From 5096add84b9e96e2e0a9c72675c442fe5433388a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 8 May 2007 00:26:04 -0700 Subject: 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 Cc: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/filesystems/proc.txt | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'Documentation') 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 ----------------------------------------------- -- cgit v1.2.3-70-g09d2