This commit adds support to add and remove keys but does not use them further.
Similar to tcp md5 a single pointer to a struct tcp_authopt_info* struct is added to struct tcp_sock, this avoids increasing memory usage. The data structures related to tcp_authopt are initialized on setsockopt and only freed on socket close.
Signed-off-by: Leonard Crestez cdleonard@gmail.com --- include/linux/tcp.h | 6 + include/net/tcp.h | 1 + include/net/tcp_authopt.h | 65 +++++++++++ include/uapi/linux/tcp.h | 79 ++++++++++++++ net/ipv4/Kconfig | 14 +++ net/ipv4/Makefile | 1 + net/ipv4/tcp.c | 27 +++++ net/ipv4/tcp_authopt.c | 223 ++++++++++++++++++++++++++++++++++++++ net/ipv4/tcp_ipv4.c | 2 + 9 files changed, 418 insertions(+) create mode 100644 include/net/tcp_authopt.h create mode 100644 net/ipv4/tcp_authopt.c
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 48d8a363319e..cfddfc720b00 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -140,10 +140,12 @@ struct tcp_request_sock { static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) { return (struct tcp_request_sock *)req; }
+struct tcp_authopt_info; + struct tcp_sock { /* inet_connection_sock has to be the first member of tcp_sock */ struct inet_connection_sock inet_conn; u16 tcp_header_len; /* Bytes of tcp header to send */ u16 gso_segs; /* Max number of segs per GSO packet */ @@ -403,10 +405,14 @@ struct tcp_sock {
/* TCP MD5 Signature Option information */ struct tcp_md5sig_info __rcu *md5sig_info; #endif
+#ifdef CONFIG_TCP_AUTHOPT + struct tcp_authopt_info __rcu *authopt_info; +#endif + /* TCP fastopen related information */ struct tcp_fastopen_request *fastopen_req; /* fastopen_rsk points to request_sock that resulted in this big * socket. Used to retransmit SYNACKs etc. */ diff --git a/include/net/tcp.h b/include/net/tcp.h index 3166dc15d7d6..bb76554e8fe5 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -182,10 +182,11 @@ void tcp_time_wait(struct sock *sk, int state, int timeo); #define TCPOPT_WINDOW 3 /* Window scaling */ #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ #define TCPOPT_SACK 5 /* SACK Block */ #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ +#define TCPOPT_AUTHOPT 29 /* Auth Option (RFC5925) */ #define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */ #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ #define TCPOPT_EXP 254 /* Experimental */ /* Magic number to be after the option value for sharing TCP * experimental options. See draft-ietf-tcpm-experimental-options-00.txt diff --git a/include/net/tcp_authopt.h b/include/net/tcp_authopt.h new file mode 100644 index 000000000000..b4277112b506 --- /dev/null +++ b/include/net/tcp_authopt.h @@ -0,0 +1,65 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +#ifndef _LINUX_TCP_AUTHOPT_H +#define _LINUX_TCP_AUTHOPT_H + +#include <uapi/linux/tcp.h> + +/** + * struct tcp_authopt_key_info - Representation of a Master Key Tuple as per RFC5925 + * + * Key structure lifetime is only protected by RCU so readers needs to hold a + * single rcu_read_lock until they're done with the key. + */ +struct tcp_authopt_key_info { + struct hlist_node node; + struct rcu_head rcu; + /* Local identifier */ + u32 local_id; + u32 flags; + /* Wire identifiers */ + u8 send_id, recv_id; + u8 alg_id; + u8 keylen; + u8 key[TCP_AUTHOPT_MAXKEYLEN]; + struct sockaddr_storage addr; +}; + +/** + * struct tcp_authopt_info - Per-socket information regarding tcp_authopt + * + * This is lazy-initialized in order to avoid increasing memory usage for + * regular TCP sockets. Once created it is only destroyed on socket close. + */ +struct tcp_authopt_info { + /** @head: List of tcp_authopt_key_info */ + struct hlist_head head; + struct rcu_head rcu; + u32 flags; + u32 src_isn; + u32 dst_isn; +}; + +#ifdef CONFIG_TCP_AUTHOPT +void tcp_authopt_clear(struct sock *sk); +int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen); +int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *key); +int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen); +#else +static inline int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + return -ENOPROTOOPT; +} +static inline int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *key) +{ + return -ENOPROTOOPT; +} +static inline void tcp_authopt_clear(struct sock *sk) +{ +} +static inline int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + return -ENOPROTOOPT; +} +#endif + +#endif /* _LINUX_TCP_AUTHOPT_H */ diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h index 8fc09e8638b3..575162e7e281 100644 --- a/include/uapi/linux/tcp.h +++ b/include/uapi/linux/tcp.h @@ -126,10 +126,12 @@ enum { #define TCP_INQ 36 /* Notify bytes available to read as a cmsg on read */
#define TCP_CM_INQ TCP_INQ
#define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */ +#define TCP_AUTHOPT 38 /* TCP Authentication Option (RFC5925) */ +#define TCP_AUTHOPT_KEY 39 /* TCP Authentication Option Key (RFC5925) */
#define TCP_REPAIR_ON 1 #define TCP_REPAIR_OFF 0 #define TCP_REPAIR_OFF_NO_WP -1 /* Turn off without window probes */ @@ -340,10 +342,87 @@ struct tcp_diag_md5sig { __u16 tcpm_keylen; __be32 tcpm_addr[4]; __u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; };
+/** + * enum tcp_authopt_flag - flags for `tcp_authopt.flags` + */ +enum tcp_authopt_flag { + /** + * @TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED: + * Configure behavior of segments with TCP-AO coming from hosts for which no + * key is configured. The default recommended by RFC is to silently accept + * such connections. + */ + TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED = (1 << 2), +}; + +/** + * struct tcp_authopt - Per-socket options related to TCP Authentication Option + */ +struct tcp_authopt { + /** @flags: Combination of &enum tcp_authopt_flag */ + __u32 flags; +}; + +/** + * enum tcp_authopt_key_flag - flags for `tcp_authopt.flags` + * + * @TCP_AUTHOPT_KEY_DEL: Delete the key by local_id and ignore all other fields. + * @TCP_AUTHOPT_KEY_EXCLUDE_OPTS: Exclude TCP options from signature. + * @TCP_AUTHOPT_KEY_ADDR_BIND: Key only valid for `tcp_authopt.addr` + */ +enum tcp_authopt_key_flag { + TCP_AUTHOPT_KEY_DEL = (1 << 0), + TCP_AUTHOPT_KEY_EXCLUDE_OPTS = (1 << 1), + TCP_AUTHOPT_KEY_ADDR_BIND = (1 << 2), +}; + +/** + * enum tcp_authopt_alg - Algorithms for TCP Authentication Option + */ +enum tcp_authopt_alg { + TCP_AUTHOPT_ALG_HMAC_SHA_1_96 = 1, + TCP_AUTHOPT_ALG_AES_128_CMAC_96 = 2, +}; + +/* for TCP_AUTHOPT_KEY socket option */ +#define TCP_AUTHOPT_MAXKEYLEN 80 + +/** + * struct tcp_authopt_key - TCP Authentication KEY + * + * Key are identified by the combination of: + * - send_id + * - recv_id + * - addr (iff TCP_AUTHOPT_KEY_ADDR_BIND) + * + * RFC5925 requires that key ids must not overlap for the same TCP connection. + * This is not enforced by linux. + */ +struct tcp_authopt_key { + /** @flags: Combination of &enum tcp_authopt_key_flag */ + __u32 flags; + /** @send_id: keyid value for send */ + __u8 send_id; + /** @recv_id: keyid value for receive */ + __u8 recv_id; + /** @alg: One of &enum tcp_authopt_alg */ + __u8 alg; + /** @keylen: Length of the key buffer */ + __u8 keylen; + /** @key: Secret key */ + __u8 key[TCP_AUTHOPT_MAXKEYLEN]; + /** + * @addr: Key is only valid for this address + * + * Ignored unless TCP_AUTHOPT_KEY_ADDR_BIND flag is set + */ + struct __kernel_sockaddr_storage addr; +}; + /* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
#define TCP_RECEIVE_ZEROCOPY_FLAG_TLB_CLEAN_HINT 0x1 struct tcp_zerocopy_receive { __u64 address; /* in: address of mapping */ diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index 87983e70f03f..6459f4ea6f1d 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -740,5 +740,19 @@ config TCP_MD5SIG RFC2385 specifies a method of giving MD5 protection to TCP sessions. Its main (only?) use is to protect BGP sessions between core routers on the Internet.
If unsure, say N. + +config TCP_AUTHOPT + bool "TCP: Authentication Option support (RFC5925)" + select CRYPTO + select CRYPTO_SHA1 + select CRYPTO_HMAC + select CRYPTO_AES + select CRYPTO_CMAC + help + RFC5925 specifies a new method of giving protection to TCP sessions. + Its intended use is to protect BGP sessions between core routers + on the Internet. It obsoletes TCP MD5 (RFC2385) but is incompatible. + + If unsure, say N. diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile index bbdd9c44f14e..d336f32ce177 100644 --- a/net/ipv4/Makefile +++ b/net/ipv4/Makefile @@ -59,10 +59,11 @@ obj-$(CONFIG_TCP_CONG_NV) += tcp_nv.o obj-$(CONFIG_TCP_CONG_VENO) += tcp_veno.o obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o +obj-$(CONFIG_TCP_AUTHOPT) += tcp_authopt.o obj-$(CONFIG_NET_SOCK_MSG) += tcp_bpf.o obj-$(CONFIG_BPF_SYSCALL) += udp_bpf.o obj-$(CONFIG_NETLABEL) += cipso_ipv4.o
obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \ diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index f931def6302e..fd90e80afa2c 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -271,10 +271,11 @@
#include <net/icmp.h> #include <net/inet_common.h> #include <net/tcp.h> #include <net/mptcp.h> +#include <net/tcp_authopt.h> #include <net/xfrm.h> #include <net/ip.h> #include <net/sock.h>
#include <linux/uaccess.h> @@ -3573,10 +3574,16 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname, case TCP_MD5SIG: case TCP_MD5SIG_EXT: err = tp->af_specific->md5_parse(sk, optname, optval, optlen); break; #endif + case TCP_AUTHOPT: + err = tcp_set_authopt(sk, optval, optlen); + break; + case TCP_AUTHOPT_KEY: + err = tcp_set_authopt_key(sk, optval, optlen); + break; case TCP_USER_TIMEOUT: /* Cap the max time in ms TCP will retry or probe the window * before giving up and aborting (ETIMEDOUT) a connection. */ if (val < 0) @@ -4219,10 +4226,30 @@ static int do_tcp_getsockopt(struct sock *sk, int level, if (!err && copy_to_user(optval, &zc, len)) err = -EFAULT; return err; } #endif +#ifdef CONFIG_TCP_AUTHOPT + case TCP_AUTHOPT: { + struct tcp_authopt info; + + if (get_user(len, optlen)) + return -EFAULT; + + lock_sock(sk); + tcp_get_authopt_val(sk, &info); + release_sock(sk); + + len = min_t(unsigned int, len, sizeof(info)); + if (put_user(len, optlen)) + return -EFAULT; + if (copy_to_user(optval, &info, len)) + return -EFAULT; + return 0; + } +#endif + default: return -ENOPROTOOPT; }
if (put_user(len, optlen)) diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c new file mode 100644 index 000000000000..f6dddc5775ff --- /dev/null +++ b/net/ipv4/tcp_authopt.c @@ -0,0 +1,223 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include <linux/kernel.h> +#include <net/tcp.h> +#include <net/tcp_authopt.h> +#include <crypto/hash.h> +#include <trace/events/tcp.h> + +/* checks that ipv4 or ipv6 addr matches. */ +static bool ipvx_addr_match(struct sockaddr_storage *a1, + struct sockaddr_storage *a2) +{ + if (a1->ss_family != a2->ss_family) + return false; + if (a1->ss_family == AF_INET && memcmp( + &((struct sockaddr_in *)a1)->sin_addr, + &((struct sockaddr_in *)a2)->sin_addr, + sizeof(struct in_addr))) + return false; + if (a1->ss_family == AF_INET6 && memcmp( + &((struct sockaddr_in6 *)a1)->sin6_addr, + &((struct sockaddr_in6 *)a2)->sin6_addr, + sizeof(struct in6_addr))) + return false; + return true; +} + +static bool tcp_authopt_key_match_exact(struct tcp_authopt_key_info *info, + struct tcp_authopt_key *key) +{ + if (info->send_id != key->send_id) + return false; + if (info->recv_id != key->recv_id) + return false; + if ((info->flags & TCP_AUTHOPT_KEY_ADDR_BIND) != (key->recv_id & TCP_AUTHOPT_KEY_ADDR_BIND)) + return false; + if (info->flags & TCP_AUTHOPT_KEY_ADDR_BIND) + if (!ipvx_addr_match(&info->addr, &key->addr)) + return false; + + return true; +} + +static struct tcp_authopt_key_info *tcp_authopt_key_lookup_exact(const struct sock *sk, + struct tcp_authopt_info *info, + struct tcp_authopt_key *ukey) +{ + struct tcp_authopt_key_info *key_info; + + hlist_for_each_entry_rcu(key_info, &info->head, node, lockdep_sock_is_held(sk)) + if (tcp_authopt_key_match_exact(key_info, ukey)) + return key_info; + + return NULL; +} + +static struct tcp_authopt_info *__tcp_authopt_info_get_or_create(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_authopt_info *info; + + info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); + if (info) + return info; + + info = kmalloc(sizeof(*info), GFP_KERNEL | __GFP_ZERO); + if (!info) + return ERR_PTR(-ENOMEM); + + sk_nocaps_add(sk, NETIF_F_GSO_MASK); + INIT_HLIST_HEAD(&info->head); + rcu_assign_pointer(tp->authopt_info, info); + + return info; +} + +#define TCP_AUTHOPT_KNOWN_FLAGS ( \ + TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED) + +int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + struct tcp_authopt opt; + struct tcp_authopt_info *info; + + sock_owned_by_me(sk); + + /* If userspace optlen is too short fill the rest with zeros */ + if (optlen > sizeof(opt)) + return -EINVAL; + memset(&opt, 0, sizeof(opt)); + if (copy_from_sockptr(&opt, optval, optlen)) + return -EFAULT; + + if (opt.flags & ~TCP_AUTHOPT_KNOWN_FLAGS) + return -EINVAL; + + info = __tcp_authopt_info_get_or_create(sk); + if (IS_ERR(info)) + return PTR_ERR(info); + + info->flags = opt.flags & TCP_AUTHOPT_KNOWN_FLAGS; + + return 0; +} + +int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct tcp_authopt_info *info; + + sock_owned_by_me(sk); + + memset(opt, 0, sizeof(*opt)); + info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk)); + if (!info) + return -EINVAL; + + opt->flags = info->flags & TCP_AUTHOPT_KNOWN_FLAGS; + + return 0; +} + +static void tcp_authopt_key_del(struct sock *sk, + struct tcp_authopt_info *info, + struct tcp_authopt_key_info *key) +{ + hlist_del_rcu(&key->node); + atomic_sub(sizeof(*key), &sk->sk_omem_alloc); + kfree_rcu(key, rcu); +} + +/* free info and keys but don't touch tp->authopt_info */ +static void __tcp_authopt_info_free(struct sock *sk, struct tcp_authopt_info *info) +{ + struct hlist_node *n; + struct tcp_authopt_key_info *key; + + hlist_for_each_entry_safe(key, n, &info->head, node) + tcp_authopt_key_del(sk, info, key); + kfree_rcu(info, rcu); +} + +/* free everything and clear tcp_sock.authopt_info to NULL */ +void tcp_authopt_clear(struct sock *sk) +{ + struct tcp_authopt_info *info; + + info = rcu_dereference_protected(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk)); + if (info) { + __tcp_authopt_info_free(sk, info); + tcp_sk(sk)->authopt_info = NULL; + } +} + +#define TCP_AUTHOPT_KEY_KNOWN_FLAGS ( \ + TCP_AUTHOPT_KEY_DEL | \ + TCP_AUTHOPT_KEY_EXCLUDE_OPTS | \ + TCP_AUTHOPT_KEY_ADDR_BIND) + +int tcp_set_authopt_key(struct sock *sk, sockptr_t optval, unsigned int optlen) +{ + struct tcp_authopt_key opt; + struct tcp_authopt_info *info; + struct tcp_authopt_key_info *key_info; + + sock_owned_by_me(sk); + + /* If userspace optlen is too short fill the rest with zeros */ + if (optlen > sizeof(opt)) + return -EINVAL; + memset(&opt, 0, sizeof(opt)); + if (copy_from_sockptr(&opt, optval, optlen)) + return -EFAULT; + + if (opt.flags & ~TCP_AUTHOPT_KEY_KNOWN_FLAGS) + return -EINVAL; + + if (opt.keylen > TCP_AUTHOPT_MAXKEYLEN) + return -EINVAL; + + /* Delete is a special case: */ + if (opt.flags & TCP_AUTHOPT_KEY_DEL) { + info = rcu_dereference_check(tcp_sk(sk)->authopt_info, lockdep_sock_is_held(sk)); + if (!info) + return -ENOENT; + key_info = tcp_authopt_key_lookup_exact(sk, info, &opt); + if (!key_info) + return -ENOENT; + tcp_authopt_key_del(sk, info, key_info); + return 0; + } + + /* check key family */ + if (opt.flags & TCP_AUTHOPT_KEY_ADDR_BIND) { + if (sk->sk_family != opt.addr.ss_family) + return -EINVAL; + } + + /* Initialize tcp_authopt_info if not already set */ + info = __tcp_authopt_info_get_or_create(sk); + if (IS_ERR(info)) + return PTR_ERR(info); + + /* If an old key exists with exact ID then remove and replace. + * RCU-protected readers might observe both and pick any. + */ + key_info = tcp_authopt_key_lookup_exact(sk, info, &opt); + if (key_info) + tcp_authopt_key_del(sk, info, key_info); + key_info = sock_kmalloc(sk, sizeof(*key_info), GFP_KERNEL | __GFP_ZERO); + if (!key_info) + return -ENOMEM; + key_info->flags = opt.flags & TCP_AUTHOPT_KEY_KNOWN_FLAGS; + key_info->send_id = opt.send_id; + key_info->recv_id = opt.recv_id; + key_info->alg_id = opt.alg; + key_info->keylen = opt.keylen; + memcpy(key_info->key, opt.key, opt.keylen); + memcpy(&key_info->addr, &opt.addr, sizeof(key_info->addr)); + hlist_add_head_rcu(&key_info->node, &info->head); + + return 0; +} diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index 2e62e0d6373a..1348615c7576 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -60,10 +60,11 @@
#include <net/net_namespace.h> #include <net/icmp.h> #include <net/inet_hashtables.h> #include <net/tcp.h> +#include <net/tcp_authopt.h> #include <net/transp_v6.h> #include <net/ipv6.h> #include <net/inet_common.h> #include <net/timewait_sock.h> #include <net/xfrm.h> @@ -2256,10 +2257,11 @@ void tcp_v4_destroy_sock(struct sock *sk) tcp_clear_md5_list(sk); kfree_rcu(rcu_dereference_protected(tp->md5sig_info, 1), rcu); tp->md5sig_info = NULL; } #endif + tcp_authopt_clear(sk);
/* Clean up a referenced TCP bind bucket. */ if (inet_csk(sk)->icsk_bind_hash) inet_put_port(sk);