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Commit e4bec827 authored by David S. Miller's avatar David S. Miller
Browse files

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



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: default avatarDavid S. Miller <davem@davemloft.net>
parent 44e36b42

include/net/esp.h

+3 −2
Original line number Diff line number Diff line
@@ -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;

net/ipv4/esp4.c

+7 −2
Original line number Diff line number Diff line
@@ -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;

net/ipv6/esp6.c

+7 −2
Original line number Diff line number Diff line
@@ -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;