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Commit 3ea4331c authored by Vasily Averin's avatar Vasily Averin Committed by Linus Torvalds
Browse files

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: default avatarVasily 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent d194e5d6

include/linux/syslog.h

+3 −3
Original line number Diff line number Diff line
@@ -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;

}

kernel/printk/printk.c

+5 −5
Original line number Diff line number Diff line
@@ -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