From 6ff1b4426e3afc61dcb67299709fde9041d59265 Mon Sep 17 00:00:00 2001
From: Eric Paris <eparis@redhat.com>
Date: Sat, 10 Feb 2007 01:43:19 -0800
Subject: [PATCH] [PATCH] make reading /proc/sys/kernel/cap-bould not require
CAP_SYS_MODULE
Reading /proc/sys/kernel/cap-bound requires CAP_SYS_MODULE. (see
proc_dointvec_bset in kernel/sysctl.c)
sysctl appears to drive all over proc reading everything it can get it's
hands on and is complaining when it is being denied access to read
cap-bound. Clearly writing to cap-bound should be a sensitive operation
but requiring CAP_SYS_MODULE to read cap-bound seems a bit to strong. I
believe the information could with reasonable certainty be obtained by
looking at a bunch of the output of /proc/pid/status which has very low
security protection, so at best we are just getting a little obfuscation of
information.
Currently SELinux policy has to 'dontaudit' capability checks for
CAP_SYS_MODULE for things like sysctl which just want to read cap-bound.
In doing so we also as a byproduct have to hide warnings of potential
exploits such as if at some time that sysctl actually tried to load a
module. I wondered if anyone would have a problem opening cap-bound up to
read from anyone?
Acked-by: Chris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
kernel/sysctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 600b33358ded..41bbba1a15da 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1961,7 +1961,7 @@ int proc_dointvec_bset(ctl_table *table, int write, struct file *filp,
{
int op;
- if (!capable(CAP_SYS_MODULE)) {
+ if (write && !capable(CAP_SYS_MODULE)) {
return -EPERM;
}