[PATCH v2 3/9] procfs: Document the proposed solution to protect procfs entries

Djalal Harouni
2013-10-01T20:30:03Z

Note the proposed solution to protect sensitive procfs entries as
code comment.

Cc: Kees Cook <keescook@chromium.org>
Suggested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Djalal Harouni <tixxdz@opendz.org>
---
fs/proc/base.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c29eeae..8d21316 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -102,6 +102,17 @@
*
* The classic example of a problem is opening file descriptors
* in /proc for a task before it execs a suid executable.
+ *
+ * Solution for sensitive files:
+ * At each system call: open(),read(),write()... Perform the
+ * ptrace_may_access() check.
+ *
+ * After open() and during each system call: read(),write()...
+ * If the cred of current have changed then perform the
+ * proc_allow_access() check after the ptrace_may_access() one.
+ *
+ * This way we can determine if current has gained more privileges
+ * by execs a suid executable.
*/

struct pid_entry {
--
1.7.11.7