/* * esp_decrypt.c : IPSec ESP decrypt node * * Copyright (c) 2015 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include <vnet/vnet.h> #include <vnet/api_errno.h> #include <vnet/ip/ip.h> #include <vnet/ipsec/ipsec.h> #include <vnet/ipsec/esp.h> #include <vnet/ipsec/ipsec_io.h> #include <vnet/ipsec/ipsec_tun.h> #define foreach_esp_decrypt_next \ _(DROP, "error-drop") \ _(IP4_INPUT, "ip4-input-no-checksum") \ _(IP6_INPUT, "ip6-input") #define _(v, s) ESP_DECRYPT_NEXT_##v, typedef enum { foreach_esp_decrypt_next #undef _ ESP_DECRYPT_N_NEXT, } esp_decrypt_next_t; #define foreach_esp_decrypt_error \ _(RX_PKTS, "ESP pkts received") \ _(DECRYPTION_FAILED, "ESP decryption failed") \ _(INTEG_ERROR, "Integrity check failed") \ _(CRYPTO_ENGINE_ERROR, "crypto engine error (packet dropped)") \ _(REPLAY, "SA replayed packet") \ _(RUNT, "undersized packet") \ _(CHAINED_BUFFER, "chained buffers (packet dropped)") \ _(OVERSIZED_HEADER, "buffer with oversized header (dropped)") \ _(NO_TAIL_SPACE, "no enough buffer tail space (dropped)") \ _(TUN_NO_PROTO, "no tunnel protocol") \ typedef enum { #define _(sym,str) ESP_DECRYPT_ERROR_##sym, foreach_esp_decrypt_error #undef _ ESP_DECRYPT_N_ERROR, } esp_decrypt_error_t; static char *esp_decrypt_error_strings[] = { #define _(sym,string) string, foreach_esp_decrypt_error #undef _ }; typedef struct { u32 seq; u32 sa_seq; u32 sa_seq_hi; ipsec_crypto_alg_t crypto_alg; ipsec_integ_alg_t integ_alg; } esp_decrypt_trace_t; /* packet trace format function */ static u8 * format_esp_decrypt_trace (u8 * s, va_list * args) { CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *); CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *); esp_decrypt_trace_t *t = va_arg (*args, esp_decrypt_trace_t *); s = format (s, "esp: crypto %U integrity %U pkt-seq %d sa-seq %u sa-seq-hi %u", format_ipsec_crypto_alg, t->crypto_alg, format_ipsec_integ_alg, t->integ_alg, t->seq, t->sa_seq, t->sa_seq_hi); return s; } typedef struct { union { struct { u8 icv_sz; u8 iv_sz; ipsec_sa_flags_t flags; u32 sa_index; }; u64 sa_data; }; u32 seq; i16 current_data; i16 current_length; u16 hdr_sz; } esp_decrypt_packet_data_t; STATIC_ASSERT_SIZEOF (esp_decrypt_packet_data_t, 3 * sizeof (u64)); #define ESP_ENCRYPT_PD_F_FD_TRANSPORT (1 << 2) always_inline uword esp_decrypt_inline (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * from_frame, int is_ip6, int is_tun) { ipsec_main_t *im = &ipsec_main; u32 thread_index = vm->thread_index; u16 buffer_data_size = vlib_buffer_get_default_data_size (vm); u16 len; ipsec_per_thread_data_t *ptd = vec_elt_at_index (im->ptd, thread_index); u32 *from = vlib_frame_vector_args (from_frame); u32 n, n_left = from_frame->n_vectors; vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs; u16 nexts[VLIB_FRAME_SIZE], *next = nexts; esp_decrypt_packet_data_t pkt_data[VLIB_FRAME_SIZE], *pd = pkt_data; esp_decrypt_packet_data_t cpd = { }; u32 current_sa_index = ~0, current_sa_bytes = 0, current_sa_pkts = 0; const u8 esp_sz = sizeof (esp_header_t); ipsec_sa_t *sa0 = 0; vlib_get_buffers (vm, from, b, n_left); vec_reset_length (ptd->crypto_ops); vec_reset_length (ptd->integ_ops); clib_memset_u16 (nexts, -1, n_left); while (n_left > 0) { u8 *payload; if (n_left > 2) { u8 *p; vlib_prefetch_buffer_header (b[2], LOAD); p = vlib_buffer_get_current (b[1]); CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD); p -= CLIB_CACHE_LINE_BYTES; CLIB_PREFETCH (p, CLIB_CACHE_LINE_BYTES, LOAD); } if (vlib_buffer_chain_linearize (vm, b[0]) != 1) { b[0]->error = node->errors[ESP_DECRYPT_ERROR_CHAINED_BUFFER]; next[0] = ESP_DECRYPT_NEXT_DROP; goto next; } if (vnet_buffer (b[0])->ipsec.sad_index != current_sa_index) { if (current_sa_pkts) vlib_increment_combined_counter (&ipsec_sa_counters, thread_index, current_sa_index, current_sa_pkts, current_sa_bytes); current_sa_bytes = current_sa_pkts = 0; current_sa_index = vnet_buffer (b[0])->ipsec.sad_index; sa0 = pool_elt_at_index (im->sad, current_sa_index); cpd.icv_sz = sa0->integ_icv_size; cpd.iv_sz = sa0->crypto_iv_size; cpd.flags = sa0->flags; cpd.sa_index = current_sa_index; } /* store packet data for next round for easier prefetch */ pd->sa_data = cpd.sa_data; pd->current_data = b[0]->current_data; pd->current_length = b[0]->current_length; pd->hdr_sz = pd->current_data - vnet_buffer (b[0])->l3_hdr_offset; payload = b[0]->data + pd->current_data; pd->seq = clib_host_to_net_u32 (((esp_header_t *) payload)->seq); /* we need 4 extra bytes for HMAC calculation when ESN are used */ if (ipsec_sa_is_set_USE_ESN (sa0) && pd->icv_sz && (pd->current_data + pd->current_length + 4 > buffer_data_size)) { b[0]->error = node->errors[ESP_DECRYPT_ERROR_NO_TAIL_SPACE]; next[0] = ESP_DECRYPT_NEXT_DROP; goto next; } /* anti-reply check */ if (ipsec_sa_anti_replay_check (sa0, pd->seq)) { b[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY]; next[0] = ESP_DECRYPT_NEXT_DROP; goto next; } if (pd->current_length < cpd.icv_sz + esp_sz + cpd.iv_sz) { b[0]->error = node->errors[ESP_DECRYPT_ERROR_RUNT]; next[0] = ESP_DECRYPT_NEXT_DROP; goto next; } len = pd->current_length - cpd.icv_sz; current_sa_pkts += 1; current_sa_bytes += pd->current_length; if (PREDICT_TRUE (sa0->integ_op_id != VNET_CRYPTO_OP_NONE)) { vnet_crypto_op_t *op; vec_add2_aligned (ptd->integ_ops, op, 1, CLIB_CACHE_LINE_BYTES); vnet_crypto_op_init (op, sa0->integ_op_id); op->key_index = sa0->integ_key_index; op->src = payload; op->flags = VNET_CRYPTO_OP_FLAG_HMAC_CHECK; op->user_data = b - bufs; op->digest = payload + len; op->digest_len = cpd.icv_sz; op->len = len; if (ipsec_sa_is_set_USE_ESN (sa0)) { /* shift ICV by 4 bytes to insert ESN */ u32 seq_hi = clib_host_to_net_u32 (sa0->seq_hi); u8 tmp[ESP_MAX_ICV_SIZE], sz = sizeof (sa0->seq_hi); clib_memcpy_fast (tmp, payload + len, ESP_MAX_ICV_SIZE); clib_memcpy_fast (payload + len, &seq_hi, sz); clib_memcpy_fast (payload + len + sz, tmp, ESP_MAX_ICV_SIZE); op->len += sz; op->digest += sz; } } payload += esp_sz; len -= esp_sz; if (sa0->crypto_enc_op_id != VNET_CRYPTO_OP_NONE) { vnet_crypto_op_t *op; vec_add2_aligned (ptd->crypto_ops, op, 1, CLIB_CACHE_LINE_BYTES); vnet_crypto_op_init (op, sa0->crypto_dec_op_id); op->key_index = sa0->crypto_key_index; op->iv = payload; if (ipsec_sa_is_set_IS_AEAD (sa0)) { esp_header_t *esp0; esp_aead_t *aad; u8 *scratch; /* * construct the AAD and the nonce (Salt || IV) in a scratch * space in front of the IP header. */ scratch = payload - esp_sz; esp0 = (esp_header_t *) (scratch); scratch -= (sizeof (*aad) + pd->hdr_sz); op->aad = scratch; esp_aad_fill (op, esp0, sa0); /* * we don't need to refer to the ESP header anymore so we * can overwrite it with the salt and use the IV where it is * to form the nonce = (Salt + IV) */ op->iv -= sizeof (sa0->salt); clib_memcpy_fast (op->iv, &sa0->salt, sizeof (sa0->salt)); op->tag = payload + len; op->tag_len = 16; } op->src = op->dst = payload += cpd.iv_sz; op->len = len - cpd.iv_sz; op->user_data = b - bufs; } /* next */ next: n_left -= 1; next += 1; pd += 1; b += 1; } vlib_increment_combined_counter (&ipsec_sa_counters, thread_index, current_sa_index, current_sa_pkts, current_sa_bytes); if ((n = vec_len (ptd->integ_ops))) { vnet_crypto_op_t *op = ptd->integ_ops; n -= vnet_crypto_process_ops (vm, op, n); while (n) { ASSERT (op - ptd->integ_ops < vec_len (ptd->integ_ops)); if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED) { u32 err, bi = op->user_data; if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC) err = ESP_DECRYPT_ERROR_INTEG_ERROR; else err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR; bufs[bi]->error = node->errors[err]; nexts[bi] = ESP_DECRYPT_NEXT_DROP; n--; } op++; } } if ((n = vec_len (ptd->crypto_ops))) { vnet_crypto_op_t *op = ptd->crypto_ops; n -= vnet_crypto_process_ops (vm, op, n); while (n) { ASSERT (op - ptd->crypto_ops < vec_len (ptd->crypto_ops)); if (op->status != VNET_CRYPTO_OP_STATUS_COMPLETED) { u32 err, bi; bi = op->user_data; if (op->status == VNET_CRYPTO_OP_STATUS_FAIL_BAD_HMAC) err = ESP_DECRYPT_ERROR_DECRYPTION_FAILED; else err = ESP_DECRYPT_ERROR_CRYPTO_ENGINE_ERROR; bufs[bi]->error = node->errors[err]; nexts[bi] = ESP_DECRYPT_NEXT_DROP; n--; } op++; } } /* Post decryption ronud - adjust packet data start and length and next node */ n_left = from_frame->n_vectors; next = nexts; pd = pkt_data; b = bufs; while (n_left) { const u8 tun_flags = IPSEC_SA_FLAG_IS_TUNNEL | IPSEC_SA_FLAG_IS_TUNNEL_V6; if (n_left >= 2) { void *data = b[1]->data + pd[1].current_data; /* buffer metadata */ vlib_prefetch_buffer_header (b[1], LOAD); /* esp_footer_t */ CLIB_PREFETCH (data + pd[1].current_length - pd[1].icv_sz - 2, CLIB_CACHE_LINE_BYTES, LOAD); /* packet headers */ CLIB_PREFETCH (data - CLIB_CACHE_LINE_BYTES, CLIB_CACHE_LINE_BYTES * 2, LOAD); } if (next[0] < ESP_DECRYPT_N_NEXT) goto trace; sa0 = vec_elt_at_index (im->sad, pd->sa_index); /* * redo the anti-reply check * in this frame say we have sequence numbers, s, s+1, s+1, s+1 * and s and s+1 are in the window. When we did the anti-replay * check above we did so against the state of the window (W), * after packet s-1. So each of the packets in the sequence will be * accepted. * This time s will be cheked against Ws-1, s+1 chceked against Ws * (i.e. the window state is updated/advnaced) * so this time the successive s+! packet will be dropped. * This is a consequence of batching the decrypts. If the * check-dcrypt-advance process was done for each packet it would * be fine. But we batch the decrypts because it's much more efficient * to do so in SW and if we offload to HW and the process is async. * * You're probably thinking, but this means an attacker can send the * above sequence and cause VPP to perform decrpyts that will fail, * and that's true. But if the attacker can determine s (a valid * sequence number in the window) which is non-trivial, it can generate * a sequence s, s+1, s+2, s+3, ... s+n and nothing will prevent any * implementation, sequential or batching, from decrypting these. */ if (ipsec_sa_anti_replay_check (sa0, pd->seq)) { b[0]->error = node->errors[ESP_DECRYPT_ERROR_REPLAY]; next[0] = ESP_DECRYPT_NEXT_DROP; goto trace; } ipsec_sa_anti_replay_advance (sa0, pd->seq); esp_footer_t *f = (esp_footer_t *) (b[0]->data + pd->current_data + pd->current_length - sizeof (*f) - pd->icv_sz); u16 adv = pd->iv_sz + esp_sz; u16 tail = sizeof (esp_footer_t) + f->pad_length + pd->icv_sz; if ((pd->flags & tun_flags) == 0 && !is_tun) /* transport mode */ { u8 udp_sz = (is_ip6 == 0 && pd->flags & IPSEC_SA_FLAG_UDP_ENCAP) ? sizeof (udp_header_t) : 0; u16 ip_hdr_sz = pd->hdr_sz - udp_sz; u8 *old_ip = b[0]->data + pd->current_data - ip_hdr_sz - udp_sz; u8 *ip = old_ip + adv + udp_sz; if (is_ip6 && ip_hdr_sz > 64) memmove (ip, old_ip, ip_hdr_sz); else clib_memcpy_le64 (ip, old_ip, ip_hdr_sz); b[0]->current_data = pd->current_data + adv - ip_hdr_sz; b[0]->current_length = pd->current_length + ip_hdr_sz - tail - adv; if (is_ip6) { ip6_header_t *ip6 = (ip6_header_t *) ip; u16 len = clib_net_to_host_u16 (ip6->payload_length); len -= adv + tail; ip6->payload_length = clib_host_to_net_u16 (len); ip6->protocol = f->next_header; next[0] = ESP_DECRYPT_NEXT_IP6_INPUT; } else { ip4_header_t *ip4 = (ip4_header_t *) ip; ip_csum_t sum = ip4->checksum; u16 len = clib_net_to_host_u16 (ip4->length); len = clib_host_to_net_u16 (len - adv - tail - udp_sz); sum = ip_csum_update (sum, ip4->protocol, f->next_header, ip4_header_t, protocol); sum = ip_csum_update (sum, ip4->length, len, ip4_header_t, length); ip4->checksum = ip_csum_fold (sum); ip4->protocol = f->next_header; ip4->length = len; next[0] = ESP_DECRYPT_NEXT_IP4_INPUT; } } else { if (PREDICT_TRUE (f->next_header == IP_PROTOCOL_IP_IN_IP)) { next[0] = ESP_DECRYPT_NEXT_IP4_INPUT; b[0]->current_data = pd->current_data + adv; b[0]->current_length = pd->current_length - adv - tail; } else if (f->next_header == IP_PROTOCOL_IPV6) { next[0] = ESP_DECRYPT_NEXT_IP6_INPUT; b[0]->current_data = pd->current_data + adv; b[0]->current_length = pd->current_length - adv - tail; } else { next[0] = ESP_DECRYPT_NEXT_DROP; b[0]->error = node->errors[ESP_DECRYPT_ERROR_DECRYPTION_FAILED]; goto trace; } if (is_tun) { if (ipsec_sa_is_set_IS_PROTECT (sa0)) { /* * Check that the reveal IP header matches that * of the tunnel we are protecting */ const ipsec_tun_protect_t *itp; itp = ipsec_tun_protect_get (vnet_buffer (b[0])-> ipsec.protect_index); if (PREDICT_TRUE (f->next_header == IP_PROTOCOL_IP_IN_IP)) { const ip4_header_t *ip4; ip4 = vlib_buffer_get_current (b[0]); if (!ip46_address_is_equal_v4 (&itp->itp_tun.src, &ip4->dst_address) || !ip46_address_is_equal_v4 (&itp->itp_tun.dst, &ip4->src_address)) { next[0] = ESP_DECRYPT_NEXT_DROP; b[0]->error = node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO]; } } else if (f->next_header == IP_PROTOCOL_IPV6) { const ip6_header_t *ip6; ip6 = vlib_buffer_get_current (b[0]); if (!ip46_address_is_equal_v6 (&itp->itp_tun.src, &ip6->dst_address) || !ip46_address_is_equal_v6 (&itp->itp_tun.dst, &ip6->src_address)) { next[0] = ESP_DECRYPT_NEXT_DROP; b[0]->error = node->errors[ESP_DECRYPT_ERROR_TUN_NO_PROTO]; } } } } } trace: if (PREDICT_FALSE (b[0]->flags & VLIB_BUFFER_IS_TRACED)) { esp_decrypt_trace_t *tr; tr = vlib_add_trace (vm, node, b[0], sizeof (*tr)); sa0 = pool_elt_at_index (im->sad, vnet_buffer (b[0])->ipsec.sad_index); tr->crypto_alg = sa0->crypto_alg; tr->integ_alg = sa0->integ_alg; tr->seq = pd->seq; tr->sa_seq = sa0->last_seq; tr->sa_seq_hi = sa0->seq_hi; } /* next */ n_left -= 1; next += 1; pd += 1; b += 1; } n_left = from_frame->n_vectors; vlib_node_increment_counter (vm, node->node_index, ESP_DECRYPT_ERROR_RX_PKTS, n_left); vlib_buffer_enqueue_to_next (vm, node, from, nexts, n_left); b = bufs; return n_left; } VLIB_NODE_FN (esp4_decrypt_node) (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * from_frame) { return esp_decrypt_inline (vm, node, from_frame, 0, 0); } VLIB_NODE_FN (esp4_decrypt_tun_node) (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * from_frame) { return esp_decrypt_inline (vm, node, from_frame, 0, 1); } VLIB_NODE_FN (esp6_decrypt_node) (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * from_frame) { return esp_decrypt_inline (vm, node, from_frame, 1, 0); } VLIB_NODE_FN (esp6_decrypt_tun_node) (vlib_main_t * vm, vlib_node_runtime_t * node, vlib_frame_t * from_frame) { return esp_decrypt_inline (vm, node, from_frame, 1, 1); } /* *INDENT-OFF* */ VLIB_REGISTER_NODE (esp4_decrypt_node) = { .name = "esp4-decrypt", .vector_size = sizeof (u32), .format_trace = format_esp_decrypt_trace, .type = VLIB_NODE_TYPE_INTERNAL, .n_errors = ARRAY_LEN(esp_decrypt_error_strings), .error_strings = esp_decrypt_error_strings, .n_next_nodes = ESP_DECRYPT_N_NEXT, .next_nodes = { #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n, foreach_esp_decrypt_next #undef _ }, }; VLIB_REGISTER_NODE (esp6_decrypt_node) = { .name = "esp6-decrypt", .vector_size = sizeof (u32), .format_trace = format_esp_decrypt_trace, .type = VLIB_NODE_TYPE_INTERNAL, .n_errors = ARRAY_LEN(esp_decrypt_error_strings), .error_strings = esp_decrypt_error_strings, .n_next_nodes = ESP_DECRYPT_N_NEXT, .next_nodes = { #define _(s,n) [ESP_DECRYPT_NEXT_##s] = n, foreach_esp_decrypt_next #undef _ }, }; VLIB_REGISTER_NODE (esp4_decrypt_tun_node) = { .name = "esp4-decrypt-tun", .vector_size = sizeof (u32), .format_trace = format_esp_decrypt_trace, .type = VLIB_NODE_TYPE_INTERNAL, .n_errors = ARRAY_LEN(esp_decrypt_error_strings), .error_strings = esp_decrypt_error_strings, .sibling_of = "esp4-decrypt", }; VLIB_REGISTER_NODE (esp6_decrypt_tun_node) = { .name = "esp6-decrypt-tun", .vector_size = sizeof (u32), .format_trace = format_esp_decrypt_trace, .type = VLIB_NODE_TYPE_INTERNAL, .n_errors = ARRAY_LEN(esp_decrypt_error_strings), .error_strings = esp_decrypt_error_strings, .sibling_of = "esp6-decrypt", }; /* *INDENT-ON* */ /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */