diff options
Diffstat (limited to 'src/quic_retry.c')
| -rw-r--r-- | src/quic_retry.c | 320 |
1 files changed, 320 insertions, 0 deletions
diff --git a/src/quic_retry.c b/src/quic_retry.c new file mode 100644 index 0000000..1c58e5e --- /dev/null +++ b/src/quic_retry.c @@ -0,0 +1,320 @@ +#include <string.h> + +#include <haproxy/clock.h> +#include <haproxy/global.h> +#include <haproxy/quic_retry.h> +#include <haproxy/quic_tls.h> +#include <haproxy/quic_trace-t.h> +#include <haproxy/trace.h> + +#define TRACE_SOURCE &trace_quic + +/* Salt length used to derive retry token secret */ +#define QUIC_RETRY_TOKEN_SALTLEN 16 /* bytes */ + +/* Copy <saddr> socket address data into <buf> buffer. + * This is the responsibility of the caller to check the output buffer is big + * enough to contain these socket address data. + * Return the number of bytes copied. + */ +static inline size_t quic_saddr_cpy(unsigned char *buf, + const struct sockaddr_storage *saddr) +{ + void *port, *addr; + unsigned char *p; + size_t port_len, addr_len; + + p = buf; + if (saddr->ss_family == AF_INET6) { + port = &((struct sockaddr_in6 *)saddr)->sin6_port; + addr = &((struct sockaddr_in6 *)saddr)->sin6_addr; + port_len = sizeof ((struct sockaddr_in6 *)saddr)->sin6_port; + addr_len = sizeof ((struct sockaddr_in6 *)saddr)->sin6_addr; + } + else { + port = &((struct sockaddr_in *)saddr)->sin_port; + addr = &((struct sockaddr_in *)saddr)->sin_addr; + port_len = sizeof ((struct sockaddr_in *)saddr)->sin_port; + addr_len = sizeof ((struct sockaddr_in *)saddr)->sin_addr; + } + memcpy(p, port, port_len); + p += port_len; + memcpy(p, addr, addr_len); + p += addr_len; + + return p - buf; +} + + +/* QUIC server only function. + * Add AAD to <add> buffer from <cid> connection ID and <addr> socket address. + * This is the responsibility of the caller to check <aad> size is big enough + * to contain these data. + * Return the number of bytes copied to <aad>. + */ +static int quic_generate_retry_token_aad(unsigned char *aad, + uint32_t version, + const struct quic_cid *cid, + const struct sockaddr_storage *addr) +{ + unsigned char *p; + + p = aad; + *(uint32_t *)p = htonl(version); + p += sizeof version; + p += quic_saddr_cpy(p, addr); + memcpy(p, cid->data, cid->len); + p += cid->len; + + return p - aad; +} + +/* QUIC server only function. + * Generate the token to be used in Retry packets. The token is written to + * <token> with <len> as length. <odcid> is the original destination connection + * ID and <dcid> is our side destination connection ID (or client source + * connection ID). + * Returns the length of the encoded token or 0 on error. + */ +int quic_generate_retry_token(unsigned char *token, size_t len, + const uint32_t version, + const struct quic_cid *odcid, + const struct quic_cid *dcid, + struct sockaddr_storage *addr) +{ + int ret = 0; + unsigned char *p; + unsigned char aad[sizeof(uint32_t) + sizeof(in_port_t) + + sizeof(struct in6_addr) + QUIC_CID_MAXLEN]; + size_t aadlen; + unsigned char salt[QUIC_RETRY_TOKEN_SALTLEN]; + unsigned char key[QUIC_TLS_KEY_LEN]; + unsigned char iv[QUIC_TLS_IV_LEN]; + const unsigned char *sec = global.cluster_secret; + size_t seclen = sizeof global.cluster_secret; + EVP_CIPHER_CTX *ctx = NULL; + const EVP_CIPHER *aead = EVP_aes_128_gcm(); + uint32_t timestamp = (uint32_t)date.tv_sec; + + TRACE_ENTER(QUIC_EV_CONN_TXPKT); + + /* The token is made of the token format byte, the ODCID prefixed by its one byte + * length, the creation timestamp, an AEAD TAG, and finally + * the random bytes used to derive the secret to encrypt the token. + */ + if (1 + odcid->len + 1 + sizeof(timestamp) + QUIC_TLS_TAG_LEN + QUIC_RETRY_TOKEN_SALTLEN > len) + goto err; + + aadlen = quic_generate_retry_token_aad(aad, version, dcid, addr); + /* TODO: RAND_bytes() should be replaced */ + if (RAND_bytes(salt, sizeof salt) != 1) { + TRACE_ERROR("RAND_bytes()", QUIC_EV_CONN_TXPKT); + goto err; + } + + if (!quic_tls_derive_retry_token_secret(EVP_sha256(), key, sizeof key, iv, sizeof iv, + salt, sizeof salt, sec, seclen)) { + TRACE_ERROR("quic_tls_derive_retry_token_secret() failed", QUIC_EV_CONN_TXPKT); + goto err; + } + + if (!quic_tls_tx_ctx_init(&ctx, aead, key)) { + TRACE_ERROR("quic_tls_tx_ctx_init() failed", QUIC_EV_CONN_TXPKT); + goto err; + } + + /* Token build */ + p = token; + *p++ = QUIC_TOKEN_FMT_RETRY, + *p++ = odcid->len; + memcpy(p, odcid->data, odcid->len); + p += odcid->len; + write_u32(p, htonl(timestamp)); + p += sizeof timestamp; + + /* Do not encrypt the QUIC_TOKEN_FMT_RETRY byte */ + if (!quic_tls_encrypt(token + 1, p - token - 1, aad, aadlen, ctx, aead, iv)) { + TRACE_ERROR("quic_tls_encrypt() failed", QUIC_EV_CONN_TXPKT); + goto err; + } + + p += QUIC_TLS_TAG_LEN; + memcpy(p, salt, sizeof salt); + p += sizeof salt; + EVP_CIPHER_CTX_free(ctx); + + ret = p - token; + leave: + TRACE_LEAVE(QUIC_EV_CONN_TXPKT); + return ret; + + err: + if (ctx) + EVP_CIPHER_CTX_free(ctx); + goto leave; +} + +/* Parse the Retry token from buffer <token> with <end> a pointer to + * one byte past the end of this buffer. This will extract the ODCID + * which will be stored into <odcid> + * + * Returns 0 on success else non-zero. + */ +int parse_retry_token(struct quic_conn *qc, + const unsigned char *token, const unsigned char *end, + struct quic_cid *odcid) +{ + int ret = 0; + uint64_t odcid_len; + uint32_t timestamp; + uint32_t now_sec = (uint32_t)date.tv_sec; + + TRACE_ENTER(QUIC_EV_CONN_LPKT, qc); + + if (!quic_dec_int(&odcid_len, &token, end)) { + TRACE_ERROR("quic_dec_int() error", QUIC_EV_CONN_LPKT, qc); + goto leave; + } + + /* RFC 9000 7.2. Negotiating Connection IDs: + * When an Initial packet is sent by a client that has not previously + * received an Initial or Retry packet from the server, the client + * populates the Destination Connection ID field with an unpredictable + * value. This Destination Connection ID MUST be at least 8 bytes in length. + */ + if (odcid_len < QUIC_ODCID_MINLEN || odcid_len > QUIC_CID_MAXLEN) { + TRACE_ERROR("wrong ODCID length", QUIC_EV_CONN_LPKT, qc); + goto leave; + } + + if (end - token < odcid_len + sizeof timestamp) { + TRACE_ERROR("too long ODCID length", QUIC_EV_CONN_LPKT, qc); + goto leave; + } + + timestamp = ntohl(read_u32(token + odcid_len)); + /* check if elapsed time is +/- QUIC_RETRY_DURATION_SEC + * to tolerate token generator is not perfectly time synced + */ + if ((uint32_t)(now_sec - timestamp) > QUIC_RETRY_DURATION_SEC && + (uint32_t)(timestamp - now_sec) > QUIC_RETRY_DURATION_SEC) { + TRACE_ERROR("token has expired", QUIC_EV_CONN_LPKT, qc); + goto leave; + } + + ret = 1; + memcpy(odcid->data, token, odcid_len); + odcid->len = odcid_len; + leave: + TRACE_LEAVE(QUIC_EV_CONN_LPKT, qc); + return !ret; +} + +/* QUIC server only function. + * + * Check the validity of the Retry token from Initial packet <pkt>. <dgram> is + * the UDP datagram containing <pkt> and <l> is the listener instance on which + * it was received. If the token is valid, the ODCID of <qc> QUIC connection + * will be put into <odcid>. <qc> is used to retrieve the QUIC version needed + * to validate the token but it can be NULL : in this case the version will be + * retrieved from the packet. + * + * Return 1 if succeeded, 0 if not. + */ + +int quic_retry_token_check(struct quic_rx_packet *pkt, + struct quic_dgram *dgram, + struct listener *l, + struct quic_conn *qc, + struct quic_cid *odcid) +{ + struct proxy *prx; + struct quic_counters *prx_counters; + int ret = 0; + unsigned char *token = pkt->token; + const uint64_t tokenlen = pkt->token_len; + unsigned char buf[128]; + unsigned char aad[sizeof(uint32_t) + QUIC_CID_MAXLEN + + sizeof(in_port_t) + sizeof(struct in6_addr)]; + size_t aadlen; + const unsigned char *salt; + unsigned char key[QUIC_TLS_KEY_LEN]; + unsigned char iv[QUIC_TLS_IV_LEN]; + const unsigned char *sec = global.cluster_secret; + size_t seclen = sizeof global.cluster_secret; + EVP_CIPHER_CTX *ctx = NULL; + const EVP_CIPHER *aead = EVP_aes_128_gcm(); + const struct quic_version *qv = qc ? qc->original_version : + pkt->version; + + TRACE_ENTER(QUIC_EV_CONN_LPKT, qc); + + /* The caller must ensure this. */ + BUG_ON(!pkt->token_len); + + prx = l->bind_conf->frontend; + prx_counters = EXTRA_COUNTERS_GET(prx->extra_counters_fe, &quic_stats_module); + + if (*pkt->token != QUIC_TOKEN_FMT_RETRY) { + /* TODO: New token check */ + TRACE_PROTO("Packet dropped", QUIC_EV_CONN_LPKT, qc, NULL, NULL, pkt->version); + goto leave; + } + + if (sizeof buf < tokenlen) { + TRACE_ERROR("too short buffer", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + /* The token is made of the token format byte, the ODCID prefixed by its one byte + * length, the creation timestamp, an AEAD TAG, and finally + * the random bytes used to derive the secret to encrypt the token. + */ + if (tokenlen < 2 + QUIC_ODCID_MINLEN + sizeof(uint32_t) + QUIC_TLS_TAG_LEN + QUIC_RETRY_TOKEN_SALTLEN || + tokenlen > 2 + QUIC_CID_MAXLEN + sizeof(uint32_t) + QUIC_TLS_TAG_LEN + QUIC_RETRY_TOKEN_SALTLEN) { + TRACE_ERROR("invalid token length", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + aadlen = quic_generate_retry_token_aad(aad, qv->num, &pkt->scid, &dgram->saddr); + salt = token + tokenlen - QUIC_RETRY_TOKEN_SALTLEN; + if (!quic_tls_derive_retry_token_secret(EVP_sha256(), key, sizeof key, iv, sizeof iv, + salt, QUIC_RETRY_TOKEN_SALTLEN, sec, seclen)) { + TRACE_ERROR("Could not derive retry secret", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + if (!quic_tls_rx_ctx_init(&ctx, aead, key)) { + TRACE_ERROR("quic_tls_rx_ctx_init() failed", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + /* The token is prefixed by a one-byte length format which is not ciphered. */ + if (!quic_tls_decrypt2(buf, token + 1, tokenlen - QUIC_RETRY_TOKEN_SALTLEN - 1, aad, aadlen, + ctx, aead, key, iv)) { + TRACE_ERROR("Could not decrypt retry token", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + if (parse_retry_token(qc, buf, buf + tokenlen - QUIC_RETRY_TOKEN_SALTLEN - 1, odcid)) { + TRACE_ERROR("Error during Initial token parsing", QUIC_EV_CONN_LPKT, qc); + goto err; + } + + EVP_CIPHER_CTX_free(ctx); + + ret = 1; + HA_ATOMIC_INC(&prx_counters->retry_validated); + + leave: + TRACE_LEAVE(QUIC_EV_CONN_LPKT, qc); + return ret; + + err: + HA_ATOMIC_INC(&prx_counters->retry_error); + if (ctx) + EVP_CIPHER_CTX_free(ctx); + goto leave; +} + + |