git: edf6dd82e966 - main - pf: fix use-after-free from pf_find_state_all
- Go to: [ bottom of page ] [ top of archives ] [ this month ]
Date: Mon, 01 Nov 2021 20:00:17 UTC
The branch main has been updated by mjg: URL: https://cgit.FreeBSD.org/src/commit/?id=edf6dd82e9662b72c17483de4de5575dd5acd972 commit edf6dd82e9662b72c17483de4de5575dd5acd972 Author: Mateusz Guzik <mjg@FreeBSD.org> AuthorDate: 2021-11-01 13:02:43 +0000 Commit: Mateusz Guzik <mjg@FreeBSD.org> CommitDate: 2021-11-01 19:59:05 +0000 pf: fix use-after-free from pf_find_state_all state was returned without any locks nor references held Reviewed by: kp Sponsored by: Rubicon Communications, LLC ("Netgate") --- sys/netpfil/pf/pf.c | 21 +++++++++++++++++++-- sys/netpfil/pf/pf_ioctl.c | 42 +++++++++++++++++++++++------------------- 2 files changed, 42 insertions(+), 21 deletions(-) diff --git a/sys/netpfil/pf/pf.c b/sys/netpfil/pf/pf.c index 61eea329a7f7..d7644b47f700 100644 --- a/sys/netpfil/pf/pf.c +++ b/sys/netpfil/pf/pf.c @@ -1510,6 +1510,9 @@ pf_find_state(struct pfi_kkif *kif, struct pf_state_key_cmp *key, u_int dir) return (NULL); } +/* + * Returns with ID hash slot locked on success. + */ struct pf_kstate * pf_find_state_all(struct pf_state_key_cmp *key, u_int dir, int *more) { @@ -1547,14 +1550,17 @@ pf_find_state_all(struct pf_state_key_cmp *key, u_int dir, int *more) second_run: TAILQ_FOREACH(s, &sk->states[idx], key_list[idx]) { if (more == NULL) { + PF_STATE_LOCK(s); PF_HASHROW_UNLOCK(kh); return (s); } if (ret) (*more)++; - else + else { ret = s; + PF_STATE_LOCK(s); + } } if (inout == 1) { inout = 0; @@ -1566,13 +1572,24 @@ second_run: return (ret); } +/* + * FIXME + * This routine is inefficient -- locks the state only to unlock immediately on + * return. + * It is racy -- after the state is unlocked nothing stops other threads from + * removing it. + */ bool pf_find_state_all_exists(struct pf_state_key_cmp *key, u_int dir) { struct pf_kstate *s; s = pf_find_state_all(key, dir, NULL); - return (s != NULL); + if (s != NULL) { + PF_STATE_UNLOCK(s); + return (true); + } + return (false); } /* END state table stuff */ diff --git a/sys/netpfil/pf/pf_ioctl.c b/sys/netpfil/pf/pf_ioctl.c index ee265de65b45..1cfedf19e662 100644 --- a/sys/netpfil/pf/pf_ioctl.c +++ b/sys/netpfil/pf/pf_ioctl.c @@ -2029,19 +2029,20 @@ pf_label_match(const struct pf_krule *rule, const char *label) static unsigned int pf_kill_matching_state(struct pf_state_key_cmp *key, int dir) { - struct pf_kstate *match; + struct pf_kstate *s; int more = 0; - unsigned int killed = 0; - /* Call with unlocked hashrow */ + s = pf_find_state_all(key, dir, &more); + if (s == NULL) + return (0); - match = pf_find_state_all(key, dir, &more); - if (match && !more) { - pf_unlink_state(match, 0); - killed++; + if (more) { + PF_STATE_UNLOCK(s); + return (0); } - return (killed); + pf_unlink_state(s, PF_ENTER_LOCKED); + return (1); } static int @@ -3159,18 +3160,21 @@ DIOCGETSTATESV2_full: key.port[didx] = pnl->dport; state = pf_find_state_all(&key, direction, &m); - - if (m > 1) - error = E2BIG; /* more than one state */ - else if (state != NULL) { - /* XXXGL: not locked read */ - sk = state->key[sidx]; - PF_ACPY(&pnl->rsaddr, &sk->addr[sidx], sk->af); - pnl->rsport = sk->port[sidx]; - PF_ACPY(&pnl->rdaddr, &sk->addr[didx], sk->af); - pnl->rdport = sk->port[didx]; - } else + if (state == NULL) { error = ENOENT; + } else { + if (m > 1) { + PF_STATE_UNLOCK(state); + error = E2BIG; /* more than one state */ + } else { + sk = state->key[sidx]; + PF_ACPY(&pnl->rsaddr, &sk->addr[sidx], sk->af); + pnl->rsport = sk->port[sidx]; + PF_ACPY(&pnl->rdaddr, &sk->addr[didx], sk->af); + pnl->rdport = sk->port[didx]; + PF_STATE_UNLOCK(state); + } + } } break; }