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mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-16 01:04:08 +08:00
linux-next/security
Jeff Vander Stoep 66f8e2f03c selinux: sidtab reverse lookup hash table
This replaces the reverse table lookup and reverse cache with a
hashtable which improves cache-miss reverse-lookup times from
O(n) to O(1)* and maintains the same performance as a reverse
cache hit.

This reduces the time needed to add a new sidtab entry from ~500us
to 5us on a Pixel 3 when there are ~10,000 sidtab entries.

The implementation uses the kernel's generic hashtable API,
It uses the context's string represtation as the hash source,
and the kernels generic string hashing algorithm full_name_hash()
to reduce the string to a 32 bit value.

This change also maintains the improvement introduced in
commit ee1a84fdfe ("selinux: overhaul sidtab to fix bug and improve
performance") which removed the need to keep the current sidtab
locked during policy reload. It does however introduce periodic
locking of the target sidtab while converting the hashtable. Sidtab
entries are never modified or removed, so the context struct stored
in the sid_to_context tree can also be used for the context_to_sid
hashtable to reduce memory usage.

This bug was reported by:
- On the selinux bug tracker.
  BUG: kernel softlockup due to too many SIDs/contexts #37
  https://github.com/SELinuxProject/selinux-kernel/issues/37
- Jovana Knezevic on Android's bugtracker.
  Bug: 140252993
  "During multi-user performance testing, we create and remove users
  many times. selinux_android_restorecon_pkgdir goes from 1ms to over
  20ms after about 200 user creations and removals. Accumulated over
  ~280 packages, that adds a significant time to user creation,
  making perf benchmarks unreliable."

* Hashtable lookup is only O(1) when n < the number of buckets.

Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Reported-by: Stephen Smalley <sds@tycho.nsa.gov>
Reported-by: Jovana Knezevic <jovanak@google.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Stephen Smalley <sds@tycho.nsa.gov>
[PM: subj tweak, removed changelog from patch description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-12-09 16:14:51 -05:00
..
apparmor + Features 2019-12-03 12:51:35 -08:00
integrity x86/efi: remove unused variables 2019-11-29 22:23:46 +11:00
keys KEYS: trusted: Remove set but not used variable 'keyhndl' 2019-11-12 21:45:37 +02:00
loadpin proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
lockdown powerpc updates for 5.5 2019-11-30 14:35:43 -08:00
safesetid security/safesetid: Replace rcu_swap_protected() with rcu_replace_pointer() 2019-10-30 08:45:57 -07:00
selinux selinux: sidtab reverse lookup hash table 2019-12-09 16:14:51 -05:00
smack pipe: Reduce #inclusion of pipe_fs_i.h 2019-10-23 17:02:34 +01:00
tomoyo treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
yama proc/sysctl: add shared variables for range check 2019-07-18 17:08:07 -07:00
commoncap.c Merge branch 'next-lsm' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-07-09 12:24:21 -07:00
device_cgroup.c device_cgroup: Export devcgroup_check_permission 2019-10-07 15:11:38 -05:00
inode.c Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
Kconfig Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
Kconfig.hardening meminit fix 2019-07-28 12:33:15 -07:00
lsm_audit.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Makefile security: Add a static lockdown policy LSM 2019-08-19 21:54:15 -07:00
min_addr.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
security.c perf_event: Add support for LSM and SELinux checks 2019-10-17 21:31:55 +02:00