NFS server is exporting a sticky directory (mode 01777) with root squashing enabled. Client has protect_regular enabled and then tries to open a file as root in that directory. File is created (with ownership set to nobody:nobody) but the open syscall returns an error. The problem is may_create_in_sticky, which rejects the open even though the file has already been created/opened. Only call may_create_in_sticky if the file hasn't already been opened or created. Cc: Christian Brauner <brauner@xxxxxxxxxx> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1976829 Reported-by: Yongchen Yang <yoyang@xxxxxxxxxx> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> --- fs/namei.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/fs/namei.c b/fs/namei.c index 1f28d3f463c3..7480b6dc8d27 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -3495,10 +3495,15 @@ static int do_open(struct nameidata *nd, return -EEXIST; if (d_is_dir(nd->path.dentry)) return -EISDIR; - error = may_create_in_sticky(mnt_userns, nd, - d_backing_inode(nd->path.dentry)); - if (unlikely(error)) - return error; + if (!(file->f_mode & (FMODE_OPENED | FMODE_CREATED))) { + error = may_create_in_sticky(mnt_userns, nd, + d_backing_inode(nd->path.dentry)); + if (unlikely(error)) { + printk("%s: f_mode=0x%x oflag=0x%x\n", + __func__, file->f_mode, open_flag); + return error; + } + } } if ((nd->flags & LOOKUP_DIRECTORY) && !d_can_lookup(nd->path.dentry)) return -ENOTDIR; -- 2.37.1
