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Date: Tue, 25 Oct 2022 14:06:48 +0800
From: Herbert Xu <herbert@...dor.apana.org.au>
To: Sabrina Dubroca <sd@...asysnail.net>
Cc: Eric Dumazet <edumazet@...gle.com>,
syzbot <syzbot+1e9af9185d8850e2c2fa@...kaller.appspotmail.com>,
davem@...emloft.net, kuba@...nel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, pabeni@...hat.com,
steffen.klassert@...unet.com, syzkaller-bugs@...glegroups.com
Subject: [v3 PATCH] af_key: Fix send_acquire race with pfkey_register
On Mon, Oct 24, 2022 at 09:20:00AM +0200, Sabrina Dubroca wrote:
> 2022-10-24, 14:06:12 +0800, Herbert Xu wrote:
> > @@ -1697,11 +1699,11 @@ static int pfkey_register(struct sock *sk, struct sk_buff *skb, const struct sad
> > pfk->registered |= (1<<hdr->sadb_msg_satype);
> > }
> >
> > - mutex_lock(&pfkey_mutex);
> > + spin_lock_bh(&pfkey_alg_lock);
> > xfrm_probe_algs();
>
> I don't think we can do that:
>
> void xfrm_probe_algs(void)
> {
> int i, status;
>
> BUG_ON(in_softirq());
Indeed. I was also wrong in stating that this bug was created by
namespaces. This race has always existed since this code was first
added.
---8<---
The function pfkey_send_acquire may race with pfkey_register
(which could even be in a different name space). This may result
in a buffer overrun.
Allocating the maximum amount of memory that could be used prevents
this.
Reported-by: syzbot+1e9af9185d8850e2c2fa@...kaller.appspotmail.com
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
diff --git a/net/key/af_key.c b/net/key/af_key.c
index c85df5b958d2..213287814328 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2905,7 +2905,7 @@ static int count_ah_combs(const struct xfrm_tmpl *t)
break;
if (!aalg->pfkey_supported)
continue;
- if (aalg_tmpl_set(t, aalg) && aalg->available)
+ if (aalg_tmpl_set(t, aalg))
sz += sizeof(struct sadb_comb);
}
return sz + sizeof(struct sadb_prop);
@@ -2923,7 +2923,7 @@ static int count_esp_combs(const struct xfrm_tmpl *t)
if (!ealg->pfkey_supported)
continue;
- if (!(ealg_tmpl_set(t, ealg) && ealg->available))
+ if (!(ealg_tmpl_set(t, ealg)))
continue;
for (k = 1; ; k++) {
@@ -2934,16 +2934,17 @@ static int count_esp_combs(const struct xfrm_tmpl *t)
if (!aalg->pfkey_supported)
continue;
- if (aalg_tmpl_set(t, aalg) && aalg->available)
+ if (aalg_tmpl_set(t, aalg))
sz += sizeof(struct sadb_comb);
}
}
return sz + sizeof(struct sadb_prop);
}
-static void dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
+static int dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
{
struct sadb_prop *p;
+ int sz = 0;
int i;
p = skb_put(skb, sizeof(struct sadb_prop));
@@ -2971,13 +2972,17 @@ static void dump_ah_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
c->sadb_comb_soft_addtime = 20*60*60;
c->sadb_comb_hard_usetime = 8*60*60;
c->sadb_comb_soft_usetime = 7*60*60;
+ sz += sizeof(*c);
}
}
+
+ return sz + sizeof(*p);
}
-static void dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
+static int dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
{
struct sadb_prop *p;
+ int sz = 0;
int i, k;
p = skb_put(skb, sizeof(struct sadb_prop));
@@ -3019,8 +3024,11 @@ static void dump_esp_combs(struct sk_buff *skb, const struct xfrm_tmpl *t)
c->sadb_comb_soft_addtime = 20*60*60;
c->sadb_comb_hard_usetime = 8*60*60;
c->sadb_comb_soft_usetime = 7*60*60;
+ sz += sizeof(*c);
}
}
+
+ return sz + sizeof(*p);
}
static int key_notify_policy_expire(struct xfrm_policy *xp, const struct km_event *c)
@@ -3150,6 +3158,7 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
struct sadb_x_sec_ctx *sec_ctx;
struct xfrm_sec_ctx *xfrm_ctx;
int ctx_size = 0;
+ int alg_size = 0;
sockaddr_size = pfkey_sockaddr_size(x->props.family);
if (!sockaddr_size)
@@ -3161,16 +3170,16 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
sizeof(struct sadb_x_policy);
if (x->id.proto == IPPROTO_AH)
- size += count_ah_combs(t);
+ alg_size = count_ah_combs(t);
else if (x->id.proto == IPPROTO_ESP)
- size += count_esp_combs(t);
+ alg_size = count_esp_combs(t);
if ((xfrm_ctx = x->security)) {
ctx_size = PFKEY_ALIGN8(xfrm_ctx->ctx_len);
size += sizeof(struct sadb_x_sec_ctx) + ctx_size;
}
- skb = alloc_skb(size + 16, GFP_ATOMIC);
+ skb = alloc_skb(size + alg_size + 16, GFP_ATOMIC);
if (skb == NULL)
return -ENOMEM;
@@ -3224,10 +3233,13 @@ static int pfkey_send_acquire(struct xfrm_state *x, struct xfrm_tmpl *t, struct
pol->sadb_x_policy_priority = xp->priority;
/* Set sadb_comb's. */
+ alg_size = 0;
if (x->id.proto == IPPROTO_AH)
- dump_ah_combs(skb, t);
+ alg_size = dump_ah_combs(skb, t);
else if (x->id.proto == IPPROTO_ESP)
- dump_esp_combs(skb, t);
+ alg_size = dump_esp_combs(skb, t);
+
+ hdr->sadb_msg_len += alg_size / 8;
/* security context */
if (xfrm_ctx) {
--
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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