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ipv6: remove hard coded limitation on ipv6_pinfo

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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 f5d547676c
("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>
This commit is contained in:
Eric Dumazet 2023-07-20 11:09:01 +00:00 committed by David S. Miller
parent 1671bcfd76
commit f5f80e32de
13 changed files with 16 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
include/linux/ipv6.h
View File

@ -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;
};

1
include/net/sock.h
View File

@ -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 */

1
net/dccp/ipv6.c
View File

@ -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,

4
net/dccp/ipv6.h
View File

@ -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;
};

4
net/ipv6/af_inet6.c
View File

@ -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);
}

1
net/ipv6/ping.c
View File

@ -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);

1
net/ipv6/raw.c
View File

@ -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,

1
net/ipv6/tcp_ipv6.c
View File

@ -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,

1
net/ipv6/udp.c
View File

@ -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,
};

1
net/ipv6/udplite.c
View File

@ -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,
};

4
net/l2tp/l2tp_ip6.c
View File

@ -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 = {

1
net/mptcp/protocol.c
View File

@ -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)

1
net/sctp/socket.c
View File

@ -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) +