[PATCH] keys: restrict contents of /proc/keys to Viewable keys
Restrict /proc/keys such that only those keys to which the current task is
granted View permission are presented.
The documentation is also updated to reflect these changes.
Signed-off-by: Michael LeMay <mdlemay@epoch.ncsc.mil>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/keys.txt b/Documentation/keys.txt
index 3bbe157..70e83cf 100644
--- a/Documentation/keys.txt
+++ b/Documentation/keys.txt
@@ -270,9 +270,17 @@
(*) /proc/keys
- This lists all the keys on the system, giving information about their
- type, description and permissions. The payload of the key is not available
- this way:
+ This lists the keys that are currently viewable by the task reading the
+ file, giving information about their type, description and permissions.
+ It is not possible to view the payload of the key this way, though some
+ information about it may be given.
+
+ The only keys included in the list are those that grant View permission to
+ the reading process whether or not it possesses them. Note that LSM
+ security checks are still performed, and may further filter out keys that
+ the current process is not authorised to view.
+
+ The contents of the file look like this:
SERIAL FLAGS USAGE EXPY PERM UID GID TYPE DESCRIPTION: SUMMARY
00000001 I----- 39 perm 1f3f0000 0 0 keyring _uid_ses.0: 1/4
@@ -300,7 +308,7 @@
(*) /proc/key-users
This file lists the tracking data for each user that has at least one key
- on the system. Such data includes quota information and statistics:
+ on the system. Such data includes quota information and statistics:
[root@andromeda root]# cat /proc/key-users
0: 46 45/45 1/100 13/10000
diff --git a/security/Kconfig b/security/Kconfig
index 34f5934..67785df 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -22,16 +22,22 @@
If you are unsure as to whether this is required, answer N.
config KEYS_DEBUG_PROC_KEYS
- bool "Enable the /proc/keys file by which all keys may be viewed"
+ bool "Enable the /proc/keys file by which keys may be viewed"
depends on KEYS
help
- This option turns on support for the /proc/keys file through which
- all the keys on the system can be listed.
+ This option turns on support for the /proc/keys file - through which
+ can be listed all the keys on the system that are viewable by the
+ reading process.
- This option is a slight security risk in that it makes it possible
- for anyone to see all the keys on the system. Normally the manager
- pretends keys that are inaccessible to a process don't exist as far
- as that process is concerned.
+ The only keys included in the list are those that grant View
+ permission to the reading process whether or not it possesses them.
+ Note that LSM security checks are still performed, and may further
+ filter out keys that the current process is not authorised to view.
+
+ Only key attributes are listed here; key payloads are not included in
+ the resulting table.
+
+ If you are unsure as to whether this is required, answer N.
config SECURITY
bool "Enable different security models"
diff --git a/security/keys/proc.c b/security/keys/proc.c
index 12b750e..686a9ee 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -137,6 +137,13 @@
struct timespec now;
unsigned long timo;
char xbuf[12];
+ int rc;
+
+ /* check whether the current task is allowed to view the key (assuming
+ * non-possession) */
+ rc = key_task_permission(make_key_ref(key, 0), current, KEY_VIEW);
+ if (rc < 0)
+ return 0;
now = current_kernel_time();