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Subject[PATCH 4/5] AF_UNIX: find peers on multicast Unix stream sockets
Date
Multicast sockets are stored in the hash table unix_multicast_socket_table.

unix_find_socket_byname() is extended to return an array of sockets matching
the name instead of only one socket. Then unix_stream_sendmsg() can find all
the multicast peers.

Signed-off-by: Alban Crequy <alban.crequy@collabora.co.uk>
---
net/unix/af_unix.c | 134 ++++++++++++++++++++++++++++++++++++++--------------
1 files changed, 99 insertions(+), 35 deletions(-)

diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index a8d9de7..f259849 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -115,11 +115,13 @@
#include <net/checksum.h>
#include <linux/security.h>

-static struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
+static struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE + 1];
static DEFINE_SPINLOCK(unix_table_lock);
static atomic_t unix_nr_socks = ATOMIC_INIT(0);
+static atomic_t unix_nr_multicast_socks = ATOMIC_INIT(0);

-#define unix_sockets_unbound (&unix_socket_table[UNIX_HASH_SIZE])
+#define unix_multicast_socket_table (&unix_socket_table[UNIX_HASH_SIZE])
+#define unix_sockets_unbound (&unix_socket_table[2 * UNIX_HASH_SIZE])

#define UNIX_ABSTRACT(sk) (unix_sk(sk)->addr->hash != UNIX_HASH_SIZE)

@@ -227,7 +229,6 @@ static void __unix_remove_socket(struct sock *sk)

static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
{
- WARN_ON(!sk_unhashed(sk));
sk_add_node(sk, list);
}

@@ -247,12 +248,14 @@ static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)

static struct sock *__unix_find_socket_byname(struct net *net,
struct sockaddr_un *sunname,
- int len, int type, unsigned hash)
+ int len, int type,
+ unsigned hash, int multicast)
{
struct sock *s;
struct hlist_node *node;
+ unsigned int index = (multicast ? UNIX_HASH_SIZE : 0) + (hash ^ type);

- sk_for_each(s, node, &unix_socket_table[hash ^ type]) {
+ sk_for_each(s, node, &unix_socket_table[index]) {
struct unix_sock *u = unix_sk(s);

if (!net_eq(sock_net(s), net))
@@ -267,29 +270,50 @@ found:
return s;
}

-static inline struct sock *unix_find_socket_byname(struct net *net,
- struct sockaddr_un *sunname,
- int len, int type,
- unsigned hash)
+static inline void unix_find_socket_byname(struct net *net,
+ struct sockaddr_un *sunname,
+ int len, int type,
+ unsigned hash,
+ int multicast,
+ struct sock **others, int max_others)
{
struct sock *s;
+ struct hlist_node *node;
+ int i = 0;
+ unsigned int index = (multicast ? UNIX_HASH_SIZE : 0) + (hash ^ type);

spin_lock(&unix_table_lock);
- s = __unix_find_socket_byname(net, sunname, len, type, hash);
- if (s)
- sock_hold(s);
+
+ sk_for_each(s, node, &unix_socket_table[index]) {
+ struct unix_sock *u = unix_sk(s);
+
+ if (!net_eq(sock_net(s), net))
+ continue;
+
+ if (u->addr->len == len &&
+ !memcmp(u->addr->name, sunname, len)) {
+
+ others[i++] = s;
+ sock_hold(s);
+ if (i == max_others)
+ break;
+ }
+ }
+
spin_unlock(&unix_table_lock);
- return s;
}

-static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)
+static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i,
+ int multicast)
{
struct sock *s;
struct hlist_node *node;
+ unsigned int index = (multicast ? UNIX_HASH_SIZE : 0)
+ + (i->i_ino & (UNIX_HASH_SIZE - 1));

spin_lock(&unix_table_lock);
sk_for_each(s, node,
- &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
+ &unix_socket_table[index]) {
struct dentry *dentry = unix_sk(s)->dentry;

if (!net_eq(sock_net(s), net))
@@ -363,6 +387,9 @@ static void unix_sock_destructor(struct sock *sk)
if (u->addr)
unix_release_addr(u->addr);

+ if (u->multicast)
+ atomic_dec(&unix_nr_multicast_socks);
+
atomic_dec(&unix_nr_socks);
local_bh_disable();
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
@@ -700,7 +727,7 @@ retry:
ordernum = (ordernum+1)&0xFFFFF;

if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
- addr->hash)) {
+ addr->hash, 0)) {
spin_unlock(&unix_table_lock);
/* Sanity yield. It is unusual case, but yet... */
if (!(ordernum&0xFF))
@@ -719,9 +746,11 @@ out: mutex_unlock(&u->readlock);
return err;
}

-static struct sock *unix_find_other(struct net *net,
- struct sockaddr_un *sunname, int len,
- int type, unsigned hash, int *error)
+static void unix_find_other(struct net *net,
+ struct sockaddr_un *sunname, int len,
+ int type, unsigned hash, int multicast,
+ struct sock **others, int max_others,
+ int *error)
{
struct sock *u;
struct path path;
@@ -740,7 +769,7 @@ static struct sock *unix_find_other(struct net *net,
err = -ECONNREFUSED;
if (!S_ISSOCK(inode->i_mode))
goto put_fail;
- u = unix_find_socket_byinode(net, inode);
+ u = unix_find_socket_byinode(net, inode, multicast);
if (!u)
goto put_fail;

@@ -754,24 +783,26 @@ static struct sock *unix_find_other(struct net *net,
sock_put(u);
goto fail;
}
+ others[0] = u;
} else {
+ int i;
err = -ECONNREFUSED;
- u = unix_find_socket_byname(net, sunname, len, type, hash);
- if (u) {
+ unix_find_socket_byname(net, sunname, len, type, hash,
+ multicast, others, max_others);
+ for(i = 0 ; i < max_others && others[i] != NULL ; i++) {
struct dentry *dentry;
- dentry = unix_sk(u)->dentry;
+ dentry = unix_sk(others[i])->dentry;
if (dentry)
- touch_atime(unix_sk(u)->mnt, dentry);
- } else
- goto fail;
+ touch_atime(unix_sk(others[i])->mnt, dentry);
+ }
}
- return u;
+ return;

put_fail:
path_put(&path);
fail:
*error = err;
- return NULL;
+ return;
}


@@ -862,7 +893,7 @@ out_mknod_drop_write:
if (!sunaddr->sun_path[0]) {
err = -EADDRINUSE;
if (__unix_find_socket_byname(net, sunaddr, addr_len,
- sk->sk_type, hash)) {
+ sk->sk_type, hash, 0)) {
unix_release_addr(addr);
goto out_unlock;
}
@@ -929,7 +960,7 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
struct sock *sk = sock->sk;
struct net *net = sock_net(sk);
struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
- struct sock *other;
+ struct sock *other = NULL;
unsigned hash;
int err;

@@ -944,7 +975,8 @@ static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
goto out;

restart:
- other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
+ unix_find_other(net, sunaddr, alen, sock->type, hash,
+ 0, &other, 1, &err);
if (!other)
goto out;

@@ -1063,7 +1095,8 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,

restart:
/* Find listening sock. */
- other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
+ unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, 0, &other,
+ 1, &err);
if (!other && !u->multicast)
goto out;

@@ -1075,6 +1108,26 @@ restart:
if (u->multicast) {
sock->state = SS_CONNECTED;
sk->sk_state = TCP_ESTABLISHED;
+
+ unix_find_other(net, sunaddr, addr_len, sk->sk_type,
+ hash, 1, &other, 1, &err);
+ if (other) {
+ otheru = unix_sk(other);
+ atomic_inc(&otheru->addr->refcnt);
+ u->addr = otheru->addr;
+ } else {
+ err = -ENOMEM;
+ u->addr = kmalloc(sizeof(*u->addr)+addr_len, GFP_KERNEL);
+ if (!u->addr)
+ return err;
+
+ memcpy(u->addr->name, sunaddr, addr_len);
+ u->addr->len = addr_len;
+ u->addr->hash = hash ^ sk->sk_type;
+ atomic_set(&u->addr->refcnt, 1);
+ }
+
+ unix_insert_socket(&unix_multicast_socket_table[u->addr->hash], sk);
return 0;
}

@@ -1427,8 +1480,8 @@ restart:
if (sunaddr == NULL)
goto out_free;

- other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
- hash, &err);
+ unix_find_other(net, sunaddr, namelen, sk->sk_type,
+ hash, 0, &other, 1, &err);
if (other == NULL)
goto out_free;
}
@@ -1530,8 +1583,12 @@ static int unix_stream_setsockopt(struct socket *sock, int level, int optname,
return -EINVAL;

if (val != 0) {
+ if (!u->multicast)
+ atomic_inc(&unix_nr_multicast_socks);
u->multicast = 1;
} else {
+ if (u->multicast)
+ atomic_dec(&unix_nr_multicast_socks);
u->multicast = 0;
}
break;
@@ -1582,6 +1639,8 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
struct sock *sk = sock->sk;
struct sock *other = NULL;
+ struct sock **others = NULL;
+ int max_others;
struct sockaddr_un *sunaddr = msg->msg_name;
int err, size;
struct sk_buff *skb;
@@ -1612,7 +1671,12 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
} else {
sunaddr = NULL;
err = -ENOTCONN;
- other = NULL; /* FIXME: get the list of other connection */
+ max_others = atomic_read(&unix_nr_multicast_socks);
+ others = kzalloc((max_others + 1) * sizeof(void *), GFP_KERNEL);
+ unix_find_other(sock_net(sk), u->addr->name,
+ u->addr->len, 0, u->addr->hash, 1, others, max_others, &err);
+ other = others[0];
+ kfree(others);
if (!other)
goto out_err;
}
--
1.7.1


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