udp: move udp->no_check6_rx to udp->udp_flags

[ Upstream commit bcbc1b1de884647aa0318bf74eb7f293d72a1e40 ]

syzbot reported that udp->no_check6_rx can be read locklessly.
Use one atomic bit from udp->udp_flags.

Fixes: 1c19448c9ba6 ("net: Make enabling of zero UDP6 csums more restrictive")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/include/linux/udp.h b/include/linux/udp.h
index e3f2a6c..8d4c383 100644 (file)
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -35,6 +35,7 @@ static inline u32 udp_hashfn(const struct net *net, u32 num, u32 mask)
 enum {
        UDP_FLAGS_CORK,         /* Cork is required */
        UDP_FLAGS_NO_CHECK6_TX, /* Send zero UDP6 checksums on TX? */
+       UDP_FLAGS_NO_CHECK6_RX, /* Allow zero UDP6 checksums on RX? */
 };
 
 struct udp_sock {
@@ -48,8 +49,7 @@ struct udp_sock {
 
        int              pending;       /* Any pending frames ? */
        __u8             encap_type;    /* Is this an Encapsulation socket? */
-       unsigned char    no_check6_rx:1,/* Allow zero UDP6 checksums on RX? */
-                        encap_enabled:1, /* This socket enabled encap
+       unsigned char    encap_enabled:1, /* This socket enabled encap
                                           * processing; UDP tunnels and
                                           * different encapsulation layer set
                                           * this
@@ -120,7 +120,7 @@ static inline void udp_set_no_check6_tx(struct sock *sk, bool val)
 
 static inline void udp_set_no_check6_rx(struct sock *sk, bool val)
 {
-       udp_sk(sk)->no_check6_rx = val;
+       udp_assign_bit(NO_CHECK6_RX, sk, val);
 }
 
 static inline bool udp_get_no_check6_tx(const struct sock *sk)
@@ -128,9 +128,9 @@ static inline bool udp_get_no_check6_tx(const struct sock *sk)
        return udp_test_bit(NO_CHECK6_TX, sk);
 }
 
-static inline bool udp_get_no_check6_rx(struct sock *sk)
+static inline bool udp_get_no_check6_rx(const struct sock *sk)
 {
-       return udp_sk(sk)->no_check6_rx;
+       return udp_test_bit(NO_CHECK6_RX, sk);
 }
 
 static inline void udp_cmsg_recv(struct msghdr *msg, struct sock *sk,

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 0c69982..cb32826 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2698,7 +2698,7 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
                break;
 
        case UDP_NO_CHECK6_RX:
-               up->no_check6_rx = valbool;
+               udp_set_no_check6_rx(sk, valbool);
                break;
 
        case UDP_SEGMENT:
@@ -2795,7 +2795,7 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname,
                break;
 
        case UDP_NO_CHECK6_RX:
-               val = up->no_check6_rx;
+               val = udp_get_no_check6_rx(sk);
                break;
 
        case UDP_SEGMENT:

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 469df0c..6e1ea30 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -858,7 +858,7 @@ start_lookup:
                /* If zero checksum and no_check is not on for
                 * the socket then skip it.
                 */
-               if (!uh->check && !udp_sk(sk)->no_check6_rx)
+               if (!uh->check && !udp_get_no_check6_rx(sk))
                        continue;
                if (!first) {
                        first = sk;
@@ -980,7 +980,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
                if (unlikely(rcu_dereference(sk->sk_rx_dst) != dst))
                        udp6_sk_rx_dst_set(sk, dst);
 
-               if (!uh->check && !udp_sk(sk)->no_check6_rx) {
+               if (!uh->check && !udp_get_no_check6_rx(sk)) {
                        if (refcounted)
                                sock_put(sk);
                        goto report_csum_error;
@@ -1002,7 +1002,7 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
        /* Unicast */
        sk = __udp6_lib_lookup_skb(skb, uh->source, uh->dest, udptable);
        if (sk) {
-               if (!uh->check && !udp_sk(sk)->no_check6_rx)
+               if (!uh->check && !udp_get_no_check6_rx(sk))
                        goto report_csum_error;
                return udp6_unicast_rcv_skb(sk, skb, uh);
        }