Merge pull request ceph#59936 from anoopcs9/client-chown-statx-fixes

client: Handle empty pathnames for `ceph_chownat()` and `ceph_statxat()`

Author: mchangir

src/client/Client.cc

@@ -8907,7 +8907,6 @@ int Client::chownat(int dirfd, const char *relpath, uid_t new_uid, gid_t new_gid
   tout(cct) << new_gid << std::endl;
   tout(cct) << flags << std::endl;
 
-  filepath path(relpath);
   InodeRef in;
   InodeRef dirinode;
 
@@ -8917,10 +8916,24 @@ int Client::chownat(int dirfd, const char *relpath, uid_t new_uid, gid_t new_gid
     return r;
   }
 
-  r = path_walk(path, &in, perms, !(flags & AT_SYMLINK_NOFOLLOW), 0, dirinode);
-  if (r < 0) {
-    return r;
+  if (!strcmp(relpath, "")) {
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+    if (flags & AT_EMPTY_PATH) {
+      in = dirinode;
+      goto out;
+    }
+#endif
+    return -CEPHFS_ENOENT;
+  } else {
+    filepath path(relpath);
+    r = path_walk(path, &in, perms, !(flags & AT_SYMLINK_NOFOLLOW), 0, dirinode);
+    if (r < 0) {
+      return r;
+    }
   }
+
+out:
+
   struct stat attr;
   attr.st_uid = new_uid;
   attr.st_gid = new_gid;
@@ -12230,19 +12243,32 @@ int Client::statxat(int dirfd, const char *relpath,
 
   unsigned mask = statx_to_mask(flags, want);
 
+  InodeRef in;
   InodeRef dirinode;
   std::scoped_lock lock(client_lock);
   int r = get_fd_inode(dirfd, &dirinode);
   if (r < 0) {
     return r;
   }
 
-  InodeRef in;
-  filepath path(relpath);
-  r = path_walk(path, &in, perms, !(flags & AT_SYMLINK_NOFOLLOW), mask, dirinode);
-  if (r < 0) {
-    return r;
+  if (!strcmp(relpath, "")) {
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+    if (flags & AT_EMPTY_PATH) {
+      in = dirinode;
+      goto out;
+    }
+#endif
+    return -CEPHFS_ENOENT;
+  } else {
+    filepath path(relpath);
+    r = path_walk(path, &in, perms, !(flags & AT_SYMLINK_NOFOLLOW), mask, dirinode);
+    if (r < 0) {
+      return r;
+    }
   }
+
+out:
+
   r = _getattr(in, mask, perms);
   if (r < 0) {
     ldout(cct, 3) << __func__ << " exit on error!" << dendl;

src/include/cephfs/ceph_ll_client.h

@@ -110,6 +110,9 @@ struct ceph_statx {
  * others in the future, we disallow setting any that aren't recognized.
  */
 #define CEPH_REQ_FLAG_MASK		(AT_SYMLINK_NOFOLLOW|AT_STATX_DONT_SYNC)
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+#define CEPH_AT_EMPTY_PATH		(CEPH_REQ_FLAG_MASK|AT_EMPTY_PATH)
+#endif
 
 /* fallocate mode flags */
 #ifndef FALLOC_FL_KEEP_SIZE

src/include/cephfs/libcephfs.h

@@ -937,7 +937,7 @@ int ceph_fstatx(struct ceph_mount_info *cmount, int fd, struct ceph_statx *stx,
  * @param relpath to the file/directory to get statistics of
  * @param stx the ceph_statx struct that will be filled in with the file's statistics.
  * @param want bitfield of CEPH_STATX_* flags showing designed attributes
- * @param flags bitfield that can be used to set AT_* modifier flags (AT_STATX_SYNC_AS_STAT, AT_STATX_FORCE_SYNC, AT_STATX_DONT_SYNC and AT_SYMLINK_NOFOLLOW)
+ * @param flags bitfield that can be used to set AT_* modifier flags (AT_STATX_DONT_SYNC, AT_SYMLINK_NOFOLLOW and AT_EMPTY_PATH)
  * @returns 0 on success or negative error code on failure.
  */
 int ceph_statxat(struct ceph_mount_info *cmount, int dirfd, const char *relpath,
@@ -1104,7 +1104,7 @@ int ceph_lchown(struct ceph_mount_info *cmount, const char *path, int uid, int g
  * @param relpath the relpath of the file/directory to change the ownership of.
  * @param uid the user id to set on the file/directory.
  * @param gid the group id to set on the file/directory.
- * @param flags bitfield that can be used to set AT_* modifier flags (AT_SYMLINK_NOFOLLOW)
+ * @param flags bitfield that can be used to set AT_* modifier flags (AT_SYMLINK_NOFOLLOW and AT_EMPTY_PATH)
  * @returns 0 on success or negative error code on failure.
  */
 int ceph_chownat(struct ceph_mount_info *cmount, int dirfd, const char *relpath,

src/libcephfs.cc

@@ -982,7 +982,11 @@ extern "C" int ceph_statxat(struct ceph_mount_info *cmount, int dirfd, const cha
 {
   if (!cmount->is_mounted())
     return -CEPHFS_ENOTCONN;
+#ifdef CEPH_AT_EMPTY_PATH
+  if (flags & ~CEPH_AT_EMPTY_PATH)
+#else
   if (flags & ~CEPH_REQ_FLAG_MASK)
+#endif
     return -CEPHFS_EINVAL;
   return cmount->get_client()->statxat(dirfd, relpath, stx, cmount->default_perms,
                                        want, flags);

src/test/libcephfs/test.cc

@@ -2706,13 +2706,34 @@ TEST(LibCephFS, Statxat) {
   ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFDIR);
   ASSERT_EQ(ceph_statxat(cmount, fd, rel_file_name_2, &stx, 0, 0), 0);
   ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFREG);
+  // test relative to root with empty relpath
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+  int dir_fd = ceph_openat(cmount, fd, dir_name, O_DIRECTORY | O_RDONLY, 0);
+  ASSERT_LE(0, dir_fd);
+  ASSERT_EQ(ceph_statxat(cmount, dir_fd, "", &stx, 0, AT_EMPTY_PATH), 0);
+  ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFDIR);
+  ASSERT_EQ(0, ceph_close(cmount, dir_fd));
+  int file_fd = ceph_openat(cmount, fd, rel_file_name_2, O_RDONLY, 0);
+  ASSERT_LE(0, file_fd);
+  ASSERT_EQ(ceph_statxat(cmount, file_fd, "", &stx, 0, AT_EMPTY_PATH), 0);
+  ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFREG);
+  ASSERT_EQ(0, ceph_close(cmount, file_fd));
+#endif
   ASSERT_EQ(0, ceph_close(cmount, fd));
 
   // test relative to dir
   fd = ceph_open(cmount, dir_path, O_DIRECTORY | O_RDONLY, 0);
   ASSERT_LE(0, fd);
   ASSERT_EQ(ceph_statxat(cmount, fd, rel_file_name_1, &stx, 0, 0), 0);
   ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFREG);
+  // test relative to dir with empty relpath
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+  int rel_file_fd = ceph_openat(cmount, fd, rel_file_name_1, O_RDONLY, 0);
+  ASSERT_LE(0, rel_file_fd);
+  ASSERT_EQ(ceph_statxat(cmount, rel_file_fd, "", &stx, 0, AT_EMPTY_PATH), 0);
+  ASSERT_EQ(stx.stx_mode & S_IFMT, S_IFREG);
+  ASSERT_EQ(0, ceph_close(cmount, rel_file_fd));
+#endif
 
   // delete the dirtree, recreate and verify
   ASSERT_EQ(0, ceph_unlink(cmount, file_path));
@@ -3265,6 +3286,13 @@ TEST(LibCephFS, Chownat) {
   // change ownership to nobody -- we assume nobody exists and id is always 65534
   ASSERT_EQ(ceph_conf_set(cmount, "client_permissions", "0"), 0);
   ASSERT_EQ(ceph_chownat(cmount, fd, rel_file_path, 65534, 65534, 0), 0);
+  // change relative fd ownership with AT_EMPTY_PATH
+#if defined(__linux__) && defined(AT_EMPTY_PATH)
+  int file_fd = ceph_openat(cmount, fd, rel_file_path, O_RDONLY, 0);
+  ASSERT_LE(0, file_fd);
+  ASSERT_EQ(ceph_chownat(cmount, file_fd, "", 65534, 65534, AT_EMPTY_PATH), 0);
+  ceph_close(cmount, file_fd);
+#endif
   ASSERT_EQ(ceph_conf_set(cmount, "client_permissions", "1"), 0);
   ceph_close(cmount, fd);