Merge branch 'udpv6_sendmsg-addr_any-fix'

Andrey Ignatov says:

====================
The patch set fixes BSD'ism in sys_sendmsg to rewrite unspecified
destination IPv6 for unconnected UDP sockets in sys_sendmsg with [::1] in
case when either CONFIG_CGROUP_BPF is enabled or when sys_sendmsg BPF hook
sets destination IPv6 to [::].

Patch 1 is the fix and provides more details.
Patch 2 adds two test cases to verify the fix.

v1->v2:
* Fix compile error in patch 1.
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 54 insertions, 7 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 9cbf363172bd..7c3505006f8e 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1390,10 +1390,7 @@ do_udp_sendmsg:
         ipc6.opt = opt;
 
         fl6.flowi6_proto = sk->sk_protocol;
-        if (!ipv6_addr_any(daddr))
-                fl6.daddr = *daddr;
-        else
-                fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
+        fl6.daddr = *daddr;
         if (ipv6_addr_any(&fl6.saddr) && !ipv6_addr_any(&np->saddr))
                 fl6.saddr = np->saddr;
         fl6.fl6_sport = inet->inet_sport;
@@ -1421,6 +1418,9 @@ do_udp_sendmsg:
                 }
         }
 
+        if (ipv6_addr_any(&fl6.daddr))
+                fl6.daddr.s6_addr[15] = 0x1; /* :: means loopback (BSD'ism) */
+
         final_p = fl6_update_dst(&fl6, opt, &final);
         if (final_p)
                 connected = false;
diff --git a/tools/testing/selftests/bpf/test_sock_addr.c b/tools/testing/selftests/bpf/test_sock_addr.c
index 73b7493d4120..d94336cbd8bd 100644
--- a/tools/testing/selftests/bpf/test_sock_addr.c
+++ b/tools/testing/selftests/bpf/test_sock_addr.c
@@ -44,6 +44,7 @@
 #define SERV6_V4MAPPED_IP       "::ffff:192.168.0.4"
 #define SRC6_IP                 "::1"
 #define SRC6_REWRITE_IP         "::6"
+#define WILDCARD6_IP            "::"
 #define SERV6_PORT              6060
 #define SERV6_REWRITE_PORT      6666
 
@@ -85,12 +86,14 @@ static int bind4_prog_load(const struct sock_addr_test *test);
 static int bind6_prog_load(const struct sock_addr_test *test);
 static int connect4_prog_load(const struct sock_addr_test *test);
 static int connect6_prog_load(const struct sock_addr_test *test);
+static int sendmsg_allow_prog_load(const struct sock_addr_test *test);
 static int sendmsg_deny_prog_load(const struct sock_addr_test *test);
 static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test);
 static int sendmsg4_rw_c_prog_load(const struct sock_addr_test *test);
 static int sendmsg6_rw_asm_prog_load(const struct sock_addr_test *test);
 static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test);
 static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test);
+static int sendmsg6_rw_wildcard_prog_load(const struct sock_addr_test *test);
 
 static struct sock_addr_test tests[] = {
         /* bind */
@@ -463,6 +466,34 @@ static struct sock_addr_test tests[] = {
                 SYSCALL_ENOTSUPP,
         },
         {
+                "sendmsg6: set dst IP = [::] (BSD'ism)",
+                sendmsg6_rw_wildcard_prog_load,
+                BPF_CGROUP_UDP6_SENDMSG,
+                BPF_CGROUP_UDP6_SENDMSG,
+                AF_INET6,
+                SOCK_DGRAM,
+                SERV6_IP,
+                SERV6_PORT,
+                SERV6_REWRITE_IP,
+                SERV6_REWRITE_PORT,
+                SRC6_REWRITE_IP,
+                SUCCESS,
+        },
+        {
+                "sendmsg6: preserve dst IP = [::] (BSD'ism)",
+                sendmsg_allow_prog_load,
+                BPF_CGROUP_UDP6_SENDMSG,
+                BPF_CGROUP_UDP6_SENDMSG,
+                AF_INET6,
+                SOCK_DGRAM,
+                WILDCARD6_IP,
+                SERV6_PORT,
+                SERV6_REWRITE_IP,
+                SERV6_PORT,
+                SRC6_IP,
+                SUCCESS,
+        },
+        {
                 "sendmsg6: deny call",
                 sendmsg_deny_prog_load,
                 BPF_CGROUP_UDP6_SENDMSG,
@@ -734,16 +765,27 @@ static int connect6_prog_load(const struct sock_addr_test *test)
         return load_path(test, CONNECT6_PROG_PATH);
 }
 
-static int sendmsg_deny_prog_load(const struct sock_addr_test *test)
+static int sendmsg_ret_only_prog_load(const struct sock_addr_test *test,
+                                      int32_t rc)
 {
         struct bpf_insn insns[] = {
-                /* return 0 */
-                BPF_MOV64_IMM(BPF_REG_0, 0),
+                /* return rc */
+                BPF_MOV64_IMM(BPF_REG_0, rc),
                 BPF_EXIT_INSN(),
         };
         return load_insns(test, insns, sizeof(insns) / sizeof(struct bpf_insn));
 }
 
+static int sendmsg_allow_prog_load(const struct sock_addr_test *test)
+{
+        return sendmsg_ret_only_prog_load(test, /*rc*/ 1);
+}
+
+static int sendmsg_deny_prog_load(const struct sock_addr_test *test)
+{
+        return sendmsg_ret_only_prog_load(test, /*rc*/ 0);
+}
+
 static int sendmsg4_rw_asm_prog_load(const struct sock_addr_test *test)
 {
         struct sockaddr_in dst4_rw_addr;
@@ -864,6 +906,11 @@ static int sendmsg6_rw_v4mapped_prog_load(const struct sock_addr_test *test)
         return sendmsg6_rw_dst_asm_prog_load(test, SERV6_V4MAPPED_IP);
 }
 
+static int sendmsg6_rw_wildcard_prog_load(const struct sock_addr_test *test)
+{
+        return sendmsg6_rw_dst_asm_prog_load(test, WILDCARD6_IP);
+}
+
 static int sendmsg6_rw_c_prog_load(const struct sock_addr_test *test)
 {
         return load_path(test, SENDMSG6_PROG_PATH);