提交 6ff1b442 编写于 作者: E Eric Paris 提交者: Linus Torvalds

[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: NChris Wright <chrisw@sous-sol.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 daa88c8d
......@@ -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;
}
......
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