From: miklos@szeredi.hu
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>
Subject: [patch 3/9] fix execute checking in permission()
Date: Thu, 09 Aug 2007 11:20:49 +0200 [thread overview]
Message-ID: <20070809092459.676107488@szeredi.hu> (raw)
In-Reply-To: <20070809092046.656183199@szeredi.hu>
[-- Attachment #1: permission_exec_fix.patch --]
[-- Type: text/plain, Size: 2515 bytes --]
From: Miklos Szeredi <mszeredi@suse.cz>
permission() checks that MAY_EXEC is only allowed on regular files if
at least one execute bit is set in the file mode.
generic_permission() already ensures this, so the extra check in
permission() is superfluous.
If the filesystem defines it's own ->permission() the check may still
be needed. In this case move it after ->permission(). This is needed
because filesystems such as FUSE may need to refresh the inode
attributes before checking permissions.
This check should be moved inside ->permission(), but that's another
story.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
Index: linux/fs/namei.c
===================================================================
--- linux.orig/fs/namei.c 2007-08-09 11:01:55.000000000 +0200
+++ linux/fs/namei.c 2007-08-09 11:04:22.000000000 +0200
@@ -227,10 +227,10 @@ int generic_permission(struct inode *ino
int permission(struct inode *inode, int mask, struct nameidata *nd)
{
- umode_t mode = inode->i_mode;
int retval, submask;
if (mask & MAY_WRITE) {
+ umode_t mode = inode->i_mode;
/*
* Nobody gets write access to a read-only fs.
@@ -246,22 +246,34 @@ int permission(struct inode *inode, int
return -EACCES;
}
-
- /*
- * MAY_EXEC on regular files requires special handling: We override
- * filesystem execute permissions if the mode bits aren't set or
- * the fs is mounted with the "noexec" flag.
- */
- if ((mask & MAY_EXEC) && S_ISREG(mode) && (!(mode & S_IXUGO) ||
- (nd && nd->mnt && (nd->mnt->mnt_flags & MNT_NOEXEC))))
- return -EACCES;
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
+ /*
+ * MAY_EXEC on regular files is denied if the fs is mounted
+ * with the "noexec" flag.
+ */
+ if (nd && nd->mnt && (nd->mnt->mnt_flags & MNT_NOEXEC))
+ return -EACCES;
+ }
/* Ordinary permission routines do not understand MAY_APPEND. */
submask = mask & ~MAY_APPEND;
- if (inode->i_op && inode->i_op->permission)
+ if (inode->i_op && inode->i_op->permission) {
retval = inode->i_op->permission(inode, submask, nd);
- else
+ if (!retval) {
+ /*
+ * Exec permission on a regular file is denied if none
+ * of the execute bits are set.
+ *
+ * This check should be done by the ->permission()
+ * method.
+ */
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode) &&
+ !(inode->i_mode & S_IXUGO))
+ return -EACCES;
+ }
+ } else {
retval = generic_permission(inode, submask, NULL);
+ }
if (retval)
return retval;
--
next prev parent reply other threads:[~2007-08-09 9:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 9:20 [patch 0/9] assorted fixes and cleanups miklos
2007-08-09 9:20 ` [patch 1/9] unprivileged mounts: fix subtype handling miklos
2007-08-09 9:20 ` [patch 2/9] VFS: check nanoseconds in utimensat miklos
2007-08-09 9:20 ` miklos [this message]
2007-08-09 9:20 ` [patch 4/9] exec: remove unnecessary check for MNT_NOEXEC miklos
2007-08-09 9:20 ` [patch 5/9] fuse: fix setting i_mode bits miklos
2007-08-09 9:20 ` [patch 6/9] fuse: clean up execute permission checking miklos
2007-08-09 9:20 ` [patch 7/9] clean out unused code in dentry pruning miklos
2007-08-09 9:20 ` [patch 8/9] UML: remove unnecessary hostfs_getattr() miklos
2007-08-09 9:20 ` [patch 9/9] fix warnings is revoked_inode.c miklos
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070809092459.676107488@szeredi.hu \
--to=miklos@szeredi.hu \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®