3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me
know.
------------------
From: Vasily Averin <v...@virtuozzo.com>
commit d194e5d666225b04c7754471df0948f645b6ab3a upstream.
The final version of commit 637241a900cb ("kmsg: honor dmesg_restrict
sysctl on /dev/kmsg") lost few hooks, as result security_syslog() are
processed incorrectly:
- open of /dev/kmsg checks syslog access permissions by using
check_syslog_permissions() where security_syslog() is not called if
dmesg_restrict is set.
- syslog syscall and /proc/kmsg calls do_syslog() where security_syslog
can be executed twice (inside check_syslog_permissions() and then
directly in do_syslog())
With this patch security_syslog() is called once only in all
syslog-related operations regardless of dmesg_restrict value.
Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg")
Signed-off-by: Vasily Averin <v...@virtuozzo.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Josh Boyer <jwbo...@redhat.com>
Cc: Eric Paris <epa...@redhat.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Kamal Mostafa <ka...@canonical.com>
---
kernel/printk/printk.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2cdd353..4b52ee5 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -484,11 +484,11 @@ int check_syslog_permissions(int type, bool from_file)
* already done the capabilities checks at open time.
*/
if (from_file && type != SYSLOG_ACTION_OPEN)
- return 0;
+ goto ok;
if (syslog_action_restricted(type)) {
if (capable(CAP_SYSLOG))
- return 0;
+ goto ok;
/*
* For historical reasons, accept CAP_SYS_ADMIN too, with
* a warning.
@@ -498,10 +498,11 @@ int check_syslog_permissions(int type, bool from_file)
"CAP_SYS_ADMIN but no CAP_SYSLOG "
"(deprecated).\n",
current->comm, task_pid_nr(current));
- return 0;
+ goto ok;
}
return -EPERM;
}
+ok:
return security_syslog(type);
}
@@ -1263,10 +1264,6 @@ int do_syslog(int type, char __user *buf, int len, bool
from_file)
if (error)
goto out;
- error = security_syslog(type);
- if (error)
- return error;
-
switch (type) {
case SYSLOG_ACTION_CLOSE: /* Close log */
break;
--
1.9.1
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