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tcp: md5: dont write skb head in tcp_md5_hash_header()

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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>
This commit is contained in:
Eric Dumazet 2011-10-24 01:52:35 -04:00 committed by David S. Miller
parent 01718e36df
commit ca35a0ef85
2 changed files with 9 additions and 7 deletions
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2
include/net/tcp.h
View File

@ -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,

14
net/ipv4/tcp.c
View File

@ -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);