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Commit ca35a0ef authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 01718e36

include/net/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

net/ipv4/tcp.c

+8 −6
Original line number Diff line number Diff line
@@ -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);