net/tls/tls_device_fallback.c

0001 /* Copyright (c) 2018, Mellanox Technologies All rights reserved.
0002  *
0003  * This software is available to you under a choice of one of two
0004  * licenses.  You may choose to be licensed under the terms of the GNU
0005  * General Public License (GPL) Version 2, available from the file
0006  * COPYING in the main directory of this source tree, or the
0007  * OpenIB.org BSD license below:
0008  *
0009  *     Redistribution and use in source and binary forms, with or
0010  *     without modification, are permitted provided that the following
0011  *     conditions are met:
0012  *
0013  *      - Redistributions of source code must retain the above
0014  *        copyright notice, this list of conditions and the following
0015  *        disclaimer.
0016  *
0017  *      - Redistributions in binary form must reproduce the above
0018  *        copyright notice, this list of conditions and the following
0019  *        disclaimer in the documentation and/or other materials
0020  *        provided with the distribution.
0021  *
0022  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
0023  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
0024  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
0025  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
0026  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
0027  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
0028  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
0029  * SOFTWARE.
0030  */
0031
0032 #include <net/tls.h>
0033 #include <crypto/aead.h>
0034 #include <crypto/scatterwalk.h>
0035 #include <net/ip6_checksum.h>
0036
0037 #include "tls.h"
0038
0039 static void chain_to_walk(struct scatterlist *sg, struct scatter_walk *walk)
0040 {
0041     struct scatterlist *src = walk->sg;
0042     int diff = walk->offset - src->offset;
0043
0044     sg_set_page(sg, sg_page(src),
0045             src->length - diff, walk->offset);
0046
0047     scatterwalk_crypto_chain(sg, sg_next(src), 2);
0048 }
0049
0050 static int tls_enc_record(struct aead_request *aead_req,
0051               struct crypto_aead *aead, char *aad,
0052               char *iv, __be64 rcd_sn,
0053               struct scatter_walk *in,
0054               struct scatter_walk *out, int *in_len,
0055               struct tls_prot_info *prot)
0056 {
0057     unsigned char buf[TLS_HEADER_SIZE + TLS_CIPHER_AES_GCM_128_IV_SIZE];
0058     struct scatterlist sg_in[3];
0059     struct scatterlist sg_out[3];
0060     u16 len;
0061     int rc;
0062
0063     len = min_t(int, *in_len, ARRAY_SIZE(buf));
0064
0065     scatterwalk_copychunks(buf, in, len, 0);
0066     scatterwalk_copychunks(buf, out, len, 1);
0067
0068     *in_len -= len;
0069     if (!*in_len)
0070         return 0;
0071
0072     scatterwalk_pagedone(in, 0, 1);
0073     scatterwalk_pagedone(out, 1, 1);
0074
0075     len = buf[4] | (buf[3] << 8);
0076     len -= TLS_CIPHER_AES_GCM_128_IV_SIZE;
0077
0078     tls_make_aad(aad, len - TLS_CIPHER_AES_GCM_128_TAG_SIZE,
0079         (char *)&rcd_sn, buf[0], prot);
0080
0081     memcpy(iv + TLS_CIPHER_AES_GCM_128_SALT_SIZE, buf + TLS_HEADER_SIZE,
0082            TLS_CIPHER_AES_GCM_128_IV_SIZE);
0083
0084     sg_init_table(sg_in, ARRAY_SIZE(sg_in));
0085     sg_init_table(sg_out, ARRAY_SIZE(sg_out));
0086     sg_set_buf(sg_in, aad, TLS_AAD_SPACE_SIZE);
0087     sg_set_buf(sg_out, aad, TLS_AAD_SPACE_SIZE);
0088     chain_to_walk(sg_in + 1, in);
0089     chain_to_walk(sg_out + 1, out);
0090
0091     *in_len -= len;
0092     if (*in_len < 0) {
0093         *in_len += TLS_CIPHER_AES_GCM_128_TAG_SIZE;
0094         /* the input buffer doesn't contain the entire record.
0095          * trim len accordingly. The resulting authentication tag
0096          * will contain garbage, but we don't care, so we won't
0097          * include any of it in the output skb
0098          * Note that we assume the output buffer length
0099          * is larger then input buffer length + tag size
0100          */
0101         if (*in_len < 0)
0102             len += *in_len;
0103
0104         *in_len = 0;
0105     }
0106
0107     if (*in_len) {
0108         scatterwalk_copychunks(NULL, in, len, 2);
0109         scatterwalk_pagedone(in, 0, 1);
0110         scatterwalk_copychunks(NULL, out, len, 2);
0111         scatterwalk_pagedone(out, 1, 1);
0112     }
0113
0114     len -= TLS_CIPHER_AES_GCM_128_TAG_SIZE;
0115     aead_request_set_crypt(aead_req, sg_in, sg_out, len, iv);
0116
0117     rc = crypto_aead_encrypt(aead_req);
0118
0119     return rc;
0120 }
0121
0122 static void tls_init_aead_request(struct aead_request *aead_req,
0123                   struct crypto_aead *aead)
0124 {
0125     aead_request_set_tfm(aead_req, aead);
0126     aead_request_set_ad(aead_req, TLS_AAD_SPACE_SIZE);
0127 }
0128
0129 static struct aead_request *tls_alloc_aead_request(struct crypto_aead *aead,
0130                            gfp_t flags)
0131 {
0132     unsigned int req_size = sizeof(struct aead_request) +
0133         crypto_aead_reqsize(aead);
0134     struct aead_request *aead_req;
0135
0136     aead_req = kzalloc(req_size, flags);
0137     if (aead_req)
0138         tls_init_aead_request(aead_req, aead);
0139     return aead_req;
0140 }
0141
0142 static int tls_enc_records(struct aead_request *aead_req,
0143                struct crypto_aead *aead, struct scatterlist *sg_in,
0144                struct scatterlist *sg_out, char *aad, char *iv,
0145                u64 rcd_sn, int len, struct tls_prot_info *prot)
0146 {
0147     struct scatter_walk out, in;
0148     int rc;
0149
0150     scatterwalk_start(&in, sg_in);
0151     scatterwalk_start(&out, sg_out);
0152
0153     do {
0154         rc = tls_enc_record(aead_req, aead, aad, iv,
0155                     cpu_to_be64(rcd_sn), &in, &out, &len, prot);
0156         rcd_sn++;
0157
0158     } while (rc == 0 && len);
0159
0160     scatterwalk_done(&in, 0, 0);
0161     scatterwalk_done(&out, 1, 0);
0162
0163     return rc;
0164 }
0165
0166 /* Can't use icsk->icsk_af_ops->send_check here because the ip addresses
0167  * might have been changed by NAT.
0168  */
0169 static void update_chksum(struct sk_buff *skb, int headln)
0170 {
0171     struct tcphdr *th = tcp_hdr(skb);
0172     int datalen = skb->len - headln;
0173     const struct ipv6hdr *ipv6h;
0174     const struct iphdr *iph;
0175
0176     /* We only changed the payload so if we are using partial we don't
0177      * need to update anything.
0178      */
0179     if (likely(skb->ip_summed == CHECKSUM_PARTIAL))
0180         return;
0181
0182     skb->ip_summed = CHECKSUM_PARTIAL;
0183     skb->csum_start = skb_transport_header(skb) - skb->head;
0184     skb->csum_offset = offsetof(struct tcphdr, check);
0185
0186     if (skb->sk->sk_family == AF_INET6) {
0187         ipv6h = ipv6_hdr(skb);
0188         th->check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
0189                          datalen, IPPROTO_TCP, 0);
0190     } else {
0191         iph = ip_hdr(skb);
0192         th->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
0193                            IPPROTO_TCP, 0);
0194     }
0195 }
0196
0197 static void complete_skb(struct sk_buff *nskb, struct sk_buff *skb, int headln)
0198 {
0199     struct sock *sk = skb->sk;
0200     int delta;
0201
0202     skb_copy_header(nskb, skb);
0203
0204     skb_put(nskb, skb->len);
0205     memcpy(nskb->data, skb->data, headln);
0206
0207     nskb->destructor = skb->destructor;
0208     nskb->sk = sk;
0209     skb->destructor = NULL;
0210     skb->sk = NULL;
0211
0212     update_chksum(nskb, headln);
0213
0214     /* sock_efree means skb must gone through skb_orphan_partial() */
0215     if (nskb->destructor == sock_efree)
0216         return;
0217
0218     delta = nskb->truesize - skb->truesize;
0219     if (likely(delta < 0))
0220         WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
0221     else if (delta)
0222         refcount_add(delta, &sk->sk_wmem_alloc);
0223 }
0224
0225 /* This function may be called after the user socket is already
0226  * closed so make sure we don't use anything freed during
0227  * tls_sk_proto_close here
0228  */
0229
0230 static int fill_sg_in(struct scatterlist *sg_in,
0231               struct sk_buff *skb,
0232               struct tls_offload_context_tx *ctx,
0233               u64 *rcd_sn,
0234               s32 *sync_size,
0235               int *resync_sgs)
0236 {
0237     int tcp_payload_offset = skb_tcp_all_headers(skb);
0238     int payload_len = skb->len - tcp_payload_offset;
0239     u32 tcp_seq = ntohl(tcp_hdr(skb)->seq);
0240     struct tls_record_info *record;
0241     unsigned long flags;
0242     int remaining;
0243     int i;
0244
0245     spin_lock_irqsave(&ctx->lock, flags);
0246     record = tls_get_record(ctx, tcp_seq, rcd_sn);
0247     if (!record) {
0248         spin_unlock_irqrestore(&ctx->lock, flags);
0249         return -EINVAL;
0250     }
0251
0252     *sync_size = tcp_seq - tls_record_start_seq(record);
0253     if (*sync_size < 0) {
0254         int is_start_marker = tls_record_is_start_marker(record);
0255
0256         spin_unlock_irqrestore(&ctx->lock, flags);
0257         /* This should only occur if the relevant record was
0258          * already acked. In that case it should be ok
0259          * to drop the packet and avoid retransmission.
0260          *
0261          * There is a corner case where the packet contains
0262          * both an acked and a non-acked record.
0263          * We currently don't handle that case and rely
0264          * on TCP to retranmit a packet that doesn't contain
0265          * already acked payload.
0266          */
0267         if (!is_start_marker)
0268             *sync_size = 0;
0269         return -EINVAL;
0270     }
0271
0272     remaining = *sync_size;
0273     for (i = 0; remaining > 0; i++) {
0274         skb_frag_t *frag = &record->frags[i];
0275
0276         __skb_frag_ref(frag);
0277         sg_set_page(sg_in + i, skb_frag_page(frag),
0278                 skb_frag_size(frag), skb_frag_off(frag));
0279
0280         remaining -= skb_frag_size(frag);
0281
0282         if (remaining < 0)
0283             sg_in[i].length += remaining;
0284     }
0285     *resync_sgs = i;
0286
0287     spin_unlock_irqrestore(&ctx->lock, flags);
0288     if (skb_to_sgvec(skb, &sg_in[i], tcp_payload_offset, payload_len) < 0)
0289         return -EINVAL;
0290
0291     return 0;
0292 }
0293
0294 static void fill_sg_out(struct scatterlist sg_out[3], void *buf,
0295             struct tls_context *tls_ctx,
0296             struct sk_buff *nskb,
0297             int tcp_payload_offset,
0298             int payload_len,
0299             int sync_size,
0300             void *dummy_buf)
0301 {
0302     sg_set_buf(&sg_out[0], dummy_buf, sync_size);
0303     sg_set_buf(&sg_out[1], nskb->data + tcp_payload_offset, payload_len);
0304     /* Add room for authentication tag produced by crypto */
0305     dummy_buf += sync_size;
0306     sg_set_buf(&sg_out[2], dummy_buf, TLS_CIPHER_AES_GCM_128_TAG_SIZE);
0307 }
0308
0309 static struct sk_buff *tls_enc_skb(struct tls_context *tls_ctx,
0310                    struct scatterlist sg_out[3],
0311                    struct scatterlist *sg_in,
0312                    struct sk_buff *skb,
0313                    s32 sync_size, u64 rcd_sn)
0314 {
0315     struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
0316     int tcp_payload_offset = skb_tcp_all_headers(skb);
0317     int payload_len = skb->len - tcp_payload_offset;
0318     void *buf, *iv, *aad, *dummy_buf;
0319     struct aead_request *aead_req;
0320     struct sk_buff *nskb = NULL;
0321     int buf_len;
0322
0323     aead_req = tls_alloc_aead_request(ctx->aead_send, GFP_ATOMIC);
0324     if (!aead_req)
0325         return NULL;
0326
0327     buf_len = TLS_CIPHER_AES_GCM_128_SALT_SIZE +
0328           TLS_CIPHER_AES_GCM_128_IV_SIZE +
0329           TLS_AAD_SPACE_SIZE +
0330           sync_size +
0331           TLS_CIPHER_AES_GCM_128_TAG_SIZE;
0332     buf = kmalloc(buf_len, GFP_ATOMIC);
0333     if (!buf)
0334         goto free_req;
0335
0336     iv = buf;
0337     memcpy(iv, tls_ctx->crypto_send.aes_gcm_128.salt,
0338            TLS_CIPHER_AES_GCM_128_SALT_SIZE);
0339     aad = buf + TLS_CIPHER_AES_GCM_128_SALT_SIZE +
0340           TLS_CIPHER_AES_GCM_128_IV_SIZE;
0341     dummy_buf = aad + TLS_AAD_SPACE_SIZE;
0342
0343     nskb = alloc_skb(skb_headroom(skb) + skb->len, GFP_ATOMIC);
0344     if (!nskb)
0345         goto free_buf;
0346
0347     skb_reserve(nskb, skb_headroom(skb));
0348
0349     fill_sg_out(sg_out, buf, tls_ctx, nskb, tcp_payload_offset,
0350             payload_len, sync_size, dummy_buf);
0351
0352     if (tls_enc_records(aead_req, ctx->aead_send, sg_in, sg_out, aad, iv,
0353                 rcd_sn, sync_size + payload_len,
0354                 &tls_ctx->prot_info) < 0)
0355         goto free_nskb;
0356
0357     complete_skb(nskb, skb, tcp_payload_offset);
0358
0359     /* validate_xmit_skb_list assumes that if the skb wasn't segmented
0360      * nskb->prev will point to the skb itself
0361      */
0362     nskb->prev = nskb;
0363
0364 free_buf:
0365     kfree(buf);
0366 free_req:
0367     kfree(aead_req);
0368     return nskb;
0369 free_nskb:
0370     kfree_skb(nskb);
0371     nskb = NULL;
0372     goto free_buf;
0373 }
0374
0375 static struct sk_buff *tls_sw_fallback(struct sock *sk, struct sk_buff *skb)
0376 {
0377     int tcp_payload_offset = skb_tcp_all_headers(skb);
0378     struct tls_context *tls_ctx = tls_get_ctx(sk);
0379     struct tls_offload_context_tx *ctx = tls_offload_ctx_tx(tls_ctx);
0380     int payload_len = skb->len - tcp_payload_offset;
0381     struct scatterlist *sg_in, sg_out[3];
0382     struct sk_buff *nskb = NULL;
0383     int sg_in_max_elements;
0384     int resync_sgs = 0;
0385     s32 sync_size = 0;
0386     u64 rcd_sn;
0387
0388     /* worst case is:
0389      * MAX_SKB_FRAGS in tls_record_info
0390      * MAX_SKB_FRAGS + 1 in SKB head and frags.
0391      */
0392     sg_in_max_elements = 2 * MAX_SKB_FRAGS + 1;
0393
0394     if (!payload_len)
0395         return skb;
0396
0397     sg_in = kmalloc_array(sg_in_max_elements, sizeof(*sg_in), GFP_ATOMIC);
0398     if (!sg_in)
0399         goto free_orig;
0400
0401     sg_init_table(sg_in, sg_in_max_elements);
0402     sg_init_table(sg_out, ARRAY_SIZE(sg_out));
0403
0404     if (fill_sg_in(sg_in, skb, ctx, &rcd_sn, &sync_size, &resync_sgs)) {
0405         /* bypass packets before kernel TLS socket option was set */
0406         if (sync_size < 0 && payload_len <= -sync_size)
0407             nskb = skb_get(skb);
0408         goto put_sg;
0409     }
0410
0411     nskb = tls_enc_skb(tls_ctx, sg_out, sg_in, skb, sync_size, rcd_sn);
0412
0413 put_sg:
0414     while (resync_sgs)
0415         put_page(sg_page(&sg_in[--resync_sgs]));
0416     kfree(sg_in);
0417 free_orig:
0418     if (nskb)
0419         consume_skb(skb);
0420     else
0421         kfree_skb(skb);
0422     return nskb;
0423 }
0424
0425 struct sk_buff *tls_validate_xmit_skb(struct sock *sk,
0426                       struct net_device *dev,
0427                       struct sk_buff *skb)
0428 {
0429     if (dev == rcu_dereference_bh(tls_get_ctx(sk)->netdev) ||
0430         netif_is_bond_master(dev))
0431         return skb;
0432
0433     return tls_sw_fallback(sk, skb);
0434 }
0435 EXPORT_SYMBOL_GPL(tls_validate_xmit_skb);
0436
0437 struct sk_buff *tls_validate_xmit_skb_sw(struct sock *sk,
0438                      struct net_device *dev,
0439                      struct sk_buff *skb)
0440 {
0441     return tls_sw_fallback(sk, skb);
0442 }
0443
0444 struct sk_buff *tls_encrypt_skb(struct sk_buff *skb)
0445 {
0446     return tls_sw_fallback(skb->sk, skb);
0447 }
0448 EXPORT_SYMBOL_GPL(tls_encrypt_skb);
0449
0450 int tls_sw_fallback_init(struct sock *sk,
0451              struct tls_offload_context_tx *offload_ctx,
0452              struct tls_crypto_info *crypto_info)
0453 {
0454     const u8 *key;
0455     int rc;
0456
0457     offload_ctx->aead_send =
0458         crypto_alloc_aead("gcm(aes)", 0, CRYPTO_ALG_ASYNC);
0459     if (IS_ERR(offload_ctx->aead_send)) {
0460         rc = PTR_ERR(offload_ctx->aead_send);
0461         pr_err_ratelimited("crypto_alloc_aead failed rc=%d\n", rc);
0462         offload_ctx->aead_send = NULL;
0463         goto err_out;
0464     }
0465
0466     key = ((struct tls12_crypto_info_aes_gcm_128 *)crypto_info)->key;
0467
0468     rc = crypto_aead_setkey(offload_ctx->aead_send, key,
0469                 TLS_CIPHER_AES_GCM_128_KEY_SIZE);
0470     if (rc)
0471         goto free_aead;
0472
0473     rc = crypto_aead_setauthsize(offload_ctx->aead_send,
0474                      TLS_CIPHER_AES_GCM_128_TAG_SIZE);
0475     if (rc)
0476         goto free_aead;
0477
0478     return 0;
0479 free_aead:
0480     crypto_free_aead(offload_ctx->aead_send);
0481 err_out:
0482     return rc;
0483 }