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| author |   Eric Biggers <ebiggers@google.com> | 2017-09-18 11:38:29 -0700 |
|---|---|---|
| committer |   David Howells <dhowells@redhat.com> | 2017-09-25 15:19:57 +0100 |
| commit | 4aa68e07d845562561f5e73c04aa521376e95252 (patch) | |
| tree | d8ca3fbc77070caa26fd327fd5d7e21a322add34 /security/keys | |
| parent | KEYS: reset parent each time before searching key_user_tree (diff) | |
| download | linux-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 'security/keys')
| -rw-r--r-- | security/keys/proc.c | 8 |
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; |