linux-stable.git/fs/proc/base.c, branch v5.12

proc/wchan: use printk format instead of lookup_symbol_name()

2021-02-26T17:41:03+00:00

To resolve the symbol fuction name for wchan, use the printk format
specifier %ps instead of manually looking up the symbol function name
via lookup_symbol_name().

Link: https://lkml.kernel.org/r/20201217165413.GA1959@ls3530.fritz.box
Signed-off-by: Helge Deller 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: make helpers idmap mount aware

2021-01-24T13:27:20+00:00

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig 
Cc: David Howells 
Cc: Al Viro 
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Signed-off-by: Christian Brauner

stat: handle idmapped mounts

2021-01-24T13:27:17+00:00

The generic_fillattr() helper fills in the basic attributes associated
with an inode. Enable it to handle idmapped mounts. If the inode is
accessed through an idmapped mount map it into the mount's user
namespace before we store the uid and gid. If the initial user namespace
is passed nothing changes so non-idmapped mounts will see identical
behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-12-christian.brauner@ubuntu.com
Cc: Christoph Hellwig 
Cc: David Howells 
Cc: Al Viro 
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Reviewed-by: James Morris 
Signed-off-by: Christian Brauner

attr: handle idmapped mounts

2021-01-24T13:27:16+00:00

When file attributes are changed most filesystems rely on the
setattr_prepare(), setattr_copy(), and notify_change() helpers for
initialization and permission checking. Let them handle idmapped mounts.
If the inode is accessed through an idmapped mount map it into the
mount's user namespace. Afterwards the checks are identical to
non-idmapped mounts. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Helpers that perform checks on the ia_uid and ia_gid fields in struct
iattr assume that ia_uid and ia_gid are intended values and have already
been mapped correctly at the userspace-kernelspace boundary as we
already do today. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-8-christian.brauner@ubuntu.com
Cc: Christoph Hellwig 
Cc: David Howells 
Cc: Al Viro 
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Signed-off-by: Christian Brauner

namei: make permission helpers idmapped mount aware

2021-01-24T13:27:16+00:00

The two helpers inode_permission() and generic_permission() are used by
the vfs to perform basic permission checking by verifying that the
caller is privileged over an inode. In order to handle idmapped mounts
we extend the two helpers with an additional user namespace argument.
On idmapped mounts the two helpers will make sure to map the inode
according to the mount's user namespace and then peform identical
permission checks to inode_permission() and generic_permission(). If the
initial user namespace is passed nothing changes so non-idmapped mounts
will see identical behavior as before.

Link: https://lore.kernel.org/r/20210121131959.646623-6-christian.brauner@ubuntu.com
Cc: Christoph Hellwig 
Cc: David Howells 
Cc: Al Viro 
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig 
Reviewed-by: James Morris 
Acked-by: Serge Hallyn 
Signed-off-by: Christian Brauner

Merge tag 'seccomp-v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2020-12-16T19:30:10+00:00

Pull seccomp updates from Kees Cook:
 "The major change here is finally gaining seccomp constant-action
  bitmaps, which internally reduces the seccomp overhead for many
  real-world syscall filters to O(1), as discussed at Plumbers this
  year.

   - Improve seccomp performance via constant-action bitmaps (YiFei Zhu
     & Kees Cook)

   - Fix bogus __user annotations (Jann Horn)

   - Add missed CONFIG for improved selftest coverage (Mickaël Salaün)"

* tag 'seccomp-v5.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  selftests/seccomp: Update kernel config
  seccomp: Remove bogus __user annotations
  seccomp/cache: Report cache data through /proc/pid/seccomp_cache
  xtensa: Enable seccomp architecture tracking
  sh: Enable seccomp architecture tracking
  s390: Enable seccomp architecture tracking
  riscv: Enable seccomp architecture tracking
  powerpc: Enable seccomp architecture tracking
  parisc: Enable seccomp architecture tracking
  csky: Enable seccomp architecture tracking
  arm: Enable seccomp architecture tracking
  arm64: Enable seccomp architecture tracking
  selftests/seccomp: Compare bitmap vs filter overhead
  x86: Enable seccomp architecture tracking
  seccomp/cache: Add "emulator" to check if filter is constant allow
  seccomp/cache: Lookup syscall allowlist bitmap for fast path

Merge branch 'akpm' (patches from Andrew)

2020-12-16T07:26:37+00:00

Merge yet more updates from Andrew Morton:

 - lots of little subsystems

 - a few post-linux-next MM material. Most of the rest awaits more
   merging of other trees.

Subsystems affected by this series: alpha, procfs, misc, core-kernel,
bitmap, lib, lz4, checkpatch, nilfs, kdump, rapidio, gcov, bfs, relay,
resource, ubsan, reboot, fault-injection, lzo, apparmor, and mm (swap,
memory-hotplug, pagemap, cleanups, and gup).

* emailed patches from Andrew Morton : (86 commits)
  mm: fix some spelling mistakes in comments
  mm: simplify follow_pte{,pmd}
  mm: unexport follow_pte_pmd
  apparmor: remove duplicate macro list_entry_is_head()
  lib/lzo/lzo1x_compress.c: make lzogeneric1x_1_compress() static
  fault-injection: handle EI_ETYPE_TRUE
  reboot: hide from sysfs not applicable settings
  reboot: allow to override reboot type if quirks are found
  reboot: remove cf9_safe from allowed types and rename cf9_force
  reboot: allow to specify reboot mode via sysfs
  reboot: refactor and comment the cpu selection code
  lib/ubsan.c: mark type_check_kinds with static keyword
  kcov: don't instrument with UBSAN
  ubsan: expand tests and reporting
  ubsan: remove UBSAN_MISC in favor of individual options
  ubsan: enable for all*config builds
  ubsan: disable UBSAN_TRAP for all*config
  ubsan: disable object-size sanitizer under GCC
  ubsan: move cc-option tests into Kconfig
  ubsan: remove redundant -Wno-maybe-uninitialized
  ...

procfs: delete duplicated words + other fixes

2020-12-16T06:46:15+00:00

Delete repeated words in fs/proc/.
{the, which}
where "which which" was changed to "with which".

Link: https://lkml.kernel.org/r/20201028191525.13413-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap 
Cc: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

exec: Transform exec_update_mutex into a rw_semaphore

2020-12-10T19:13:32+00:00

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 
Cc: Vasiliy Kulikov 
Cc: Al Viro 
Cc: Bernd Edlinger 
Cc: Oleg Nesterov 
Cc: Christopher Yeoh 
Cc: Cyrill Gorcunov 
Cc: Sargun Dhillon 
Cc: Christian Brauner 
Cc: Arnd Bergmann 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Arnaldo Carvalho de Melo 
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

seccomp/cache: Report cache data through /proc/pid/seccomp_cache

2020-11-20T19:16:35+00:00

Currently the kernel does not provide an infrastructure to translate
architecture numbers to a human-readable name. Translating syscall
numbers to syscall names is possible through FTRACE_SYSCALL
infrastructure but it does not provide support for compat syscalls.

This will create a file for each PID as /proc/pid/seccomp_cache.
The file will be empty when no seccomp filters are loaded, or be
in the format of:
  
where ALLOW means the cache is guaranteed to allow the syscall,
and filter means the cache will pass the syscall to the BPF filter.

For the docker default profile on x86_64 it looks like:
x86_64 0 ALLOW
x86_64 1 ALLOW
x86_64 2 ALLOW
x86_64 3 ALLOW
[...]
x86_64 132 ALLOW
x86_64 133 ALLOW
x86_64 134 FILTER
x86_64 135 FILTER
x86_64 136 FILTER
x86_64 137 ALLOW
x86_64 138 ALLOW
x86_64 139 FILTER
x86_64 140 ALLOW
x86_64 141 ALLOW
[...]

This file is guarded by CONFIG_SECCOMP_CACHE_DEBUG with a default
of N because I think certain users of seccomp might not want the
application to know which syscalls are definitely usable. For
the same reason, it is also guarded by CAP_SYS_ADMIN.

Suggested-by: Jann Horn 
Link: https://lore.kernel.org/lkml/CAG48ez3Ofqp4crXGksLmZY6=fGrF_tWyUCg7PBkAetvbbOPeOA@mail.gmail.com/
Signed-off-by: YiFei Zhu 
Signed-off-by: Kees Cook 
Link: https://lore.kernel.org/r/94e663fa53136f5a11f432c661794d1ee7060779.1605101222.git.yifeifz2@illinois.edu