From: Al Viro <viro@zeniv.linux.org.uk>
To: netdev@vger.kernel.org
Cc: David Miller <davem@davemloft.net>
Subject: [PATCH 6/8] unix_bind_bsd(): move done_path_create() call after dealing with ->bindlock
Date: Sat, 19 Jun 2021 03:50:31 +0000 [thread overview]
Message-ID: <20210619035033.2347136-6-viro@zeniv.linux.org.uk> (raw)
In-Reply-To: <20210619035033.2347136-1-viro@zeniv.linux.org.uk>
Final preparations for doing unlink on failure past the successful
mknod. We can't hold ->bindlock over ->mknod() or ->unlink(), since
either might do sb_start_write() (e.g. on overlayfs). However, we
can do it while holding filesystem and VFS locks - doing
kern_path_create()
vfs_mknod()
grab ->bindlock
if u->addr had been set
drop ->bindlock
done_path_create
return -EINVAL
else
assign the address to socket
drop ->bindlock
done_path_create
return 0
would be deadlock-free. Here we massage unix_bind_bsd() to that
form. We are still doing equivalent transformations.
Next commit will *not* be an equivalent transformation - it will
add a call of vfs_unlink() before done_path_create() in "alread bound"
case.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
net/unix/af_unix.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index d5ec0abd389d..3c389a6bf670 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -988,8 +988,8 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr)
struct unix_sock *u = unix_sk(sk);
umode_t mode = S_IFSOCK |
(SOCK_INODE(sk->sk_socket)->i_mode & ~current_umask());
- struct path parent, path;
struct user_namespace *ns; // barf...
+ struct path parent;
struct dentry *dentry;
unsigned int hash;
int err;
@@ -1007,36 +1007,32 @@ static int unix_bind_bsd(struct sock *sk, struct unix_address *addr)
* All right, let's create it.
*/
err = security_path_mknod(&parent, dentry, mode, 0);
- if (!err) {
+ if (!err)
err = vfs_mknod(ns, d_inode(parent.dentry), dentry, mode, 0);
- if (!err) {
- path.mnt = mntget(parent.mnt);
- path.dentry = dget(dentry);
- }
- }
- done_path_create(&parent, dentry);
- if (err)
+ if (err) {
+ done_path_create(&parent, dentry);
return err;
-
+ }
err = mutex_lock_interruptible(&u->bindlock);
if (err) {
- path_put(&path);
+ done_path_create(&parent, dentry);
return err;
}
-
if (u->addr) {
mutex_unlock(&u->bindlock);
- path_put(&path);
+ done_path_create(&parent, dentry);
return -EINVAL;
}
addr->hash = UNIX_HASH_SIZE;
- hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE - 1);
+ hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);
spin_lock(&unix_table_lock);
- u->path = path;
+ u->path.mnt = mntget(parent.mnt);
+ u->path.dentry = dget(dentry);
__unix_set_addr(sk, addr, hash);
spin_unlock(&unix_table_lock);
mutex_unlock(&u->bindlock);
+ done_path_create(&parent, dentry);
return 0;
}
--
2.11.0
next prev parent reply other threads:[~2021-06-19 3:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-19 3:48 [PATCHSET] AF_UNIX bind(2) cleanup on failures after mknod Al Viro
2021-06-19 3:50 ` [PATCH 1/8] af_unix: take address assignment/hash insertion into a new helper Al Viro
2021-06-19 3:50 ` [PATCH 2/8] unix_bind(): allocate addr earlier Al Viro
2021-06-19 3:50 ` [PATCH 3/8] unix_bind(): separate BSD and abstract cases Al Viro
2021-06-19 3:50 ` [PATCH 4/8] unix_bind(): take BSD and abstract address cases into new helpers Al Viro
2021-06-19 3:50 ` [PATCH 5/8] fold unix_mknod() into unix_bind_bsd() Al Viro
2021-06-19 3:50 ` Al Viro [this message]
2021-06-19 3:50 ` [PATCH 7/8] unix_bind_bsd(): unlink if we fail after successful mknod Al Viro
2021-06-19 3:50 ` [PATCH 8/8] __unix_find_socket_byname(): don't pass hash and type separately Al Viro
2021-06-21 19:30 ` [PATCH 1/8] af_unix: take address assignment/hash insertion into a new helper patchwork-bot+netdevbpf
-- strict thread matches above, loose matches on Subject: below --
2021-02-22 19:06 [PATCHSET] making unix_bind() undo mknod on failure Al Viro
2021-02-22 19:12 ` [PATCH 1/8] af_unix: take address assignment/hash insertion into a new helper Al Viro
2021-02-22 19:12 ` [PATCH 6/8] unix_bind_bsd(): move done_path_create() call after dealing with ->bindlock Al Viro
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