_ROOT_[UG]ID, it makes more
sense to use these values in u_[ug]id of proc inodes.  In other words:
although uid/gid in the inode is not read during test_perm, the inode
logically belongs to the root of the namespace.  I have confirmed this
with Eric Biederman at LPC and in this thread:
  https://lore.kernel.org/lkml/87k1kzjdff.fsf@xmission.com

Consequences
============

Since the i_[ug]id values of proc nodes are not used for permissions
checks, this change usually makes no functional difference.  However, it
causes an issue in a setup where:

 * a namespace container is created without root user in container -
   hence the i_[ug]id of proc nodes are set to INVALID_[UG]ID

 * container creator tries to configure it by writing /proc/sys files,
   e.g. writing /proc/sys/kernel/shmmax to configure shared memory limit

Kernel does not allow to open an inode for writing if its i_[ug]id are
invalid, making it impossible to write shmmax and thus - configure the
container.

Using a container with no root mapping is apparently rare, but we do use
this configuration at Google.  Also, we use a generic tool to configure
the container limits, and the inability to write any of them causes a
failure.

History
=======

The invalid uids/gids in inodes first appeared due to 81754357770e (fs:
Update i_[ug]id_(read|write) to translate relative to s_user_ns).
However, AFAIK, this did not immediately cause any issues.  The
inability to write to these "invalid" inodes was only caused by a later
commit 0bd23d09b874 (vfs: Don't modify inodes with a uid or gid unknown
to the vfs).

Tested: Used a repro program that creates a user namespace without any
mapping and stat'ed /proc/$PID/root/proc/sys/kernel/shmmax from outside.
Before the change, it shows the overflow uid, with the change it's 0.
The overflow uid indicates that the uid in the inode is not correct and
thus it is not possible to open the file for writing.

Link: http://lkml.kernel.org/r/20190708115130.250149-1-rburny@google.com
Fixes: 0bd23d09b874 ("vfs: Don't modify inodes with a uid or gid unknown to the vfs")
Signed-off-by: Radoslaw Burny 
Acked-by: Luis Chamberlain 
Cc: Kees Cook 
Cc: "Eric W . Biederman" 
Cc: Seth Forshee 
Cc: John Sperbeck 
Cc: Alexey Dobriyan 
Cc: 	[4.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

fs/proc/array.c: allow reporting eip/esp for all coredumping threads

2019-06-29T08:43:44+00:00

0a1eb2d474ed ("fs/proc: Stop reporting eip and esp in /proc/PID/stat")
stopped reporting eip/esp and fd7d56270b52 ("fs/proc: Report eip/esp in
/prod/PID/stat for coredumping") reintroduced the feature to fix a
regression with userspace core dump handlers (such as minicoredumper).

Because PF_DUMPCORE is only set for the primary thread, this didn't fix
the original problem for secondary threads.  Allow reporting the eip/esp
for all threads by checking for PF_EXITING as well.  This is set for all
the other threads when they are killed.  coredump_wait() waits for all the
tasks to become inactive before proceeding to invoke a core dumper.

Link: http://lkml.kernel.org/r/87y32p7i7a.fsf@linutronix.de
Link: http://lkml.kernel.org/r/20190522161614.628-1-jlu@pengutronix.de
Fixes: fd7d56270b526ca3 ("fs/proc: Report eip/esp in /prod/PID/stat for coredumping")
Signed-off-by: John Ogness 
Reported-by: Jan Luebbe 
Tested-by: Jan Luebbe 
Cc: Alexey Dobriyan 
Cc: Andy Lutomirski 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: remove useless d_is_dir() check

2019-06-27T10:25:09+00:00

Remove the d_is_dir() check from tgid_pidfd_to_pid().

It is pointless since you should never get &proc_tgid_base_operations
for f_op on a non-directory.

Suggested-by: Al Viro 
Signed-off-by: Christian Brauner