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esp6: Add support for IPsec extended sequence numbers
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This patch adds IPsec extended sequence numbers support to esp6.
We use the authencesn crypto algorithm to handle esp with separate
encryption/authentication algorithms.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Steffen Klassert authored and David S. Miller committed Mar 14, 2011
1 parent 0dc49e9 commit d212a4c
Showing 1 changed file with 86 additions and 19 deletions.
105 changes: 86 additions & 19 deletions net/ipv6/esp6.c
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Original file line number Diff line number Diff line change
Expand Up @@ -54,16 +54,20 @@ static u32 esp6_get_mtu(struct xfrm_state *x, int mtu);
/*
* Allocate an AEAD request structure with extra space for SG and IV.
*
* For alignment considerations the IV is placed at the front, followed
* by the request and finally the SG list.
* For alignment considerations the upper 32 bits of the sequence number are
* placed at the front, if present. Followed by the IV, the request and finally
* the SG list.
*
* TODO: Use spare space in skb for this where possible.
*/
static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags, int seqihlen)
{
unsigned int len;

len = crypto_aead_ivsize(aead);
len = seqihlen;

len += crypto_aead_ivsize(aead);

if (len) {
len += crypto_aead_alignmask(aead) &
~(crypto_tfm_ctx_alignment() - 1);
Expand All @@ -78,10 +82,16 @@ static void *esp_alloc_tmp(struct crypto_aead *aead, int nfrags)
return kmalloc(len, GFP_ATOMIC);
}

static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp)
static inline __be32 *esp_tmp_seqhi(void *tmp)
{
return PTR_ALIGN((__be32 *)tmp, __alignof__(__be32));
}

static inline u8 *esp_tmp_iv(struct crypto_aead *aead, void *tmp, int seqhilen)
{
return crypto_aead_ivsize(aead) ?
PTR_ALIGN((u8 *)tmp, crypto_aead_alignmask(aead) + 1) : tmp;
PTR_ALIGN((u8 *)tmp + seqhilen,
crypto_aead_alignmask(aead) + 1) : tmp + seqhilen;
}

static inline struct aead_givcrypt_request *esp_tmp_givreq(
Expand Down Expand Up @@ -145,8 +155,12 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
int plen;
int tfclen;
int nfrags;
int assoclen;
int sglists;
int seqhilen;
u8 *iv;
u8 *tail;
__be32 *seqhi;
struct esp_data *esp = x->data;

/* skb is pure payload to encrypt */
Expand Down Expand Up @@ -175,14 +189,25 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
goto error;
nfrags = err;

tmp = esp_alloc_tmp(aead, nfrags + 1);
assoclen = sizeof(*esph);
sglists = 1;
seqhilen = 0;

if (x->props.flags & XFRM_STATE_ESN) {
sglists += 2;
seqhilen += sizeof(__be32);
assoclen += seqhilen;
}

tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
if (!tmp)
goto error;

iv = esp_tmp_iv(aead, tmp);
seqhi = esp_tmp_seqhi(tmp);
iv = esp_tmp_iv(aead, tmp, seqhilen);
req = esp_tmp_givreq(aead, iv);
asg = esp_givreq_sg(aead, req);
sg = asg + 1;
sg = asg + sglists;

/* Fill padding... */
tail = skb_tail_pointer(trailer);
Expand Down Expand Up @@ -210,11 +235,19 @@ static int esp6_output(struct xfrm_state *x, struct sk_buff *skb)
skb_to_sgvec(skb, sg,
esph->enc_data + crypto_aead_ivsize(aead) - skb->data,
clen + alen);
sg_init_one(asg, esph, sizeof(*esph));

if ((x->props.flags & XFRM_STATE_ESN)) {
sg_init_table(asg, 3);
sg_set_buf(asg, &esph->spi, sizeof(__be32));
*seqhi = htonl(XFRM_SKB_CB(skb)->seq.output.hi);
sg_set_buf(asg + 1, seqhi, seqhilen);
sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
} else
sg_init_one(asg, esph, sizeof(*esph));

aead_givcrypt_set_callback(req, 0, esp_output_done, skb);
aead_givcrypt_set_crypt(req, sg, sg, clen, iv);
aead_givcrypt_set_assoc(req, asg, sizeof(*esph));
aead_givcrypt_set_assoc(req, asg, assoclen);
aead_givcrypt_set_giv(req, esph->enc_data,
XFRM_SKB_CB(skb)->seq.output.low);

Expand Down Expand Up @@ -292,8 +325,12 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
struct sk_buff *trailer;
int elen = skb->len - sizeof(*esph) - crypto_aead_ivsize(aead);
int nfrags;
int assoclen;
int sglists;
int seqhilen;
int ret = 0;
void *tmp;
__be32 *seqhi;
u8 *iv;
struct scatterlist *sg;
struct scatterlist *asg;
Expand All @@ -314,12 +351,24 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)
}

ret = -ENOMEM;
tmp = esp_alloc_tmp(aead, nfrags + 1);

assoclen = sizeof(*esph);
sglists = 1;
seqhilen = 0;

if (x->props.flags & XFRM_STATE_ESN) {
sglists += 2;
seqhilen += sizeof(__be32);
assoclen += seqhilen;
}

tmp = esp_alloc_tmp(aead, nfrags + sglists, seqhilen);
if (!tmp)
goto out;

ESP_SKB_CB(skb)->tmp = tmp;
iv = esp_tmp_iv(aead, tmp);
seqhi = esp_tmp_seqhi(tmp);
iv = esp_tmp_iv(aead, tmp, seqhilen);
req = esp_tmp_req(aead, iv);
asg = esp_req_sg(aead, req);
sg = asg + 1;
Expand All @@ -333,11 +382,19 @@ static int esp6_input(struct xfrm_state *x, struct sk_buff *skb)

sg_init_table(sg, nfrags);
skb_to_sgvec(skb, sg, sizeof(*esph) + crypto_aead_ivsize(aead), elen);
sg_init_one(asg, esph, sizeof(*esph));

if ((x->props.flags & XFRM_STATE_ESN)) {
sg_init_table(asg, 3);
sg_set_buf(asg, &esph->spi, sizeof(__be32));
*seqhi = XFRM_SKB_CB(skb)->seq.input.hi;
sg_set_buf(asg + 1, seqhi, seqhilen);
sg_set_buf(asg + 2, &esph->seq_no, sizeof(__be32));
} else
sg_init_one(asg, esph, sizeof(*esph));

aead_request_set_callback(req, 0, esp_input_done, skb);
aead_request_set_crypt(req, sg, sg, elen, iv);
aead_request_set_assoc(req, asg, sizeof(*esph));
aead_request_set_assoc(req, asg, assoclen);

ret = crypto_aead_decrypt(req);
if (ret == -EINPROGRESS)
Expand Down Expand Up @@ -443,10 +500,20 @@ static int esp_init_authenc(struct xfrm_state *x)
goto error;

err = -ENAMETOOLONG;
if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME, "authenc(%s,%s)",
x->aalg ? x->aalg->alg_name : "digest_null",
x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
goto error;

if ((x->props.flags & XFRM_STATE_ESN)) {
if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
"authencesn(%s,%s)",
x->aalg ? x->aalg->alg_name : "digest_null",
x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
goto error;
} else {
if (snprintf(authenc_name, CRYPTO_MAX_ALG_NAME,
"authenc(%s,%s)",
x->aalg ? x->aalg->alg_name : "digest_null",
x->ealg->alg_name) >= CRYPTO_MAX_ALG_NAME)
goto error;
}

aead = crypto_alloc_aead(authenc_name, 0, 0);
err = PTR_ERR(aead);
Expand Down

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