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Subject[patch 10/14] vfs: pass flags to dentry_permission()
From: Miklos Szeredi <mszeredi@suse.cz>

Switch last argument of dentry_permission() from nameidata to flags.

This requires the MNT_NOEXEC checking to be moved from
dentry_permission() to vfs_permission().

The following dentry_permission() callers passed a non-NULL nameidata:

vfs_permission()

This remained almost equivalent, except that ordering of the
MNT_NOEXEC check and the IS_RDONLY/IS_IMMUTABLE checks has been
changed. However the IS_RDONLY check should never trigger, because
of the per-mount read-only checking. The IS_IMMUTABLE check returns
the same error value (-EACCES) as the MNT_NOEXEC check, so this
change is not visible.

lookup_hash()

Make it call vfs_permission().

may_create()

This does not always have the nameidata available, but it operates
on a directory, so the MNT_NOEXEC check would never have triggered
anyway.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/ecryptfs/inode.c | 3 +--
fs/namei.c | 49 +++++++++++++++++++++++++------------------------
fs/nfsd/nfsfh.c | 2 +-
fs/nfsd/vfs.c | 5 ++---
fs/xattr.c | 2 +-
include/linux/fs.h | 2 +-
ipc/mqueue.c | 2 +-
7 files changed, 32 insertions(+), 33 deletions(-)
Index: linux-2.6/fs/ecryptfs/inode.c
===================================================================
--- linux-2.6.orig/fs/ecryptfs/inode.c 2008-05-21 16:38:28.000000000 +0200
+++ linux-2.6/fs/ecryptfs/inode.c 2008-05-21 17:44:30.000000000 +0200
@@ -811,9 +811,8 @@ static int
ecryptfs_permission(struct dentry *dentry, int mask, int flags)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
- struct nameidata nd = { .flags = flags };

- return dentry_permission(lower_dentry, mask, &nd);
+ return dentry_permission(lower_dentry, mask, flags);
}

/**
Index: linux-2.6/fs/namei.c
===================================================================
--- linux-2.6.orig/fs/namei.c 2008-05-21 17:33:07.000000000 +0200
+++ linux-2.6/fs/namei.c 2008-05-21 17:55:13.000000000 +0200
@@ -226,14 +226,10 @@ int generic_permission(struct inode *ino
return -EACCES;
}

-int dentry_permission(struct dentry *dentry, int mask, struct nameidata *nd)
+int dentry_permission(struct dentry *dentry, int mask, int flags)
{
struct inode *inode = dentry->d_inode;
int retval, submask;
- struct vfsmount *mnt = NULL;
-
- if (nd)
- mnt = nd->path.mnt;

if (mask & MAY_WRITE) {
umode_t mode = inode->i_mode;
@@ -252,20 +248,10 @@ int dentry_permission(struct dentry *den
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 (mnt && (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) {
- retval = inode->i_op->permission(dentry, submask,
- nd ? nd->flags : 0);
+ retval = inode->i_op->permission(dentry, submask, flags);
if (!retval) {
/*
* Exec permission on a regular file is denied if none
@@ -288,7 +274,7 @@ int dentry_permission(struct dentry *den
if (retval)
return retval;

- return security_inode_permission(inode, mask, nd ? nd->flags : 0);
+ return security_inode_permission(inode, mask, flags);
}

/**
@@ -303,7 +289,21 @@ int dentry_permission(struct dentry *den
*/
int vfs_permission(struct nameidata *nd, int mask)
{
- return dentry_permission(nd->path.dentry, mask, nd);
+ struct dentry *dentry = nd->path.dentry;
+ struct inode *inode = dentry->d_inode;
+
+ if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
+ struct vfsmount *mnt = nd->path.mnt;
+
+ /*
+ * MAY_EXEC on regular files is denied if the fs is mounted
+ * with the "noexec" flag.
+ */
+ if (mnt->mnt_flags & MNT_NOEXEC)
+ return -EACCES;
+ }
+
+ return dentry_permission(dentry, mask, nd->flags);
}

/**
@@ -320,7 +320,7 @@ int vfs_permission(struct nameidata *nd,
*/
int file_permission(struct file *file, int mask)
{
- return dentry_permission(file->f_path.dentry, mask, NULL);
+ return dentry_permission(file->f_path.dentry, mask, 0);
}

/*
@@ -1343,7 +1343,7 @@ static struct dentry *lookup_hash(struct
{
int err;

- err = dentry_permission(nd->path.dentry, MAY_EXEC, nd);
+ err = vfs_permission(nd, MAY_EXEC);
if (err)
return ERR_PTR(err);
return __lookup_hash(&nd->last, nd->path.dentry, nd);
@@ -1391,7 +1391,7 @@ struct dentry *lookup_one_len(const char
if (err)
return ERR_PTR(err);

- err = dentry_permission(base, MAY_EXEC, NULL);
+ err = dentry_permission(base, MAY_EXEC, 0);
if (err)
return ERR_PTR(err);
return __lookup_hash(&this, base, NULL);
@@ -1483,7 +1483,7 @@ static int may_delete(struct dentry *dir
BUG_ON(victim->d_parent->d_inode != dir);
audit_inode_child(victim->d_name.name, victim, dir);

- error = dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC, NULL);
+ error = dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC, 0);
if (error)
return error;
if (IS_APPEND(dir))
@@ -1520,7 +1520,8 @@ static inline int may_create(struct dent
return -EEXIST;
if (IS_DEADDIR(dir_dentry->d_inode))
return -ENOENT;
- return dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC, nd);
+ return dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC,
+ nd ? nd->flags : 0);
}

/*
@@ -2682,7 +2683,7 @@ static int vfs_rename_dir(struct inode *
* we'll need to flip '..'.
*/
if (new_dir != old_dir) {
- error = dentry_permission(old_dentry, MAY_WRITE, NULL);
+ error = dentry_permission(old_dentry, MAY_WRITE, 0);
if (error)
return error;
}
Index: linux-2.6/fs/nfsd/nfsfh.c
===================================================================
--- linux-2.6.orig/fs/nfsd/nfsfh.c 2008-05-21 16:36:07.000000000 +0200
+++ linux-2.6/fs/nfsd/nfsfh.c 2008-05-21 17:44:30.000000000 +0200
@@ -51,7 +51,7 @@ static int nfsd_acceptable(void *expv, s
/* make sure parents give x permission to user */
int err;
parent = dget_parent(tdentry);
- err = dentry_permission(parent, MAY_EXEC, NULL);
+ err = dentry_permission(parent, MAY_EXEC, 0);
if (err < 0) {
dput(parent);
break;
Index: linux-2.6/fs/nfsd/vfs.c
===================================================================
--- linux-2.6.orig/fs/nfsd/vfs.c 2008-05-21 16:36:07.000000000 +0200
+++ linux-2.6/fs/nfsd/vfs.c 2008-05-21 17:44:30.000000000 +0200
@@ -1942,13 +1942,12 @@ nfsd_permission(struct svc_rqst *rqstp,
inode->i_uid == current->fsuid)
return 0;

- err = dentry_permission(dentry, acc & (MAY_READ|MAY_WRITE|MAY_EXEC),
- NULL);
+ err = dentry_permission(dentry, acc & (MAY_READ|MAY_WRITE|MAY_EXEC), 0);

/* Allow read access to binaries even when mode 111 */
if (err == -EACCES && S_ISREG(inode->i_mode) &&
acc == (MAY_READ | MAY_OWNER_OVERRIDE))
- err = dentry_permission(dentry, MAY_EXEC, NULL);
+ err = dentry_permission(dentry, MAY_EXEC, 0);

return err? nfserrno(err) : 0;
}
Index: linux-2.6/fs/xattr.c
===================================================================
--- linux-2.6.orig/fs/xattr.c 2008-05-21 16:36:07.000000000 +0200
+++ linux-2.6/fs/xattr.c 2008-05-21 17:44:30.000000000 +0200
@@ -65,7 +65,7 @@ xattr_permission(struct dentry *dentry,
return -EPERM;
}

- return dentry_permission(dentry, mask, NULL);
+ return dentry_permission(dentry, mask, 0);
}

static int
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h 2008-05-21 16:38:28.000000000 +0200
+++ linux-2.6/include/linux/fs.h 2008-05-21 17:44:30.000000000 +0200
@@ -1758,7 +1758,7 @@ extern sector_t bmap(struct inode *, sec
#endif
extern int notify_change(struct dentry *, struct iattr *);
extern int path_setattr(struct path *, struct iattr *);
-extern int dentry_permission(struct dentry *, int, struct nameidata *);
+extern int dentry_permission(struct dentry *, int, int);
extern int generic_permission(struct inode *, int,
int (*check_acl)(struct inode *, int));

Index: linux-2.6/ipc/mqueue.c
===================================================================
--- linux-2.6.orig/ipc/mqueue.c 2008-05-21 16:36:07.000000000 +0200
+++ linux-2.6/ipc/mqueue.c 2008-05-21 17:44:30.000000000 +0200
@@ -653,7 +653,7 @@ static int oflag2acc[O_ACCMODE] = { MAY_
return ERR_PTR(-EINVAL);
}

- if (dentry_permission(dentry, oflag2acc[oflag & O_ACCMODE], NULL)) {
+ if (dentry_permission(dentry, oflag2acc[oflag & O_ACCMODE], 0)) {
dput(dentry);
mntput(mqueue_mnt);
return ERR_PTR(-EACCES);
--


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