[PATCH AUTOSEL 6.13 28/32] cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()

[PATCH AUTOSEL 6.13 28/32] cifs: Throw -EOPNOTSUPP error on unsupported reparse point type from parse_reparse_point()

[Sasha Levin]

From: Pali Rohár <pali@kernel.org>

[ Upstream commit cad3fc0a4c8cef07b07ceddc137f582267577250 ]

This would help to track and detect by caller if the reparse point type was
processed or not.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/reparse.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/smb/client/reparse.c b/fs/smb/client/reparse.c
index b387dfbaf16b0..a93127c94aff9 100644
--- a/fs/smb/client/reparse.c
+++ b/fs/smb/client/reparse.c
@@ -724,13 +724,12 @@ int parse_reparse_point(struct reparse_data_buffer *buf,
 				 le32_to_cpu(buf->ReparseTag));
 			return -EIO;
 		}
-		break;
+		return 0;
 	default:
 		cifs_tcon_dbg(VFS | ONCE, "unhandled reparse tag: 0x%08x\n",
 			      le32_to_cpu(buf->ReparseTag));
-		break;
+		return -EOPNOTSUPP;
 	}
-	return 0;
 }
 
 int smb2_parse_reparse_point(struct cifs_sb_info *cifs_sb,
-- 
2.39.5

[PATCH AUTOSEL 6.13 29/32] cifs: Treat unhandled directory name surrogate reparse points as mount directory nodes

[Sasha Levin]

From: Pali Rohár <pali@kernel.org>

[ Upstream commit b587fd128660d48cd2122f870f720ff8e2b4abb3 ]

If the reparse point was not handled (indicated by the -EOPNOTSUPP from
ops->parse_reparse_point() call) but reparse tag is of type name surrogate
directory type, then treat is as a new mount point.

Name surrogate reparse point represents another named entity in the system.

From SMB client point of view, this another entity is resolved on the SMB
server, and server serves its content automatically. Therefore from Linux
client point of view, this name surrogate reparse point of directory type
crosses mount point.

Signed-off-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/client/inode.c    | 13 +++++++++++++
 fs/smb/common/smbfsctl.h |  3 +++
 2 files changed, 16 insertions(+)

diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index f146e06c97eb6..564f113bf739d 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -1215,6 +1215,19 @@ static int reparse_info_to_fattr(struct cifs_open_info_data *data,
 			rc = server->ops->parse_reparse_point(cifs_sb,
 							      full_path,
 							      iov, data);
+			/*
+			 * If the reparse point was not handled but it is the
+			 * name surrogate which points to directory, then treat
+			 * is as a new mount point. Name surrogate reparse point
+			 * represents another named entity in the system.
+			 */
+			if (rc == -EOPNOTSUPP &&
+			    IS_REPARSE_TAG_NAME_SURROGATE(data->reparse.tag) &&
+			    (le32_to_cpu(data->fi.Attributes) & ATTR_DIRECTORY)) {
+				rc = 0;
+				cifs_create_junction_fattr(fattr, sb);
+				goto out;
+			}
 		}
 		break;
 	}
diff --git a/fs/smb/common/smbfsctl.h b/fs/smb/common/smbfsctl.h
index 4b379e84c46b9..3253a18ecb5cb 100644
--- a/fs/smb/common/smbfsctl.h
+++ b/fs/smb/common/smbfsctl.h
@@ -159,6 +159,9 @@
 #define IO_REPARSE_TAG_LX_CHR	     0x80000025
 #define IO_REPARSE_TAG_LX_BLK	     0x80000026
 
+/* If Name Surrogate Bit is set, the file or directory represents another named entity in the system. */
+#define IS_REPARSE_TAG_NAME_SURROGATE(tag) (!!((tag) & 0x20000000))
+
 /* fsctl flags */
 /* If Flags is set to this value, the request is an FSCTL not ioctl request */
 #define SMB2_0_IOCTL_IS_FSCTL		0x00000001
-- 
2.39.5