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authorLinus Torvalds <torvalds@linux-foundation.org>2012-01-10 16:42:48 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-01-10 16:42:48 -0800
commit40ba587923ae67090d9f141c1d3c951be5c1420e (patch)
tree342a72fc0ee13a0d2496ef970b64dfeadf1355d2 /Documentation/filesystems
parent54c2c5761febcca46c8037d3a81612991e6c209a (diff)
parent6b550f9495947fc279d12c38feaf98500e8d0646 (diff)
downloadlwn-40ba587923ae67090d9f141c1d3c951be5c1420e.tar.gz
lwn-40ba587923ae67090d9f141c1d3c951be5c1420e.zip
Merge branch 'akpm' (aka "Andrew's patch-bomb")
Andrew elucidates: - First installmeant of MM. We have a HUGE number of MM patches this time. It's crazy. - MAINTAINERS updates - backlight updates - leds - checkpatch updates - misc ELF stuff - rtc updates - reiserfs - procfs - some misc other bits * akpm: (124 commits) user namespace: make signal.c respect user namespaces workqueue: make alloc_workqueue() take printf fmt and args for name procfs: add hidepid= and gid= mount options procfs: parse mount options procfs: introduce the /proc/<pid>/map_files/ directory procfs: make proc_get_link to use dentry instead of inode signal: add block_sigmask() for adding sigmask to current->blocked sparc: make SA_NOMASK a synonym of SA_NODEFER reiserfs: don't lock root inode searching reiserfs: don't lock journal_init() reiserfs: delay reiserfs lock until journal initialization reiserfs: delete comments referring to the BKL drivers/rtc/interface.c: fix alarm rollover when day or month is out-of-range drivers/rtc/rtc-twl.c: add DT support for RTC inside twl4030/twl6030 drivers/rtc/: remove redundant spi driver bus initialization drivers/rtc/rtc-jz4740.c: make jz4740_rtc_driver static drivers/rtc/rtc-mc13xxx.c: make mc13xxx_rtc_idtable static rtc: convert drivers/rtc/* to use module_platform_driver() drivers/rtc/rtc-wm831x.c: convert to devm_kzalloc() drivers/rtc/rtc-wm831x.c: remove unused period IRQ handler ...
Diffstat (limited to 'Documentation/filesystems')
-rw-r--r--Documentation/filesystems/proc.txt39
1 files changed, 39 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 0ec91f03422e..12fee132fbe2 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -41,6 +41,8 @@ Table of Contents
3.5 /proc/<pid>/mountinfo - Information about mounts
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
+ 4 Configuring procfs
+ 4.1 Mount options
------------------------------------------------------------------------------
Preface
@@ -1542,3 +1544,40 @@ a task to set its own or one of its thread siblings comm value. The comm value
is limited in size compared to the cmdline value, so writing anything longer
then the kernel's TASK_COMM_LEN (currently 16 chars) will result in a truncated
comm value.
+
+
+------------------------------------------------------------------------------
+Configuring procfs
+------------------------------------------------------------------------------
+
+4.1 Mount options
+---------------------
+
+The following mount options are supported:
+
+ hidepid= Set /proc/<pid>/ access mode.
+ gid= Set the group authorized to learn processes information.
+
+hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories
+(default).
+
+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. This makes it impossible to learn whether any user runs
+specific program (given the program doesn't reveal itself by its behaviour).
+As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users,
+poorly written programs passing sensitive information via program arguments are
+now protected against local eavesdroppers.
+
+hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other
+users. It doesn't mean that it hides a fact whether a process with a specific
+pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"),
+but it hides process' uid and gid, which may be learned by stat()'ing
+/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering
+information about running processes, whether some daemon runs with elevated
+privileges, whether other user runs some sensitive program, whether other users
+run any program at all, etc.
+
+gid= defines a group authorized to learn processes information otherwise
+prohibited by hidepid=. If you use some daemon like identd which needs to learn
+information about processes information, just add identd to this group.