diff options
| -rw-r--r-- | fs/fhandle.c | 22 | ||||
| -rw-r--r-- | include/uapi/linux/fcntl.h | 5 |
2 files changed, 19 insertions, 8 deletions
diff --git a/fs/fhandle.c b/fs/fhandle.c index f2bc27d1975e..4a635cf787fc 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -16,7 +16,7 @@ static long do_sys_name_to_handle(const struct path *path, struct file_handle __user *ufh, - int __user *mnt_id) + int __user *mnt_id, int fh_flags) { long retval; struct file_handle f_handle; @@ -24,11 +24,14 @@ static long do_sys_name_to_handle(const struct path *path, struct file_handle *handle = NULL; /* - * We need to make sure whether the file system - * support decoding of the file handle + * We need to make sure whether the file system support decoding of + * the file handle if decodeable file handle was requested. + * Otherwise, even empty export_operations are sufficient to opt-in + * to encoding FIDs. */ if (!path->dentry->d_sb->s_export_op || - !path->dentry->d_sb->s_export_op->fh_to_dentry) + (!(fh_flags & EXPORT_FH_FID) && + !path->dentry->d_sb->s_export_op->fh_to_dentry)) return -EOPNOTSUPP; if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) @@ -45,10 +48,10 @@ static long do_sys_name_to_handle(const struct path *path, /* convert handle size to multiple of sizeof(u32) */ handle_dwords = f_handle.handle_bytes >> 2; - /* we ask for a non connected handle */ + /* we ask for a non connectable maybe decodeable file handle */ retval = exportfs_encode_fh(path->dentry, (struct fid *)handle->f_handle, - &handle_dwords, 0); + &handle_dwords, fh_flags); handle->handle_type = retval; /* convert handle size to bytes */ handle_bytes = handle_dwords * sizeof(u32); @@ -84,6 +87,7 @@ static long do_sys_name_to_handle(const struct path *path, * @handle: resulting file handle * @mnt_id: mount id of the file system containing the file * @flag: flag value to indicate whether to follow symlink or not + * and whether a decodable file handle is required. * * @handle->handle_size indicate the space available to store the * variable part of the file handle in bytes. If there is not @@ -96,17 +100,19 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, { struct path path; int lookup_flags; + int fh_flags; int err; - if ((flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH)) != 0) + if (flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH | AT_HANDLE_FID)) return -EINVAL; lookup_flags = (flag & AT_SYMLINK_FOLLOW) ? LOOKUP_FOLLOW : 0; + fh_flags = (flag & AT_HANDLE_FID) ? EXPORT_FH_FID : 0; if (flag & AT_EMPTY_PATH) lookup_flags |= LOOKUP_EMPTY; err = user_path_at(dfd, name, lookup_flags, &path); if (!err) { - err = do_sys_name_to_handle(&path, handle, mnt_id); + err = do_sys_name_to_handle(&path, handle, mnt_id, fh_flags); path_put(&path); } return err; diff --git a/include/uapi/linux/fcntl.h b/include/uapi/linux/fcntl.h index e8c07da58c9f..6c80f96049bd 100644 --- a/include/uapi/linux/fcntl.h +++ b/include/uapi/linux/fcntl.h @@ -112,4 +112,9 @@ #define AT_RECURSIVE 0x8000 /* Apply to the entire subtree */ +/* Flags for name_to_handle_at(2). We reuse AT_ flag space to save bits... */ +#define AT_HANDLE_FID AT_REMOVEDIR /* file handle is needed to + compare object identity and may not + be usable to open_by_handle_at(2) */ + #endif /* _UAPI_LINUX_FCNTL_H */ |