From 3b59df46a449ec9975146d71318c4777ad086744 Mon Sep 17 00:00:00 2001 From: Steffen Klassert Date: Tue, 4 Sep 2012 00:03:29 +0000 Subject: xfrm: Workaround incompatibility of ESN and async crypto ESN for esp is defined in RFC 4303. This RFC assumes that the sequence number counters are always up to date. However, this is not true if an async crypto algorithm is employed. If the sequence number counters are not up to date on sequence number check, we may incorrectly update the upper 32 bit of the sequence number. This leads to a DOS. We workaround this by comparing the upper sequence number, (used for authentication) with the upper sequence number computed after the async processing. We drop the packet if these numbers are different. To do this, we introduce a recheck function that does this check in the ESN case. Signed-off-by: Steffen Klassert Acked-by: Herbert Xu Signed-off-by: David S. Miller --- net/xfrm/xfrm_input.c | 2 +- net/xfrm/xfrm_replay.c | 15 +++++++++++++++ 2 files changed, 16 insertions(+), 1 deletion(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index 54a0dc2e2f8..ab2bb42fe09 100644 --- a/net/xfrm/xfrm_input.c +++ b/net/xfrm/xfrm_input.c @@ -212,7 +212,7 @@ resume: /* only the first xfrm gets the encap type */ encap_type = 0; - if (async && x->repl->check(x, skb, seq)) { + if (async && x->repl->recheck(x, skb, seq)) { XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR); goto drop_unlock; } diff --git a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c index 2f6d11d04a2..3efb07d3eb2 100644 --- a/net/xfrm/xfrm_replay.c +++ b/net/xfrm/xfrm_replay.c @@ -420,6 +420,18 @@ err: return -EINVAL; } +static int xfrm_replay_recheck_esn(struct xfrm_state *x, + struct sk_buff *skb, __be32 net_seq) +{ + if (unlikely(XFRM_SKB_CB(skb)->seq.input.hi != + htonl(xfrm_replay_seqhi(x, net_seq)))) { + x->stats.replay_window++; + return -EINVAL; + } + + return xfrm_replay_check_esn(x, skb, net_seq); +} + static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq) { unsigned int bitnr, nr, i; @@ -479,6 +491,7 @@ static void xfrm_replay_advance_esn(struct xfrm_state *x, __be32 net_seq) static struct xfrm_replay xfrm_replay_legacy = { .advance = xfrm_replay_advance, .check = xfrm_replay_check, + .recheck = xfrm_replay_check, .notify = xfrm_replay_notify, .overflow = xfrm_replay_overflow, }; @@ -486,6 +499,7 @@ static struct xfrm_replay xfrm_replay_legacy = { static struct xfrm_replay xfrm_replay_bmp = { .advance = xfrm_replay_advance_bmp, .check = xfrm_replay_check_bmp, + .recheck = xfrm_replay_check_bmp, .notify = xfrm_replay_notify_bmp, .overflow = xfrm_replay_overflow_bmp, }; @@ -493,6 +507,7 @@ static struct xfrm_replay xfrm_replay_bmp = { static struct xfrm_replay xfrm_replay_esn = { .advance = xfrm_replay_advance_esn, .check = xfrm_replay_check_esn, + .recheck = xfrm_replay_recheck_esn, .notify = xfrm_replay_notify_bmp, .overflow = xfrm_replay_overflow_esn, }; -- cgit v1.2.3 From ee8372dd1989287c5eedb69d44bac43f69e496f1 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Mon, 10 Sep 2012 22:09:45 +0000 Subject: xfrm: invalidate dst on policy insertion/deletion When a policy is inserted or deleted, all dst should be recalculated. Signed-off-by: Nicolas Dichtel Signed-off-by: David S. Miller --- net/xfrm/xfrm_policy.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 5a2aa17e4d3..ab2ce7d5152 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -585,6 +585,7 @@ int xfrm_policy_insert(int dir, struct xfrm_policy *policy, int excl) xfrm_pol_hold(policy); net->xfrm.policy_count[dir]++; atomic_inc(&flow_cache_genid); + rt_genid_bump(net); if (delpol) __xfrm_policy_unlink(delpol, dir); policy->index = delpol ? delpol->index : xfrm_gen_index(net, dir); -- cgit v1.2.3 From 864745d291b5ba80ea0bd0edcbe67273de368836 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Thu, 13 Sep 2012 11:41:26 +0000 Subject: xfrm_user: return error pointer instead of NULL When dump_one_state() returns an error, e.g. because of a too small buffer to dump the whole xfrm state, xfrm_state_netlink() returns NULL instead of an error pointer. But its callers expect an error pointer and therefore continue to operate on a NULL skbuff. This could lead to a privilege escalation (execution of user code in kernel context) if the attacker has CAP_NET_ADMIN and is able to map address 0. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index e75d8e47f35..dac08e2a5a9 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -878,6 +878,7 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb, { struct xfrm_dump_info info; struct sk_buff *skb; + int err; skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC); if (!skb) @@ -888,9 +889,10 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb, info.nlmsg_seq = seq; info.nlmsg_flags = 0; - if (dump_one_state(x, 0, &info)) { + err = dump_one_state(x, 0, &info); + if (err) { kfree_skb(skb); - return NULL; + return ERR_PTR(err); } return skb; -- cgit v1.2.3 From c25463722509fef0ed630b271576a8c9a70236f3 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Fri, 14 Sep 2012 09:58:32 +0000 Subject: xfrm_user: return error pointer instead of NULL #2 When dump_one_policy() returns an error, e.g. because of a too small buffer to dump the whole xfrm policy, xfrm_policy_netlink() returns NULL instead of an error pointer. But its caller expects an error pointer and therefore continues to operate on a NULL skbuff. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index dac08e2a5a9..d12b62547ad 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1548,6 +1548,7 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb, { struct xfrm_dump_info info; struct sk_buff *skb; + int err; skb = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL); if (!skb) @@ -1558,9 +1559,10 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb, info.nlmsg_seq = seq; info.nlmsg_flags = 0; - if (dump_one_policy(xp, dir, 0, &info) < 0) { + err = dump_one_policy(xp, dir, 0, &info); + if (err) { kfree_skb(skb); - return NULL; + return ERR_PTR(err); } return skb; -- cgit v1.2.3 From 433a19548061bb5457b6ab77ed7ea58ca6e43ddb Mon Sep 17 00:00:00 2001 From: Li RongQing Date: Mon, 17 Sep 2012 22:40:10 +0000 Subject: xfrm: fix a read lock imbalance in make_blackhole if xfrm_policy_get_afinfo returns 0, it has already released the read lock, xfrm_policy_put_afinfo should not be called again. Signed-off-by: Li RongQing Signed-off-by: David S. Miller --- net/xfrm/xfrm_policy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index ab2ce7d5152..387848e9007 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1764,7 +1764,7 @@ static struct dst_entry *make_blackhole(struct net *net, u16 family, if (!afinfo) { dst_release(dst_orig); - ret = ERR_PTR(-EINVAL); + return ERR_PTR(-EINVAL); } else { ret = afinfo->blackhole_route(net, dst_orig); } -- cgit v1.2.3 From 4c87308bdea31a7b4828a51f6156e6f721a1fcc9 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Wed, 19 Sep 2012 11:33:38 +0000 Subject: xfrm_user: fix info leak in copy_to_user_auth() copy_to_user_auth() fails to initialize the remainder of alg_name and therefore discloses up to 54 bytes of heap memory via netlink to userland. Use strncpy() instead of strcpy() to fill the trailing bytes of alg_name with null bytes. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d12b62547ad..40dd50d6c4c 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -742,7 +742,7 @@ static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff *skb) return -EMSGSIZE; algo = nla_data(nla); - strcpy(algo->alg_name, auth->alg_name); + strncpy(algo->alg_name, auth->alg_name, sizeof(algo->alg_name)); memcpy(algo->alg_key, auth->alg_key, (auth->alg_key_len + 7) / 8); algo->alg_key_len = auth->alg_key_len; -- cgit v1.2.3 From f778a636713a435d3a922c60b1622a91136560c1 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Wed, 19 Sep 2012 11:33:39 +0000 Subject: xfrm_user: fix info leak in copy_to_user_state() The memory reserved to dump the xfrm state includes the padding bytes of struct xfrm_usersa_info added by the compiler for alignment (7 for amd64, 3 for i386). Add an explicit memset(0) before filling the buffer to avoid the info leak. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 40dd50d6c4c..d585459dc8b 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -689,6 +689,7 @@ out: static void copy_to_user_state(struct xfrm_state *x, struct xfrm_usersa_info *p) { + memset(p, 0, sizeof(*p)); memcpy(&p->id, &x->id, sizeof(p->id)); memcpy(&p->sel, &x->sel, sizeof(p->sel)); memcpy(&p->lft, &x->lft, sizeof(p->lft)); -- cgit v1.2.3 From 7b789836f434c87168eab067cfbed1ec4783dffd Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Wed, 19 Sep 2012 11:33:40 +0000 Subject: xfrm_user: fix info leak in copy_to_user_policy() The memory reserved to dump the xfrm policy includes multiple padding bytes added by the compiler for alignment (padding bytes in struct xfrm_selector and struct xfrm_userpolicy_info). Add an explicit memset(0) before filling the buffer to avoid the heap info leak. Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index d585459dc8b..84dd85ceeee 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1320,6 +1320,7 @@ static void copy_from_user_policy(struct xfrm_policy *xp, struct xfrm_userpolicy static void copy_to_user_policy(struct xfrm_policy *xp, struct xfrm_userpolicy_info *p, int dir) { + memset(p, 0, sizeof(*p)); memcpy(&p->sel, &xp->selector, sizeof(p->sel)); memcpy(&p->lft, &xp->lft, sizeof(p->lft)); memcpy(&p->curlft, &xp->curlft, sizeof(p->curlft)); -- cgit v1.2.3 From 1f86840f897717f86d523a13e99a447e6a5d2fa5 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Wed, 19 Sep 2012 11:33:41 +0000 Subject: xfrm_user: fix info leak in copy_to_user_tmpl() The memory used for the template copy is a local stack variable. As struct xfrm_user_tmpl contains multiple holes added by the compiler for alignment, not initializing the memory will lead to leaking stack bytes to userland. Add an explicit memset(0) to avoid the info leak. Initial version of the patch by Brad Spengler. Cc: Brad Spengler Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 1 + 1 file changed, 1 insertion(+) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 84dd85ceeee..8024b3dea8c 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1425,6 +1425,7 @@ static int copy_to_user_tmpl(struct xfrm_policy *xp, struct sk_buff *skb) struct xfrm_user_tmpl *up = &vec[i]; struct xfrm_tmpl *kp = &xp->xfrm_vec[i]; + memset(up, 0, sizeof(*up)); memcpy(&up->id, &kp->id, sizeof(up->id)); up->family = kp->encap_family; memcpy(&up->saddr, &kp->saddr, sizeof(up->saddr)); -- cgit v1.2.3 From ecd7918745234e423dd87fcc0c077da557909720 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Thu, 20 Sep 2012 10:01:49 +0000 Subject: xfrm_user: ensure user supplied esn replay window is valid The current code fails to ensure that the netlink message actually contains as many bytes as the header indicates. If a user creates a new state or updates an existing one but does not supply the bytes for the whole ESN replay window, the kernel copies random heap bytes into the replay bitmap, the ones happen to follow the XFRMA_REPLAY_ESN_VAL netlink attribute. This leads to following issues: 1. The replay window has random bits set confusing the replay handling code later on. 2. A malicious user could use this flaw to leak up to ~3.5kB of heap memory when she has access to the XFRM netlink interface (requires CAP_NET_ADMIN). Known users of the ESN replay window are strongSwan and Steffen's iproute2 patch (). The latter uses the interface with a bitmap supplied while the former does not. strongSwan is therefore prone to run into issue 1. To fix both issues without breaking existing userland allow using the XFRMA_REPLAY_ESN_VAL netlink attribute with either an empty bitmap or a fully specified one. For the former case we initialize the in-kernel bitmap with zero, for the latter we copy the user supplied bitmap. For state updates the full bitmap must be supplied. To prevent overflows in the bitmap length calculation the maximum size of bmp_len is limited to 128 by this patch -- resulting in a maximum replay window of 4096 packets. This should be sufficient for all real life scenarios (RFC 4303 recommends a default replay window size of 64). Cc: Steffen Klassert Cc: Martin Willi Cc: Ben Hutchings Signed-off-by: Mathias Krause Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 31 +++++++++++++++++++++++++------ 1 file changed, 25 insertions(+), 6 deletions(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 8024b3dea8c..5927065e97c 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -123,9 +123,21 @@ static inline int verify_replay(struct xfrm_usersa_info *p, struct nlattr **attrs) { struct nlattr *rt = attrs[XFRMA_REPLAY_ESN_VAL]; + struct xfrm_replay_state_esn *rs; - if ((p->flags & XFRM_STATE_ESN) && !rt) - return -EINVAL; + if (p->flags & XFRM_STATE_ESN) { + if (!rt) + return -EINVAL; + + rs = nla_data(rt); + + if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8) + return -EINVAL; + + if (nla_len(rt) < xfrm_replay_state_esn_len(rs) && + nla_len(rt) != sizeof(*rs)) + return -EINVAL; + } if (!rt) return 0; @@ -370,14 +382,15 @@ static inline int xfrm_replay_verify_len(struct xfrm_replay_state_esn *replay_es struct nlattr *rp) { struct xfrm_replay_state_esn *up; + int ulen; if (!replay_esn || !rp) return 0; up = nla_data(rp); + ulen = xfrm_replay_state_esn_len(up); - if (xfrm_replay_state_esn_len(replay_esn) != - xfrm_replay_state_esn_len(up)) + if (nla_len(rp) < ulen || xfrm_replay_state_esn_len(replay_esn) != ulen) return -EINVAL; return 0; @@ -388,22 +401,28 @@ static int xfrm_alloc_replay_state_esn(struct xfrm_replay_state_esn **replay_esn struct nlattr *rta) { struct xfrm_replay_state_esn *p, *pp, *up; + int klen, ulen; if (!rta) return 0; up = nla_data(rta); + klen = xfrm_replay_state_esn_len(up); + ulen = nla_len(rta) >= klen ? klen : sizeof(*up); - p = kmemdup(up, xfrm_replay_state_esn_len(up), GFP_KERNEL); + p = kzalloc(klen, GFP_KERNEL); if (!p) return -ENOMEM; - pp = kmemdup(up, xfrm_replay_state_esn_len(up), GFP_KERNEL); + pp = kzalloc(klen, GFP_KERNEL); if (!pp) { kfree(p); return -ENOMEM; } + memcpy(p, up, ulen); + memcpy(pp, up, ulen); + *replay_esn = p; *preplay_esn = pp; -- cgit v1.2.3 From e3ac104d41a97b42316915020ba228c505447d21 Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Wed, 19 Sep 2012 11:33:43 +0000 Subject: xfrm_user: don't copy esn replay window twice for new states The ESN replay window was already fully initialized in xfrm_alloc_replay_state_esn(). No need to copy it again. Cc: Steffen Klassert Signed-off-by: Mathias Krause Acked-by: Steffen Klassert Signed-off-by: David S. Miller --- net/xfrm/xfrm_user.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) (limited to 'net/xfrm') diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 5927065e97c..289f4bf18ff 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -461,10 +461,11 @@ static void copy_from_user_state(struct xfrm_state *x, struct xfrm_usersa_info * * somehow made shareable and move it to xfrm_state.c - JHS * */ -static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs) +static void xfrm_update_ae_params(struct xfrm_state *x, struct nlattr **attrs, + int update_esn) { struct nlattr *rp = attrs[XFRMA_REPLAY_VAL]; - struct nlattr *re = attrs[XFRMA_REPLAY_ESN_VAL]; + struct nlattr *re = update_esn ? attrs[XFRMA_REPLAY_ESN_VAL] : NULL; struct nlattr *lt = attrs[XFRMA_LTIME_VAL]; struct nlattr *et = attrs[XFRMA_ETIMER_THRESH]; struct nlattr *rt = attrs[XFRMA_REPLAY_THRESH]; @@ -574,7 +575,7 @@ static struct xfrm_state *xfrm_state_construct(struct net *net, goto error; /* override default values from above */ - xfrm_update_ae_params(x, attrs); + xfrm_update_ae_params(x, attrs, 0); return x; @@ -1848,7 +1849,7 @@ static int xfrm_new_ae(struct sk_buff *skb, struct nlmsghdr *nlh, goto out; spin_lock_bh(&x->lock); - xfrm_update_ae_params(x, attrs); + xfrm_update_ae_params(x, attrs, 1); spin_unlock_bh(&x->lock); c.event = nlh->nlmsg_type; -- cgit v1.2.3