From: Rong Zhang <ulin0208@gmail.com>
Date: Wed, 7 May 2025 07:35:34 +0000 (+0800)
Subject: fs/ntfs3: correctly create symlink for relative path
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b1e9d89408f402858c00103f9831b25ffa0994d3;p=thirdparty%2Fkernel%2Fstable.git

fs/ntfs3: correctly create symlink for relative path

After applying this patch, could correctly create symlink:

ln -s "relative/path/to/file" symlink

Signed-off-by: Rong Zhang <ulin0208@gmail.com>
[almaz.alexandrovich@paragon-software.com: added cpu_to_le32 macro to
rs->Flags assignment]
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
---

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 0a653ee7fe089..8bfe354776544 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -1062,10 +1062,10 @@ int inode_read_data(struct inode *inode, void *data, size_t bytes)
  * Number of bytes for REPARSE_DATA_BUFFER(IO_REPARSE_TAG_SYMLINK)
  * for unicode string of @uni_len length.
  */
-static inline u32 ntfs_reparse_bytes(u32 uni_len)
+static inline u32 ntfs_reparse_bytes(u32 uni_len, bool is_absolute)
 {
 	/* Header + unicode string + decorated unicode string. */
-	return sizeof(short) * (2 * uni_len + 4) +
+	return sizeof(short) * (2 * uni_len + (is_absolute ? 4 : 0)) +
 	       offsetof(struct REPARSE_DATA_BUFFER,
 			SymbolicLinkReparseBuffer.PathBuffer);
 }
@@ -1078,8 +1078,11 @@ ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
 	struct REPARSE_DATA_BUFFER *rp;
 	__le16 *rp_name;
 	typeof(rp->SymbolicLinkReparseBuffer) *rs;
+	bool is_absolute;
 
-	rp = kzalloc(ntfs_reparse_bytes(2 * size + 2), GFP_NOFS);
+	is_absolute = (strlen(symname) > 1 && symname[1] == ':');
+
+	rp = kzalloc(ntfs_reparse_bytes(2 * size + 2, is_absolute), GFP_NOFS);
 	if (!rp)
 		return ERR_PTR(-ENOMEM);
 
@@ -1094,7 +1097,7 @@ ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
 		goto out;
 
 	/* err = the length of unicode name of symlink. */
-	*nsize = ntfs_reparse_bytes(err);
+	*nsize = ntfs_reparse_bytes(err, is_absolute);
 
 	if (*nsize > sbi->reparse.max_size) {
 		err = -EFBIG;
@@ -1114,7 +1117,7 @@ ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
 
 	/* PrintName + SubstituteName. */
 	rs->SubstituteNameOffset = cpu_to_le16(sizeof(short) * err);
-	rs->SubstituteNameLength = cpu_to_le16(sizeof(short) * err + 8);
+	rs->SubstituteNameLength = cpu_to_le16(sizeof(short) * err + (is_absolute ? 8 : 0));
 	rs->PrintNameLength = rs->SubstituteNameOffset;
 
 	/*
@@ -1122,16 +1125,18 @@ ntfs_create_reparse_buffer(struct ntfs_sb_info *sbi, const char *symname,
 	 * parse this path.
 	 * 0-absolute path 1- relative path (SYMLINK_FLAG_RELATIVE).
 	 */
-	rs->Flags = 0;
+	rs->Flags = cpu_to_le32(is_absolute ? 0 : SYMLINK_FLAG_RELATIVE);
 
-	memmove(rp_name + err + 4, rp_name, sizeof(short) * err);
+	memmove(rp_name + err + (is_absolute ? 4 : 0), rp_name, sizeof(short) * err);
 
-	/* Decorate SubstituteName. */
-	rp_name += err;
-	rp_name[0] = cpu_to_le16('\\');
-	rp_name[1] = cpu_to_le16('?');
-	rp_name[2] = cpu_to_le16('?');
-	rp_name[3] = cpu_to_le16('\\');
+	if (is_absolute) {
+		/* Decorate SubstituteName. */
+		rp_name += err;
+		rp_name[0] = cpu_to_le16('\\');
+		rp_name[1] = cpu_to_le16('?');
+		rp_name[2] = cpu_to_le16('?');
+		rp_name[3] = cpu_to_le16('\\');
+	}
 
 	return rp;
 out: