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af_unix: Acquire/Release per-netns hash table's locks.
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This commit adds extra spin_lock/spin_unlock() for a per-netns
hash table inside the existing ones for unix_table_locks.

As of this commit, sockets are still linked in the global hash
table.  After putting sockets in a per-netns hash table and
removing the old one in the next patch, we remove the global
locks in the last patch.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Kuniyuki Iwashima authored and David S. Miller committed Jun 22, 2022
1 parent b6e8113 commit 79b05be
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Showing 2 changed files with 66 additions and 32 deletions.
75 changes: 51 additions & 24 deletions net/unix/af_unix.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -158,7 +158,8 @@ static unsigned int unix_abstract_hash(struct sockaddr_un *sunaddr,
return hash & UNIX_HASH_MOD;
}

static void unix_table_double_lock(unsigned int hash1, unsigned int hash2)
static void unix_table_double_lock(struct net *net,
unsigned int hash1, unsigned int hash2)
{
/* hash1 and hash2 is never the same because
* one is between 0 and UNIX_HASH_MOD, and
Expand All @@ -169,10 +170,17 @@ static void unix_table_double_lock(unsigned int hash1, unsigned int hash2)

spin_lock(&unix_table_locks[hash1]);
spin_lock_nested(&unix_table_locks[hash2], SINGLE_DEPTH_NESTING);

spin_lock(&net->unx.table.locks[hash1]);
spin_lock_nested(&net->unx.table.locks[hash2], SINGLE_DEPTH_NESTING);
}

static void unix_table_double_unlock(unsigned int hash1, unsigned int hash2)
static void unix_table_double_unlock(struct net *net,
unsigned int hash1, unsigned int hash2)
{
spin_unlock(&net->unx.table.locks[hash1]);
spin_unlock(&net->unx.table.locks[hash2]);

spin_unlock(&unix_table_locks[hash1]);
spin_unlock(&unix_table_locks[hash2]);
}
Expand Down Expand Up @@ -316,17 +324,21 @@ static void __unix_set_addr_hash(struct sock *sk, struct unix_address *addr,
__unix_insert_socket(sk);
}

static void unix_remove_socket(struct sock *sk)
static void unix_remove_socket(struct net *net, struct sock *sk)
{
spin_lock(&unix_table_locks[sk->sk_hash]);
spin_lock(&net->unx.table.locks[sk->sk_hash]);
__unix_remove_socket(sk);
spin_unlock(&net->unx.table.locks[sk->sk_hash]);
spin_unlock(&unix_table_locks[sk->sk_hash]);
}

static void unix_insert_unbound_socket(struct sock *sk)
static void unix_insert_unbound_socket(struct net *net, struct sock *sk)
{
spin_lock(&unix_table_locks[sk->sk_hash]);
spin_lock(&net->unx.table.locks[sk->sk_hash]);
__unix_insert_socket(sk);
spin_unlock(&net->unx.table.locks[sk->sk_hash]);
spin_unlock(&unix_table_locks[sk->sk_hash]);
}

Expand Down Expand Up @@ -356,28 +368,33 @@ static inline struct sock *unix_find_socket_byname(struct net *net,
struct sock *s;

spin_lock(&unix_table_locks[hash]);
spin_lock(&net->unx.table.locks[hash]);
s = __unix_find_socket_byname(net, sunname, len, hash);
if (s)
sock_hold(s);
spin_unlock(&net->unx.table.locks[hash]);
spin_unlock(&unix_table_locks[hash]);
return s;
}

static struct sock *unix_find_socket_byinode(struct inode *i)
static struct sock *unix_find_socket_byinode(struct net *net, struct inode *i)
{
unsigned int hash = unix_bsd_hash(i);
struct sock *s;

spin_lock(&unix_table_locks[hash]);
spin_lock(&net->unx.table.locks[hash]);
sk_for_each(s, &unix_socket_table[hash]) {
struct dentry *dentry = unix_sk(s)->path.dentry;

if (dentry && d_backing_inode(dentry) == i) {
sock_hold(s);
spin_unlock(&net->unx.table.locks[hash]);
spin_unlock(&unix_table_locks[hash]);
return s;
}
}
spin_unlock(&net->unx.table.locks[hash]);
spin_unlock(&unix_table_locks[hash]);
return NULL;
}
Expand Down Expand Up @@ -576,12 +593,12 @@ static void unix_sock_destructor(struct sock *sk)
static void unix_release_sock(struct sock *sk, int embrion)
{
struct unix_sock *u = unix_sk(sk);
struct path path;
struct sock *skpair;
struct sk_buff *skb;
struct path path;
int state;

unix_remove_socket(sk);
unix_remove_socket(sock_net(sk), sk);

/* Clear state */
unix_state_lock(sk);
Expand Down Expand Up @@ -930,7 +947,7 @@ static struct sock *unix_create1(struct net *net, struct socket *sock, int kern,
init_waitqueue_head(&u->peer_wait);
init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
memset(&u->scm_stat, 0, sizeof(struct scm_stat));
unix_insert_unbound_socket(sk);
unix_insert_unbound_socket(net, sk);

sock_prot_inuse_add(net, sk->sk_prot, 1);

Expand Down Expand Up @@ -1015,7 +1032,7 @@ static struct sock *unix_find_bsd(struct net *net, struct sockaddr_un *sunaddr,
if (!S_ISSOCK(inode->i_mode))
goto path_put;

sk = unix_find_socket_byinode(inode);
sk = unix_find_socket_byinode(net, inode);
if (!sk)
goto path_put;

Expand Down Expand Up @@ -1074,6 +1091,7 @@ static int unix_autobind(struct sock *sk)
{
unsigned int new_hash, old_hash = sk->sk_hash;
struct unix_sock *u = unix_sk(sk);
struct net *net = sock_net(sk);
struct unix_address *addr;
u32 lastnum, ordernum;
int err;
Expand Down Expand Up @@ -1102,11 +1120,10 @@ static int unix_autobind(struct sock *sk)
sprintf(addr->name->sun_path + 1, "%05x", ordernum);

new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
unix_table_double_lock(old_hash, new_hash);
unix_table_double_lock(net, old_hash, new_hash);

if (__unix_find_socket_byname(sock_net(sk), addr->name, addr->len,
new_hash)) {
unix_table_double_unlock(old_hash, new_hash);
if (__unix_find_socket_byname(net, addr->name, addr->len, new_hash)) {
unix_table_double_unlock(net, old_hash, new_hash);

/* __unix_find_socket_byname() may take long time if many names
* are already in use.
Expand All @@ -1124,7 +1141,7 @@ static int unix_autobind(struct sock *sk)
}

__unix_set_addr_hash(sk, addr, new_hash);
unix_table_double_unlock(old_hash, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
err = 0;

out: mutex_unlock(&u->bindlock);
Expand All @@ -1138,6 +1155,7 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
(SOCK_INODE(sk->sk_socket)->i_mode & ~current_umask());
unsigned int new_hash, old_hash = sk->sk_hash;
struct unix_sock *u = unix_sk(sk);
struct net *net = sock_net(sk);
struct user_namespace *ns; // barf...
struct unix_address *addr;
struct dentry *dentry;
Expand Down Expand Up @@ -1178,11 +1196,11 @@ static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
goto out_unlock;

new_hash = unix_bsd_hash(d_backing_inode(dentry));
unix_table_double_lock(old_hash, new_hash);
unix_table_double_lock(net, old_hash, new_hash);
u->path.mnt = mntget(parent.mnt);
u->path.dentry = dget(dentry);
__unix_set_addr_hash(sk, addr, new_hash);
unix_table_double_unlock(old_hash, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
mutex_unlock(&u->bindlock);
done_path_create(&parent, dentry);
return 0;
Expand All @@ -1205,6 +1223,7 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
{
unsigned int new_hash, old_hash = sk->sk_hash;
struct unix_sock *u = unix_sk(sk);
struct net *net = sock_net(sk);
struct unix_address *addr;
int err;

Expand All @@ -1222,19 +1241,18 @@ static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
}

new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
unix_table_double_lock(old_hash, new_hash);
unix_table_double_lock(net, old_hash, new_hash);

if (__unix_find_socket_byname(sock_net(sk), addr->name, addr->len,
new_hash))
if (__unix_find_socket_byname(net, addr->name, addr->len, new_hash))
goto out_spin;

__unix_set_addr_hash(sk, addr, new_hash);
unix_table_double_unlock(old_hash, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
mutex_unlock(&u->bindlock);
return 0;

out_spin:
unix_table_double_unlock(old_hash, new_hash);
unix_table_double_unlock(net, old_hash, new_hash);
err = -EADDRINUSE;
out_mutex:
mutex_unlock(&u->bindlock);
Expand Down Expand Up @@ -3237,15 +3255,18 @@ static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
static struct sock *unix_get_first(struct seq_file *seq, loff_t *pos)
{
unsigned long bucket = get_bucket(*pos);
struct net *net = seq_file_net(seq);
struct sock *sk;

while (bucket < UNIX_HASH_SIZE) {
spin_lock(&unix_table_locks[bucket]);
spin_lock(&net->unx.table.locks[bucket]);

sk = unix_from_bucket(seq, pos);
if (sk)
return sk;

spin_unlock(&net->unx.table.locks[bucket]);
spin_unlock(&unix_table_locks[bucket]);

*pos = set_bucket_offset(++bucket, 1);
Expand All @@ -3258,11 +3279,13 @@ static struct sock *unix_get_next(struct seq_file *seq, struct sock *sk,
loff_t *pos)
{
unsigned long bucket = get_bucket(*pos);
struct net *net = seq_file_net(seq);

for (sk = sk_next(sk); sk; sk = sk_next(sk))
if (sock_net(sk) == seq_file_net(seq))
if (sock_net(sk) == net)
return sk;

spin_unlock(&net->unx.table.locks[bucket]);
spin_unlock(&unix_table_locks[bucket]);

*pos = set_bucket_offset(++bucket, 1);
Expand Down Expand Up @@ -3292,8 +3315,10 @@ static void unix_seq_stop(struct seq_file *seq, void *v)
{
struct sock *sk = v;

if (sk)
if (sk) {
spin_unlock(&seq_file_net(seq)->unx.table.locks[sk->sk_hash]);
spin_unlock(&unix_table_locks[sk->sk_hash]);
}
}

static int unix_seq_show(struct seq_file *seq, void *v)
Expand Down Expand Up @@ -3381,14 +3406,15 @@ static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)

{
struct bpf_unix_iter_state *iter = seq->private;
struct net *net = seq_file_net(seq);
unsigned int expected = 1;
struct sock *sk;

sock_hold(start_sk);
iter->batch[iter->end_sk++] = start_sk;

for (sk = sk_next(start_sk); sk; sk = sk_next(sk)) {
if (sock_net(sk) != seq_file_net(seq))
if (sock_net(sk) != net)
continue;

if (iter->end_sk < iter->max_sk) {
Expand All @@ -3399,6 +3425,7 @@ static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)
expected++;
}

spin_unlock(&net->unx.table.locks[start_sk->sk_hash]);
spin_unlock(&unix_table_locks[start_sk->sk_hash]);

return expected;
Expand Down
23 changes: 15 additions & 8 deletions net/unix/diag.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -195,9 +195,9 @@ static int sk_diag_dump(struct sock *sk, struct sk_buff *skb, struct unix_diag_r

static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
struct unix_diag_req *req;
int num, s_num, slot, s_slot;
struct net *net = sock_net(skb->sk);
int num, s_num, slot, s_slot;
struct unix_diag_req *req;

req = nlmsg_data(cb->nlh);

Expand All @@ -209,6 +209,7 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)

num = 0;
spin_lock(&unix_table_locks[slot]);
spin_lock(&net->unx.table.locks[slot]);
sk_for_each(sk, &unix_socket_table[slot]) {
if (!net_eq(sock_net(sk), net))
continue;
Expand All @@ -220,12 +221,14 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
NETLINK_CB(cb->skb).portid,
cb->nlh->nlmsg_seq,
NLM_F_MULTI) < 0) {
spin_unlock(&net->unx.table.locks[slot]);
spin_unlock(&unix_table_locks[slot]);
goto done;
}
next:
num++;
}
spin_unlock(&net->unx.table.locks[slot]);
spin_unlock(&unix_table_locks[slot]);
}
done:
Expand All @@ -235,19 +238,22 @@ static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
}

static struct sock *unix_lookup_by_ino(unsigned int ino)
static struct sock *unix_lookup_by_ino(struct net *net, unsigned int ino)
{
struct sock *sk;
int i;

for (i = 0; i < UNIX_HASH_SIZE; i++) {
spin_lock(&unix_table_locks[i]);
spin_lock(&net->unx.table.locks[i]);
sk_for_each(sk, &unix_socket_table[i])
if (ino == sock_i_ino(sk)) {
sock_hold(sk);
spin_unlock(&net->unx.table.locks[i]);
spin_unlock(&unix_table_locks[i]);
return sk;
}
spin_unlock(&net->unx.table.locks[i]);
spin_unlock(&unix_table_locks[i]);
}
return NULL;
Expand All @@ -257,16 +263,17 @@ static int unix_diag_get_exact(struct sk_buff *in_skb,
const struct nlmsghdr *nlh,
struct unix_diag_req *req)
{
int err = -EINVAL;
struct sock *sk;
struct sk_buff *rep;
unsigned int extra_len;
struct net *net = sock_net(in_skb->sk);
unsigned int extra_len;
struct sk_buff *rep;
struct sock *sk;
int err;

err = -EINVAL;
if (req->udiag_ino == 0)
goto out_nosk;

sk = unix_lookup_by_ino(req->udiag_ino);
sk = unix_lookup_by_ino(net, req->udiag_ino);
err = -ENOENT;
if (sk == NULL)
goto out_nosk;
Expand Down

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