smb: client: allow creating special files via reparse points

Add support for creating special files (e.g. char/block devices,
sockets, fifos) via NFS reparse points on SMB2+, which are fully
supported by most SMB servers and documented in MS-FSCC.

smb2_get_reparse_inode() creates the file with a corresponding reparse
point buffer set in @iov through a single roundtrip to the server.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311260746.HOJ039BV-lkp@intel.com/
Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/smb/client/cifsproto.h

@@ -211,8 +211,12 @@ int cifs_get_inode_info(struct inode **inode, const char *full_path,
 bool cifs_reparse_point_to_fattr(struct cifs_sb_info *cifs_sb,
 				 struct cifs_fattr *fattr,
 				 struct cifs_open_info_data *data);
-extern int smb311_posix_get_inode_info(struct inode **pinode, const char *search_path,
-			struct super_block *sb, unsigned int xid);
+
+extern int smb311_posix_get_inode_info(struct inode **inode,
+				       const char *full_path,
+				       struct cifs_open_info_data *data,
+				       struct super_block *sb,
+				       const unsigned int xid);
 extern int cifs_get_inode_info_unix(struct inode **pinode,
 			const unsigned char *search_path,
 			struct super_block *sb, unsigned int xid);

fs/smb/client/dir.c

@@ -680,9 +680,10 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
 		 full_path, d_inode(direntry));
 
 again:
-	if (pTcon->posix_extensions)
-		rc = smb311_posix_get_inode_info(&newInode, full_path, parent_dir_inode->i_sb, xid);
-	else if (pTcon->unix_ext) {
+	if (pTcon->posix_extensions) {
+		rc = smb311_posix_get_inode_info(&newInode, full_path, NULL,
+						 parent_dir_inode->i_sb, xid);
+	} else if (pTcon->unix_ext) {
 		rc = cifs_get_inode_info_unix(&newInode, full_path,
 					      parent_dir_inode->i_sb, xid);
 	} else {

fs/smb/client/file.c

@@ -1020,14 +1020,16 @@ cifs_reopen_file(struct cifsFileInfo *cfile, bool can_flush)
 		if (!is_interrupt_error(rc))
 			mapping_set_error(inode->i_mapping, rc);
 
-		if (tcon->posix_extensions)
-			rc = smb311_posix_get_inode_info(&inode, full_path, inode->i_sb, xid);
-		else if (tcon->unix_ext)
+		if (tcon->posix_extensions) {
+			rc = smb311_posix_get_inode_info(&inode, full_path,
+							 NULL, inode->i_sb, xid);
+		} else if (tcon->unix_ext) {
 			rc = cifs_get_inode_info_unix(&inode, full_path,
 						      inode->i_sb, xid);
-		else
+		} else {
 			rc = cifs_get_inode_info(&inode, full_path, NULL,
 						 inode->i_sb, xid, NULL);
+		}
 	}
 	/*
 	 * Else we are writing out data to server already and could deadlock if

fs/smb/client/inode.c

@@ -1061,7 +1061,9 @@ static int reparse_info_to_fattr(struct cifs_open_info_data *data,
 				 const unsigned int xid,
 				 struct cifs_tcon *tcon,
 				 const char *full_path,
-				 struct cifs_fattr *fattr)
+				 struct cifs_fattr *fattr,
+				 struct cifs_sid *owner,
+				 struct cifs_sid *group)
 {
 	struct TCP_Server_Info *server = tcon->ses->server;
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
@@ -1092,7 +1094,8 @@ static int reparse_info_to_fattr(struct cifs_open_info_data *data,
 		rc = 0;
 		goto out;
 	default:
-		if (data->symlink_target) {
+		/* Check for cached reparse point data */
+		if (data->symlink_target || data->reparse.buf) {
 			rc = 0;
 		} else if (server->ops->parse_reparse_point) {
 			rc = server->ops->parse_reparse_point(cifs_sb,
@@ -1101,7 +1104,10 @@ static int reparse_info_to_fattr(struct cifs_open_info_data *data,
 		break;
 	}
 
-	cifs_open_info_to_fattr(fattr, data, sb);
+	if (tcon->posix_extensions)
+		smb311_posix_info_to_fattr(fattr, data, owner, group, sb);
+	else
+		cifs_open_info_to_fattr(fattr, data, sb);
 out:
 	free_rsp_buf(rsp_buftype, rsp_iov.iov_base);
 	return rc;
@@ -1152,7 +1158,8 @@ static int cifs_get_fattr(struct cifs_open_info_data *data,
 		 */
 		if (cifs_open_data_reparse(data)) {
 			rc = reparse_info_to_fattr(data, sb, xid, tcon,
-						   full_path, fattr);
+						   full_path, fattr,
+						   NULL, NULL);
 		} else {
 			cifs_open_info_to_fattr(fattr, data, sb);
 		}
@@ -1290,39 +1297,49 @@ int cifs_get_inode_info(struct inode **inode,
 	return rc;
 }
 
-static int smb311_posix_get_fattr(struct cifs_fattr *fattr,
+static int smb311_posix_get_fattr(struct cifs_open_info_data *data,
+				  struct cifs_fattr *fattr,
 				  const char *full_path,
 				  struct super_block *sb,
 				  const unsigned int xid)
 {
-	struct cifs_open_info_data data = {};
+	struct cifs_open_info_data tmp_data = {};
 	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
 	struct cifs_tcon *tcon;
 	struct tcon_link *tlink;
 	struct cifs_sid owner, group;
 	int tmprc;
-	int rc;
+	int rc = 0;
 
 	tlink = cifs_sb_tlink(cifs_sb);
 	if (IS_ERR(tlink))
 		return PTR_ERR(tlink);
 	tcon = tlink_tcon(tlink);
 
 	/*
-	 * 1. Fetch file metadata
+	 * 1. Fetch file metadata if not provided (data)
 	 */
-
-	rc = smb311_posix_query_path_info(xid, tcon, cifs_sb,
-					  full_path, &data,
-					  &owner, &group);
+	if (!data) {
+		rc = smb311_posix_query_path_info(xid, tcon, cifs_sb,
+						  full_path, &tmp_data,
+						  &owner, &group);
+		data = &tmp_data;
+	}
 
 	/*
 	 * 2. Convert it to internal cifs metadata (fattr)
 	 */
 
 	switch (rc) {
 	case 0:
-		smb311_posix_info_to_fattr(fattr, &data, &owner, &group, sb);
+		if (cifs_open_data_reparse(data)) {
+			rc = reparse_info_to_fattr(data, sb, xid, tcon,
+						   full_path, fattr,
+						   &owner, &group);
+		} else {
+			smb311_posix_info_to_fattr(fattr, data,
+						   &owner, &group, sb);
+		}
 		break;
 	case -EREMOTE:
 		/* DFS link, no metadata available on this server */
@@ -1353,12 +1370,15 @@ static int smb311_posix_get_fattr(struct cifs_fattr *fattr,
 
 out:
 	cifs_put_tlink(tlink);
-	cifs_free_open_info(&data);
+	cifs_free_open_info(data);
 	return rc;
 }
 
-int smb311_posix_get_inode_info(struct inode **inode, const char *full_path,
-				struct super_block *sb, const unsigned int xid)
+int smb311_posix_get_inode_info(struct inode **inode,
+				const char *full_path,
+				struct cifs_open_info_data *data,
+				struct super_block *sb,
+				const unsigned int xid)
 {
 	struct cifs_fattr fattr = {};
 	int rc;
@@ -1368,7 +1388,7 @@ int smb311_posix_get_inode_info(struct inode **inode, const char *full_path,
 		return 0;
 	}
 
-	rc = smb311_posix_get_fattr(&fattr, full_path, sb, xid);
+	rc = smb311_posix_get_fattr(data, &fattr, full_path, sb, xid);
 	if (rc)
 		goto out;
 
@@ -1516,7 +1536,7 @@ struct inode *cifs_root_iget(struct super_block *sb)
 
 	convert_delimiter(path, CIFS_DIR_SEP(cifs_sb));
 	if (tcon->posix_extensions)
-		rc = smb311_posix_get_fattr(&fattr, path, sb, xid);
+		rc = smb311_posix_get_fattr(NULL, &fattr, path, sb, xid);
 	else
 		rc = cifs_get_fattr(NULL, sb, xid, NULL, &fattr, &inode, path);
 
@@ -1889,16 +1909,18 @@ cifs_mkdir_qinfo(struct inode *parent, struct dentry *dentry, umode_t mode,
 	int rc = 0;
 	struct inode *inode = NULL;
 
-	if (tcon->posix_extensions)
-		rc = smb311_posix_get_inode_info(&inode, full_path, parent->i_sb, xid);
+	if (tcon->posix_extensions) {
+		rc = smb311_posix_get_inode_info(&inode, full_path,
+						 NULL, parent->i_sb, xid);
 #ifdef CONFIG_CIFS_ALLOW_INSECURE_LEGACY
-	else if (tcon->unix_ext)
+	} else if (tcon->unix_ext) {
 		rc = cifs_get_inode_info_unix(&inode, full_path, parent->i_sb,
 					      xid);
 #endif /* CONFIG_CIFS_ALLOW_INSECURE_LEGACY */
-	else
+	} else {
 		rc = cifs_get_inode_info(&inode, full_path, NULL, parent->i_sb,
 					 xid, NULL);
+	}
 
 	if (rc)
 		return rc;
@@ -2579,13 +2601,15 @@ int cifs_revalidate_dentry_attr(struct dentry *dentry)
 		 dentry, cifs_get_time(dentry), jiffies);
 
 again:
-	if (cifs_sb_master_tcon(CIFS_SB(sb))->posix_extensions)
-		rc = smb311_posix_get_inode_info(&inode, full_path, sb, xid);
-	else if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext)
+	if (cifs_sb_master_tcon(CIFS_SB(sb))->posix_extensions) {
+		rc = smb311_posix_get_inode_info(&inode, full_path,
+						 NULL, sb, xid);
+	} else if (cifs_sb_master_tcon(CIFS_SB(sb))->unix_ext) {
 		rc = cifs_get_inode_info_unix(&inode, full_path, sb, xid);
-	else
+	} else {
 		rc = cifs_get_inode_info(&inode, full_path, NULL, sb,
 					 xid, NULL);
+	}
 	if (rc == -EAGAIN && count++ < 10)
 		goto again;
 out:

fs/smb/client/link.c

@@ -614,14 +614,16 @@ cifs_symlink(struct mnt_idmap *idmap, struct inode *inode,
 					cifs_sb_target->local_nls); */
 
 	if (rc == 0) {
-		if (pTcon->posix_extensions)
-			rc = smb311_posix_get_inode_info(&newinode, full_path, inode->i_sb, xid);
-		else if (pTcon->unix_ext)
+		if (pTcon->posix_extensions) {
+			rc = smb311_posix_get_inode_info(&newinode, full_path,
+							 NULL, inode->i_sb, xid);
+		} else if (pTcon->unix_ext) {
 			rc = cifs_get_inode_info_unix(&newinode, full_path,
 						      inode->i_sb, xid);
-		else
+		} else {
 			rc = cifs_get_inode_info(&newinode, full_path, NULL,
 						 inode->i_sb, xid, NULL);
+		}
 
 		if (rc != 0) {
 			cifs_dbg(FYI, "Create symlink ok, getinodeinfo fail rc = %d\n",

fs/smb/client/smb2glob.h

@@ -23,17 +23,20 @@
  * Identifiers for functions that use the open, operation, close pattern
  * in smb2inode.c:smb2_compound_op()
  */
-#define SMB2_OP_SET_DELETE 1
-#define SMB2_OP_SET_INFO 2
-#define SMB2_OP_QUERY_INFO 3
-#define SMB2_OP_QUERY_DIR 4
-#define SMB2_OP_MKDIR 5
-#define SMB2_OP_RENAME 6
-#define SMB2_OP_DELETE 7
-#define SMB2_OP_HARDLINK 8
-#define SMB2_OP_SET_EOF 9
-#define SMB2_OP_RMDIR 10
-#define SMB2_OP_POSIX_QUERY_INFO 11
+enum smb2_compound_ops {
+	SMB2_OP_SET_DELETE = 1,
+	SMB2_OP_SET_INFO,
+	SMB2_OP_QUERY_INFO,
+	SMB2_OP_QUERY_DIR,
+	SMB2_OP_MKDIR,
+	SMB2_OP_RENAME,
+	SMB2_OP_DELETE,
+	SMB2_OP_HARDLINK,
+	SMB2_OP_SET_EOF,
+	SMB2_OP_RMDIR,
+	SMB2_OP_POSIX_QUERY_INFO,
+	SMB2_OP_SET_REPARSE
+};
 
 /* Used when constructing chained read requests. */
 #define CHAINED_REQUEST 1

fs/smb/client/smb2inode.c

@@ -347,6 +347,22 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 			smb2_set_related(&rqst[num_rqst++]);
 			trace_smb3_hardlink_enter(xid, ses->Suid, tcon->tid, full_path);
 			break;
+		case SMB2_OP_SET_REPARSE:
+			rqst[num_rqst].rq_iov = vars->io_iov;
+			rqst[num_rqst].rq_nvec = ARRAY_SIZE(vars->io_iov);
+
+			rc = SMB2_ioctl_init(tcon, server, &rqst[num_rqst],
+					     COMPOUND_FID, COMPOUND_FID,
+					     FSCTL_SET_REPARSE_POINT,
+					     in_iov[i].iov_base,
+					     in_iov[i].iov_len, 0);
+			if (rc)
+				goto finished;
+			smb2_set_next_command(tcon, &rqst[num_rqst]);
+			smb2_set_related(&rqst[num_rqst++]);
+			trace_smb3_set_reparse_compound_enter(xid, ses->Suid,
+							      tcon->tid, full_path);
+			break;
 		default:
 			cifs_dbg(VFS, "Invalid command\n");
 			rc = -EINVAL;
@@ -503,6 +519,16 @@ static int smb2_compound_op(const unsigned int xid, struct cifs_tcon *tcon,
 								  tcon->tid);
 			SMB2_set_info_free(&rqst[num_rqst++]);
 			break;
+		case SMB2_OP_SET_REPARSE:
+			if (rc) {
+				trace_smb3_set_reparse_compound_err(xid,  ses->Suid,
+								    tcon->tid, rc);
+			} else {
+				trace_smb3_set_reparse_compound_done(xid, ses->Suid,
+								     tcon->tid);
+			}
+			SMB2_ioctl_free(&rqst[num_rqst++]);
+			break;
 		}
 	}
 	SMB2_close_free(&rqst[num_rqst]);
@@ -887,3 +913,52 @@ smb2_set_file_info(struct inode *inode, const char *full_path,
 	cifs_put_tlink(tlink);
 	return rc;
 }
+
+struct inode *smb2_get_reparse_inode(struct cifs_open_info_data *data,
+				     struct super_block *sb,
+				     const unsigned int xid,
+				     struct cifs_tcon *tcon,
+				     const char *full_path,
+				     struct kvec *iov)
+{
+	struct cifs_sb_info *cifs_sb = CIFS_SB(sb);
+	struct cifsFileInfo *cfile;
+	struct inode *new = NULL;
+	struct kvec in_iov[2];
+	int cmds[2];
+	int da, co, cd;
+	int rc;
+
+	da = SYNCHRONIZE | DELETE |
+		FILE_READ_ATTRIBUTES |
+		FILE_WRITE_ATTRIBUTES;
+	co = CREATE_NOT_DIR | OPEN_REPARSE_POINT;
+	cd = FILE_CREATE;
+	cmds[0] = SMB2_OP_SET_REPARSE;
+	in_iov[0] = *iov;
+	in_iov[1].iov_base = data;
+	in_iov[1].iov_len = sizeof(*data);
+
+	if (tcon->posix_extensions) {
+		cmds[1] = SMB2_OP_POSIX_QUERY_INFO;
+		cifs_get_writable_path(tcon, full_path, FIND_WR_ANY, &cfile);
+		rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,
+				      da, cd, co, ACL_NO_MODE, in_iov,
+				      cmds, 2, cfile, NULL, NULL, NULL, NULL);
+		if (!rc) {
+			rc = smb311_posix_get_inode_info(&new, full_path,
+							 data, sb, xid);
+		}
+	} else {
+		cmds[1] = SMB2_OP_QUERY_INFO;
+		cifs_get_writable_path(tcon, full_path, FIND_WR_ANY, &cfile);
+		rc = smb2_compound_op(xid, tcon, cifs_sb, full_path,
+				      da, cd, co, ACL_NO_MODE, in_iov,
+				      cmds, 2, cfile, NULL, NULL, NULL, NULL);
+		if (!rc) {
+			rc = cifs_get_inode_info(&new, full_path,
+						 data, sb, xid, NULL);
+		}
+	}
+	return rc ? ERR_PTR(rc) : new;
+}