linux-kernel - [PATCH 4/4] cifs: Fix querying of WSL CHR and BLK reparse points over SMB1

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Message-Id: <20241227173841.22949-4-pali@kernel.org>
Date: Fri, 27 Dec 2024 18:38:41 +0100
From: Pali Rohár <pali@...nel.org>
To: Steve French <sfrench@...ba.org>,
	Paulo Alcantara <pc@...guebit.com>
Cc: linux-cifs@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] cifs: Fix querying of WSL CHR and BLK reparse points over SMB1

When reparse point in SMB1 query_path_info() callback was detected then
query also for EA $LXDEV. In this EA are stored device major and minor
numbers used by WSL CHR and BLK reparse points. Without major and minor
numbers, stat() syscall does not work for char and block devices.

Similar code is already in SMB2+ query_path_info() callback function.

Signed-off-by: Pali Rohár <pali@...nel.org>
---
 fs/smb/client/smb1ops.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/fs/smb/client/smb1ops.c b/fs/smb/client/smb1ops.c
index 3af3f64b0cba..c52fc4c1557c 100644
--- a/fs/smb/client/smb1ops.c
+++ b/fs/smb/client/smb1ops.c
@@ -568,6 +568,42 @@ static int cifs_query_path_info(const unsigned int xid,
 		data->reparse_point = le32_to_cpu(fi.Attributes) & ATTR_REPARSE;
 	}
 
+#ifdef CONFIG_CIFS_XATTR
+	/*
+	 * For WSL CHR and BLK reparse points it is required to fetch
+	 * EA $LXDEV which contains major and minor device numbers.
+	 */
+	if (!rc && data->reparse_point) {
+		struct smb2_file_full_ea_info *ea;
+
+		ea = (struct smb2_file_full_ea_info *)data->wsl.eas;
+		rc = CIFSSMBQAllEAs(xid, tcon, full_path, SMB2_WSL_XATTR_DEV,
+				    &ea->ea_data[SMB2_WSL_XATTR_NAME_LEN + 1],
+				    SMB2_WSL_XATTR_DEV_SIZE, cifs_sb);
+		if (rc == SMB2_WSL_XATTR_DEV_SIZE) {
+			ea->next_entry_offset = cpu_to_le32(0);
+			ea->flags = 0;
+			ea->ea_name_length = SMB2_WSL_XATTR_NAME_LEN;
+			ea->ea_value_length = cpu_to_le16(SMB2_WSL_XATTR_DEV_SIZE);
+			memcpy(&ea->ea_data[0], SMB2_WSL_XATTR_DEV, SMB2_WSL_XATTR_NAME_LEN + 1);
+			data->wsl.eas_len = sizeof(*ea) + SMB2_WSL_XATTR_NAME_LEN + 1 +
+					    SMB2_WSL_XATTR_DEV_SIZE;
+			rc = 0;
+		} else if (rc >= 0) {
+			/* It is an error if EA $LXDEV has wrong size. */
+			rc = -EINVAL;
+		} else {
+			/*
+			 * In all other cases ignore error if fetching
+			 * of EA $LXDEV failed. It is needed only for
+			 * WSL CHR and BLK reparse points and wsl_to_fattr()
+			 * handle the case when EA is missing.
+			 */
+			rc = 0;
+		}
+	}
+#endif
+
 	return rc;
 }
 
-- 
2.20.1