diff options
| author | Eric Biggers <ebiggers@google.com> | 2019-02-22 15:36:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-27 10:07:00 +0100 |
| commit | dc070cdb427e42a6b6b503427a029083e307ed34 (patch) | |
| tree | d8c7a2b8b9e2c9f9760f15457f8dcbf18a9f0919 /security | |
| parent | acf476e026ee99e6cf2ad169f938b4668112582b (diff) | |
KEYS: always initialize keyring_index_key::desc_len
commit ede0fa98a900e657d1fcd80b50920efc896c1a4c upstream.
syzbot hit the 'BUG_ON(index_key->desc_len == 0);' in __key_link_begin()
called from construct_alloc_key() during sys_request_key(), because the
length of the key description was never calculated.
The problem is that we rely on ->desc_len being initialized by
search_process_keyrings(), specifically by search_nested_keyrings().
But, if the process isn't subscribed to any keyrings that never happens.
Fix it by always initializing keyring_index_key::desc_len as soon as the
description is set, like we already do in some places.
The following program reproduces the BUG_ON() when it's run as root and
no session keyring has been installed. If it doesn't work, try removing
pam_keyinit.so from /etc/pam.d/login and rebooting.
#include <stdlib.h>
#include <unistd.h>
#include <keyutils.h>
int main(void)
{
int id = add_key("keyring", "syz", NULL, 0, KEY_SPEC_USER_KEYRING);
keyctl_setperm(id, KEY_OTH_WRITE);
setreuid(5000, 5000);
request_key("user", "desc", "", id);
}
Reported-by: syzbot+ec24e95ea483de0a24da@syzkaller.appspotmail.com
Fixes: b2a4df200d57 ("KEYS: Expand the capacity of a keyring")
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.morris@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/keys/keyring.c | 4 | ||||
| -rw-r--r-- | security/keys/proc.c | 3 | ||||
| -rw-r--r-- | security/keys/request_key.c | 1 | ||||
| -rw-r--r-- | security/keys/request_key_auth.c | 2 |
4 files changed, 4 insertions, 6 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 4e9b4d23e20e..7308067dcc5d 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -652,9 +652,6 @@ static bool search_nested_keyrings(struct key *keyring, BUG_ON((ctx->flags & STATE_CHECKS) == 0 || (ctx->flags & STATE_CHECKS) == STATE_CHECKS); - if (ctx->index_key.description) - ctx->index_key.desc_len = strlen(ctx->index_key.description); - /* Check to see if this top-level keyring is what we are looking for * and whether it is valid or not. */ @@ -912,6 +909,7 @@ key_ref_t keyring_search(key_ref_t keyring, struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, + .index_key.desc_len = strlen(description), .cred = current_cred(), .match_data.cmp = key_default_cmp, .match_data.raw_data = description, diff --git a/security/keys/proc.c b/security/keys/proc.c index 036128682463..ec493ddadd11 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -186,8 +186,7 @@ static int proc_keys_show(struct seq_file *m, void *v) int rc; struct keyring_search_context ctx = { - .index_key.type = key->type, - .index_key.description = key->description, + .index_key = key->index_key, .cred = current_cred(), .match_data.cmp = lookup_user_key_possessed, .match_data.raw_data = key, diff --git a/security/keys/request_key.c b/security/keys/request_key.c index cb7f8f730c6d..aa292e01c562 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -544,6 +544,7 @@ struct key *request_key_and_link(struct key_type *type, struct keyring_search_context ctx = { .index_key.type = type, .index_key.description = description, + .index_key.desc_len = strlen(description), .cred = current_cred(), .match_data.cmp = key_default_cmp, .match_data.raw_data = description, diff --git a/security/keys/request_key_auth.c b/security/keys/request_key_auth.c index ba74a0b4d1cb..f60baeb338e5 100644 --- a/security/keys/request_key_auth.c +++ b/security/keys/request_key_auth.c @@ -254,7 +254,7 @@ struct key *key_get_instantiation_authkey(key_serial_t target_id) struct key *authkey; key_ref_t authkey_ref; - sprintf(description, "%x", target_id); + ctx.index_key.desc_len = sprintf(description, "%x", target_id); authkey_ref = search_process_keyrings(&ctx); |