udplite: fix various data-races

[ Upstream commit 882af43a0fc37e26d85fb0df0c9edd3bed928de4 ]

udp->pcflag, udp->pcslen and udp->pcrlen reads/writes are racy.

Move udp->pcflag to udp->udp_flags for atomicity,
and add READ_ONCE()/WRITE_ONCE() annotations for pcslen and pcrlen.

Fixes: ba4e58eca8aa ("[NET]: Supporting UDP-Lite (RFC 3828) in Linux")
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 58156ed..d041887 100644 (file)
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -40,6 +40,8 @@ enum {
        UDP_FLAGS_ACCEPT_FRAGLIST,
        UDP_FLAGS_ACCEPT_L4,
        UDP_FLAGS_ENCAP_ENABLED, /* This socket enabled encap */
+       UDP_FLAGS_UDPLITE_SEND_CC, /* set via udplite setsockopt */
+       UDP_FLAGS_UDPLITE_RECV_CC, /* set via udplite setsockopt */
 };
 
 struct udp_sock {
@@ -54,10 +56,6 @@ struct udp_sock {
        int              pending;       /* Any pending frames ? */
        __u8             encap_type;    /* Is this an Encapsulation socket? */
 
-/* indicator bits used by pcflag: */
-#define UDPLITE_SEND_CC  0x1           /* set via udplite setsockopt         */
-#define UDPLITE_RECV_CC  0x2           /* set via udplite setsocktopt        */
-       __u8             pcflag;        /* marks socket as UDP-Lite if > 0    */
        /*
         * Following member retains the information to create a UDP header
         * when the socket is uncorked.

diff --git a/include/net/udplite.h b/include/net/udplite.h
index bd33ff2..786919d 100644 (file)
--- a/include/net/udplite.h
+++ b/include/net/udplite.h
@@ -66,14 +66,18 @@ static inline int udplite_checksum_init(struct sk_buff *skb, struct udphdr *uh)
 /* Fast-path computation of checksum. Socket may not be locked. */
 static inline __wsum udplite_csum(struct sk_buff *skb)
 {
-       const struct udp_sock *up = udp_sk(skb->sk);
        const int off = skb_transport_offset(skb);
+       const struct sock *sk = skb->sk;
        int len = skb->len - off;
 
-       if ((up->pcflag & UDPLITE_SEND_CC) && up->pcslen < len) {
-               if (0 < up->pcslen)
-                       len = up->pcslen;
-               udp_hdr(skb)->len = htons(up->pcslen);
+       if (udp_test_bit(UDPLITE_SEND_CC, sk)) {
+               u16 pcslen = READ_ONCE(udp_sk(sk)->pcslen);
+
+               if (pcslen < len) {
+                       if (pcslen > 0)
+                               len = pcslen;
+                       udp_hdr(skb)->len = htons(pcslen);
+               }
        }
        skb->ip_summed = CHECKSUM_NONE;     /* no HW support for checksumming */
 

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 2eeab4a..c3ff984 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -2120,7 +2120,8 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
        /*
         *      UDP-Lite specific tests, ignored on UDP sockets
         */
-       if ((up->pcflag & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
+       if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+               u16 pcrlen = READ_ONCE(up->pcrlen);
 
                /*
                 * MIB statistics other than incrementing the error count are
@@ -2133,7 +2134,7 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
                 * delivery of packets with coverage values less than a value
                 * provided by the application."
                 */
-               if (up->pcrlen == 0) {          /* full coverage was set  */
+               if (pcrlen == 0) {          /* full coverage was set  */
                        net_dbg_ratelimited("UDPLite: partial coverage %d while full coverage %d requested\n",
                                            UDP_SKB_CB(skb)->cscov, skb->len);
                        goto drop;
@@ -2144,9 +2145,9 @@ static int udp_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
                 * that it wants x while sender emits packets of smaller size y.
                 * Therefore the above ...()->partial_cov statement is essential.
                 */
-               if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
+               if (UDP_SKB_CB(skb)->cscov < pcrlen) {
                        net_dbg_ratelimited("UDPLite: coverage %d too small, need min %d\n",
-                                           UDP_SKB_CB(skb)->cscov, up->pcrlen);
+                                           UDP_SKB_CB(skb)->cscov, pcrlen);
                        goto drop;
                }
        }
@@ -2729,8 +2730,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
                        val = 8;
                else if (val > USHRT_MAX)
                        val = USHRT_MAX;
-               up->pcslen = val;
-               up->pcflag |= UDPLITE_SEND_CC;
+               WRITE_ONCE(up->pcslen, val);
+               udp_set_bit(UDPLITE_SEND_CC, sk);
                break;
 
        /* The receiver specifies a minimum checksum coverage value. To make
@@ -2743,8 +2744,8 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
                        val = 8;
                else if (val > USHRT_MAX)
                        val = USHRT_MAX;
-               up->pcrlen = val;
-               up->pcflag |= UDPLITE_RECV_CC;
+               WRITE_ONCE(up->pcrlen, val);
+               udp_set_bit(UDPLITE_RECV_CC, sk);
                break;
 
        default:
@@ -2808,11 +2809,11 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname,
        /* The following two cannot be changed on UDP sockets, the return is
         * always 0 (which corresponds to the full checksum coverage of UDP). */
        case UDPLITE_SEND_CSCOV:
-               val = up->pcslen;
+               val = READ_ONCE(up->pcslen);
                break;
 
        case UDPLITE_RECV_CSCOV:
-               val = up->pcrlen;
+               val = READ_ONCE(up->pcrlen);
                break;
 
        default:

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 0e79d18..f60ba42 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -727,16 +727,17 @@ static int udpv6_queue_rcv_one_skb(struct sock *sk, struct sk_buff *skb)
        /*
         * UDP-Lite specific tests, ignored on UDP sockets (see net/ipv4/udp.c).
         */
-       if ((up->pcflag & UDPLITE_RECV_CC)  &&  UDP_SKB_CB(skb)->partial_cov) {
+       if (udp_test_bit(UDPLITE_RECV_CC, sk) && UDP_SKB_CB(skb)->partial_cov) {
+               u16 pcrlen = READ_ONCE(up->pcrlen);
 
-               if (up->pcrlen == 0) {          /* full coverage was set  */
+               if (pcrlen == 0) {          /* full coverage was set  */
                        net_dbg_ratelimited("UDPLITE6: partial coverage %d while full coverage %d requested\n",
                                            UDP_SKB_CB(skb)->cscov, skb->len);
                        goto drop;
                }
-               if (UDP_SKB_CB(skb)->cscov  <  up->pcrlen) {
+               if (UDP_SKB_CB(skb)->cscov < pcrlen) {
                        net_dbg_ratelimited("UDPLITE6: coverage %d too small, need min %d\n",
-                                           UDP_SKB_CB(skb)->cscov, up->pcrlen);
+                                           UDP_SKB_CB(skb)->cscov, pcrlen);
                        goto drop;
                }
        }