linux/fs/proc
Eric W. Biederman 7c60c48f58 sysctl: Improve the sysctl sanity checks
- Stop validating subdirectories now that we only register leaf tables

- Cleanup and improve the duplicate filename check.
  * Run the duplicate filename check under the sysctl_lock to guarantee
    we never add duplicate names.
  * Reduce the duplicate filename check to nearly O(M*N) where M is the
    number of entries in tthe table we are registering and N is the
    number of entries in the directory before we got there.

- Move the duplicate filename check into it's own function and call
  it directtly from __register_sysctl_table

- Kill the config option as the sanity checks are now cheap enough
  the config option is unnecessary. The original reason for the config
  option was because we had a huge table used to verify the proc filename
  to binary sysctl mapping.  That table has now evolved into the binary_sysctl
  translation layer and is no longer part of the sysctl_check code.

- Tighten up the permission checks.  Guarnateeing that files only have read
  or write permissions.

- Removed redudant check for parents having a procname as now everything has
  a procname.

- Generalize the backtrace logic so that we print a backtrace from
  any failure of __register_sysctl_table that was not caused by
  a memmory allocation failure.  The backtrace allows us to track
  down who erroneously registered a sysctl table.

Bechmark before (CONFIG_SYSCTL_CHECK=y):
    make-dummies 0 999 -> 12s
    rmmod dummy        -> 0.08s

Bechmark before (CONFIG_SYSCTL_CHECK=n):
    make-dummies 0 999 -> 0.7s
    rmmod dummy        -> 0.06s
    make-dummies 0 99999 -> 1m13s
    rmmod dummy          -> 0.38s

Benchmark after:
    make-dummies 0 999 -> 0.65s
    rmmod dummy        -> 0.055s
    make-dummies 0 9999 -> 1m10s
    rmmod dummy         -> 0.39s

The sysctl sanity checks now impose no measurable cost.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-01-24 16:40:27 -08:00
..
array.c Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-security 2012-01-14 18:36:33 -08:00
base.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/audit 2012-01-17 16:41:31 -08:00
cmdline.c proc: switch /proc/cmdline to seq_file 2008-10-23 14:29:04 +04:00
consoles.c console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
cpuinfo.c proc: move /proc/cpuinfo code to fs/proc/cpuinfo.c 2008-10-23 15:05:11 +04:00
devices.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
generic.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
inode.c procfs: add hidepid= and gid= mount options 2012-01-10 16:30:54 -08:00
internal.h sysctl: Move the implementation into fs/proc/proc_sysctl.c 2012-01-24 16:37:54 -08:00
interrupts.c proc: move /proc/interrupts boilerplate code to fs/proc/interrupts.c 2008-10-23 15:15:46 +04:00
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
kcore.c /proc/kcore: fix seeking 2011-01-13 08:03:17 -08:00
kmsg.c procfs: Use generic_file_llseek in /proc/kmsg 2010-04-09 16:35:41 +02:00
loadavg.c sched, timers: cleanup avenrun users 2009-05-15 15:32:45 +02:00
Makefile ns: proc files for namespace naming policy. 2011-05-10 14:31:44 -07:00
meminfo.c fs/proc/meminfo.c: fix compilation error 2011-12-09 07:50:28 -08:00
mmu.c fs/proc/mmu.c: headers butchery 2007-10-17 08:42:48 -07:00
namespaces.c vfs: trim includes a bit 2012-01-03 22:57:13 -05:00
nommu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page.c thp: remove PG_buddy 2011-01-13 17:32:43 -08:00
proc_devtree.c of/flattree: Drop an uninteresting message to pr_debug level 2011-03-02 13:45:18 -07:00
proc_net.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
proc_sysctl.c sysctl: Improve the sysctl sanity checks 2012-01-24 16:40:27 -08:00
proc_tty.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
root.c procfs: add hidepid= and gid= mount options 2012-01-10 16:30:54 -08:00
softirqs.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
stat.c sched/accounting, proc: Fix /proc/stat interrupts sum 2012-01-16 08:13:27 +01:00
task_mmu.c mm: distinguish between mlocked and pinned pages 2011-10-31 17:30:46 -07:00
task_nommu.c report errors in /proc/*/*map* sanely 2011-03-23 16:36:50 -04:00
uptime.c Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip 2011-12-19 19:23:15 +01:00
version.c proc: switch /proc/version to seq_file 2008-10-23 14:19:58 +04:00
vmcore.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00