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authorVasily Averin <vvs@virtuozzo.com>2015-06-25 15:01:44 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-08-03 09:29:15 -0700
commitae41bfc68161ea5d280091ccb9593e9f68d5db44 (patch)
tree029689038552ce42f443902e949b3c219bd83618
parentf843b096c026fba1c2c584a5b9644bb2974bbff7 (diff)
security_syslog() should be called once only
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 <vvs@virtuozzo.com> Cc: Kees Cook <keescook@chromium.org> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Eric Paris <eparis@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--kernel/printk/printk.c11
1 files changed, 4 insertions, 7 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index c099b082cd02..bff0169e1ad8 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;