From: NeilBrown <neilb@suse.de>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: linux-fsdevel@vger.kernel.org, Dave Hansen <haveblue@us.ibm.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH 09/10] VFS: Remove read-only checks from dentry_permission
Date: Mon, 06 Sep 2010 10:50:29 +1000 [thread overview]
Message-ID: <20100906005029.20775.70918.stgit@localhost.localdomain> (raw)
In-Reply-To: <20100906004829.20775.68828.stgit@localhost.localdomain>
It is not sufficient to depend on the the "filesystem is readonly"
tests in dentry_permission as it does not check if the vfsmnt is
readonly.
All call sites already call mnt_want_write or __mnt_is_readonly which
includes the test on MS_RDONLY.
So remove this test from dentry_permission as it simply duplicates
tests done elsewhere.
This allows ovl_permission to be significantly simplified.
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NeilBrown <neilb@suse.de>
---
fs/namei.c | 15 +--------------
fs/overlayfs/overlayfs.c | 26 ++------------------------
2 files changed, 3 insertions(+), 38 deletions(-)
diff --git a/fs/namei.c b/fs/namei.c
index 6042564..291a839 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -254,22 +254,9 @@ int dentry_permission(struct dentry *dentry, int mask)
struct inode *inode = dentry->d_inode;
int retval;
- if (mask & MAY_WRITE) {
- umode_t mode = inode->i_mode;
-
- /*
- * Nobody gets write access to a read-only fs.
- */
- if (IS_RDONLY(inode) &&
- (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode)))
- return -EROFS;
-
- /*
- * Nobody gets write access to an immutable file.
- */
+ if (mask & MAY_WRITE)
if (IS_IMMUTABLE(inode))
return -EACCES;
- }
if (inode->i_op->permission)
retval = inode->i_op->permission(dentry, mask);
diff --git a/fs/overlayfs/overlayfs.c b/fs/overlayfs/overlayfs.c
index cdeafa7..749109a 100644
--- a/fs/overlayfs/overlayfs.c
+++ b/fs/overlayfs/overlayfs.c
@@ -1127,31 +1127,9 @@ static int ovl_dir_getattr(struct vfsmount *mnt, struct dentry *dentry,
static int ovl_permission(struct dentry *dentry, int mask)
{
struct ovl_entry *ue = dentry->d_fsdata;
- struct inode *inode;
- int err;
-
- if (ue->upperpath.dentry)
- return dentry_permission(ue->upperpath.dentry, mask);
-
- inode = ue->lowerpath.dentry->d_inode;
- if (!(mask & MAY_WRITE) || special_file(inode->i_mode))
- return dentry_permission(ue->lowerpath.dentry, mask);
-
- /* Don't check for read-only fs */
- if (mask & MAY_WRITE) {
- if (IS_IMMUTABLE(inode))
- return -EACCES;
- }
-
- if (inode->i_op->permission)
- err = inode->i_op->permission(ue->lowerpath.dentry, mask);
- else
- err = generic_permission(inode, mask, inode->i_op->check_acl);
-
- if (err)
- return err;
+ struct path *realpath = ovl_path(ue);
- return security_inode_permission(inode, mask);
+ return dentry_permission(realpath->dentry, mask);
}
static int ovl_create_object(struct dentry *dentry, int mode, dev_t rdev,
next prev parent reply other threads:[~2010-09-06 0:50 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-06 0:50 [PATCH 00/10] Assorted fixes/enhancements for overlayfs NeilBrown
2010-09-06 0:50 ` [PATCH 02/10] ovl: minimal remount support NeilBrown
2010-09-06 0:50 ` [PATCH 03/10] ovl: use correct seek function for directories NeilBrown
2010-09-06 0:50 ` [PATCH 01/10] ovl: small optimisation for ovl_lookup NeilBrown
2010-09-06 16:57 ` Miklos Szeredi
2010-09-06 0:50 ` [PATCH 08/10] VFS: tiny optimisation in open_other handling NeilBrown
2010-09-06 0:50 ` [PATCH 04/10] ovl: initialise is_real before use NeilBrown
2010-09-06 0:50 ` [PATCH 05/10] ovl: make sure fsync is never called on the lower filesystem NeilBrown
2010-09-06 17:16 ` Miklos Szeredi
2010-09-06 0:50 ` [PATCH 10/10] ovl: Assorted updates to Documentation/filesystems/overlayfs.txt NeilBrown
2010-09-06 0:50 ` [PATCH 07/10] ovl: add initial revalidate support NeilBrown
2010-09-16 14:47 ` Miklos Szeredi
2010-09-21 2:40 ` Neil Brown
2010-09-06 0:50 ` NeilBrown [this message]
2010-09-06 19:10 ` [PATCH 09/10] VFS: Remove read-only checks from dentry_permission Miklos Szeredi
2010-09-08 7:47 ` Neil Brown
2010-09-08 8:58 ` Miklos Szeredi
2010-09-07 15:58 ` Dave Hansen
2010-09-06 0:50 ` [PATCH 06/10] ovl: rename ovl_fill_cache to ovl_dir_read NeilBrown
2010-09-06 19:23 ` [PATCH 00/10] Assorted fixes/enhancements for overlayfs Miklos Szeredi
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