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authorKees Cook <kees@outflux.net>2007-05-08 00:26:04 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-08 11:15:02 -0700
commit5096add84b9e96e2e0a9c72675c442fe5433388a (patch)
treef0444013cb7db32596d2b6febafc1ee4c2a4ea1f /Documentation/filesystems
parent4a1ccb5b1eff949a90ab830869cb23d6609c3d5f (diff)
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.txt7
1 files changed, 7 insertions, 0 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 3f4b226572e..4f3e84c520a 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
-----------------------------------------------