linux-kernel - [PATCH 07/46] jfs: dont overwrite dentry name in d

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:	Sat, 27 Nov 2010 20:44:37 +1100
From:	Nick Piggin <npiggin@...nel.dk>
To:	linux-fsdevel@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH 07/46] jfs: dont overwrite dentry name in d_revalidate

Use vfat's method for dealing with negative dentries to preserve case,
rather than overwrite dentry name in d_revalidate, which is a bit ugly
and also gets in the way of doing lock-free path walking.

Signed-off-by: Nick Piggin <npiggin@...nel.dk>
---
 fs/jfs/namei.c |   43 +++++++++++++++++++++++++++++++++++--------
 1 files changed, 35 insertions(+), 8 deletions(-)

diff --git a/fs/jfs/namei.c b/fs/jfs/namei.c
index 231ca4a..2da1546 100644
--- a/fs/jfs/namei.c
+++ b/fs/jfs/namei.c
@@ -18,6 +18,7 @@
  */
 
 #include <linux/fs.h>
+#include <linux/namei.h>
 #include <linux/ctype.h>
 #include <linux/quotaops.h>
 #include <linux/exportfs.h>
@@ -1597,21 +1598,47 @@ static int jfs_ci_compare(struct dentry *dir, struct qstr *a, struct qstr *b)
 			goto out;
 	}
 	result = 0;
+out:
+	return result;
+}
 
+static int jfs_ci_revalidate(struct dentry *dentry, struct nameidata *nd)
+{
 	/*
-	 * We want creates to preserve case.  A negative dentry, a, that
-	 * has a different case than b may cause a new entry to be created
-	 * with the wrong case.  Since we can't tell if a comes from a negative
-	 * dentry, we blindly replace it with b.  This should be harmless if
-	 * a is not a negative dentry.
+	 * This is not negative dentry. Always valid.
+	 *
+	 * Note, rename() to existing directory entry will have ->d_inode,
+	 * and will use existing name which isn't specified name by user.
+	 *
+	 * We may be able to drop this positive dentry here. But dropping
+	 * positive dentry isn't good idea. So it's unsupported like
+	 * rename("filename", "FILENAME") for now.
 	 */
-	memcpy((unsigned char *)a->name, b->name, a->len);
-out:
-	return result;
+	if (dentry->d_inode)
+		return 1;
+
+	/*
+	 * This may be nfsd (or something), anyway, we can't see the
+	 * intent of this. So, since this can be for creation, drop it.
+	 */
+	if (!nd)
+		return 0;
+
+	/*
+	 * Drop the negative dentry, in order to make sure to use the
+	 * case sensitive name which is specified by user if this is
+	 * for creation.
+	 */
+	if (!(nd->flags & (LOOKUP_CONTINUE | LOOKUP_PARENT))) {
+		if (nd->flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
+			return 0;
+	}
+	return 1;
 }
 
 const struct dentry_operations jfs_ci_dentry_operations =
 {
 	.d_hash = jfs_ci_hash,
 	.d_compare = jfs_ci_compare,
+	.d_revalidate = jfs_ci_revalidate,
 };
-- 
1.7.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/