From 56c1731b280dc71febf5df80fcac1923ea973ab8 Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 19 Jun 2021 03:50:31 +0000
Subject: unix_bind_bsd(): move done_path_create() call after dealing with
->bindlock
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/unix/af_unix.c | 26 +++++++++++---------------
1 file changed, 11 insertions(+), 15 deletions(-)
(limited to 'net/unix/af_unix.c')
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index fe337dc98400..25dda9ca9d15 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -989,8 +989,8 @@ 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;
@@ -1008,36 +1008,32 @@ 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;
}
--
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