inet_diag: fix oops for IPv4 AF_INET6 TCP SYN-RECV state

Fix inet_diag to be aware of the fact that AF_INET6 TCP connections
instantiated for IPv4 traffic and in the SYN-RECV state were actually
created with inet_reqsk_alloc(), instead of inet6_reqsk_alloc(). This
means that for such connections inet6_rsk(req) returns a pointer to a
random spot in memory up to roughly 64KB beyond the end of the
request_sock.

With this bug, for a server using AF_INET6 TCP sockets and serving
IPv4 traffic, an inet_diag user like `ss state SYN-RECV` would lead to
inet_diag_fill_req() causing an oops or the export to user space of 16
bytes of kernel memory as a garbage IPv6 address, depending on where
the garbage inet6_rsk(req) pointed.

Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
index 0c34bfabc11fc8bcb8056a67abf0feb0b652154f..16cfa42cfd992b06d19527906a61be9238767f0f 100644 (file)
--- a/net/ipv4/inet_diag.c
+++ b/net/ipv4/inet_diag.c
@@ -44,6 +44,10 @@ struct inet_diag_entry {
        u16 dport;
        u16 family;
        u16 userlocks;
+#if IS_ENABLED(CONFIG_IPV6)
+       struct in6_addr saddr_storage;  /* for IPv4-mapped-IPv6 addresses */
+       struct in6_addr daddr_storage;  /* for IPv4-mapped-IPv6 addresses */
+#endif
 };
 
 static DEFINE_MUTEX(inet_diag_table_mutex);
@@ -596,6 +600,36 @@ static int inet_twsk_diag_dump(struct inet_timewait_sock *tw,
                                   cb->nlh->nlmsg_seq, NLM_F_MULTI, cb->nlh);
 }
 
+/* Get the IPv4, IPv6, or IPv4-mapped-IPv6 local and remote addresses
+ * from a request_sock. For IPv4-mapped-IPv6 we must map IPv4 to IPv6.
+ */
+static inline void inet_diag_req_addrs(const struct sock *sk,
+                                      const struct request_sock *req,
+                                      struct inet_diag_entry *entry)
+{
+       struct inet_request_sock *ireq = inet_rsk(req);
+
+#if IS_ENABLED(CONFIG_IPV6)
+       if (sk->sk_family == AF_INET6) {
+               if (req->rsk_ops->family == AF_INET6) {
+                       entry->saddr = inet6_rsk(req)->loc_addr.s6_addr32;
+                       entry->daddr = inet6_rsk(req)->rmt_addr.s6_addr32;
+               } else if (req->rsk_ops->family == AF_INET) {
+                       ipv6_addr_set_v4mapped(ireq->loc_addr,
+                                              &entry->saddr_storage);
+                       ipv6_addr_set_v4mapped(ireq->rmt_addr,
+                                              &entry->daddr_storage);
+                       entry->saddr = entry->saddr_storage.s6_addr32;
+                       entry->daddr = entry->daddr_storage.s6_addr32;
+               }
+       } else
+#endif
+       {
+               entry->saddr = &ireq->loc_addr;
+               entry->daddr = &ireq->rmt_addr;
+       }
+}
+
 static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk,
                              struct request_sock *req,
                              struct user_namespace *user_ns,
@@ -637,8 +671,10 @@ static int inet_diag_fill_req(struct sk_buff *skb, struct sock *sk,
        r->idiag_inode = 0;
 #if IS_ENABLED(CONFIG_IPV6)
        if (r->idiag_family == AF_INET6) {
-               *(struct in6_addr *)r->id.idiag_src = inet6_rsk(req)->loc_addr;
-               *(struct in6_addr *)r->id.idiag_dst = inet6_rsk(req)->rmt_addr;
+               struct inet_diag_entry entry;
+               inet_diag_req_addrs(sk, req, &entry);
+               memcpy(r->id.idiag_src, entry.saddr, sizeof(struct in6_addr));
+               memcpy(r->id.idiag_dst, entry.daddr, sizeof(struct in6_addr));
        }
 #endif
 
@@ -691,18 +727,7 @@ static int inet_diag_dump_reqs(struct sk_buff *skb, struct sock *sk,
                                continue;
 
                        if (bc) {
-                               entry.saddr =
-#if IS_ENABLED(CONFIG_IPV6)
-                                       (entry.family == AF_INET6) ?
-                                       inet6_rsk(req)->loc_addr.s6_addr32 :
-#endif
-                                       &ireq->loc_addr;
-                               entry.daddr =
-#if IS_ENABLED(CONFIG_IPV6)
-                                       (entry.family == AF_INET6) ?
-                                       inet6_rsk(req)->rmt_addr.s6_addr32 :
-#endif
-                                       &ireq->rmt_addr;
+                               inet_diag_req_addrs(sk, req, &entry);
                                entry.dport = ntohs(ireq->rmt_port);
 
                                if (!inet_diag_bc_run(bc, &entry))