The patch titled
Subject: security_syslog() should be called once only
has been added to the -mm tree. Its filename is
security_syslog-should-be-called-once-only.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/security_syslog-should-be-called-once-only.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/security_syslog-should-be-called-once-only.patch
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------------------------------------------------------
From: Vasily Averin <vvs@xxxxxxxxxxxxx>
Subject: security_syslog() should be called once only
The final version of 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@xxxxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Josh Boyer <jwboyer@xxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/printk/printk.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
diff -puN kernel/printk/printk.c~security_syslog-should-be-called-once-only kernel/printk/printk.c
--- a/kernel/printk/printk.c~security_syslog-should-be-called-once-only
+++ a/kernel/printk/printk.c
@@ -496,11 +496,11 @@ int check_syslog_permissions(int type, b
* 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.
@@ -510,10 +510,11 @@ int check_syslog_permissions(int type, b
"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);
}
@@ -1299,10 +1300,6 @@ int do_syslog(int type, char __user *buf
if (error)
goto out;
- error = security_syslog(type);
- if (error)
- return error;
-
switch (type) {
case SYSLOG_ACTION_CLOSE: /* Close log */
break;
_
Patches currently in -mm which might be from vvs@xxxxxxxxxxxxx are
security_syslog-should-be-called-once-only.patch
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