[v8,01/26] tcp: authopt: Initial support and key management

Commit Message

Leonard Crestez Sept. 5, 2022, 7:05 a.m. UTC

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 <[e-mail]>
---
 include/linux/tcp.h             |   9 +
 include/net/net_namespace.h     |   4 +
 include/net/netns/tcp_authopt.h |  12 ++
 include/net/tcp.h               |   1 +
 include/net/tcp_authopt.h       |  70 +++++++
 include/uapi/linux/tcp.h        |  81 ++++++++
 net/ipv4/Kconfig                |  14 ++
 net/ipv4/Makefile               |   1 +
 net/ipv4/tcp.c                  |  32 ++++
 net/ipv4/tcp_authopt.c          | 317 ++++++++++++++++++++++++++++++++
 net/ipv4/tcp_ipv4.c             |   2 +
 11 files changed, 543 insertions(+)
 create mode 100644 include/net/netns/tcp_authopt.h
 create mode 100644 include/net/tcp_authopt.h
 create mode 100644 net/ipv4/tcp_authopt.c

Comments

Eric Dumazet Sept. 6, 2022, 10:57 p.m. UTC | #1

On Mon, Sep 5, 2022 at 12:06 AM Leonard Crestez <[e-mail]> wrote:
>
> 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.
>

Thanks Leonard.

Small points from my side, please find them attached.

> Signed-off-by: Leonard Crestez <[e-mail]>
> ---
>  include/linux/tcp.h             |   9 +
>  include/net/net_namespace.h     |   4 +
>  include/net/netns/tcp_authopt.h |  12 ++
>  include/net/tcp.h               |   1 +
>  include/net/tcp_authopt.h       |  70 +++++++
>  include/uapi/linux/tcp.h        |  81 ++++++++
>  net/ipv4/Kconfig                |  14 ++
>  net/ipv4/Makefile               |   1 +
>  net/ipv4/tcp.c                  |  32 ++++
>  net/ipv4/tcp_authopt.c          | 317 ++++++++++++++++++++++++++++++++
>  net/ipv4/tcp_ipv4.c             |   2 +
>  11 files changed, 543 insertions(+)
>  create mode 100644 include/net/netns/tcp_authopt.h
>  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 a9fbe22732c3..551942883f06 100644
> --- a/include/linux/tcp.h
> +++ b/include/linux/tcp.h
> @@ -170,10 +170,12 @@ 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    */
> @@ -434,10 +436,14 @@ 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.
>          */
> @@ -484,10 +490,13 @@ struct tcp_timewait_sock {
>         int                       tw_ts_recent_stamp;
>         u32                       tw_tx_delay;
>  #ifdef CONFIG_TCP_MD5SIG
>         struct tcp_md5sig_key     *tw_md5_key;
>  #endif
> +#ifdef CONFIG_TCP_AUTHOPT
> +       struct tcp_authopt_info   *tw_authopt_info;
> +#endif
>  };
>
>  static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
>  {
>         return (struct tcp_timewait_sock *)sk;
> diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
> index 8c3587d5c308..30964366951d 100644
> --- a/include/net/net_namespace.h
> +++ b/include/net/net_namespace.h
> @@ -35,10 +35,11 @@
>  #include <net/netns/can.h>
>  #include <net/netns/xdp.h>
>  #include <net/netns/smc.h>
>  #include <net/netns/bpf.h>
>  #include <net/netns/mctp.h>
> +#include <net/netns/tcp_authopt.h>
>  #include <net/net_trackers.h>
>  #include <linux/ns_common.h>
>  #include <linux/idr.h>
>  #include <linux/skbuff.h>
>  #include <linux/notifier.h>
> @@ -184,10 +185,13 @@ struct net {
>  #endif
>         struct sock             *diag_nlsk;
>  #if IS_ENABLED(CONFIG_SMC)
>         struct netns_smc        smc;
>  #endif
> +#if IS_ENABLED(CONFIG_TCP_AUTHOPT)
> +       struct netns_tcp_authopt        tcp_authopt;
> +#endif
>  } __randomize_layout;
>
>  #include <linux/seq_file_net.h>
>
>  /* Init's network namespace */
> diff --git a/include/net/netns/tcp_authopt.h b/include/net/netns/tcp_authopt.h
> new file mode 100644
> index 000000000000..03b7f4e58448
> --- /dev/null
> +++ b/include/net/netns/tcp_authopt.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef __NETNS_TCP_AUTHOPT_H__
> +#define __NETNS_TCP_AUTHOPT_H__
> +
> +#include <linux/mutex.h>
> +
> +struct netns_tcp_authopt {
> +       struct hlist_head head;
> +       struct mutex mutex;
> +};
> +
> +#endif /* __NETNS_TCP_AUTHOPT_H__ */
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index d10962b9f0d0..9955a88faf9b 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -184,10 +184,11 @@ 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..bc2cff82830d
> --- /dev/null
> +++ b/include/net/tcp_authopt.h
> @@ -0,0 +1,70 @@
> +/* SPDX-License-Identifier: GPL-2.0-or-later */
> +#ifndef _LINUX_TCP_AUTHOPT_H
> +#define _LINUX_TCP_AUTHOPT_H
> +
> +#include <uapi/linux/tcp.h>
> +#include <net/netns/tcp_authopt.h>
> +#include <linux/tcp.h>
> +
> +/**
> + * struct tcp_authopt_key_info - Representation of a Master Key Tuple as per RFC5925
> + *
> + * Key structure lifetime is protected by RCU so send/recv code needs to hold a
> + * single rcu_read_lock until they're done with the key.
> + *
> + * Global keys can be cached in sockets, this requires increasing kref.
> + */
> +struct tcp_authopt_key_info {
> +       /** @node: node in &netns_tcp_authopt.head list */
> +       struct hlist_node node;
> +       /** @rcu: for kfree_rcu */
> +       struct rcu_head rcu;
> +       /** @ref: for kref_put */
> +       struct kref ref;
> +       /** @flags: Combination of &enum tcp_authopt_key_flag */
> +       u32 flags;
> +       /** @send_id: Same as &tcp_authopt_key.send_id */
> +       u8 send_id;
> +       /** @recv_id: Same as &tcp_authopt_key.recv_id */
> +       u8 recv_id;
> +       /** @alg_id: Same as &tcp_authopt_key.alg */
> +       u8 alg_id;
> +       /** @keylen: Same as &tcp_authopt_key.keylen */
> +       u8 keylen;
> +       /** @key: Same as &tcp_authopt_key.key */
> +       u8 key[TCP_AUTHOPT_MAXKEYLEN];
> +       /** @addr: Same as &tcp_authopt_key.addr */
> +       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 {
> +       /** @rcu: for kfree_rcu */
> +       struct rcu_head rcu;
> +       /** @flags: Combination of &enum tcp_authopt_flag */
> +       u32 flags;
> +       /** @src_isn: Local Initial Sequence Number */
> +       u32 src_isn;
> +       /** @dst_isn: Remote Initial Sequence Number */
> +       u32 dst_isn;
> +};
> +
> +#ifdef CONFIG_TCP_AUTHOPT
> +DECLARE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
> +#define tcp_authopt_needed (static_branch_unlikely(&tcp_authopt_needed_key))
> +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 void tcp_authopt_clear(struct sock *sk)
> +{
> +}
> +#endif
> +
> +#endif /* _LINUX_TCP_AUTHOPT_H */
> diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> index 8fc09e8638b3..76d7be6b27f4 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 +342,89 @@ 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 and ignore non-id 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: HMAC-SHA-1-96 as described in RFC5926 */
> +       TCP_AUTHOPT_ALG_HMAC_SHA_1_96 = 1,
> +       /** @TCP_AUTHOPT_ALG_AES_128_CMAC_96: AES-128-CMAC-96 as described in RFC5926 */
> +       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 e983bb0c5012..75f7e3c75ea6 100644
> --- a/net/ipv4/Kconfig
> +++ b/net/ipv4/Kconfig
> @@ -739,5 +739,19 @@ 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 306b94dedc8d..6a0357cf05b5 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -270,10 +270,11 @@
>
>  #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>
> @@ -3703,10 +3704,18 @@ static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
>  #ifdef CONFIG_TCP_MD5SIG
>         case TCP_MD5SIG:
>         case TCP_MD5SIG_EXT:
>                 err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
>                 break;
> +#endif
> +#ifdef CONFIG_TCP_AUTHOPT
> +       case TCP_AUTHOPT:
> +               err = tcp_set_authopt(sk, optval, optlen);
> +               break;
> +       case TCP_AUTHOPT_KEY:
> +               err = tcp_set_authopt_key(sk, optval, optlen);
> +               break;
>  #endif
>         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.
>                  */
> @@ -4354,10 +4363,33 @@ 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;
> +               int err;
> +
> +               if (get_user(len, optlen))
> +                       return -EFAULT;
> +
> +               lock_sock(sk);
> +               err = tcp_get_authopt_val(sk, &info);
> +               release_sock(sk);
> +
> +               if (err)
> +                       return err;
> +               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..d38e9c89c89d
> --- /dev/null
> +++ b/net/ipv4/tcp_authopt.c
> @@ -0,0 +1,317 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include <net/tcp_authopt.h>
> +#include <net/ipv6.h>
> +#include <net/tcp.h>
> +#include <linux/kref.h>
> +
> +/* This is enabled when first struct tcp_authopt_info is allocated and never released */
> +DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
> +EXPORT_SYMBOL(tcp_authopt_needed_key);
> +
> +static inline struct netns_tcp_authopt *sock_net_tcp_authopt(const struct sock *sk)
> +{
> +       return &sock_net(sk)->tcp_authopt;
> +}
> +
> +static void tcp_authopt_key_release_kref(struct kref *ref)
> +{
> +       struct tcp_authopt_key_info *key = container_of(ref, struct tcp_authopt_key_info, ref);
> +
> +       kfree_rcu(key, rcu);
> +}
> +
> +static void tcp_authopt_key_put(struct tcp_authopt_key_info *key)
> +{
> +       if (key)
> +               kref_put(&key->ref, tcp_authopt_key_release_kref);
> +}
> +
> +static void tcp_authopt_key_del(struct netns_tcp_authopt *net,
> +                               struct tcp_authopt_key_info *key)
> +{
> +       lockdep_assert_held(&net->mutex);
> +       hlist_del_rcu(&key->node);
> +       key->flags |= TCP_AUTHOPT_KEY_DEL;
> +       kref_put(&key->ref, tcp_authopt_key_release_kref);
> +}
> +
> +/* Free info and keys.
> + * Don't touch tp->authopt_info, it might not even be assigned yes.
> + */
> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
> +{
> +       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_free(sk, info);
> +               tcp_sk(sk)->authopt_info = NULL;

RCU rules at deletion mandate that the pointer must be cleared before
the call_rcu()/kfree_rcu() call.

It is possible that current MD5 code has an issue here, let's not copy/paste it.

> +       }
> +}
> +
> +/* 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 &&
> +           (((struct sockaddr_in *)a1)->sin_addr.s_addr !=
> +            ((struct sockaddr_in *)a2)->sin_addr.s_addr))
> +               return false;
> +       if (a1->ss_family == AF_INET6 &&
> +           !ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,
> +                            &((struct sockaddr_in6 *)a2)->sin6_addr))
> +               return false;
> +       return true;
> +}

Always surprising to see this kind of generic helper being added in a patch.

> +
> +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->flags & 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 netns_tcp_authopt *net,
> +                                                                struct tcp_authopt_key *ukey)
> +{
> +       struct tcp_authopt_key_info *key_info;
> +
> +       hlist_for_each_entry_rcu(key_info, &net->head, node, lockdep_is_held(&net->mutex))
> +               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 = kzalloc(sizeof(*info), GFP_KERNEL);
> +       if (!info)
> +               return ERR_PTR(-ENOMEM);
> +
> +       /* Never released: */
> +       static_branch_inc(&tcp_authopt_needed_key);
> +       sk_gso_disable(sk);
> +       rcu_assign_pointer(tp->authopt_info, info);
> +
> +       return info;
> +}
> +
> +#define TCP_AUTHOPT_KNOWN_FLAGS ( \
> +       TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED)
> +
> +/* Like copy_from_sockptr except tolerate different optlen for compatibility reasons
> + *
> + * If the src is shorter then it's from an old userspace and the rest of dst is
> + * filled with zeros.
> + *
> + * If the dst is shorter then src is from a newer userspace and we only accept
> + * if the rest of the option is all zeros.
> + *
> + * This allows sockopts to grow as long as for new fields zeros has no effect.
> + */
> +static int _copy_from_sockptr_tolerant(u8 *dst,
> +                                      unsigned int dstlen,
> +                                      sockptr_t src,
> +                                      unsigned int srclen)
> +{
> +       int err;
> +
> +       /* If userspace optlen is too short fill the rest with zeros */
> +       if (srclen > dstlen) {
> +               if (sockptr_is_kernel(src))
> +                       return -EINVAL;
> +               err = check_zeroed_user(src.user + dstlen, srclen - dstlen);
> +               if (err < 0)
> +                       return err;
> +               if (err == 0)
> +                       return -EINVAL;
> +       }
> +       err = copy_from_sockptr(dst, src, min(srclen, dstlen));
> +       if (err)
> +               return err;
> +       if (srclen < dstlen)
> +               memset(dst + srclen, 0, dstlen - srclen);
> +
> +       return err;
> +}
> +
> +int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen)
> +{
> +       struct tcp_authopt opt;
> +       struct tcp_authopt_info *info;
> +       int err;
> +
> +       sock_owned_by_me(sk);
> +
> +       err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
> +       if (err)
> +               return err;
> +
> +       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;
> +
> +       memset(opt, 0, sizeof(*opt));
> +       sock_owned_by_me(sk);
> +
> +       info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));

Probably not a big deal, but it seems the prior sock_owned_by_me()
might be redundant.

> +       if (!info)
> +               return -ENOENT;
> +
> +       opt->flags = info->flags & TCP_AUTHOPT_KNOWN_FLAGS;
> +
> +       return 0;
> +}
> +
> +#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, *old_key_info;
> +       struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk);
> +       int err;
> +
> +       sock_owned_by_me(sk);
> +       if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
> +               return -EPERM;
> +
> +       err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
> +       if (err)
> +               return err;
> +
> +       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) {
> +               mutex_lock(&net->mutex);
> +               key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
> +               if (key_info) {
> +                       tcp_authopt_key_del(net, key_info);
> +                       err = 0;
> +               } else {
> +                       err = -ENOENT;
> +               }
> +               mutex_unlock(&net->mutex);
> +               return err;
> +       }
> +
> +       /* 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);
> +
> +       key_info = kmalloc(sizeof(*key_info), GFP_KERNEL | __GFP_ZERO);

kzalloc() ?

> +       if (!key_info)
> +               return -ENOMEM;
> +       mutex_lock(&net->mutex);
> +       kref_init(&key_info->ref);
> +       /* If an old key exists with exact ID then remove and replace.
> +        * RCU-protected readers might observe both and pick any.
> +        */
> +       old_key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
> +       if (old_key_info)
> +               tcp_authopt_key_del(net, old_key_info);
> +       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, &net->head);
> +       mutex_unlock(&net->mutex);
> +
> +       return 0;
> +}
> +
> +static int tcp_authopt_init_net(struct net *full_net)

Hmmm... our convention is to use "struct net *net"

> +{
> +       struct netns_tcp_authopt *net = &full_net->tcp_authopt;

Here, you should use a different name ...

> +
> +       mutex_init(&net->mutex);
> +       INIT_HLIST_HEAD(&net->head);
> +
> +       return 0;
> +}
> +
> +static void tcp_authopt_exit_net(struct net *full_net)
> +{
> +       struct netns_tcp_authopt *net = &full_net->tcp_authopt;
> +       struct tcp_authopt_key_info *key;
> +       struct hlist_node *n;
> +

Same remark here. Please reserve @net for a "struct net" pointer.

> +       mutex_lock(&net->mutex);
> +
> +       hlist_for_each_entry_safe(key, n, &net->head, node) {
> +               hlist_del_rcu(&key->node);
> +               tcp_authopt_key_put(key);
> +       }
> +
> +       mutex_unlock(&net->mutex);
> +}
> +
> +static struct pernet_operations net_ops = {
> +       .init = tcp_authopt_init_net,
> +       .exit = tcp_authopt_exit_net,
> +};
> +
> +static int __init tcp_authopt_init(void)
> +{
> +       return register_pernet_subsys(&net_ops);
> +}
> +late_initcall(tcp_authopt_init);
> diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
> index 01b31f5c7aba..f6d1dba31ca4 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>
> @@ -2267,10 +2268,11 @@ 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);

Do we really own the socket lock at this point ?


>
>         /* Clean up a referenced TCP bind bucket. */
>         if (inet_csk(sk)->icsk_bind_hash)
>                 inet_put_port(sk);
>
> --
> 2.25.1
>

Leonard Crestez Sept. 7, 2022, 4:19 p.m. UTC | #2

On 9/7/22 01:57, Eric Dumazet wrote:
> On Mon, Sep 5, 2022 at 12:06 AM Leonard Crestez <[e-mail]> wrote:
>>
>> 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.
>>
> 
> Thanks Leonard.
> 
> Small points from my side, please find them attached.

...

>> +/* Free info and keys.
>> + * Don't touch tp->authopt_info, it might not even be assigned yes.
>> + */
>> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
>> +{
>> +       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_free(sk, info);
>> +               tcp_sk(sk)->authopt_info = NULL;
> 
> RCU rules at deletion mandate that the pointer must be cleared before
> the call_rcu()/kfree_rcu() call.
> 
> It is possible that current MD5 code has an issue here, let's not copy/paste it.

OK. Is there a need for some special form of assignment or is current 
plain form enough?

> 
>> +       }
>> +}
>> +
>> +/* 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 &&
>> +           (((struct sockaddr_in *)a1)->sin_addr.s_addr !=
>> +            ((struct sockaddr_in *)a2)->sin_addr.s_addr))
>> +               return false;
>> +       if (a1->ss_family == AF_INET6 &&
>> +           !ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,
>> +                            &((struct sockaddr_in6 *)a2)->sin6_addr))
>> +               return false;
>> +       return true;
>> +}
> 
> Always surprising to see this kind of generic helper being added in a patch.

I remember looking for an equivalent and not finding it. Many places 
have distinct code paths for ipv4 and ipv6 and my use of 
"sockaddr_storage" as ipv4/ipv6 union is uncommon.

It also wastes some memory.

>> +int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt)
>> +{
>> +       struct tcp_sock *tp = tcp_sk(sk);
>> +       struct tcp_authopt_info *info;
>> +
>> +       memset(opt, 0, sizeof(*opt));
>> +       sock_owned_by_me(sk);
>> +
>> +       info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));
> 
> Probably not a big deal, but it seems the prior sock_owned_by_me()
> might be redundant.

The sock_owned_by_me call checks checks lockdep_sock_is_held

The rcu_dereference_check call checks lockdep_sock_is_held || 
rcu_read_lock_held()

This is a getsockopt so caller ensures socket locking but 
rcu_read_lock_held() == 0.

The sock_owned_by_me is indeed redundant because it seems very unlikely 
the sockopt calling conditions will be changes. It was mostly there to 
clarify for myself because I had probably at one time with locking 
warnings. I guess they can be removed.

>> +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, *old_key_info;
>> +       struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk);
>> +       int err;
>> +
>> +       sock_owned_by_me(sk);
>> +       if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
>> +               return -EPERM;
>> +
>> +       err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
>> +       if (err)
>> +               return err;
>> +
>> +       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) {
>> +               mutex_lock(&net->mutex);
>> +               key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
>> +               if (key_info) {
>> +                       tcp_authopt_key_del(net, key_info);
>> +                       err = 0;
>> +               } else {
>> +                       err = -ENOENT;
>> +               }
>> +               mutex_unlock(&net->mutex);
>> +               return err;
>> +       }
>> +
>> +       /* 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);
>> +
>> +       key_info = kmalloc(sizeof(*key_info), GFP_KERNEL | __GFP_ZERO);
> 
> kzalloc() ?

Yes

>> +static int tcp_authopt_init_net(struct net *full_net)
> 
> Hmmm... our convention is to use "struct net *net"
> 
>> +{
>> +       struct netns_tcp_authopt *net = &full_net->tcp_authopt;
> 
> Here, you should use a different name ...

OK, will replace with net_ao

>> @@ -2267,10 +2268,11 @@ 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);
> 
> Do we really own the socket lock at this point ?

Not sure how I would tell but there is a lockdep_sock_is_held check 
inside tcp_authopt_clear. I also added sock_owned_by_me and there were 
no warnings.

Eric Dumazet Sept. 7, 2022, 4:28 p.m. UTC | #3

On Wed, Sep 7, 2022 at 9:19 AM Leonard Crestez <[e-mail]> wrote:
>
> On 9/7/22 01:57, Eric Dumazet wrote:
> > On Mon, Sep 5, 2022 at 12:06 AM Leonard Crestez <[e-mail]> wrote:
> >>
> >> 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.
> >>
> >
> > Thanks Leonard.
> >
> > Small points from my side, please find them attached.
>
> ...
>
> >> +/* Free info and keys.
> >> + * Don't touch tp->authopt_info, it might not even be assigned yes.
> >> + */
> >> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
> >> +{
> >> +       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_free(sk, info);
> >> +               tcp_sk(sk)->authopt_info = NULL;
> >
> > RCU rules at deletion mandate that the pointer must be cleared before
> > the call_rcu()/kfree_rcu() call.
> >
> > It is possible that current MD5 code has an issue here, let's not copy/paste it.
>
> OK. Is there a need for some special form of assignment or is current
> plain form enough?

It is the right way (when clearing the pointer), no need for another form.

>
> >
> >> +       }
> >> +}
> >> +
> >> +/* 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 &&
> >> +           (((struct sockaddr_in *)a1)->sin_addr.s_addr !=
> >> +            ((struct sockaddr_in *)a2)->sin_addr.s_addr))
> >> +               return false;
> >> +       if (a1->ss_family == AF_INET6 &&
> >> +           !ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,
> >> +                            &((struct sockaddr_in6 *)a2)->sin6_addr))
> >> +               return false;
> >> +       return true;
> >> +}
> >
> > Always surprising to see this kind of generic helper being added in a patch.
>
> I remember looking for an equivalent and not finding it. Many places
> have distinct code paths for ipv4 and ipv6 and my use of
> "sockaddr_storage" as ipv4/ipv6 union is uncommon.

inetpeer_addr_cmp() might do it (and we also could fix a bug in it it
seems, at least for __tcp_get_metrics() usage :/

>
> It also wastes some memory.
>
> >> +int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt)
> >> +{
> >> +       struct tcp_sock *tp = tcp_sk(sk);
> >> +       struct tcp_authopt_info *info;
> >> +
> >> +       memset(opt, 0, sizeof(*opt));
> >> +       sock_owned_by_me(sk);
> >> +
> >> +       info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));
> >
> > Probably not a big deal, but it seems the prior sock_owned_by_me()
> > might be redundant.
>
> The sock_owned_by_me call checks checks lockdep_sock_is_held
>
> The rcu_dereference_check call checks lockdep_sock_is_held ||
> rcu_read_lock_held()

Then if you own the socket lock, no need for rcu_dereference_check()

It could be instead an rcu_dereference_protected(). This is stronger, because
if your thread no longer owns the socket lock, but is inside
rcu_read_lock(), we would
still get a proper lockdep splat.

>
> This is a getsockopt so caller ensures socket locking but
> rcu_read_lock_held() == 0.
>
> The sock_owned_by_me is indeed redundant because it seems very unlikely
> the sockopt calling conditions will be changes. It was mostly there to
> clarify for myself because I had probably at one time with locking
> warnings. I guess they can be removed.
>
> >> +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, *old_key_info;
> >> +       struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk);
> >> +       int err;
> >> +
> >> +       sock_owned_by_me(sk);
> >> +       if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
> >> +               return -EPERM;
> >> +
> >> +       err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
> >> +       if (err)
> >> +               return err;
> >> +
> >> +       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) {
> >> +               mutex_lock(&net->mutex);
> >> +               key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
> >> +               if (key_info) {
> >> +                       tcp_authopt_key_del(net, key_info);
> >> +                       err = 0;
> >> +               } else {
> >> +                       err = -ENOENT;
> >> +               }
> >> +               mutex_unlock(&net->mutex);
> >> +               return err;
> >> +       }
> >> +
> >> +       /* 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);
> >> +
> >> +       key_info = kmalloc(sizeof(*key_info), GFP_KERNEL | __GFP_ZERO);
> >
> > kzalloc() ?
>
> Yes
>
> >> +static int tcp_authopt_init_net(struct net *full_net)
> >
> > Hmmm... our convention is to use "struct net *net"
> >
> >> +{
> >> +       struct netns_tcp_authopt *net = &full_net->tcp_authopt;
> >
> > Here, you should use a different name ...
>
> OK, will replace with net_ao
>
> >> @@ -2267,10 +2268,11 @@ 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);
> >
> > Do we really own the socket lock at this point ?
>
> Not sure how I would tell but there is a lockdep_sock_is_held check
> inside tcp_authopt_clear. I also added sock_owned_by_me and there were
> no warnings.

Ok then :)

Leonard Crestez Sept. 7, 2022, 6:09 p.m. UTC | #4

On 9/7/22 19:28, Eric Dumazet wrote:
> On Wed, Sep 7, 2022 at 9:19 AM Leonard Crestez <[e-mail]> wrote:
>>
>> On 9/7/22 01:57, Eric Dumazet wrote:
>>> On Mon, Sep 5, 2022 at 12:06 AM Leonard Crestez <[e-mail]> wrote:
>>>>
>>>> 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.
>>>>
>>>
>>> Thanks Leonard.
>>>
>>> Small points from my side, please find them attached.
>>
>> ...
>>
>>>> +/* Free info and keys.
>>>> + * Don't touch tp->authopt_info, it might not even be assigned yes.
>>>> + */
>>>> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
>>>> +{
>>>> +       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_free(sk, info);
>>>> +               tcp_sk(sk)->authopt_info = NULL;
>>>
>>> RCU rules at deletion mandate that the pointer must be cleared before
>>> the call_rcu()/kfree_rcu() call.
>>>
>>> It is possible that current MD5 code has an issue here, let's not copy/paste it.
>>
>> OK. Is there a need for some special form of assignment or is current
>> plain form enough?
> 
> It is the right way (when clearing the pointer), no need for another form.

OK

>>>> +/* 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 &&
>>>> +           (((struct sockaddr_in *)a1)->sin_addr.s_addr !=
>>>> +            ((struct sockaddr_in *)a2)->sin_addr.s_addr))
>>>> +               return false;
>>>> +       if (a1->ss_family == AF_INET6 &&
>>>> +           !ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,
>>>> +                            &((struct sockaddr_in6 *)a2)->sin6_addr))
>>>> +               return false;
>>>> +       return true;
>>>> +}
>>>
>>> Always surprising to see this kind of generic helper being added in a patch.
>>
>> I remember looking for an equivalent and not finding it. Many places
>> have distinct code paths for ipv4 and ipv6 and my use of
>> "sockaddr_storage" as ipv4/ipv6 union is uncommon.
> 
> inetpeer_addr_cmp() might do it (and we also could fix a bug in it it
> seems, at least for __tcp_get_metrics() usage :/

That uses a different `struct inetpeer_addr` which also has some extra 
"vif" fields for ipv4 that I don't know about.

Everybody seems to be rolling their own ipv4/v6 union, other examples 
are `struct tcp_md5_addr` and `xfrm_address_t`. struct sockaddr_storage 
is "more standard" but also larger so maybe that's why others don't use it.

>>>> +int tcp_get_authopt_val(struct sock *sk, struct tcp_authopt *opt)
>>>> +{
>>>> +       struct tcp_sock *tp = tcp_sk(sk);
>>>> +       struct tcp_authopt_info *info;
>>>> +
>>>> +       memset(opt, 0, sizeof(*opt));
>>>> +       sock_owned_by_me(sk);
>>>> +
>>>> +       info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));
>>>
>>> Probably not a big deal, but it seems the prior sock_owned_by_me()
>>> might be redundant.
>>
>> The sock_owned_by_me call checks checks lockdep_sock_is_held
>>
>> The rcu_dereference_check call checks lockdep_sock_is_held ||
>> rcu_read_lock_held()
> 
> Then if you own the socket lock, no need for rcu_dereference_check()
> 
> It could be instead an rcu_dereference_protected(). This is stronger, because
> if your thread no longer owns the socket lock, but is inside
> rcu_read_lock(), we would
> still get a proper lockdep splat.

Ok, I think there are several places where rcu_dereference_check is 
incorrectly used instead of rcu_dereference_protected.

Paolo Abeni Sept. 8, 2022, 6:35 a.m. UTC | #5

On Mon, 2022-09-05 at 10:05 +0300, Leonard Crestez wrote:
[...]
> diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
> new file mode 100644
> index 000000000000..d38e9c89c89d
> --- /dev/null
> +++ b/net/ipv4/tcp_authopt.c
> @@ -0,0 +1,317 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include <net/tcp_authopt.h>
> +#include <net/ipv6.h>
> +#include <net/tcp.h>
> +#include <linux/kref.h>
> +
> +/* This is enabled when first struct tcp_authopt_info is allocated and never released */
> +DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
> +EXPORT_SYMBOL(tcp_authopt_needed_key);
> +
> +static inline struct netns_tcp_authopt *sock_net_tcp_authopt(const struct sock *sk)
> +{
> +	return &sock_net(sk)->tcp_authopt;
> +}

Please have a look at PW report for this series, there are a bunch of
issues to be addressed, e.g. above 'static inline' should be just
'static'


> +
> +static void tcp_authopt_key_release_kref(struct kref *ref)
> +{
> +	struct tcp_authopt_key_info *key = container_of(ref, struct tcp_authopt_key_info, ref);
> +
> +	kfree_rcu(key, rcu);
> +}
> +
> +static void tcp_authopt_key_put(struct tcp_authopt_key_info *key)
> +{
> +	if (key)
> +		kref_put(&key->ref, tcp_authopt_key_release_kref);
> +}
> +
> +static void tcp_authopt_key_del(struct netns_tcp_authopt *net,
> +				struct tcp_authopt_key_info *key)
> +{
> +	lockdep_assert_held(&net->mutex);
> +	hlist_del_rcu(&key->node);
> +	key->flags |= TCP_AUTHOPT_KEY_DEL;
> +	kref_put(&key->ref, tcp_authopt_key_release_kref);
> +}
> +
> +/* Free info and keys.
> + * Don't touch tp->authopt_info, it might not even be assigned yes.
> + */
> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)

this need to be 'static'.

I'm sorry to bring the next topic this late (If already discussed, I
missed that point), is possible to split this series in smaller chunks?


Cheers,

Paolo

Leonard Crestez Sept. 8, 2022, 10:47 a.m. UTC | #6

On 9/8/22 09:35, Paolo Abeni wrote:
> On Mon, 2022-09-05 at 10:05 +0300, Leonard Crestez wrote:
> [...]
>> diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
>> new file mode 100644
>> index 000000000000..d38e9c89c89d
>> --- /dev/null
>> +++ b/net/ipv4/tcp_authopt.c
>> @@ -0,0 +1,317 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +
>> +#include <net/tcp_authopt.h>
>> +#include <net/ipv6.h>
>> +#include <net/tcp.h>
>> +#include <linux/kref.h>
>> +
>> +/* This is enabled when first struct tcp_authopt_info is allocated and never released */
>> +DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
>> +EXPORT_SYMBOL(tcp_authopt_needed_key);
>> +
>> +static inline struct netns_tcp_authopt *sock_net_tcp_authopt(const struct sock *sk)
>> +{
>> +	return &sock_net(sk)->tcp_authopt;
>> +}
> 
> Please have a look at PW report for this series, there are a bunch of
> issues to be addressed, e.g. above 'static inline' should be just
> 'static'

What is a "PW report"? I can't find any info about this.

>> +static void tcp_authopt_key_release_kref(struct kref *ref)
>> +{
>> +	struct tcp_authopt_key_info *key = container_of(ref, struct tcp_authopt_key_info, ref);
>> +
>> +	kfree_rcu(key, rcu);
>> +}
>> +
>> +static void tcp_authopt_key_put(struct tcp_authopt_key_info *key)
>> +{
>> +	if (key)
>> +		kref_put(&key->ref, tcp_authopt_key_release_kref);
>> +}
>> +
>> +static void tcp_authopt_key_del(struct netns_tcp_authopt *net,
>> +				struct tcp_authopt_key_info *key)
>> +{
>> +	lockdep_assert_held(&net->mutex);
>> +	hlist_del_rcu(&key->node);
>> +	key->flags |= TCP_AUTHOPT_KEY_DEL;
>> +	kref_put(&key->ref, tcp_authopt_key_release_kref);
>> +}
>> +
>> +/* Free info and keys.
>> + * Don't touch tp->authopt_info, it might not even be assigned yes.
>> + */
>> +void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
> 
> this need to be 'static'.

Tried this and it's later called from tcp_twsk_destructor.

> I'm sorry to bring the next topic this late (If already discussed, I
> missed that point), is possible to split this series in smaller chunks?

It's already 26 patches and 3675 added lines, less that 150 lines per 
patch seems reasonable?

The split is already somewhat artificial, for example there are patches 
that "add crypto" without actually using it because then it would be too 
large.

Some features could be dropped for later in order to make this smaller, 
for example TCP_REPAIR doesn't have many usecases. Features like 
prefixlen, vrf binding and ipv4-mapped-ipv6 were explicitly requested by 
maintainers so I included them as separate patches in the main series.

--
Regards,
Leonard

David Ahern Sept. 8, 2022, 10:53 a.m. UTC | #7

On 9/8/22 4:47 AM, Leonard Crestez wrote:
> On 9/8/22 09:35, Paolo Abeni wrote:
>> On Mon, 2022-09-05 at 10:05 +0300, Leonard Crestez wrote:
>> [...]
>>> diff --git a/net/ipv4/tcp_authopt.c b/net/ipv4/tcp_authopt.c
>>> new file mode 100644
>>> index 000000000000..d38e9c89c89d
>>> --- /dev/null
>>> +++ b/net/ipv4/tcp_authopt.c
>>> @@ -0,0 +1,317 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>> +
>>> +#include <net/tcp_authopt.h>
>>> +#include <net/ipv6.h>
>>> +#include <net/tcp.h>
>>> +#include <linux/kref.h>
>>> +
>>> +/* This is enabled when first struct tcp_authopt_info is allocated
>>> and never released */
>>> +DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
>>> +EXPORT_SYMBOL(tcp_authopt_needed_key);
>>> +
>>> +static inline struct netns_tcp_authopt *sock_net_tcp_authopt(const
>>> struct sock *sk)
>>> +{
>>> +    return &sock_net(sk)->tcp_authopt;
>>> +}
>>
>> Please have a look at PW report for this series, there are a bunch of
>> issues to be addressed, e.g. above 'static inline' should be just
>> 'static'
> 
> What is a "PW report"? I can't find any info about this.

patchworks: https://patchwork.kernel.org/project/netdevbpf/list/

This set:
https://patchwork.kernel.org/project/netdevbpf/list/?series=&submitter=116101&state=7&q=&archive=&delegate=


>> I'm sorry to bring the next topic this late (If already discussed, I
>> missed that point), is possible to split this series in smaller chunks?
> 
> It's already 26 patches and 3675 added lines, less that 150 lines per
> patch seems reasonable?
> 
> The split is already somewhat artificial, for example there are patches
> that "add crypto" without actually using it because then it would be too
> large.
> 
> Some features could be dropped for later in order to make this smaller,
> for example TCP_REPAIR doesn't have many usecases. Features like
> prefixlen, vrf binding and ipv4-mapped-ipv6 were explicitly requested by
> maintainers so I included them as separate patches in the main series.
> 

The tests could be dropped from the first set along with TCP_REPAIR and
 /proc/net/tcp_authopt patch. That would get it down to 21 patches. From
there the refactor patches could be sent first in a separate PR that
would get it down to 19. Those 19 are the core feature split into small
patches; they should come in together IMHO.

Patch

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index a9fbe22732c3..551942883f06 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -170,10 +170,12 @@  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	*/
@@ -434,10 +436,14 @@  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.
 	 */
@@ -484,10 +490,13 @@  struct tcp_timewait_sock {
 	int			  tw_ts_recent_stamp;
 	u32			  tw_tx_delay;
 #ifdef CONFIG_TCP_MD5SIG
 	struct tcp_md5sig_key	  *tw_md5_key;
 #endif
+#ifdef CONFIG_TCP_AUTHOPT
+	struct tcp_authopt_info	  *tw_authopt_info;
+#endif
 };
 
 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk)
 {
 	return (struct tcp_timewait_sock *)sk;
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index 8c3587d5c308..30964366951d 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -35,10 +35,11 @@ 
 #include <net/netns/can.h>
 #include <net/netns/xdp.h>
 #include <net/netns/smc.h>
 #include <net/netns/bpf.h>
 #include <net/netns/mctp.h>
+#include <net/netns/tcp_authopt.h>
 #include <net/net_trackers.h>
 #include <linux/ns_common.h>
 #include <linux/idr.h>
 #include <linux/skbuff.h>
 #include <linux/notifier.h>
@@ -184,10 +185,13 @@  struct net {
 #endif
 	struct sock		*diag_nlsk;
 #if IS_ENABLED(CONFIG_SMC)
 	struct netns_smc	smc;
 #endif
+#if IS_ENABLED(CONFIG_TCP_AUTHOPT)
+	struct netns_tcp_authopt	tcp_authopt;
+#endif
 } __randomize_layout;
 
 #include <linux/seq_file_net.h>
 
 /* Init's network namespace */
diff --git a/include/net/netns/tcp_authopt.h b/include/net/netns/tcp_authopt.h
new file mode 100644
index 000000000000..03b7f4e58448
--- /dev/null
+++ b/include/net/netns/tcp_authopt.h
@@ -0,0 +1,12 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NETNS_TCP_AUTHOPT_H__
+#define __NETNS_TCP_AUTHOPT_H__
+
+#include <linux/mutex.h>
+
+struct netns_tcp_authopt {
+	struct hlist_head head;
+	struct mutex mutex;
+};
+
+#endif /* __NETNS_TCP_AUTHOPT_H__ */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index d10962b9f0d0..9955a88faf9b 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -184,10 +184,11 @@  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..bc2cff82830d
--- /dev/null
+++ b/include/net/tcp_authopt.h
@@ -0,0 +1,70 @@ 
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+#ifndef _LINUX_TCP_AUTHOPT_H
+#define _LINUX_TCP_AUTHOPT_H
+
+#include <uapi/linux/tcp.h>
+#include <net/netns/tcp_authopt.h>
+#include <linux/tcp.h>
+
+/**
+ * struct tcp_authopt_key_info - Representation of a Master Key Tuple as per RFC5925
+ *
+ * Key structure lifetime is protected by RCU so send/recv code needs to hold a
+ * single rcu_read_lock until they're done with the key.
+ *
+ * Global keys can be cached in sockets, this requires increasing kref.
+ */
+struct tcp_authopt_key_info {
+	/** @node: node in &netns_tcp_authopt.head list */
+	struct hlist_node node;
+	/** @rcu: for kfree_rcu */
+	struct rcu_head rcu;
+	/** @ref: for kref_put */
+	struct kref ref;
+	/** @flags: Combination of &enum tcp_authopt_key_flag */
+	u32 flags;
+	/** @send_id: Same as &tcp_authopt_key.send_id */
+	u8 send_id;
+	/** @recv_id: Same as &tcp_authopt_key.recv_id */
+	u8 recv_id;
+	/** @alg_id: Same as &tcp_authopt_key.alg */
+	u8 alg_id;
+	/** @keylen: Same as &tcp_authopt_key.keylen */
+	u8 keylen;
+	/** @key: Same as &tcp_authopt_key.key */
+	u8 key[TCP_AUTHOPT_MAXKEYLEN];
+	/** @addr: Same as &tcp_authopt_key.addr */
+	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 {
+	/** @rcu: for kfree_rcu */
+	struct rcu_head rcu;
+	/** @flags: Combination of &enum tcp_authopt_flag */
+	u32 flags;
+	/** @src_isn: Local Initial Sequence Number */
+	u32 src_isn;
+	/** @dst_isn: Remote Initial Sequence Number */
+	u32 dst_isn;
+};
+
+#ifdef CONFIG_TCP_AUTHOPT
+DECLARE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
+#define tcp_authopt_needed (static_branch_unlikely(&tcp_authopt_needed_key))
+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 void tcp_authopt_clear(struct sock *sk)
+{
+}
+#endif
+
+#endif /* _LINUX_TCP_AUTHOPT_H */
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8fc09e8638b3..76d7be6b27f4 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 +342,89 @@  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 and ignore non-id 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: HMAC-SHA-1-96 as described in RFC5926 */
+	TCP_AUTHOPT_ALG_HMAC_SHA_1_96 = 1,
+	/** @TCP_AUTHOPT_ALG_AES_128_CMAC_96: AES-128-CMAC-96 as described in RFC5926 */
+	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 e983bb0c5012..75f7e3c75ea6 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -739,5 +739,19 @@  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 306b94dedc8d..6a0357cf05b5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -270,10 +270,11 @@ 
 
 #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>
@@ -3703,10 +3704,18 @@  static int do_tcp_setsockopt(struct sock *sk, int level, int optname,
 #ifdef CONFIG_TCP_MD5SIG
 	case TCP_MD5SIG:
 	case TCP_MD5SIG_EXT:
 		err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
 		break;
+#endif
+#ifdef CONFIG_TCP_AUTHOPT
+	case TCP_AUTHOPT:
+		err = tcp_set_authopt(sk, optval, optlen);
+		break;
+	case TCP_AUTHOPT_KEY:
+		err = tcp_set_authopt_key(sk, optval, optlen);
+		break;
 #endif
 	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.
 		 */
@@ -4354,10 +4363,33 @@  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;
+		int err;
+
+		if (get_user(len, optlen))
+			return -EFAULT;
+
+		lock_sock(sk);
+		err = tcp_get_authopt_val(sk, &info);
+		release_sock(sk);
+
+		if (err)
+			return err;
+		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..d38e9c89c89d
--- /dev/null
+++ b/net/ipv4/tcp_authopt.c
@@ -0,0 +1,317 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <net/tcp_authopt.h>
+#include <net/ipv6.h>
+#include <net/tcp.h>
+#include <linux/kref.h>
+
+/* This is enabled when first struct tcp_authopt_info is allocated and never released */
+DEFINE_STATIC_KEY_FALSE(tcp_authopt_needed_key);
+EXPORT_SYMBOL(tcp_authopt_needed_key);
+
+static inline struct netns_tcp_authopt *sock_net_tcp_authopt(const struct sock *sk)
+{
+	return &sock_net(sk)->tcp_authopt;
+}
+
+static void tcp_authopt_key_release_kref(struct kref *ref)
+{
+	struct tcp_authopt_key_info *key = container_of(ref, struct tcp_authopt_key_info, ref);
+
+	kfree_rcu(key, rcu);
+}
+
+static void tcp_authopt_key_put(struct tcp_authopt_key_info *key)
+{
+	if (key)
+		kref_put(&key->ref, tcp_authopt_key_release_kref);
+}
+
+static void tcp_authopt_key_del(struct netns_tcp_authopt *net,
+				struct tcp_authopt_key_info *key)
+{
+	lockdep_assert_held(&net->mutex);
+	hlist_del_rcu(&key->node);
+	key->flags |= TCP_AUTHOPT_KEY_DEL;
+	kref_put(&key->ref, tcp_authopt_key_release_kref);
+}
+
+/* Free info and keys.
+ * Don't touch tp->authopt_info, it might not even be assigned yes.
+ */
+void tcp_authopt_free(struct sock *sk, struct tcp_authopt_info *info)
+{
+	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_free(sk, info);
+		tcp_sk(sk)->authopt_info = NULL;
+	}
+}
+
+/* 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 &&
+	    (((struct sockaddr_in *)a1)->sin_addr.s_addr !=
+	     ((struct sockaddr_in *)a2)->sin_addr.s_addr))
+		return false;
+	if (a1->ss_family == AF_INET6 &&
+	    !ipv6_addr_equal(&((struct sockaddr_in6 *)a1)->sin6_addr,
+			     &((struct sockaddr_in6 *)a2)->sin6_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->flags & 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 netns_tcp_authopt *net,
+								 struct tcp_authopt_key *ukey)
+{
+	struct tcp_authopt_key_info *key_info;
+
+	hlist_for_each_entry_rcu(key_info, &net->head, node, lockdep_is_held(&net->mutex))
+		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 = kzalloc(sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return ERR_PTR(-ENOMEM);
+
+	/* Never released: */
+	static_branch_inc(&tcp_authopt_needed_key);
+	sk_gso_disable(sk);
+	rcu_assign_pointer(tp->authopt_info, info);
+
+	return info;
+}
+
+#define TCP_AUTHOPT_KNOWN_FLAGS ( \
+	TCP_AUTHOPT_FLAG_REJECT_UNEXPECTED)
+
+/* Like copy_from_sockptr except tolerate different optlen for compatibility reasons
+ *
+ * If the src is shorter then it's from an old userspace and the rest of dst is
+ * filled with zeros.
+ *
+ * If the dst is shorter then src is from a newer userspace and we only accept
+ * if the rest of the option is all zeros.
+ *
+ * This allows sockopts to grow as long as for new fields zeros has no effect.
+ */
+static int _copy_from_sockptr_tolerant(u8 *dst,
+				       unsigned int dstlen,
+				       sockptr_t src,
+				       unsigned int srclen)
+{
+	int err;
+
+	/* If userspace optlen is too short fill the rest with zeros */
+	if (srclen > dstlen) {
+		if (sockptr_is_kernel(src))
+			return -EINVAL;
+		err = check_zeroed_user(src.user + dstlen, srclen - dstlen);
+		if (err < 0)
+			return err;
+		if (err == 0)
+			return -EINVAL;
+	}
+	err = copy_from_sockptr(dst, src, min(srclen, dstlen));
+	if (err)
+		return err;
+	if (srclen < dstlen)
+		memset(dst + srclen, 0, dstlen - srclen);
+
+	return err;
+}
+
+int tcp_set_authopt(struct sock *sk, sockptr_t optval, unsigned int optlen)
+{
+	struct tcp_authopt opt;
+	struct tcp_authopt_info *info;
+	int err;
+
+	sock_owned_by_me(sk);
+
+	err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
+	if (err)
+		return err;
+
+	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;
+
+	memset(opt, 0, sizeof(*opt));
+	sock_owned_by_me(sk);
+
+	info = rcu_dereference_check(tp->authopt_info, lockdep_sock_is_held(sk));
+	if (!info)
+		return -ENOENT;
+
+	opt->flags = info->flags & TCP_AUTHOPT_KNOWN_FLAGS;
+
+	return 0;
+}
+
+#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, *old_key_info;
+	struct netns_tcp_authopt *net = sock_net_tcp_authopt(sk);
+	int err;
+
+	sock_owned_by_me(sk);
+	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+		return -EPERM;
+
+	err = _copy_from_sockptr_tolerant((u8 *)&opt, sizeof(opt), optval, optlen);
+	if (err)
+		return err;
+
+	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) {
+		mutex_lock(&net->mutex);
+		key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
+		if (key_info) {
+			tcp_authopt_key_del(net, key_info);
+			err = 0;
+		} else {
+			err = -ENOENT;
+		}
+		mutex_unlock(&net->mutex);
+		return err;
+	}
+
+	/* 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);
+
+	key_info = kmalloc(sizeof(*key_info), GFP_KERNEL | __GFP_ZERO);
+	if (!key_info)
+		return -ENOMEM;
+	mutex_lock(&net->mutex);
+	kref_init(&key_info->ref);
+	/* If an old key exists with exact ID then remove and replace.
+	 * RCU-protected readers might observe both and pick any.
+	 */
+	old_key_info = tcp_authopt_key_lookup_exact(sk, net, &opt);
+	if (old_key_info)
+		tcp_authopt_key_del(net, old_key_info);
+	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, &net->head);
+	mutex_unlock(&net->mutex);
+
+	return 0;
+}
+
+static int tcp_authopt_init_net(struct net *full_net)
+{
+	struct netns_tcp_authopt *net = &full_net->tcp_authopt;
+
+	mutex_init(&net->mutex);
+	INIT_HLIST_HEAD(&net->head);
+
+	return 0;
+}
+
+static void tcp_authopt_exit_net(struct net *full_net)
+{
+	struct netns_tcp_authopt *net = &full_net->tcp_authopt;
+	struct tcp_authopt_key_info *key;
+	struct hlist_node *n;
+
+	mutex_lock(&net->mutex);
+
+	hlist_for_each_entry_safe(key, n, &net->head, node) {
+		hlist_del_rcu(&key->node);
+		tcp_authopt_key_put(key);
+	}
+
+	mutex_unlock(&net->mutex);
+}
+
+static struct pernet_operations net_ops = {
+	.init = tcp_authopt_init_net,
+	.exit = tcp_authopt_exit_net,
+};
+
+static int __init tcp_authopt_init(void)
+{
+	return register_pernet_subsys(&net_ops);
+}
+late_initcall(tcp_authopt_init);
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 01b31f5c7aba..f6d1dba31ca4 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>
@@ -2267,10 +2268,11 @@  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);