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Subject[PATCH] tcp: bind() use stronger condition for bind_conflict
Date
We must try harder to get unique (addr, port) pairs when
doing port autoselection for sockets with SO_REUSEADDR
option set.

We achieve this by adding a relaxation parameter to
inet_csk_bind_conflict. When 'relax' parameter is off
we return a conflict whenever the current searched
pair (addr, port) is not unique.

This tries to address the problems reported in patch:
8d238b25b1ec22a73b1c2206f111df2faaff8285
Revert "tcp: bind() fix when many ports are bound"

Signed-off-by: Alexandru Copot <alex.mihai.c@gmail.com>
Signed-off-by: Daniel Baluta <dbaluta@ixiacom.com>
---
include/net/inet6_connection_sock.h | 2 +-
include/net/inet_connection_sock.h | 4 ++--
net/ipv4/inet_connection_sock.c | 17 +++++++++++++----
net/ipv6/inet6_connection_sock.c | 3 ++-
4 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/include/net/inet6_connection_sock.h b/include/net/inet6_connection_sock.h
index 3207e58..9d29ae2 100644
--- a/include/net/inet6_connection_sock.h
+++ b/include/net/inet6_connection_sock.h
@@ -23,7 +23,7 @@ struct sock;
struct sockaddr;

extern int inet6_csk_bind_conflict(const struct sock *sk,
- const struct inet_bind_bucket *tb);
+ const struct inet_bind_bucket *tb, int relax);

extern struct dst_entry* inet6_csk_route_req(struct sock *sk,
const struct request_sock *req);
diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index dbf9aab..f05a032 100644
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -60,7 +60,7 @@ struct inet_connection_sock_af_ops {
#endif
void (*addr2sockaddr)(struct sock *sk, struct sockaddr *);
int (*bind_conflict)(const struct sock *sk,
- const struct inet_bind_bucket *tb);
+ const struct inet_bind_bucket *tb, int relax);
};

/** inet_connection_sock - INET connection oriented sock
@@ -245,7 +245,7 @@ extern struct request_sock *inet_csk_search_req(const struct sock *sk,
const __be32 raddr,
const __be32 laddr);
extern int inet_csk_bind_conflict(const struct sock *sk,
- const struct inet_bind_bucket *tb);
+ const struct inet_bind_bucket *tb, int relax);
extern int inet_csk_get_port(struct sock *sk, unsigned short snum);

extern struct dst_entry* inet_csk_route_req(struct sock *sk,
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 19d66ce..bf50e77 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -53,7 +53,7 @@ void inet_get_local_port_range(int *low, int *high)
EXPORT_SYMBOL(inet_get_local_port_range);

int inet_csk_bind_conflict(const struct sock *sk,
- const struct inet_bind_bucket *tb)
+ const struct inet_bind_bucket *tb, int relax)
{
struct sock *sk2;
struct hlist_node *node;
@@ -79,6 +79,13 @@ int inet_csk_bind_conflict(const struct sock *sk,
sk2_rcv_saddr == sk_rcv_saddr(sk))
break;
}
+ if (!relax && reuse && sk2->sk_reuse &&
+ sk2->sk_state != TCP_LISTEN) {
+ const __be32 sk2_rcv_saddr = sk_rcv_saddr(sk2);
+ if (!sk2_rcv_saddr || !sk_rcv_saddr(sk) ||
+ sk2_rcv_saddr == sk_rcv_saddr(sk))
+ break;
+ }
}
}
return node != NULL;
@@ -122,12 +129,13 @@ again:
(tb->num_owners < smallest_size || smallest_size == -1)) {
smallest_size = tb->num_owners;
smallest_rover = rover;
- if (atomic_read(&hashinfo->bsockets) > (high - low) + 1) {
+ if (atomic_read(&hashinfo->bsockets) > (high - low) + 1 &&
+ !inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, 0)) {
snum = smallest_rover;
goto tb_found;
}
}
- if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
+ if (!inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, 0)) {
snum = rover;
goto tb_found;
}
@@ -178,12 +186,13 @@ tb_found:
goto success;
} else {
ret = 1;
- if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb)) {
+ if (inet_csk(sk)->icsk_af_ops->bind_conflict(sk, tb, 1)) {
if (sk->sk_reuse && sk->sk_state != TCP_LISTEN &&
smallest_size != -1 && --attempts >= 0) {
spin_unlock(&head->lock);
goto again;
}
+
goto fail_unlock;
}
}
diff --git a/net/ipv6/inet6_connection_sock.c b/net/ipv6/inet6_connection_sock.c
index 02dd203..dfc8bc3 100644
--- a/net/ipv6/inet6_connection_sock.c
+++ b/net/ipv6/inet6_connection_sock.c
@@ -28,7 +28,8 @@
#include <net/inet6_connection_sock.h>

int inet6_csk_bind_conflict(const struct sock *sk,
- const struct inet_bind_bucket *tb)
+ const struct inet_bind_bucket *tb,
+ int relax)
{
const struct sock *sk2;
const struct hlist_node *node;
--
1.7.9.4


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