s3: VFS: Add SMB_VFS_READ_DFS_PATHAT().

Not yet used.

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

examples/VFS/skel_opaque.c

@@ -112,6 +112,16 @@ static NTSTATUS skel_create_dfs_pathat(struct vfs_handle_struct *handle,
 	return NT_STATUS_NOT_IMPLEMENTED;
 }
 
+static NTSTATUS skel_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count)
+{
+	return NT_STATUS_NOT_IMPLEMENTED;
+}
+
 static DIR *skel_opendir(vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			const char *mask,
@@ -1042,6 +1052,7 @@ static struct vfs_fn_pointers skel_opaque_fns = {
 	.fs_capabilities_fn = skel_fs_capabilities,
 	.get_dfs_referrals_fn = skel_get_dfs_referrals,
 	.create_dfs_pathat_fn = skel_create_dfs_pathat,
+	.read_dfs_pathat_fn = skel_read_dfs_pathat,
 	.snap_check_path_fn = skel_snap_check_path,
 	.snap_create_fn = skel_snap_create,
 	.snap_delete_fn = skel_snap_delete,

examples/VFS/skel_transparent.c

@@ -113,6 +113,21 @@ static NTSTATUS skel_create_dfs_pathat(struct vfs_handle_struct *handle,
 					referral_count);
 }
 
+static NTSTATUS skel_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count)
+{
+	return SMB_VFS_NEXT_READ_DFS_PATHAT(handle,
+					mem_ctx,
+					dirfsp,
+					smb_fname,
+					ppreflist,
+					preferral_count);
+}
+
 static DIR *skel_opendir(vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			const char *mask,
@@ -1344,6 +1359,7 @@ static struct vfs_fn_pointers skel_transparent_fns = {
 	.fs_capabilities_fn = skel_fs_capabilities,
 	.get_dfs_referrals_fn = skel_get_dfs_referrals,
 	.create_dfs_pathat_fn = skel_create_dfs_pathat,
+	.read_dfs_pathat_fn = skel_read_dfs_pathat,
 	.snap_check_path_fn = skel_snap_check_path,
 	.snap_create_fn = skel_snap_create,
 	.snap_delete_fn = skel_snap_delete,

source3/include/vfs.h

@@ -289,6 +289,7 @@
 /* Version 42 - Remove struct write_cache *wcp from files_struct */
 /* Version 42 - SMB_VFS_NTIMES() receives null times based on UTIMES_OMIT */
 /* Version 42 - Add SMB_VFS_CREATE_DFS_PATHAT() */
+/* Version 42 - Add SMB_VFS_READ_DFS_PATHAT() */
 
 #define SMB_VFS_INTERFACE_VERSION 42
 
@@ -716,6 +717,12 @@ struct vfs_fn_pointers {
 				const struct smb_filename *smb_fname,
 				const struct referral *reflist,
 				size_t referral_count);
+	NTSTATUS (*read_dfs_pathat_fn)(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count);
 
 	/* Directory operations */
 
@@ -1224,6 +1231,12 @@ NTSTATUS smb_vfs_call_create_dfs_pathat(struct vfs_handle_struct *handle,
 				const struct smb_filename *smb_fname,
 				const struct referral *reflist,
 				size_t referral_count);
+NTSTATUS smb_vfs_call_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count);
 DIR *smb_vfs_call_opendir(struct vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			const char *mask,
@@ -1666,6 +1679,12 @@ NTSTATUS vfs_not_implemented_create_dfs_pathat(struct vfs_handle_struct *handle,
 				const struct smb_filename *smb_fname,
 				const struct referral *reflist,
 				size_t referral_count);
+NTSTATUS vfs_not_implemented_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count);
 DIR *vfs_not_implemented_opendir(vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			const char *mask,

source3/include/vfs_macros.h

@@ -90,6 +90,20 @@
 		(smb_fname), \
 		(reflist), \
 		(count))
+#define SMB_VFS_READ_DFS_PATHAT(conn, mem_ctx, dirfsp, smb_fname, ppreflist, pcount) \
+	smb_vfs_call_read_dfs_pathat((conn)->vfs_handles, \
+		(mem_ctx), \
+		(dirfsp), \
+		(smb_fname), \
+		(ppreflist), \
+		(pcount))
+#define SMB_VFS_NEXT_READ_DFS_PATHAT(handle, mem_ctx, dirfsp, smb_fname, ppreflist, pcount) \
+        smb_vfs_call_read_dfs_pathat((handle)->next, \
+		(mem_ctx), \
+                (dirfsp), \
+                (smb_fname), \
+                (ppreflist), \
+                (pcount))
 
 /* Directory operations */
 #define SMB_VFS_OPENDIR(conn, smb_fname, mask, attr) \

source3/modules/vfs_default.c

@@ -404,6 +404,108 @@ static NTSTATUS vfswrap_create_dfs_pathat(struct vfs_handle_struct *handle,
 	return status;
 }
 
+/*
+ * Read and return the contents of a DFS redirect given a
+ * pathname. A caller can pass in NULL for ppreflist and
+ * preferral_count but still determine if this was a
+ * DFS redirect point by getting NT_STATUS_OK back
+ * without incurring the overhead of reading and parsing
+ * the referral contents.
+ */
+
+static NTSTATUS vfswrap_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count)
+{
+	NTSTATUS status = NT_STATUS_NO_MEMORY;
+	size_t bufsize;
+	char *link_target = NULL;
+	int referral_len;
+	bool ok;
+#if defined(HAVE_BROKEN_READLINK)
+	char link_target_buf[PATH_MAX];
+#else
+	char link_target_buf[7];
+#endif
+
+	SMB_ASSERT(dirfsp == dirfsp->conn->cwd_fsp);
+
+	if (ppreflist == NULL && preferral_count == NULL) {
+		/*
+		 * We're only checking if this is a DFS
+		 * redirect. We don't need to return data.
+		 */
+		bufsize = sizeof(link_target_buf);
+		link_target = link_target_buf;
+	} else {
+		bufsize = PATH_MAX;
+		link_target = talloc_array(mem_ctx, char, bufsize);
+		if (!link_target) {
+			goto err;
+		}
+	}
+
+	referral_len = readlinkat(dirfsp->fh->fd,
+				smb_fname->base_name,
+				link_target,
+				bufsize - 1);
+	if (referral_len == -1) {
+		if (errno == EINVAL) {
+			/*
+			 * If the path isn't a link, readlinkat
+			 * returns EINVAL. Allow the caller to
+			 * detect this.
+			 */
+			DBG_INFO("%s is not a link.\n", smb_fname->base_name);
+			status = NT_STATUS_OBJECT_TYPE_MISMATCH;
+		} else {
+			status = map_nt_error_from_unix(errno);
+			DBG_ERR("Error reading "
+				"msdfs link %s: %s\n",
+				smb_fname->base_name,
+				strerror(errno));
+		}
+                goto err;
+        }
+	link_target[referral_len] = '\0';
+
+	DBG_INFO("%s -> %s\n",
+			smb_fname->base_name,
+			link_target);
+
+	if (!strnequal(link_target, "msdfs:", 6)) {
+		status = NT_STATUS_OBJECT_TYPE_MISMATCH;
+		goto err;
+	}
+
+	if (ppreflist == NULL && preferral_count == NULL) {
+		/* Early return for checking if this is a DFS link. */
+		return NT_STATUS_OK;
+	}
+
+	ok = parse_msdfs_symlink(mem_ctx,
+			lp_msdfs_shuffle_referrals(SNUM(handle->conn)),
+			link_target,
+			ppreflist,
+			preferral_count);
+
+	if (ok) {
+		status = NT_STATUS_OK;
+	} else {
+		status = NT_STATUS_NO_MEMORY;
+	}
+
+  err:
+
+	if (link_target != link_target_buf) {
+		TALLOC_FREE(link_target);
+	}
+	return status;
+}
+
 static NTSTATUS vfswrap_snap_check_path(struct vfs_handle_struct *handle,
 					TALLOC_CTX *mem_ctx,
 					const char *service_path,
@@ -3517,6 +3619,7 @@ static struct vfs_fn_pointers vfs_default_fns = {
 	.fs_capabilities_fn = vfswrap_fs_capabilities,
 	.get_dfs_referrals_fn = vfswrap_get_dfs_referrals,
 	.create_dfs_pathat_fn = vfswrap_create_dfs_pathat,
+	.read_dfs_pathat_fn = vfswrap_read_dfs_pathat,
 	.snap_check_path_fn = vfswrap_snap_check_path,
 	.snap_create_fn = vfswrap_snap_create,
 	.snap_delete_fn = vfswrap_snap_delete,

source3/modules/vfs_not_implemented.c

@@ -106,6 +106,16 @@ NTSTATUS vfs_not_implemented_create_dfs_pathat(struct vfs_handle_struct *handle,
 	return NT_STATUS_NOT_IMPLEMENTED;
 }
 
+NTSTATUS vfs_not_implemented_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count)
+{
+	return NT_STATUS_NOT_IMPLEMENTED;
+}
+
 DIR *vfs_not_implemented_opendir(vfs_handle_struct *handle,
 			const struct smb_filename *smb_fname,
 			const char *mask,
@@ -1047,6 +1057,7 @@ static struct vfs_fn_pointers vfs_not_implemented_fns = {
 	.fs_capabilities_fn = vfs_not_implemented_fs_capabilities,
 	.get_dfs_referrals_fn = vfs_not_implemented_get_dfs_referrals,
 	.create_dfs_pathat_fn = vfs_not_implemented_create_dfs_pathat,
+	.read_dfs_pathat_fn = vfs_not_implemented_read_dfs_pathat,
 	.snap_check_path_fn = vfs_not_implemented_snap_check_path,
 	.snap_create_fn = vfs_not_implemented_snap_create,
 	.snap_delete_fn = vfs_not_implemented_snap_delete,

source3/smbd/vfs.c

@@ -1577,6 +1577,22 @@ NTSTATUS smb_vfs_call_create_dfs_pathat(struct vfs_handle_struct *handle,
 						referral_count);
 }
 
+NTSTATUS smb_vfs_call_read_dfs_pathat(struct vfs_handle_struct *handle,
+				TALLOC_CTX *mem_ctx,
+				struct files_struct *dirfsp,
+				const struct smb_filename *smb_fname,
+				struct referral **ppreflist,
+				size_t *preferral_count)
+{
+	VFS_FIND(read_dfs_pathat);
+	return handle->fns->read_dfs_pathat_fn(handle,
+						mem_ctx,
+						dirfsp,
+						smb_fname,
+						ppreflist,
+						preferral_count);
+}
+
 DIR *smb_vfs_call_opendir(struct vfs_handle_struct *handle,
 					const struct smb_filename *smb_fname,
 					const char *mask,