tcp: Fix MD5 signatures for non-linear skbs
Currently, the MD5 code assumes that the SKBs are linear and, in the case
that they aren't, happily goes off and hashes off the end of the SKB and
into random memory.
Reported by Stephen Hemminger in [1]. Advice thanks to Stephen and Evgeniy
Polyakov. Also includes a couple of missed route_caps from Stephen's patch
in [2].
[1] http://marc.info/?l=linux-netdev&m=121445989106145&w=2
[2] http://marc.info/?l=linux-netdev&m=121459157816964&w=2
Signed-off-by: Adam Langley <agl@imperialviolet.org>
Acked-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 827e613..0b491bf 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2465,76 +2465,6 @@
static struct tcp_md5sig_pool **tcp_md5sig_pool;
static DEFINE_SPINLOCK(tcp_md5sig_pool_lock);
-int tcp_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
- int bplen,
- struct tcphdr *th, unsigned int tcplen,
- struct tcp_md5sig_pool *hp)
-{
- struct scatterlist sg[4];
- __u16 data_len;
- int block = 0;
- __sum16 cksum;
- struct hash_desc *desc = &hp->md5_desc;
- int err;
- unsigned int nbytes = 0;
-
- sg_init_table(sg, 4);
-
- /* 1. The TCP pseudo-header */
- sg_set_buf(&sg[block++], &hp->md5_blk, bplen);
- nbytes += bplen;
-
- /* 2. The TCP header, excluding options, and assuming a
- * checksum of zero
- */
- cksum = th->check;
- th->check = 0;
- sg_set_buf(&sg[block++], th, sizeof(*th));
- nbytes += sizeof(*th);
-
- /* 3. The TCP segment data (if any) */
- data_len = tcplen - (th->doff << 2);
- if (data_len > 0) {
- u8 *data = (u8 *)th + (th->doff << 2);
- sg_set_buf(&sg[block++], data, data_len);
- nbytes += data_len;
- }
-
- /* 4. an independently-specified key or password, known to both
- * TCPs and presumably connection-specific
- */
- sg_set_buf(&sg[block++], key->key, key->keylen);
- nbytes += key->keylen;
-
- sg_mark_end(&sg[block - 1]);
-
- /* Now store the hash into the packet */
- err = crypto_hash_init(desc);
- if (err) {
- if (net_ratelimit())
- printk(KERN_WARNING "%s(): hash_init failed\n", __func__);
- return -1;
- }
- err = crypto_hash_update(desc, sg, nbytes);
- if (err) {
- if (net_ratelimit())
- printk(KERN_WARNING "%s(): hash_update failed\n", __func__);
- return -1;
- }
- err = crypto_hash_final(desc, md5_hash);
- if (err) {
- if (net_ratelimit())
- printk(KERN_WARNING "%s(): hash_final failed\n", __func__);
- return -1;
- }
-
- /* Reset header */
- th->check = cksum;
-
- return 0;
-}
-EXPORT_SYMBOL(tcp_calc_md5_hash);
-
static void __tcp_free_md5sig_pool(struct tcp_md5sig_pool **pool)
{
int cpu;
@@ -2658,6 +2588,63 @@
}
EXPORT_SYMBOL(__tcp_put_md5sig_pool);
+
+int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
+ struct tcphdr *th)
+{
+ struct scatterlist sg;
+ int err;
+
+ __sum16 old_checksum = th->check;
+ th->check = 0;
+ /* options aren't included in the hash */
+ sg_init_one(&sg, th, sizeof(struct tcphdr));
+ err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(struct tcphdr));
+ th->check = old_checksum;
+ return err;
+}
+
+EXPORT_SYMBOL(tcp_md5_hash_header);
+
+int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *hp,
+ struct sk_buff *skb, unsigned header_len)
+{
+ struct scatterlist sg;
+ const struct tcphdr *tp = tcp_hdr(skb);
+ struct hash_desc *desc = &hp->md5_desc;
+ unsigned i;
+ const unsigned head_data_len = skb_headlen(skb) > header_len ?
+ skb_headlen(skb) - header_len : 0;
+ const struct skb_shared_info *shi = skb_shinfo(skb);
+
+ sg_init_table(&sg, 1);
+
+ sg_set_buf(&sg, ((u8 *) tp) + header_len, head_data_len);
+ if (crypto_hash_update(desc, &sg, head_data_len))
+ return 1;
+
+ for (i = 0; i < shi->nr_frags; ++i) {
+ const struct skb_frag_struct *f = &shi->frags[i];
+ sg_set_page(&sg, f->page, f->size, f->page_offset);
+ if (crypto_hash_update(desc, &sg, f->size))
+ return 1;
+ }
+
+ return 0;
+}
+
+EXPORT_SYMBOL(tcp_md5_hash_skb_data);
+
+int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, struct tcp_md5sig_key *key)
+{
+ struct scatterlist sg;
+
+ sg_init_one(&sg, key->key, key->keylen);
+ return crypto_hash_update(&hp->md5_desc, &sg, key->keylen);
+}
+
+EXPORT_SYMBOL(tcp_md5_hash_key);
+
#endif
void tcp_done(struct sock *sk)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 29adc66..5400d75 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -87,9 +87,8 @@
#ifdef CONFIG_TCP_MD5SIG
static struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk,
__be32 addr);
-static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
- __be32 saddr, __be32 daddr,
- struct tcphdr *th, unsigned int tcplen);
+static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
+ __be32 daddr, __be32 saddr, struct tcphdr *th);
#else
static inline
struct tcp_md5sig_key *tcp_v4_md5_do_lookup(struct sock *sk, __be32 addr)
@@ -583,11 +582,9 @@
arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
rep.th.doff = arg.iov[0].iov_len / 4;
- tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[1],
- key,
- ip_hdr(skb)->daddr,
- ip_hdr(skb)->saddr,
- &rep.th, arg.iov[0].iov_len);
+ tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[1],
+ key, ip_hdr(skb)->daddr,
+ ip_hdr(skb)->saddr, &rep.th);
}
#endif
arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
@@ -657,11 +654,9 @@
arg.iov[0].iov_len += TCPOLEN_MD5SIG_ALIGNED;
rep.th.doff = arg.iov[0].iov_len/4;
- tcp_v4_do_calc_md5_hash((__u8 *)&rep.opt[offset],
- key,
- ip_hdr(skb)->daddr,
- ip_hdr(skb)->saddr,
- &rep.th, arg.iov[0].iov_len);
+ tcp_v4_md5_hash_hdr((__u8 *) &rep.opt[offset],
+ key, ip_hdr(skb)->daddr,
+ ip_hdr(skb)->saddr, &rep.th);
}
#endif
arg.csum = csum_tcpudp_nofold(ip_hdr(skb)->daddr,
@@ -989,28 +984,16 @@
newkey, cmd.tcpm_keylen);
}
-static int tcp_v4_do_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
- __be32 saddr, __be32 daddr,
- struct tcphdr *th,
- unsigned int tcplen)
+static int tcp_v4_md5_hash_pseudoheader(struct tcp_md5sig_pool *hp,
+ __be32 daddr, __be32 saddr, int nbytes)
{
- struct tcp_md5sig_pool *hp;
struct tcp4_pseudohdr *bp;
- int err;
-
- /*
- * Okay, so RFC2385 is turned on for this connection,
- * so we need to generate the MD5 hash for the packet now.
- */
-
- hp = tcp_get_md5sig_pool();
- if (!hp)
- goto clear_hash_noput;
+ struct scatterlist sg;
bp = &hp->md5_blk.ip4;
/*
- * The TCP pseudo-header (in the order: source IP address,
+ * 1. the TCP pseudo-header (in the order: source IP address,
* destination IP address, zero-padded protocol number, and
* segment length)
*/
@@ -1018,48 +1001,95 @@
bp->daddr = daddr;
bp->pad = 0;
bp->protocol = IPPROTO_TCP;
- bp->len = htons(tcplen);
+ bp->len = cpu_to_be16(nbytes);
- err = tcp_calc_md5_hash(md5_hash, key, sizeof(*bp),
- th, tcplen, hp);
- if (err)
+ sg_init_one(&sg, bp, sizeof(*bp));
+ return crypto_hash_update(&hp->md5_desc, &sg, sizeof(*bp));
+}
+
+static int tcp_v4_md5_hash_hdr(char *md5_hash, struct tcp_md5sig_key *key,
+ __be32 daddr, __be32 saddr, struct tcphdr *th)
+{
+ struct tcp_md5sig_pool *hp;
+ struct hash_desc *desc;
+
+ hp = tcp_get_md5sig_pool();
+ if (!hp)
+ goto clear_hash_noput;
+ desc = &hp->md5_desc;
+
+ if (crypto_hash_init(desc))
+ goto clear_hash;
+ if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, th->doff << 2))
+ goto clear_hash;
+ if (tcp_md5_hash_header(hp, th))
+ goto clear_hash;
+ if (tcp_md5_hash_key(hp, key))
+ goto clear_hash;
+ if (crypto_hash_final(desc, md5_hash))
goto clear_hash;
- /* Free up the crypto pool */
tcp_put_md5sig_pool();
-out:
return 0;
+
clear_hash:
tcp_put_md5sig_pool();
clear_hash_noput:
memset(md5_hash, 0, 16);
- goto out;
+ return 1;
}
-int tcp_v4_calc_md5_hash(char *md5_hash, struct tcp_md5sig_key *key,
- struct sock *sk,
- struct dst_entry *dst,
- struct request_sock *req,
- struct tcphdr *th,
- unsigned int tcplen)
+int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
+ struct sock *sk, struct request_sock *req,
+ struct sk_buff *skb)
{
+ struct tcp_md5sig_pool *hp;
+ struct hash_desc *desc;
+ struct tcphdr *th = tcp_hdr(skb);
__be32 saddr, daddr;
if (sk) {
saddr = inet_sk(sk)->saddr;
daddr = inet_sk(sk)->daddr;
+ } else if (req) {
+ saddr = inet_rsk(req)->loc_addr;
+ daddr = inet_rsk(req)->rmt_addr;
} else {
- struct rtable *rt = (struct rtable *)dst;
- BUG_ON(!rt);
- saddr = rt->rt_src;
- daddr = rt->rt_dst;
+ const struct iphdr *iph = ip_hdr(skb);
+ saddr = iph->saddr;
+ daddr = iph->daddr;
}
- return tcp_v4_do_calc_md5_hash(md5_hash, key,
- saddr, daddr,
- th, tcplen);
+
+ hp = tcp_get_md5sig_pool();
+ if (!hp)
+ goto clear_hash_noput;
+ desc = &hp->md5_desc;
+
+ if (crypto_hash_init(desc))
+ goto clear_hash;
+
+ if (tcp_v4_md5_hash_pseudoheader(hp, daddr, saddr, skb->len))
+ goto clear_hash;
+ if (tcp_md5_hash_header(hp, th))
+ goto clear_hash;
+ if (tcp_md5_hash_skb_data(hp, skb, th->doff << 2))
+ goto clear_hash;
+ if (tcp_md5_hash_key(hp, key))
+ goto clear_hash;
+ if (crypto_hash_final(desc, md5_hash))
+ goto clear_hash;
+
+ tcp_put_md5sig_pool();
+ return 0;
+
+clear_hash:
+ tcp_put_md5sig_pool();
+clear_hash_noput:
+ memset(md5_hash, 0, 16);
+ return 1;
}
-EXPORT_SYMBOL(tcp_v4_calc_md5_hash);
+EXPORT_SYMBOL(tcp_v4_md5_hash_skb);
static int tcp_v4_inbound_md5_hash(struct sock *sk, struct sk_buff *skb)
{
@@ -1104,10 +1134,9 @@
/* Okay, so this is hash_expected and hash_location -
* so we need to calculate the checksum.
*/
- genhash = tcp_v4_do_calc_md5_hash(newhash,
- hash_expected,
- iph->saddr, iph->daddr,
- th, skb->len);
+ genhash = tcp_v4_md5_hash_skb(newhash,
+ hash_expected,
+ NULL, NULL, skb);
if (genhash || memcmp(hash_location, newhash, 16) != 0) {
if (net_ratelimit()) {
@@ -1356,6 +1385,7 @@
if (newkey != NULL)
tcp_v4_md5_do_add(newsk, inet_sk(sk)->daddr,
newkey, key->keylen);
+ newsk->sk_route_caps &= ~NETIF_F_GSO_MASK;
}
#endif
@@ -1719,7 +1749,7 @@
#ifdef CONFIG_TCP_MD5SIG
static struct tcp_sock_af_ops tcp_sock_ipv4_specific = {
.md5_lookup = tcp_v4_md5_lookup,
- .calc_md5_hash = tcp_v4_calc_md5_hash,
+ .calc_md5_hash = tcp_v4_md5_hash_skb,
.md5_add = tcp_v4_md5_add_func,
.md5_parse = tcp_v4_parse_md5_keys,
};
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 36a1970..958ff48 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -540,8 +540,10 @@
* room for it.
*/
md5 = tp->af_specific->md5_lookup(sk, sk);
- if (md5)
+ if (md5) {
tcp_header_size += TCPOLEN_MD5SIG_ALIGNED;
+ sk->sk_route_caps &= ~NETIF_F_GSO_MASK;
+ }
#endif
skb_push(skb, tcp_header_size);
@@ -602,10 +604,7 @@
/* Calculate the MD5 hash, as we have all we need now */
if (md5) {
tp->af_specific->calc_md5_hash(md5_hash_location,
- md5,
- sk, NULL, NULL,
- tcp_hdr(skb),
- skb->len);
+ md5, sk, NULL, skb);
}
#endif
@@ -2264,10 +2263,7 @@
/* Okay, we have all we need - do the md5 hash if needed */
if (md5) {
tp->af_specific->calc_md5_hash(md5_hash_location,
- md5,
- NULL, dst, req,
- tcp_hdr(skb),
- skb->len);
+ md5, NULL, req, skb);
}
#endif