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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 /fs/proc/task_nommu.c
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 'fs/proc/task_nommu.c')
-rw-r--r--fs/proc/task_nommu.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 7cddf6b8635a..d8b8c7183c24 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -2,6 +2,7 @@
#include <linux/mm.h>
#include <linux/file.h>
#include <linux/mount.h>
+#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include "internal.h"
@@ -143,6 +144,12 @@ out:
static int show_map(struct seq_file *m, void *_vml)
{
struct vm_list_struct *vml = _vml;
+ struct proc_maps_private *priv = m->private;
+ struct task_struct *task = priv->task;
+
+ if (maps_protect && !ptrace_may_attach(task))
+ return -EACCES;
+
return nommu_vma_show(m, vml->vma);
}