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check_syslog_permissions() cleanup 

Patch fixes drawbacks in heck_syslog_permissions() noticed by AKPM:
"from_file handling makes me cry.

That's not a boolean - it's an enumerated value with two values
currently defined.

But the code in check_syslog_permissions() treats it as a boolean and
also hardwires the knowledge that SYSLOG_FROM_PROC == 1 (or == `true`).

And the name is wrong: it should be called from_proc to match
SYSLOG_FROM_PROC."

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>
hifive-unleashed-5.1
Vasily Averin 2015-06-25 15:01:47 -07:00 committed by Linus Torvalds
parent d194e5d666
commit 3ea4331c60
2 changed files with 8 additions and 8 deletions
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6
include/linux/syslog.h
View File

@ -47,12 +47,12 @@
#define SYSLOG_FROM_READER 0
#define SYSLOG_FROM_PROC 1
int do_syslog(int type, char __user *buf, int count, bool from_file);
int do_syslog(int type, char __user *buf, int count, int source);
#ifdef CONFIG_PRINTK
int check_syslog_permissions(int type, bool from_file);
int check_syslog_permissions(int type, int source);
#else
static inline int check_syslog_permissions(int type, bool from_file)
static inline int check_syslog_permissions(int type, int source)
{
return 0;
}

10
kernel/printk/printk.c
View File

@ -489,13 +489,13 @@ static int syslog_action_restricted(int type)
type != SYSLOG_ACTION_SIZE_BUFFER;
}
int check_syslog_permissions(int type, bool from_file)
int check_syslog_permissions(int type, int source)
{
/*
* If this is from /proc/kmsg and we've already opened it, then we've
* already done the capabilities checks at open time.
*/
if (from_file && type != SYSLOG_ACTION_OPEN)
if (source == SYSLOG_FROM_PROC && type != SYSLOG_ACTION_OPEN)
goto ok;
if (syslog_action_restricted(type)) {
@ -1290,13 +1290,13 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
return len;
}
int do_syslog(int type, char __user *buf, int len, bool from_file)
int do_syslog(int type, char __user *buf, int len, int source)
{
bool clear = false;
static int saved_console_loglevel = LOGLEVEL_DEFAULT;
int error;
error = check_syslog_permissions(type, from_file);
error = check_syslog_permissions(type, source);
if (error)
goto out;
@ -1379,7 +1379,7 @@ int do_syslog(int type, char __user *buf, int len, bool from_file)
syslog_prev = 0;
syslog_partial = 0;
}
if (from_file) {
if (source == SYSLOG_FROM_PROC) {
/*
* Short-cut for poll(/"proc/kmsg") which simply checks
* for pending data, not the size; return the count of