[tip:timers/core] posix-clocks: Check write permissions in posix syscalls

tip-bot for Torben Hohn
2011-03-12T20:31:30Z

Commit-ID: 6e6823d17b157f185be09f4c70181299f9273f0b
Gitweb: http://git.kernel.org/tip/6e6823d17b157f185be09f4c70181299f9273f0b
Author: Torben Hohn <torbenh@gmx.de>
AuthorDate: Thu, 3 Mar 2011 18:26:14 +0100
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitDate: Sat, 12 Mar 2011 21:27:07 +0100

posix-clocks: Check write permissions in posix syscalls

pc_clock_settime() and pc_clock_adjtime() do not check whether the fd
was opened in write mode, so a clock can be set with a read only fd.

[ tglx: We deliberately do not return -EPERM as we want this to be
distingushable from the capability based permission check ]

Signed-off-by: Torben Hohn <torbenh@gmx.de>
LKML-Reference: <1299173174-348-4-git-send-email-torbenh@gmx.de>
Cc: Richard Cochran <richard.cochran@omicron.at>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/posix-clock.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index 04498cb..25028dd 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -287,11 +287,16 @@ static int pc_clock_adjtime(clockid_t id, struct timex *tx)
if (err)
return err;

+ if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
+ err = -EACCES;
+ goto out;
+ }
+
if (cd.clk->ops.clock_adjtime)
err = cd.clk->ops.clock_adjtime(cd.clk, tx);
else
err = -EOPNOTSUPP;
-
+out:
put_clock_desc(&cd);

return err;
@@ -344,11 +349,16 @@ static int pc_clock_settime(clockid_t id, const struct timespec *ts)
if (err)
return err;

+ if ((cd.fp->f_mode & FMODE_WRITE) == 0) {
+ err = -EACCES;
+ goto out;
+ }
+
if (cd.clk->ops.clock_settime)
err = cd.clk->ops.clock_settime(cd.clk, ts);
else
err = -EOPNOTSUPP;
-
+out:
put_clock_desc(&cd);

return err;