Messages in this thread Patch in this message | | | Date | Sun, 24 May 2015 19:18:40 +0300 | From | Vasily Averin <> | Subject | [PATCH v2] security_syslog() should be called once only |
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v2: subject changed, patch comment modified
Fixes: 637241a900cb ("kmsg: honor dmesg_restrict sysctl on /dev/kmsg")
Final version of patch 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.
Signed-off-by: Vasily Averin <vvs@virtuozzo.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 c099b08..bff0169 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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