ipv6: remove hard coded limitation on ipv6_pinfo

IPv6 inet sockets are supposed to have a "struct ipv6_pinfo"
field at the end of their definition, so that inet6_sk_generic()
can derive from socket size the offset of the "struct ipv6_pinfo".

This is very fragile, and prevents adding bigger alignment
in sockets, because inet6_sk_generic() does not work
if the compiler adds padding after the ipv6_pinfo component.

We are currently working on a patch series to reorganize
TCP structures for better data locality and found issues
similar to the one fixed in commit f5d547676ca0
("tcp: fix tcp_inet6_sk() for 32bit kernels")

Alternative would be to force an alignment on "struct ipv6_pinfo",
greater or equal to __alignof__(any ipv6 sock) to ensure there is
no padding. This does not look great.

v2: fix typo in mptcp_proto_v6_init() (Paolo)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Chao Wu <wwchao@google.com>
Cc: Wei Wang <weiwan@google.com>
Cc: Coco Li <lixiaoyan@google.com>
Cc: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index ed3d110..0295b47 100644 (file)
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -200,14 +200,7 @@ struct inet6_cork {
        u8 tclass;
 };
 
-/**
- * struct ipv6_pinfo - ipv6 private area
- *
- * In the struct sock hierarchy (tcp6_sock, upd6_sock, etc)
- * this _must_ be the last member, so that inet6_sk_generic
- * is able to calculate its offset from the base struct sock
- * by using the struct proto->slab_obj_size member. -acme
- */
+/* struct ipv6_pinfo - ipv6 private area */
 struct ipv6_pinfo {
        struct in6_addr         saddr;
        struct in6_pktinfo      sticky_pktinfo;
@@ -307,19 +300,19 @@ struct raw6_sock {
        __u32                   offset;         /* checksum offset  */
        struct icmp6_filter     filter;
        __u32                   ip6mr_table;
-       /* ipv6_pinfo has to be the last member of raw6_sock, see inet6_sk_generic */
+
        struct ipv6_pinfo       inet6;
 };
 
 struct udp6_sock {
        struct udp_sock   udp;
-       /* ipv6_pinfo has to be the last member of udp6_sock, see inet6_sk_generic */
+
        struct ipv6_pinfo inet6;
 };
 
 struct tcp6_sock {
        struct tcp_sock   tcp;
-       /* ipv6_pinfo has to be the last member of tcp6_sock, see inet6_sk_generic */
+
        struct ipv6_pinfo inet6;
 };
 

diff --git a/include/net/sock.h b/include/net/sock.h
index 2eb916d..7ae44bf 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1339,6 +1339,7 @@ struct proto {
 
        struct kmem_cache       *slab;
        unsigned int            obj_size;
+       unsigned int            ipv6_pinfo_offset;
        slab_flags_t            slab_flags;
        unsigned int            useroffset;     /* Usercopy region offset */
        unsigned int            usersize;       /* Usercopy region size */

diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 7249ef2..e03b533 100644 (file)
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1056,6 +1056,7 @@ static struct proto dccp_v6_prot = {
        .orphan_count      = &dccp_orphan_count,
        .max_header        = MAX_DCCP_HEADER,
        .obj_size          = sizeof(struct dccp6_sock),
+       .ipv6_pinfo_offset = offsetof(struct dccp6_sock, inet6),
        .slab_flags        = SLAB_TYPESAFE_BY_RCU,
        .rsk_prot          = &dccp6_request_sock_ops,
        .twsk_prot         = &dccp6_timewait_sock_ops,

diff --git a/net/dccp/ipv6.h b/net/dccp/ipv6.h
index 7e4c2a3..c5d14c4 100644 (file)
--- a/net/dccp/ipv6.h
+++ b/net/dccp/ipv6.h
@@ -13,10 +13,6 @@
 
 struct dccp6_sock {
        struct dccp_sock  dccp;
-       /*
-        * ipv6_pinfo has to be the last member of dccp6_sock,
-        * see inet6_sk_generic.
-        */
        struct ipv6_pinfo inet6;
 };
 

diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 5d593dd..9f9c4b8 100644 (file)
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -102,9 +102,9 @@ bool ipv6_mod_enabled(void)
 }
 EXPORT_SYMBOL_GPL(ipv6_mod_enabled);
 
-static __inline__ struct ipv6_pinfo *inet6_sk_generic(struct sock *sk)
+static struct ipv6_pinfo *inet6_sk_generic(struct sock *sk)
 {
-       const int offset = sk->sk_prot->obj_size - sizeof(struct ipv6_pinfo);
+       const int offset = sk->sk_prot->ipv6_pinfo_offset;
 
        return (struct ipv6_pinfo *)(((u8 *)sk) + offset);
 }

diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index f804c11..2a0e8bc 100644 (file)
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -215,6 +215,7 @@ struct proto pingv6_prot = {
        .get_port =     ping_get_port,
        .put_port =     ping_unhash,
        .obj_size =     sizeof(struct raw6_sock),
+       .ipv6_pinfo_offset = offsetof(struct raw6_sock, inet6),
 };
 EXPORT_SYMBOL_GPL(pingv6_prot);
 

diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index ac1cef0..0fcf1b8 100644 (file)
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -1216,6 +1216,7 @@ struct proto rawv6_prot = {
        .hash              = raw_hash_sk,
        .unhash            = raw_unhash_sk,
        .obj_size          = sizeof(struct raw6_sock),
+       .ipv6_pinfo_offset = offsetof(struct raw6_sock, inet6),
        .useroffset        = offsetof(struct raw6_sock, filter),
        .usersize          = sizeof_field(struct raw6_sock, filter),
        .h.raw_hash        = &raw_v6_hashinfo,

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 4714eb6..1b4529e 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2175,6 +2175,7 @@ struct proto tcpv6_prot = {
        .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_tcp_rmem),
        .max_header             = MAX_TCP_HEADER,
        .obj_size               = sizeof(struct tcp6_sock),
+       .ipv6_pinfo_offset = offsetof(struct tcp6_sock, inet6),
        .slab_flags             = SLAB_TYPESAFE_BY_RCU,
        .twsk_prot              = &tcp6_timewait_sock_ops,
        .rsk_prot               = &tcp6_request_sock_ops,

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b7c972a..95c75d8 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1798,6 +1798,7 @@ struct proto udpv6_prot = {
        .sysctl_wmem_offset     = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
        .sysctl_rmem_offset     = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
        .obj_size               = sizeof(struct udp6_sock),
+       .ipv6_pinfo_offset = offsetof(struct udp6_sock, inet6),
        .h.udp_table            = NULL,
        .diag_destroy           = udp_abort,
 };

diff --git a/net/ipv6/udplite.c b/net/ipv6/udplite.c
index 8e010d0..267d491 100644 (file)
--- a/net/ipv6/udplite.c
+++ b/net/ipv6/udplite.c
@@ -67,6 +67,7 @@ struct proto udplitev6_prot = {
        .sysctl_wmem_offset = offsetof(struct net, ipv4.sysctl_udp_wmem_min),
        .sysctl_rmem_offset = offsetof(struct net, ipv4.sysctl_udp_rmem_min),
        .obj_size          = sizeof(struct udp6_sock),
+       .ipv6_pinfo_offset = offsetof(struct udp6_sock, inet6),
        .h.udp_table       = &udplite_table,
 };
 

diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index b1623f9..2eee95a 100644 (file)
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -36,9 +36,6 @@ struct l2tp_ip6_sock {
        u32                     conn_id;
        u32                     peer_conn_id;
 
-       /* ipv6_pinfo has to be the last member of l2tp_ip6_sock, see
-        * inet6_sk_generic
-        */
        struct ipv6_pinfo       inet6;
 };
 
@@ -730,6 +727,7 @@ static struct proto l2tp_ip6_prot = {
        .hash              = l2tp_ip6_hash,
        .unhash            = l2tp_ip6_unhash,
        .obj_size          = sizeof(struct l2tp_ip6_sock),
+       .ipv6_pinfo_offset = offsetof(struct l2tp_ip6_sock, inet6),
 };
 
 static const struct proto_ops l2tp_ip6_ops = {

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 3613489..22323b1 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3988,6 +3988,7 @@ int __init mptcp_proto_v6_init(void)
        strcpy(mptcp_v6_prot.name, "MPTCPv6");
        mptcp_v6_prot.slab = NULL;
        mptcp_v6_prot.obj_size = sizeof(struct mptcp6_sock);
+       mptcp_v6_prot.ipv6_pinfo_offset = offsetof(struct mptcp6_sock, np);
 
        err = proto_register(&mptcp_v6_prot, 1);
        if (err)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 9388d98..6e3d28a 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -9732,6 +9732,7 @@ struct proto sctpv6_prot = {
        .unhash         = sctp_unhash,
        .no_autobind    = true,
        .obj_size       = sizeof(struct sctp6_sock),
+       .ipv6_pinfo_offset = offsetof(struct sctp6_sock, inet6),
        .useroffset     = offsetof(struct sctp6_sock, sctp.subscribe),
        .usersize       = offsetof(struct sctp6_sock, sctp.initmsg) -
                                offsetof(struct sctp6_sock, sctp.subscribe) +