linux-kernel - [PATCH v3] erofs: fix file handle encoding for 64-bit NIDs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <20250429134257.690176-1-lihongbo22@huawei.com>
Date: Tue, 29 Apr 2025 13:42:57 +0000
From: Hongbo Li <lihongbo22@...wei.com>
To: <xiang@...nel.org>, <chao@...nel.org>, <zbestahu@...il.com>,
	<jefflexu@...ux.alibaba.com>
CC: <dhavale@...gle.com>, <linux-erofs@...ts.ozlabs.org>,
	<linux-kernel@...r.kernel.org>, <lihongbo22@...wei.com>
Subject: [PATCH v3] erofs: fix file handle encoding for 64-bit NIDs

In erofs, the inode number has the location information of
files. The default encode_fh uses the ino32, this will lack
of some information when the file is too big. So we need
the internal helpers to encode filehandle.

It is easy to reproduce test:
  1. prepare an erofs image with nid bigger than UINT_MAX
  2. mount -t erofs foo.img /mnt/erofs
  3. set exportfs with configuration: /mnt/erofs *(rw,sync,
     no_root_squash)
  4. mount -t nfs $IP:/mnt/erofs /mnt/nfs
  5. md5sum /mnt/nfs/foo # foo is the file which nid bigger
     than UINT_MAX.
For overlayfs case, the under filesystem's file handle is
encoded in ovl_fb.fid, it is same as NFS's case.

Fixes: 3e917cc305c6 ("erofs: make filesystem exportable")
Signed-off-by: Hongbo Li <lihongbo22@...wei.com>
---
v2: https://lore.kernel.org/all/20250429074109.689075-1-lihongbo22@huawei.com/
  - Assign parent nid with correct value.

v1: https://lore.kernel.org/all/20250429011139.686847-1-lihongbo22@huawei.com/
   - Encode generation into file handle and minor clean code.
   - Update the commiti's title.
---
 fs/erofs/super.c | 54 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 46 insertions(+), 8 deletions(-)

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index cadec6b1b554..28b3701165cc 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -511,24 +511,62 @@ static int erofs_fc_parse_param(struct fs_context *fc,
 	return 0;
 }
 
-static struct inode *erofs_nfs_get_inode(struct super_block *sb,
-					 u64 ino, u32 generation)
+static int erofs_encode_fh(struct inode *inode, u32 *fh, int *max_len,
+			   struct inode *parent)
 {
-	return erofs_iget(sb, ino);
+	int len = parent ? 6 : 3;
+	erofs_nid_t nid;
+	u32 generation;
+
+	if (*max_len < len) {
+		*max_len = len;
+		return FILEID_INVALID;
+	}
+
+	nid = EROFS_I(inode)->nid;
+	generation = inode->i_generation;
+	fh[0] = (u32)(nid >> 32);
+	fh[1] = (u32)(nid & 0xffffffff);
+	fh[2] = generation;
+
+	if (parent) {
+		nid = EROFS_I(parent)->nid;
+		generation = parent->i_generation;
+
+		fh[3] = (u32)(nid >> 32);
+		fh[4] = (u32)(nid & 0xffffffff);
+		fh[5] = generation;
+	}
+
+	*max_len = len;
+	return parent ? FILEID_INO64_GEN_PARENT : FILEID_INO64_GEN;
 }
 
 static struct dentry *erofs_fh_to_dentry(struct super_block *sb,
 		struct fid *fid, int fh_len, int fh_type)
 {
-	return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
-				    erofs_nfs_get_inode);
+	erofs_nid_t nid;
+
+	if ((fh_type != FILEID_INO64_GEN &&
+	     fh_type != FILEID_INO64_GEN_PARENT) || fh_len < 3)
+		return NULL;
+
+	nid = (u64) fid->raw[0] << 32;
+	nid |= (u64) fid->raw[1];
+	return d_obtain_alias(erofs_iget(sb, nid));
 }
 
 static struct dentry *erofs_fh_to_parent(struct super_block *sb,
 		struct fid *fid, int fh_len, int fh_type)
 {
-	return generic_fh_to_parent(sb, fid, fh_len, fh_type,
-				    erofs_nfs_get_inode);
+	erofs_nid_t nid;
+
+	if (fh_type != FILEID_INO64_GEN_PARENT || fh_len < 6)
+		return NULL;
+
+	nid = (u64) fid->raw[3] << 32;
+	nid |= (u64) fid->raw[4];
+	return d_obtain_alias(erofs_iget(sb, nid));
 }
 
 static struct dentry *erofs_get_parent(struct dentry *child)
@@ -544,7 +582,7 @@ static struct dentry *erofs_get_parent(struct dentry *child)
 }
 
 static const struct export_operations erofs_export_ops = {
-	.encode_fh = generic_encode_ino32_fh,
+	.encode_fh = erofs_encode_fh,
 	.fh_to_dentry = erofs_fh_to_dentry,
 	.fh_to_parent = erofs_fh_to_parent,
 	.get_parent = erofs_get_parent,
-- 
2.22.0