linux/fs/proc
Vasiliy Kulikov 0499680a42 procfs: add hidepid= and gid= mount options
Add support for mount options to restrict access to /proc/PID/
directories.  The default backward-compatible "relaxed" behaviour is left
untouched.

The first mount option is called "hidepid" and its value defines how much
info about processes we want to be available for non-owners:

hidepid=0 (default) means the old behavior - anybody may read all
world-readable /proc/PID/* files.

hidepid=1 means users may not access any /proc/<pid>/ directories, but
their own.  Sensitive files like cmdline, sched*, status are now protected
against other users.  As permission checking done in proc_pid_permission()
and files' permissions are left untouched, programs expecting specific
files' modes are not confused.

hidepid=2 means hidepid=1 plus all /proc/PID/ will be invisible to other
users.  It doesn't mean that it hides whether a process exists (it can be
learned by other means, e.g.  by kill -0 $PID), but it hides process' euid
and egid.  It compicates intruder's task of gathering info about running
processes, whether some daemon runs with elevated privileges, whether
another user runs some sensitive program, whether other users run any
program at all, etc.

gid=XXX defines a group that will be able to gather all processes' info
(as in hidepid=0 mode).  This group should be used instead of putting
nonroot user in sudoers file or something.  However, untrusted users (like
daemons, etc.) which are not supposed to monitor the tasks in the whole
system should not be added to the group.

hidepid=1 or higher is designed to restrict access to procfs files, which
might reveal some sensitive private information like precise keystrokes
timings:

http://www.openwall.com/lists/oss-security/2011/11/05/3

hidepid=1/2 doesn't break monitoring userspace tools.  ps, top, pgrep, and
conky gracefully handle EPERM/ENOENT and behave as if the current user is
the only user running processes.  pstree shows the process subtree which
contains "pstree" process.

Note: the patch doesn't deal with setuid/setgid issues of keeping
preopened descriptors of procfs files (like
https://lkml.org/lkml/2011/2/7/368).  We rely on that the leaked
information like the scheduling counters of setuid apps doesn't threaten
anybody's privacy - only the user started the setuid program may read the
counters.

Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg KH <greg@kroah.com>
Cc: Theodore Tso <tytso@MIT.EDU>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: James Morris <jmorris@namei.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-01-10 16:30:54 -08:00
..
array.c [S390] cputime: add sparse checking and cleanup 2011-12-15 14:56:19 +01:00
base.c procfs: add hidepid= and gid= mount options 2012-01-10 16:30:54 -08:00
cmdline.c
consoles.c console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
cpuinfo.c
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 procfs: parse mount options 2012-01-10 16:30:54 -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
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 Merge branch 'akpm' (Andrew's incoming - part two) 2011-11-02 16:07:27 -07:00
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 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-01-06 08:44:54 -08:00
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
vmcore.c fs: add export.h to files using EXPORT_SYMBOL/THIS_MODULE macros 2011-10-31 19:30:31 -04:00