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[IPSEC] esp: Defer output IV initialization to first use.

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First of all, if the xfrm_state only gets used for input
packets this entropy is a complete waste.

Secondly, it is often the case that a configuration loads
many rules (perhaps even dynamically) and they don't all
necessarily ever get used.

This get_random_bytes() call was showing up in the profiles
for xfrm_state inserts which is how I noticed this.

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2006-09-22 15:17:35 -07:00
parent 44e36b42a8
commit e4bec827fe
3 changed files with 17 additions and 6 deletions
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5
include/net/esp.h
View file

@ -15,13 +15,14 @@ struct esp_data
struct {
u8 *key; /* Key */
int key_len; /* Key length */
u8 *ivec; /* ivec buffer */
int padlen; /* 0..255 */
/* ivlen is offset from enc_data, where encrypted data start.
* It is logically different of crypto_tfm_alg_ivsize(tfm).
* We assume that it is either zero (no ivec), or
* >= crypto_tfm_alg_ivsize(tfm). */
int ivlen;
int padlen; /* 0..255 */
int ivinitted;
u8 *ivec; /* ivec buffer */
struct crypto_blkcipher *tfm; /* crypto handle */
} conf;

9
net/ipv4/esp4.c
View file

@ -95,8 +95,13 @@ static int esp_output(struct xfrm_state *x, struct sk_buff *skb)
esph->seq_no = htonl(++x->replay.oseq);
xfrm_aevent_doreplay(x);
if (esp->conf.ivlen)
if (esp->conf.ivlen) {
if (unlikely(!esp->conf.ivinitted)) {
get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
esp->conf.ivinitted = 1;
}
crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
}
do {
struct scatterlist *sg = &esp->sgbuf[0];
@ -378,7 +383,7 @@ static int esp_init_state(struct xfrm_state *x)
esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
if (unlikely(esp->conf.ivec == NULL))
goto error;
get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
esp->conf.ivinitted = 0;
}
if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
goto error;

9
net/ipv6/esp6.c
View file

@ -99,8 +99,13 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
esph->seq_no = htonl(++x->replay.oseq);
xfrm_aevent_doreplay(x);
if (esp->conf.ivlen)
if (esp->conf.ivlen) {
if (unlikely(!esp->conf.ivinitted)) {
get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
esp->conf.ivinitted = 1;
}
crypto_blkcipher_set_iv(tfm, esp->conf.ivec, esp->conf.ivlen);
}
do {
struct scatterlist *sg = &esp->sgbuf[0];
@ -353,7 +358,7 @@ static int esp6_init_state(struct xfrm_state *x)
esp->conf.ivec = kmalloc(esp->conf.ivlen, GFP_KERNEL);
if (unlikely(esp->conf.ivec == NULL))
goto error;
get_random_bytes(esp->conf.ivec, esp->conf.ivlen);
esp->conf.ivinitted = 0;
}
if (crypto_blkcipher_setkey(tfm, esp->conf.key, esp->conf.key_len))
goto error;