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authorEric Biggers <ebiggers@google.com>2017-09-18 11:38:29 -0700
committerDavid Howells <dhowells@redhat.com>2017-09-25 15:19:57 +0100
commit4aa68e07d845562561f5e73c04aa521376e95252 (patch)
treed8ca3fbc77070caa26fd327fd5d7e21a322add34 /security
parentKEYS: reset parent each time before searching key_user_tree (diff)
downloadlinux-dev-4aa68e07d845562561f5e73c04aa521376e95252.tar.xz
linux-dev-4aa68e07d845562561f5e73c04aa521376e95252.zip
KEYS: restrict /proc/keys by credentials at open time
When checking for permission to view keys whilst reading from /proc/keys, we should use the credentials with which the /proc/keys file was opened. This is because, in a classic type of exploit, it can be possible to bypass checks for the *current* credentials by passing the file descriptor to a suid program. Following commit 34dbbcdbf633 ("Make file credentials available to the seqfile interfaces") we can finally fix it. So let's do it. Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to '')
-rw-r--r--security/keys/proc.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/security/keys/proc.c b/security/keys/proc.c
index bf08d02b6646..de834309d100 100644
--- a/security/keys/proc.c
+++ b/security/keys/proc.c
@@ -187,7 +187,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
struct keyring_search_context ctx = {
.index_key.type = key->type,
.index_key.description = key->description,
- .cred = current_cred(),
+ .cred = m->file->f_cred,
.match_data.cmp = lookup_user_key_possessed,
.match_data.raw_data = key,
.match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
@@ -207,11 +207,7 @@ static int proc_keys_show(struct seq_file *m, void *v)
}
}
- /* 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
- */
+ /* check whether the current task is allowed to view the key */
rc = key_task_permission(key_ref, ctx.cred, KEY_NEED_VIEW);
if (rc < 0)
return 0;