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authorFlorian Westphal <fw@strlen.de>2020-02-06 00:39:37 +0100
committerDavid S. Miller <davem@davemloft.net>2020-02-06 11:25:09 +0100
commitb0519de8b3f1caf10632aca55def999ec2d2f1bc (patch)
treeb95ccc010e7691b0715d76e2b9f74e4489876894 /net
parent0202d293c2faecba791ba4afc5aec086249c393d (diff)
downloadlinux-b0519de8b3f1caf10632aca55def999ec2d2f1bc.tar.bz2
mptcp: fix use-after-free for ipv6
Turns out that when we accept a new subflow, the newly created inet_sk(tcp_sk)->pinet6 points at the ipv6_pinfo structure of the listener socket. This wasn't caught by the selftest because it closes the accepted fd before the listening one. adding a close(listenfd) after accept returns is enough: BUG: KASAN: use-after-free in inet6_getname+0x6ba/0x790 Read of size 1 at addr ffff88810e310866 by task mptcp_connect/2518 Call Trace: inet6_getname+0x6ba/0x790 __sys_getpeername+0x10b/0x250 __x64_sys_getpeername+0x6f/0xb0 also alter test program to exercise this. Reported-by: Christoph Paasch <cpaasch@apple.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/mptcp/protocol.c36
1 files changed, 33 insertions, 3 deletions
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 353f2d16b986..73780b4cb108 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -24,6 +24,13 @@
#define MPTCP_SAME_STATE TCP_MAX_STATES
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+struct mptcp6_sock {
+ struct mptcp_sock msk;
+ struct ipv6_pinfo np;
+};
+#endif
+
/* If msk has an initial subflow socket, and the MP_CAPABLE handshake has not
* completed yet or has failed, return the subflow socket.
* Otherwise return NULL.
@@ -627,6 +634,30 @@ static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
inet_sk(msk)->inet_rcv_saddr = inet_sk(ssk)->inet_rcv_saddr;
}
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+static struct ipv6_pinfo *mptcp_inet6_sk(const struct sock *sk)
+{
+ unsigned int offset = sizeof(struct mptcp6_sock) - sizeof(struct ipv6_pinfo);
+
+ return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
+}
+#endif
+
+struct sock *mptcp_sk_clone_lock(const struct sock *sk)
+{
+ struct sock *nsk = sk_clone_lock(sk, GFP_ATOMIC);
+
+ if (!nsk)
+ return NULL;
+
+#if IS_ENABLED(CONFIG_MPTCP_IPV6)
+ if (nsk->sk_family == AF_INET6)
+ inet_sk(nsk)->pinet6 = mptcp_inet6_sk(nsk);
+#endif
+
+ return nsk;
+}
+
static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
bool kern)
{
@@ -657,7 +688,7 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
lock_sock(sk);
local_bh_disable();
- new_mptcp_sock = sk_clone_lock(sk, GFP_ATOMIC);
+ new_mptcp_sock = mptcp_sk_clone_lock(sk);
if (!new_mptcp_sock) {
*err = -ENOBUFS;
local_bh_enable();
@@ -1206,8 +1237,7 @@ int mptcp_proto_v6_init(void)
strcpy(mptcp_v6_prot.name, "MPTCPv6");
mptcp_v6_prot.slab = NULL;
mptcp_v6_prot.destroy = mptcp_v6_destroy;
- mptcp_v6_prot.obj_size = sizeof(struct mptcp_sock) +
- sizeof(struct ipv6_pinfo);
+ mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
err = proto_register(&mptcp_v6_prot, 1);
if (err)