cifs: Add support for reading attributes on SMB2+

SMB1 already has support to read attributes. This adds similar support
to SMB2+.

With this patch, tools such as 'getfattr' will now work with SMB2+ shares.

RH-bz: 1110709

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/smb2ops.c

@@ -426,6 +426,138 @@ smb2_query_file_info(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
+static ssize_t
+move_smb2_ea_to_cifs(char *dst, size_t dst_size,
+		     struct smb2_file_full_ea_info *src, size_t src_size,
+		     const unsigned char *ea_name)
+{
+	int rc = 0;
+	unsigned int ea_name_len = ea_name ? strlen(ea_name) : 0;
+	char *name, *value;
+	size_t name_len, value_len, user_name_len;
+
+	while (src_size > 0) {
+		name = &src->ea_data[0];
+		name_len = (size_t)src->ea_name_length;
+		value = &src->ea_data[src->ea_name_length + 1];
+		value_len = (size_t)le16_to_cpu(src->ea_value_length);
+
+		if (name_len == 0) {
+			break;
+		}
+
+		if (src_size < 8 + name_len + 1 + value_len) {
+			cifs_dbg(FYI, "EA entry goes beyond length of list\n");
+			rc = -EIO;
+			goto out;
+		}
+
+		if (ea_name) {
+			if (ea_name_len == name_len &&
+			    memcmp(ea_name, name, name_len) == 0) {
+				rc = value_len;
+				if (dst_size == 0)
+					goto out;
+				if (dst_size < value_len) {
+					rc = -ERANGE;
+					goto out;
+				}
+				memcpy(dst, value, value_len);
+				goto out;
+			}
+		} else {
+			/* 'user.' plus a terminating null */
+			user_name_len = 5 + 1 + name_len;
+
+			rc += user_name_len;
+
+			if (dst_size >= user_name_len) {
+				dst_size -= user_name_len;
+				memcpy(dst, "user.", 5);
+				dst += 5;
+				memcpy(dst, src->ea_data, name_len);
+				dst += name_len;
+				*dst = 0;
+				++dst;
+			} else if (dst_size == 0) {
+				/* skip copy - calc size only */
+			} else {
+				/* stop before overrun buffer */
+				rc = -ERANGE;
+				break;
+			}
+		}
+
+		if (!src->next_entry_offset)
+			break;
+
+		if (src_size < le32_to_cpu(src->next_entry_offset)) {
+			/* stop before overrun buffer */
+			rc = -ERANGE;
+			break;
+		}
+		src_size -= le32_to_cpu(src->next_entry_offset);
+		src = (void *)((char *)src +
+			       le32_to_cpu(src->next_entry_offset));
+	}
+
+	/* didn't find the named attribute */
+	if (ea_name)
+		rc = -ENODATA;
+
+out:
+	return (ssize_t)rc;
+}
+
+static ssize_t
+smb2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+	       const unsigned char *path, const unsigned char *ea_name,
+	       char *ea_data, size_t buf_size,
+	       struct cifs_sb_info *cifs_sb)
+{
+	int rc;
+	__le16 *utf16_path;
+	__u8 oplock = SMB2_OPLOCK_LEVEL_NONE;
+	struct cifs_open_parms oparms;
+	struct cifs_fid fid;
+	struct smb2_file_full_ea_info *smb2_data;
+
+	utf16_path = cifs_convert_path_to_utf16(path, cifs_sb);
+	if (!utf16_path)
+		return -ENOMEM;
+
+	oparms.tcon = tcon;
+	oparms.desired_access = FILE_READ_EA;
+	oparms.disposition = FILE_OPEN;
+	oparms.create_options = 0;
+	oparms.fid = &fid;
+	oparms.reconnect = false;
+
+	rc = SMB2_open(xid, &oparms, utf16_path, &oplock, NULL, NULL);
+	kfree(utf16_path);
+	if (rc) {
+		cifs_dbg(FYI, "open failed rc=%d\n", rc);
+		return rc;
+	}
+
+	smb2_data = kzalloc(SMB2_MAX_EA_BUF, GFP_KERNEL);
+	if (smb2_data == NULL) {
+		SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+		return -ENOMEM;
+	}
+
+	rc = SMB2_query_eas(xid, tcon, fid.persistent_fid, fid.volatile_fid,
+			    smb2_data);
+	SMB2_close(xid, tcon, fid.persistent_fid, fid.volatile_fid);
+
+	if (!rc)
+		rc = move_smb2_ea_to_cifs(ea_data, buf_size, smb2_data,
+					  SMB2_MAX_EA_BUF, ea_name);
+
+	kfree(smb2_data);
+	return rc;
+}
+
 static bool
 smb2_can_echo(struct TCP_Server_Info *server)
 {
@@ -2572,6 +2704,9 @@ struct smb_version_operations smb20_operations = {
 	.dir_needs_close = smb2_dir_needs_close,
 	.get_dfs_refer = smb2_get_dfs_refer,
 	.select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+	.query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
 	.get_acl = get_smb2_acl,
 	.get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2662,6 +2797,9 @@ struct smb_version_operations smb21_operations = {
 	.enum_snapshots = smb3_enum_snapshots,
 	.get_dfs_refer = smb2_get_dfs_refer,
 	.select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+	.query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
 	.get_acl = get_smb2_acl,
 	.get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2762,6 +2900,9 @@ struct smb_version_operations smb30_operations = {
 	.receive_transform = smb3_receive_transform,
 	.get_dfs_refer = smb2_get_dfs_refer,
 	.select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+	.query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 #ifdef CONFIG_CIFS_ACL
 	.get_acl = get_smb2_acl,
 	.get_acl_by_fid = get_smb2_acl_by_fid,
@@ -2863,6 +3004,9 @@ struct smb_version_operations smb311_operations = {
 	.receive_transform = smb3_receive_transform,
 	.get_dfs_refer = smb2_get_dfs_refer,
 	.select_sectype = smb2_select_sectype,
+#ifdef CONFIG_CIFS_XATTR
+	.query_all_EAs = smb2_query_eas,
+#endif /* CIFS_XATTR */
 };
 #endif /* CIFS_SMB311 */
 

fs/cifs/smb2pdu.c

@@ -2145,6 +2145,18 @@ query_info(const unsigned int xid, struct cifs_tcon *tcon,
 	return rc;
 }
 
+int SMB2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+	u64 persistent_fid, u64 volatile_fid,
+	struct smb2_file_full_ea_info *data)
+{
+	return query_info(xid, tcon, persistent_fid, volatile_fid,
+			  FILE_FULL_EA_INFORMATION, SMB2_O_INFO_FILE, 0,
+			  SMB2_MAX_EA_BUF,
+			  sizeof(struct smb2_file_full_ea_info),
+			  (void **)&data,
+			  NULL);
+}
+
 int SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
 	u64 persistent_fid, u64 volatile_fid, struct smb2_file_all_info *data)
 {

fs/cifs/smb2pdu.h

@@ -1178,6 +1178,16 @@ struct smb2_file_link_info { /* encoding of request for level 11 */
 	char   FileName[0];     /* Name to be assigned to new link */
 } __packed; /* level 11 Set */
 
+#define SMB2_MAX_EA_BUF 2048
+
+struct smb2_file_full_ea_info { /* encoding of response for level 15 */
+	__le32 next_entry_offset;
+	__u8   flags;
+	__u8   ea_name_length;
+	__le16 ea_value_length;
+	char   ea_data[0]; /* \0 terminated name plus value */
+} __packed; /* level 15 Set */
+
 /*
  * This level 18, although with struct with same name is different from cifs
  * level 0x107. Level 0x107 has an extra u64 between AccessFlags and

fs/cifs/smb2proto.h

@@ -132,6 +132,9 @@ extern int SMB2_close(const unsigned int xid, struct cifs_tcon *tcon,
 		      u64 persistent_file_id, u64 volatile_file_id);
 extern int SMB2_flush(const unsigned int xid, struct cifs_tcon *tcon,
 		      u64 persistent_file_id, u64 volatile_file_id);
+extern int SMB2_query_eas(const unsigned int xid, struct cifs_tcon *tcon,
+			  u64 persistent_file_id, u64 volatile_file_id,
+			  struct smb2_file_full_ea_info *data);
 extern int SMB2_query_info(const unsigned int xid, struct cifs_tcon *tcon,
 			   u64 persistent_file_id, u64 volatile_file_id,
 			   struct smb2_file_all_info *data);