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authorEric Dumazet <eric.dumazet@gmail.com>2011-10-24 01:52:35 -0400
committerDavid S. Miller <davem@davemloft.net>2011-10-24 01:52:35 -0400
commitca35a0ef85e8ed6df6d5ab01fb6c3530cca0c469 (patch)
tree3a6d0c107ec48823bb3e437f1f91d2276facb46d
parentbonding: Add a forgetten sysfs_attr_init on class_attr_bonding_masters (diff)
downloadlinux-dev-ca35a0ef85e8ed6df6d5ab01fb6c3530cca0c469.tar.xz
linux-dev-ca35a0ef85e8ed6df6d5ab01fb6c3530cca0c469.zip
tcp: md5: dont write skb head in tcp_md5_hash_header()
tcp_md5_hash_header() writes into skb header a temporary zero value, this might confuse other users of this area. Since tcphdr is small (20 bytes), copy it in a temporary variable and make the change in the copy. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
-rw-r--r--include/net/tcp.h2
-rw-r--r--net/ipv4/tcp.c14
2 files changed, 9 insertions, 7 deletions
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 3edef0bebdd1..910cc29f9e97 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1209,7 +1209,7 @@ extern void tcp_free_md5sig_pool(void);
extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
extern void tcp_put_md5sig_pool(void);
-extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, struct tcphdr *);
+extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
unsigned header_len);
extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 704adad8f07f..eefc61e3d0e4 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2994,17 +2994,19 @@ void tcp_put_md5sig_pool(void)
EXPORT_SYMBOL(tcp_put_md5sig_pool);
int tcp_md5_hash_header(struct tcp_md5sig_pool *hp,
- struct tcphdr *th)
+ const struct tcphdr *th)
{
struct scatterlist sg;
+ struct tcphdr hdr;
int err;
- __sum16 old_checksum = th->check;
- th->check = 0;
+ /* We are not allowed to change tcphdr, make a local copy */
+ memcpy(&hdr, th, sizeof(hdr));
+ hdr.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;
+ sg_init_one(&sg, &hdr, sizeof(hdr));
+ err = crypto_hash_update(&hp->md5_desc, &sg, sizeof(hdr));
return err;
}
EXPORT_SYMBOL(tcp_md5_hash_header);