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| author | Kees Cook <kees@outflux.net> | 2007-05-08 11:26:04 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-08 22:15:02 +0400 |
| commit | 5096add84b9e96e2e0a9c72675c442fe5433388a (patch) | |
| tree | f0444013cb7db32596d2b6febafc1ee4c2a4ea1f /Documentation/filesystems | |
| parent | 4a1ccb5b1eff949a90ab830869cb23d6609c3d5f (diff) | |
| download | linux-5096add84b9e96e2e0a9c72675c442fe5433388a.tar.xz | |
proc: maps protection
The /proc/pid/ "maps", "smaps", and "numa_maps" files contain sensitive
information about the memory location and usage of processes. Issues:
- maps should not be world-readable, especially if programs expect any
kind of ASLR protection from local attackers.
- maps cannot just be 0400 because "-D_FORTIFY_SOURCE=2 -O2" makes glibc
check the maps when %n is in a *printf call, and a setuid(getuid())
process wouldn't be able to read its own maps file. (For reference
see http://lkml.org/lkml/2006/1/22/150)
- a system-wide toggle is needed to allow prior behavior in the case of
non-root applications that depend on access to the maps contents.
This change implements a check using "ptrace_may_attach" before allowing
access to read the maps contents. To control this protection, the new knob
/proc/sys/kernel/maps_protect has been added, with corresponding updates to
the procfs documentation.
[akpm@linux-foundation.org: build fixes]
[akpm@linux-foundation.org: New sysctl numbers are old hat]
Signed-off-by: Kees Cook <kees@outflux.net>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/proc.txt | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 3f4b226572e7..4f3e84c520a5 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1138,6 +1138,13 @@ determine whether or not they are still functioning properly. Because the NMI watchdog shares registers with oprofile, by disabling the NMI watchdog, oprofile may have more registers to utilize. +maps_protect +------------ + +Enables/Disables the protection of the per-process proc entries "maps" and +"smaps". When enabled, the contents of these files are visible only to +readers that are allowed to ptrace() the given process. + 2.4 /proc/sys/vm - The virtual memory subsystem ----------------------------------------------- |