linux-kernel - [PATCH 3.16 134/294] cifs: return ENAMETOOLONG for overlong names in cifs_open()/cifs

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

Date:   Mon, 06 Nov 2017 23:03:02 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Ronnie Sahlberg" <lsahlber@...hat.com>,
        "Steve French" <smfrench@...il.com>
Subject: [PATCH 3.16 134/294] cifs: return ENAMETOOLONG for overlong names
 in cifs_open()/cifs_lookup()

3.16.50-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ronnie Sahlberg <lsahlber@...hat.com>

commit d3edede29f74d335f81d95a4588f5f136a9f7dcf upstream.

Add checking for the path component length and verify it is <= the maximum
that the server advertizes via FileFsAttributeInformation.

With this patch cifs.ko will now return ENAMETOOLONG instead of ENOENT
when users to access an overlong path.

To test this, try to cd into a (non-existing) directory on a CIFS share
that has a too long name:
cd /mnt/aaaaaaaaaaaaaaa...

and it now should show a good error message from the shell:
bash: cd: /mnt/aaaaaaaaaaaaaaaa...aaaaaa: File name too long

rh bz 1153996

Signed-off-by: Ronnie Sahlberg <lsahlber@...hat.com>
Signed-off-by: Steve French <smfrench@...il.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/cifs/dir.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -183,15 +183,20 @@ cifs_bp_rename_retry:
 }
 
 /*
+ * Don't allow path components longer than the server max.
  * Don't allow the separator character in a path component.
  * The VFS will not allow "/", but "\" is allowed by posix.
  */
 static int
-check_name(struct dentry *direntry)
+check_name(struct dentry *direntry, struct cifs_tcon *tcon)
 {
 	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
 	int i;
 
+	if (unlikely(direntry->d_name.len >
+		     tcon->fsAttrInfo.MaxPathNameComponentLength))
+		return -ENAMETOOLONG;
+
 	if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS)) {
 		for (i = 0; i < direntry->d_name.len; i++) {
 			if (direntry->d_name.name[i] == '\\') {
@@ -489,10 +494,6 @@ cifs_atomic_open(struct inode *inode, st
 		return finish_no_open(file, res);
 	}
 
-	rc = check_name(direntry);
-	if (rc)
-		return rc;
-
 	xid = get_xid();
 
 	cifs_dbg(FYI, "parent inode = 0x%p name is: %s and dentry = 0x%p\n",
@@ -505,6 +506,11 @@ cifs_atomic_open(struct inode *inode, st
 	}
 
 	tcon = tlink_tcon(tlink);
+
+	rc = check_name(direntry, tcon);
+	if (rc)
+		goto out_free_xid;
+
 	server = tcon->ses->server;
 
 	if (server->ops->new_lease_key)
@@ -752,7 +758,7 @@ cifs_lookup(struct inode *parent_dir_ino
 	}
 	pTcon = tlink_tcon(tlink);
 
-	rc = check_name(direntry);
+	rc = check_name(direntry, pTcon);
 	if (rc)
 		goto lookup_out;