KEYS: Make /proc/keys check to see if a key is possessed before security check
Make /proc/keys check to see if the calling process possesses each key before
performing the security check. The possession check can be skipped if the key
doesn't have the possessor-view permission bit set.
This causes the keys a process possesses to show up in /proc/keys, even if they
don't have matching user/group/other view permissions.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/keys/internal.h b/security/keys/internal.h
index 38783dc..addb67b 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -114,6 +114,10 @@
const void *description,
key_match_func_t match);
+extern key_ref_t search_my_process_keyrings(struct key_type *type,
+ const void *description,
+ key_match_func_t match,
+ const struct cred *cred);
extern key_ref_t search_process_keyrings(struct key_type *type,
const void *description,
key_match_func_t match,
@@ -134,6 +138,7 @@
struct key *dest_keyring,
unsigned long flags);
+extern int lookup_user_key_possessed(const struct key *key, const void *target);
extern key_ref_t lookup_user_key(key_serial_t id, unsigned long flags,
key_perm_t perm);
#define KEY_LOOKUP_CREATE 0x01
diff --git a/security/keys/proc.c b/security/keys/proc.c
index 068b66e..70373966 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -184,20 +184,36 @@
static int proc_keys_show(struct seq_file *m, void *v)
{
+ const struct cred *cred = current_cred();
struct rb_node *_p = v;
struct key *key = rb_entry(_p, struct key, serial_node);
struct timespec now;
unsigned long timo;
+ key_ref_t key_ref, skey_ref;
char xbuf[12];
int rc;
+ key_ref = make_key_ref(key, 0);
+
+ /* determine if the key is possessed by this process (a test we can
+ * skip if the key does not indicate the possessor can view it
+ */
+ if (key->perm & KEY_POS_VIEW) {
+ skey_ref = search_my_process_keyrings(key->type, key,
+ lookup_user_key_possessed,
+ cred);
+ if (!IS_ERR(skey_ref)) {
+ key_ref_put(skey_ref);
+ key_ref = make_key_ref(key, 1);
+ }
+ }
+
/* check whether the current task is allowed to view the key (assuming
* non-possession)
* - the caller holds a spinlock, and thus the RCU read lock, making our
* access to __current_cred() safe
*/
- rc = key_task_permission(make_key_ref(key, 0), current_cred(),
- KEY_VIEW);
+ rc = key_task_permission(key_ref, cred, KEY_VIEW);
if (rc < 0)
return 0;
diff --git a/security/keys/process_keys.c b/security/keys/process_keys.c
index 6b8e4ff..f8e7251 100644
--- a/security/keys/process_keys.c
+++ b/security/keys/process_keys.c
@@ -309,22 +309,19 @@
/*****************************************************************************/
/*
- * search the process keyrings for the first matching key
+ * search only my process keyrings for the first matching key
* - we use the supplied match function to see if the description (or other
* feature of interest) matches
* - we return -EAGAIN if we didn't find any matching key
* - we return -ENOKEY if we found only negative matching keys
*/
-key_ref_t search_process_keyrings(struct key_type *type,
- const void *description,
- key_match_func_t match,
- const struct cred *cred)
+key_ref_t search_my_process_keyrings(struct key_type *type,
+ const void *description,
+ key_match_func_t match,
+ const struct cred *cred)
{
- struct request_key_auth *rka;
key_ref_t key_ref, ret, err;
- might_sleep();
-
/* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
* searchable, but we failed to find a key or we found a negative key;
* otherwise we want to return a sample error (probably -EACCES) if
@@ -424,6 +421,36 @@
}
}
+ /* no key - decide on the error we're going to go for */
+ key_ref = ret ? ret : err;
+
+found:
+ return key_ref;
+}
+
+/*****************************************************************************/
+/*
+ * search the process keyrings for the first matching key
+ * - we use the supplied match function to see if the description (or other
+ * feature of interest) matches
+ * - we return -EAGAIN if we didn't find any matching key
+ * - we return -ENOKEY if we found only negative matching keys
+ */
+key_ref_t search_process_keyrings(struct key_type *type,
+ const void *description,
+ key_match_func_t match,
+ const struct cred *cred)
+{
+ struct request_key_auth *rka;
+ key_ref_t key_ref, ret = ERR_PTR(-EACCES), err;
+
+ might_sleep();
+
+ key_ref = search_my_process_keyrings(type, description, match, cred);
+ if (!IS_ERR(key_ref))
+ goto found;
+ err = key_ref;
+
/* if this process has an instantiation authorisation key, then we also
* search the keyrings of the process mentioned there
* - we don't permit access to request_key auth keys via this method
@@ -446,24 +473,19 @@
if (!IS_ERR(key_ref))
goto found;
- switch (PTR_ERR(key_ref)) {
- case -EAGAIN: /* no key */
- if (ret)
- break;
- case -ENOKEY: /* negative key */
- ret = key_ref;
- break;
- default:
- err = key_ref;
- break;
- }
+ ret = key_ref;
} else {
up_read(&cred->request_key_auth->sem);
}
}
/* no key - decide on the error we're going to go for */
- key_ref = ret ? ret : err;
+ if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY))
+ key_ref = ERR_PTR(-ENOKEY);
+ else if (err == ERR_PTR(-EACCES))
+ key_ref = ret;
+ else
+ key_ref = err;
found:
return key_ref;
@@ -474,7 +496,7 @@
/*
* see if the key we're looking at is the target key
*/
-static int lookup_user_key_possessed(const struct key *key, const void *target)
+int lookup_user_key_possessed(const struct key *key, const void *target)
{
return key == target;