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net/tls: Add support of AES128-CCM based ciphers
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Added support for AES128-CCM based record encryption. AES128-CCM is
similar to AES128-GCM. Both of them have same salt/iv/mac size. The
notable difference between the two is that while invoking AES128-CCM
operation, the salt||nonce (which is passed as IV) has to be prefixed
with a hardcoded value '2'. Further, CCM implementation in kernel
requires IV passed in crypto_aead_request() to be full '16' bytes.
Therefore, the record structure 'struct tls_rec' has been modified to
reserve '16' bytes for IV. This works for both GCM and CCM based cipher.

Signed-off-by: Vakul Garg <vakul.garg@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Vakul Garg authored and David S. Miller committed Mar 20, 2019
1 parent 6a23c0a commit f295b3a
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Showing 4 changed files with 97 additions and 31 deletions.
15 changes: 13 additions & 2 deletions include/net/tls.h
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Original file line number Diff line number Diff line change
Expand Up @@ -60,6 +60,17 @@
#define TLS_AAD_SPACE_SIZE 13
#define TLS_DEVICE_NAME_MAX 32

#define MAX_IV_SIZE 16

/* For AES-CCM, the full 16-bytes of IV is made of '4' fields of given sizes.
*
* IV[16] = b0[1] || implicit nonce[4] || explicit nonce[8] || length[3]
*
* The field 'length' is encoded in field 'b0' as '(length width - 1)'.
* Hence b0 contains (3 - 1) = 2.
*/
#define TLS_AES_CCM_IV_B0_BYTE 2

/*
* This structure defines the routines for Inline TLS driver.
* The following routines are optional and filled with a
Expand Down Expand Up @@ -123,8 +134,7 @@ struct tls_rec {
struct scatterlist sg_content_type;

char aad_space[TLS_AAD_SPACE_SIZE];
u8 iv_data[TLS_CIPHER_AES_GCM_128_IV_SIZE +
TLS_CIPHER_AES_GCM_128_SALT_SIZE];
u8 iv_data[MAX_IV_SIZE];
struct aead_request aead_req;
u8 aead_req_ctx[];
};
Expand Down Expand Up @@ -219,6 +229,7 @@ struct tls_prot_info {
u16 tag_size;
u16 overhead_size;
u16 iv_size;
u16 salt_size;
u16 rec_seq_size;
u16 aad_size;
u16 tail_size;
Expand Down
15 changes: 15 additions & 0 deletions include/uapi/linux/tls.h
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Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,13 @@
#define TLS_CIPHER_AES_GCM_256_TAG_SIZE 16
#define TLS_CIPHER_AES_GCM_256_REC_SEQ_SIZE 8

#define TLS_CIPHER_AES_CCM_128 53
#define TLS_CIPHER_AES_CCM_128_IV_SIZE 8
#define TLS_CIPHER_AES_CCM_128_KEY_SIZE 16
#define TLS_CIPHER_AES_CCM_128_SALT_SIZE 4
#define TLS_CIPHER_AES_CCM_128_TAG_SIZE 16
#define TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE 8

#define TLS_SET_RECORD_TYPE 1
#define TLS_GET_RECORD_TYPE 2

Expand All @@ -94,4 +101,12 @@ struct tls12_crypto_info_aes_gcm_256 {
unsigned char rec_seq[TLS_CIPHER_AES_GCM_256_REC_SEQ_SIZE];
};

struct tls12_crypto_info_aes_ccm_128 {
struct tls_crypto_info info;
unsigned char iv[TLS_CIPHER_AES_CCM_128_IV_SIZE];
unsigned char key[TLS_CIPHER_AES_CCM_128_KEY_SIZE];
unsigned char salt[TLS_CIPHER_AES_CCM_128_SALT_SIZE];
unsigned char rec_seq[TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE];
};

#endif /* _UAPI_LINUX_TLS_H */
31 changes: 18 additions & 13 deletions net/tls/tls_main.c
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Original file line number Diff line number Diff line change
Expand Up @@ -469,27 +469,32 @@ static int do_tls_setsockopt_conf(struct sock *sk, char __user *optval,

switch (crypto_info->cipher_type) {
case TLS_CIPHER_AES_GCM_128:
optsize = sizeof(struct tls12_crypto_info_aes_gcm_128);
break;
case TLS_CIPHER_AES_GCM_256: {
optsize = crypto_info->cipher_type == TLS_CIPHER_AES_GCM_128 ?
sizeof(struct tls12_crypto_info_aes_gcm_128) :
sizeof(struct tls12_crypto_info_aes_gcm_256);
if (optlen != optsize) {
rc = -EINVAL;
goto err_crypto_info;
}
rc = copy_from_user(crypto_info + 1, optval + sizeof(*crypto_info),
optlen - sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto err_crypto_info;
}
optsize = sizeof(struct tls12_crypto_info_aes_gcm_256);
break;
}
case TLS_CIPHER_AES_CCM_128:
optsize = sizeof(struct tls12_crypto_info_aes_ccm_128);
break;
default:
rc = -EINVAL;
goto err_crypto_info;
}

if (optlen != optsize) {
rc = -EINVAL;
goto err_crypto_info;
}

rc = copy_from_user(crypto_info + 1, optval + sizeof(*crypto_info),
optlen - sizeof(*crypto_info));
if (rc) {
rc = -EFAULT;
goto err_crypto_info;
}

if (tx) {
#ifdef CONFIG_TLS_DEVICE
rc = tls_set_device_offload(sk, ctx);
Expand Down
67 changes: 51 additions & 16 deletions net/tls/tls_sw.c
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Original file line number Diff line number Diff line change
Expand Up @@ -42,8 +42,6 @@
#include <net/strparser.h>
#include <net/tls.h>

#define MAX_IV_SIZE TLS_CIPHER_AES_GCM_128_IV_SIZE

static int __skb_nsg(struct sk_buff *skb, int offset, int len,
unsigned int recursion_level)
{
Expand Down Expand Up @@ -479,11 +477,18 @@ static int tls_do_encryption(struct sock *sk,
struct tls_rec *rec = ctx->open_rec;
struct sk_msg *msg_en = &rec->msg_encrypted;
struct scatterlist *sge = sk_msg_elem(msg_en, start);
int rc;
int rc, iv_offset = 0;

/* For CCM based ciphers, first byte of IV is a constant */
if (prot->cipher_type == TLS_CIPHER_AES_CCM_128) {
rec->iv_data[0] = TLS_AES_CCM_IV_B0_BYTE;
iv_offset = 1;
}

memcpy(&rec->iv_data[iv_offset], tls_ctx->tx.iv,
prot->iv_size + prot->salt_size);

memcpy(rec->iv_data, tls_ctx->tx.iv, sizeof(rec->iv_data));
xor_iv_with_seq(prot->version, rec->iv_data,
tls_ctx->tx.rec_seq);
xor_iv_with_seq(prot->version, rec->iv_data, tls_ctx->tx.rec_seq);

sge->offset += prot->prepend_size;
sge->length -= prot->prepend_size;
Expand Down Expand Up @@ -1344,6 +1349,7 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
struct scatterlist *sgout = NULL;
const int data_len = rxm->full_len - prot->overhead_size +
prot->tail_size;
int iv_offset = 0;

if (*zc && (out_iov || out_sg)) {
if (out_iov)
Expand Down Expand Up @@ -1386,18 +1392,25 @@ static int decrypt_internal(struct sock *sk, struct sk_buff *skb,
aad = (u8 *)(sgout + n_sgout);
iv = aad + prot->aad_size;

/* For CCM based ciphers, first byte of nonce+iv is always '2' */
if (prot->cipher_type == TLS_CIPHER_AES_CCM_128) {
iv[0] = 2;
iv_offset = 1;
}

/* Prepare IV */
err = skb_copy_bits(skb, rxm->offset + TLS_HEADER_SIZE,
iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
iv + iv_offset + prot->salt_size,
prot->iv_size);
if (err < 0) {
kfree(mem);
return err;
}
if (prot->version == TLS_1_3_VERSION)
memcpy(iv, tls_ctx->rx.iv, crypto_aead_ivsize(ctx->aead_recv));
memcpy(iv + iv_offset, tls_ctx->rx.iv,
crypto_aead_ivsize(ctx->aead_recv));
else
memcpy(iv, tls_ctx->rx.iv, TLS_CIPHER_AES_GCM_128_SALT_SIZE);
memcpy(iv + iv_offset, tls_ctx->rx.iv, prot->salt_size);

xor_iv_with_seq(prot->version, iv, tls_ctx->rx.rec_seq);

Expand Down Expand Up @@ -2152,14 +2165,15 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
struct tls_crypto_info *crypto_info;
struct tls12_crypto_info_aes_gcm_128 *gcm_128_info;
struct tls12_crypto_info_aes_gcm_256 *gcm_256_info;
struct tls12_crypto_info_aes_ccm_128 *ccm_128_info;
struct tls_sw_context_tx *sw_ctx_tx = NULL;
struct tls_sw_context_rx *sw_ctx_rx = NULL;
struct cipher_context *cctx;
struct crypto_aead **aead;
struct strp_callbacks cb;
u16 nonce_size, tag_size, iv_size, rec_seq_size;
u16 nonce_size, tag_size, iv_size, rec_seq_size, salt_size;
struct crypto_tfm *tfm;
char *iv, *rec_seq, *key, *salt;
char *iv, *rec_seq, *key, *salt, *cipher_name;
size_t keysize;
int rc = 0;

Expand Down Expand Up @@ -2224,6 +2238,8 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
keysize = TLS_CIPHER_AES_GCM_128_KEY_SIZE;
key = gcm_128_info->key;
salt = gcm_128_info->salt;
salt_size = TLS_CIPHER_AES_GCM_128_SALT_SIZE;
cipher_name = "gcm(aes)";
break;
}
case TLS_CIPHER_AES_GCM_256: {
Expand All @@ -2239,6 +2255,25 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
keysize = TLS_CIPHER_AES_GCM_256_KEY_SIZE;
key = gcm_256_info->key;
salt = gcm_256_info->salt;
salt_size = TLS_CIPHER_AES_GCM_256_SALT_SIZE;
cipher_name = "gcm(aes)";
break;
}
case TLS_CIPHER_AES_CCM_128: {
nonce_size = TLS_CIPHER_AES_CCM_128_IV_SIZE;
tag_size = TLS_CIPHER_AES_CCM_128_TAG_SIZE;
iv_size = TLS_CIPHER_AES_CCM_128_IV_SIZE;
iv = ((struct tls12_crypto_info_aes_ccm_128 *)crypto_info)->iv;
rec_seq_size = TLS_CIPHER_AES_CCM_128_REC_SEQ_SIZE;
rec_seq =
((struct tls12_crypto_info_aes_ccm_128 *)crypto_info)->rec_seq;
ccm_128_info =
(struct tls12_crypto_info_aes_ccm_128 *)crypto_info;
keysize = TLS_CIPHER_AES_CCM_128_KEY_SIZE;
key = ccm_128_info->key;
salt = ccm_128_info->salt;
salt_size = TLS_CIPHER_AES_CCM_128_SALT_SIZE;
cipher_name = "ccm(aes)";
break;
}
default:
Expand Down Expand Up @@ -2268,24 +2303,24 @@ int tls_set_sw_offload(struct sock *sk, struct tls_context *ctx, int tx)
prot->overhead_size = prot->prepend_size +
prot->tag_size + prot->tail_size;
prot->iv_size = iv_size;
cctx->iv = kmalloc(iv_size + TLS_CIPHER_AES_GCM_128_SALT_SIZE,
GFP_KERNEL);
prot->salt_size = salt_size;
cctx->iv = kmalloc(iv_size + salt_size, GFP_KERNEL);
if (!cctx->iv) {
rc = -ENOMEM;
goto free_priv;
}
/* Note: 128 & 256 bit salt are the same size */
memcpy(cctx->iv, salt, TLS_CIPHER_AES_GCM_128_SALT_SIZE);
memcpy(cctx->iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, iv, iv_size);
prot->rec_seq_size = rec_seq_size;
memcpy(cctx->iv, salt, salt_size);
memcpy(cctx->iv + salt_size, iv, iv_size);
cctx->rec_seq = kmemdup(rec_seq, rec_seq_size, GFP_KERNEL);
if (!cctx->rec_seq) {
rc = -ENOMEM;
goto free_iv;
}

if (!*aead) {
*aead = crypto_alloc_aead("gcm(aes)", 0, 0);
*aead = crypto_alloc_aead(cipher_name, 0, 0);
if (IS_ERR(*aead)) {
rc = PTR_ERR(*aead);
*aead = NULL;
Expand Down

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