From 29044dae2e746949ad4b9cbdbfb248994d1dcdb4 Mon Sep 17 00:00:00 2001 From: Amir Goldstein Date: Thu, 20 Jan 2022 23:53:05 +0200 Subject: [PATCH] fsnotify: fix fsnotify hooks in pseudo filesystems Commit 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify will have access to a positive dentry. This allowed a race where opening the deleted file via cached dentry is now possible after receiving the IN_DELETE event. To fix the regression in pseudo filesystems, convert d_delete() calls to d_drop() (see commit 46c46f8df9aa ("devpts_pty_kill(): don't bother with d_delete()") and move the fsnotify hook after d_drop(). Add a missing fsnotify_unlink() hook in nfsdfs that was found during the audit of fsnotify hooks in pseudo filesystems. Note that the fsnotify hooks in simple_recursive_removal() follow d_invalidate(), so they require no change. Link: https://lore.kernel.org/r/20220120215305.282577-2-amir73il@gmail.com Reported-by: Ivan Delalande Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/ Fixes: 49246466a989 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()") Cc: stable@vger.kernel.org # v5.3+ Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara --- fs/configfs/dir.c | 6 +++--- fs/devpts/inode.c | 2 +- fs/nfsd/nfsctl.c | 5 +++-- net/sunrpc/rpc_pipe.c | 4 ++-- 4 files changed, 9 insertions(+), 8 deletions(-) diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c index 1466b5d..d3cd2a9 100644 --- a/fs/configfs/dir.c +++ b/fs/configfs/dir.c @@ -1780,8 +1780,8 @@ void configfs_unregister_group(struct config_group *group) configfs_detach_group(&group->cg_item); d_inode(dentry)->i_flags |= S_DEAD; dont_mount(dentry); + d_drop(dentry); fsnotify_rmdir(d_inode(parent), dentry); - d_delete(dentry); inode_unlock(d_inode(parent)); dput(dentry); @@ -1922,10 +1922,10 @@ void configfs_unregister_subsystem(struct configfs_subsystem *subsys) configfs_detach_group(&group->cg_item); d_inode(dentry)->i_flags |= S_DEAD; dont_mount(dentry); - fsnotify_rmdir(d_inode(root), dentry); inode_unlock(d_inode(dentry)); - d_delete(dentry); + d_drop(dentry); + fsnotify_rmdir(d_inode(root), dentry); inode_unlock(d_inode(root)); diff --git a/fs/devpts/inode.c b/fs/devpts/inode.c index 42e5a76..4f25015a 100644 --- a/fs/devpts/inode.c +++ b/fs/devpts/inode.c @@ -621,8 +621,8 @@ void devpts_pty_kill(struct dentry *dentry) dentry->d_fsdata = NULL; drop_nlink(dentry->d_inode); - fsnotify_unlink(d_inode(dentry->d_parent), dentry); d_drop(dentry); + fsnotify_unlink(d_inode(dentry->d_parent), dentry); dput(dentry); /* d_alloc_name() in devpts_pty_new() */ } diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index b9f27fb..68b020f 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1247,7 +1247,8 @@ static void nfsdfs_remove_file(struct inode *dir, struct dentry *dentry) clear_ncl(d_inode(dentry)); dget(dentry); ret = simple_unlink(dir, dentry); - d_delete(dentry); + d_drop(dentry); + fsnotify_unlink(dir, dentry); dput(dentry); WARN_ON_ONCE(ret); } @@ -1338,8 +1339,8 @@ void nfsd_client_rmdir(struct dentry *dentry) dget(dentry); ret = simple_rmdir(dir, dentry); WARN_ON_ONCE(ret); + d_drop(dentry); fsnotify_rmdir(dir, dentry); - d_delete(dentry); dput(dentry); inode_unlock(dir); } diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index ee5336d..35588f0 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -600,9 +600,9 @@ static int __rpc_rmdir(struct inode *dir, struct dentry *dentry) dget(dentry); ret = simple_rmdir(dir, dentry); + d_drop(dentry); if (!ret) fsnotify_rmdir(dir, dentry); - d_delete(dentry); dput(dentry); return ret; } @@ -613,9 +613,9 @@ static int __rpc_unlink(struct inode *dir, struct dentry *dentry) dget(dentry); ret = simple_unlink(dir, dentry); + d_drop(dentry); if (!ret) fsnotify_unlink(dir, dentry); - d_delete(dentry); dput(dentry); return ret; } -- 2.7.4