diff options
Diffstat (limited to 'fs/fhandle.c')
| -rw-r--r-- | fs/fhandle.c | 75 |
1 files changed, 69 insertions, 6 deletions
diff --git a/fs/fhandle.c b/fs/fhandle.c index 5f801139358e..ec9145047dfc 100644 --- a/fs/fhandle.c +++ b/fs/fhandle.c @@ -31,6 +31,14 @@ static long do_sys_name_to_handle(const struct path *path, if (!exportfs_can_encode_fh(path->dentry->d_sb->s_export_op, fh_flags)) return -EOPNOTSUPP; + /* + * A request to encode a connectable handle for a disconnected dentry + * is unexpected since AT_EMPTY_PATH is not allowed. + */ + if (fh_flags & EXPORT_FH_CONNECTABLE && + WARN_ON(path->dentry->d_flags & DCACHE_DISCONNECTED)) + return -EINVAL; + if (copy_from_user(&f_handle, ufh, sizeof(struct file_handle))) return -EFAULT; @@ -45,7 +53,7 @@ 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 connectable maybe decodeable file handle */ + /* Encode a possibly decodeable/connectable file handle */ retval = exportfs_encode_fh(path->dentry, (struct fid *)handle->f_handle, &handle_dwords, fh_flags); @@ -67,8 +75,23 @@ static long do_sys_name_to_handle(const struct path *path, * non variable part of the file_handle */ handle_bytes = 0; - } else + } else { + /* + * When asked to encode a connectable file handle, encode this + * property in the file handle itself, so that we later know + * how to decode it. + * For sanity, also encode in the file handle if the encoded + * object is a directory and verify this during decode, because + * decoding directory file handles is quite different than + * decoding connectable non-directory file handles. + */ + if (fh_flags & EXPORT_FH_CONNECTABLE) { + handle->handle_type |= FILEID_IS_CONNECTABLE; + if (d_is_dir(path->dentry)) + fh_flags |= FILEID_IS_DIR; + } retval = 0; + } /* copy the mount id */ if (unique_mntid) { if (put_user(real_mount(path->mnt)->mnt_id_unique, @@ -109,15 +132,30 @@ SYSCALL_DEFINE5(name_to_handle_at, int, dfd, const char __user *, name, { struct path path; int lookup_flags; - int fh_flags; + int fh_flags = 0; int err; if (flag & ~(AT_SYMLINK_FOLLOW | AT_EMPTY_PATH | AT_HANDLE_FID | - AT_HANDLE_MNT_ID_UNIQUE)) + AT_HANDLE_MNT_ID_UNIQUE | AT_HANDLE_CONNECTABLE)) + return -EINVAL; + + /* + * AT_HANDLE_FID means there is no intention to decode file handle + * AT_HANDLE_CONNECTABLE means there is an intention to decode a + * connected fd (with known path), so these flags are conflicting. + * AT_EMPTY_PATH could be used along with a dfd that refers to a + * disconnected non-directory, which cannot be used to encode a + * connectable file handle, because its parent is unknown. + */ + if (flag & AT_HANDLE_CONNECTABLE && + flag & (AT_HANDLE_FID | AT_EMPTY_PATH)) return -EINVAL; + else if (flag & AT_HANDLE_FID) + fh_flags |= EXPORT_FH_FID; + else if (flag & AT_HANDLE_CONNECTABLE) + fh_flags |= EXPORT_FH_CONNECTABLE; 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); @@ -207,7 +245,13 @@ static int vfs_dentry_acceptable(void *context, struct dentry *dentry) if (!(ctx->flags & HANDLE_CHECK_SUBTREE) || d == root) retval = 1; - WARN_ON_ONCE(d != root && d != root->d_sb->s_root); + /* + * exportfs_decode_fh_raw() does not call acceptable() callback with + * a disconnected directory dentry, so we should have reached either + * mount fd directory or sb root. + */ + if (ctx->fh_flags & EXPORT_FH_DIR_ONLY) + WARN_ON_ONCE(d != root && d != root->d_sb->s_root); dput(d); return retval; } @@ -306,6 +350,12 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, retval = -EINVAL; goto out_path; } + if (f_handle.handle_type < 0 || + FILEID_USER_FLAGS(f_handle.handle_type) & ~FILEID_VALID_USER_FLAGS) { + retval = -EINVAL; + goto out_path; + } + handle = kmalloc(struct_size(handle, f_handle, f_handle.handle_bytes), GFP_KERNEL); if (!handle) { @@ -321,6 +371,19 @@ static int handle_to_path(int mountdirfd, struct file_handle __user *ufh, goto out_handle; } + /* + * If handle was encoded with AT_HANDLE_CONNECTABLE, verify that we + * are decoding an fd with connected path, which is accessible from + * the mount fd path. + */ + if (f_handle.handle_type & FILEID_IS_CONNECTABLE) { + ctx.fh_flags |= EXPORT_FH_CONNECTABLE; + ctx.flags |= HANDLE_CHECK_SUBTREE; + } + if (f_handle.handle_type & FILEID_IS_DIR) + ctx.fh_flags |= EXPORT_FH_DIR_ONLY; + /* Filesystem code should not be exposed to user flags */ + handle->handle_type &= ~FILEID_USER_FLAGS_MASK; retval = do_handle_to_path(handle, path, &ctx); out_handle: |