tcp: md5: add TCP_MD5SIG_EXT socket option to set a key address prefix

Replace first padding in the tcp_md5sig structure with a new flag field
and address prefix length so it can be specified when configuring a new
key for TCP MD5 signature. The tcpm_flags field will only be used if the
socket option is TCP_MD5SIG_EXT to avoid breaking existing programs, and
tcpm_prefixlen only when the TCP_MD5SIG_FLAG_PREFIX flag is set.

Signed-off-by: Bob Gilligan <gilligan@arista.com>
Signed-off-by: Eric Mowat <mowat@arista.com>
Signed-off-by: Ivan Delalande <colona@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 8f4076d..d0751b7 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -1848,6 +1848,7 @@ struct tcp_sock_af_ops {
                                         const struct sock *sk,
                                         const struct sk_buff *skb);
        int             (*md5_parse)(struct sock *sk,
+                                    int optname,
                                     char __user *optval,
                                     int optlen);
 #endif

diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 8204dce..a5507c9 100644 (file)
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -117,7 +117,8 @@ enum {
 #define TCP_SAVED_SYN          28      /* Get SYN headers recorded for connection */
 #define TCP_REPAIR_WINDOW      29      /* Get/set window parameters */
 #define TCP_FASTOPEN_CONNECT   30      /* Attempt FastOpen with connect */
-#define TCP_ULP                31      /* Attach a ULP to a TCP connection */
+#define TCP_ULP                        31      /* Attach a ULP to a TCP connection */
+#define TCP_MD5SIG_EXT         32      /* TCP MD5 Signature with extensions */
 
 struct tcp_repair_opt {
        __u32   opt_code;
@@ -235,11 +236,15 @@ enum {
 /* for TCP_MD5SIG socket option */
 #define TCP_MD5SIG_MAXKEYLEN   80
 
+/* tcp_md5sig extension flags for TCP_MD5SIG_EXT */
+#define TCP_MD5SIG_FLAG_PREFIX         1       /* address prefix length */
+
 struct tcp_md5sig {
        struct __kernel_sockaddr_storage tcpm_addr;     /* address associated */
-       __u16   __tcpm_pad1;                            /* zero */
+       __u8    tcpm_flags;                             /* extension flags */
+       __u8    tcpm_prefixlen;                         /* address prefix */
        __u16   tcpm_keylen;                            /* key length */
-       __u32   __tcpm_pad2;                            /* zero */
+       __u32   __tcpm_pad;                             /* zero */
        __u8    tcpm_key[TCP_MD5SIG_MAXKEYLEN];         /* key (binary) */
 };
 

diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index 11e4ee2..058f509 100644 (file)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2714,8 +2714,9 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
 
 #ifdef CONFIG_TCP_MD5SIG
        case TCP_MD5SIG:
+       case TCP_MD5SIG_EXT:
                /* Read the IP->Key mappings from userspace */
-               err = tp->af_specific->md5_parse(sk, optval, optlen);
+               err = tp->af_specific->md5_parse(sk, optname, optval, optlen);
                break;
 #endif
        case TCP_USER_TIMEOUT:

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a3c6786..bf407f3 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1066,11 +1066,12 @@ static void tcp_clear_md5_list(struct sock *sk)
        }
 }
 
-static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
-                                int optlen)
+static int tcp_v4_parse_md5_keys(struct sock *sk, int optname,
+                                char __user *optval, int optlen)
 {
        struct tcp_md5sig cmd;
        struct sockaddr_in *sin = (struct sockaddr_in *)&cmd.tcpm_addr;
+       u8 prefixlen = 32;
 
        if (optlen < sizeof(cmd))
                return -EINVAL;
@@ -1081,15 +1082,22 @@ static int tcp_v4_parse_md5_keys(struct sock *sk, char __user *optval,
        if (sin->sin_family != AF_INET)
                return -EINVAL;
 
+       if (optname == TCP_MD5SIG_EXT &&
+           cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
+               prefixlen = cmd.tcpm_prefixlen;
+               if (prefixlen > 32)
+                       return -EINVAL;
+       }
+
        if (!cmd.tcpm_keylen)
                return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
-                                     AF_INET, 32);
+                                     AF_INET, prefixlen);
 
        if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
                return -EINVAL;
 
        return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin->sin_addr.s_addr,
-                             AF_INET, 32, cmd.tcpm_key, cmd.tcpm_keylen,
+                             AF_INET, prefixlen, cmd.tcpm_key, cmd.tcpm_keylen,
                              GFP_KERNEL);
 }
 

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 2616893..68dc747 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -515,11 +515,12 @@ static struct tcp_md5sig_key *tcp_v6_md5_lookup(const struct sock *sk,
        return tcp_v6_md5_do_lookup(sk, &addr_sk->sk_v6_daddr);
 }
 
-static int tcp_v6_parse_md5_keys(struct sock *sk, char __user *optval,
-                                int optlen)
+static int tcp_v6_parse_md5_keys(struct sock *sk, int optname,
+                                char __user *optval, int optlen)
 {
        struct tcp_md5sig cmd;
        struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *)&cmd.tcpm_addr;
+       u8 prefixlen;
 
        if (optlen < sizeof(cmd))
                return -EINVAL;
@@ -530,12 +531,22 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, char __user *optval,
        if (sin6->sin6_family != AF_INET6)
                return -EINVAL;
 
+       if (optname == TCP_MD5SIG_EXT &&
+           cmd.tcpm_flags & TCP_MD5SIG_FLAG_PREFIX) {
+               prefixlen = cmd.tcpm_prefixlen;
+               if (prefixlen > 128 || (ipv6_addr_v4mapped(&sin6->sin6_addr) &&
+                                       prefixlen > 32))
+                       return -EINVAL;
+       } else {
+               prefixlen = ipv6_addr_v4mapped(&sin6->sin6_addr) ? 32 : 128;
+       }
+
        if (!cmd.tcpm_keylen) {
                if (ipv6_addr_v4mapped(&sin6->sin6_addr))
                        return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
-                                             AF_INET, 32);
+                                             AF_INET, prefixlen);
                return tcp_md5_do_del(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
-                                     AF_INET6, 128);
+                                     AF_INET6, prefixlen);
        }
 
        if (cmd.tcpm_keylen > TCP_MD5SIG_MAXKEYLEN)
@@ -543,12 +554,12 @@ static int tcp_v6_parse_md5_keys(struct sock *sk, char __user *optval,
 
        if (ipv6_addr_v4mapped(&sin6->sin6_addr))
                return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr.s6_addr32[3],
-                                     AF_INET, 32, cmd.tcpm_key,
+                                     AF_INET, prefixlen, cmd.tcpm_key,
                                      cmd.tcpm_keylen, GFP_KERNEL);
 
        return tcp_md5_do_add(sk, (union tcp_md5_addr *)&sin6->sin6_addr,
-                             AF_INET6, 128, cmd.tcpm_key, cmd.tcpm_keylen,
-                             GFP_KERNEL);
+                             AF_INET6, prefixlen, cmd.tcpm_key,
+                             cmd.tcpm_keylen, GFP_KERNEL);
 }
 
 static int tcp_v6_md5_hash_headers(struct tcp_md5sig_pool *hp,