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Subject[patch 14/14] vfs: path_permission() clean up flags
From: Miklos Szeredi <mszeredi@suse.cz>

Currently callers of path_permission() either pass zero or
nameidata->flags as the flags argument. Passing lookup flags to
filesystems is completely unecessary, only the "intent" flags are
interesting.

More specifically nfs uses LOOKUP_ACCESS and LOOKUP_OPEN flags, while
fuse uses LOOKUP_ACCESS and LOOKUP_CHDIR flags.

So clean up path_permission() calls to just pass these flags.

In case of LOOKUP_CHDIR and LOOKUP_ACCESS the lookup routines need not
be passed these flags at all, they are only needed for the permission
checks.

Also remove the nameidata argument of may_create(). NFS doesn't need
LOOKUP_OPEN in this case, since it handles the creation checks on the
parent directory specially anyway.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
---
fs/exec.c | 4 ++--
fs/inotify_user.c | 2 +-
fs/namei.c | 25 +++++++++++--------------
fs/open.c | 15 +++++++--------
fs/utimes.c | 2 +-
net/unix/af_unix.c | 2 +-
6 files changed, 23 insertions(+), 27 deletions(-)

Index: linux-2.6/fs/exec.c
===================================================================
--- linux-2.6.orig/fs/exec.c 2008-05-21 18:15:02.000000000 +0200
+++ linux-2.6/fs/exec.c 2008-05-21 18:30:34.000000000 +0200
@@ -116,7 +116,7 @@ asmlinkage long sys_uselib(const char __
if (!S_ISREG(nd.path.dentry->d_inode->i_mode))
goto exit;

- error = path_permission(&nd.path, MAY_READ | MAY_EXEC, nd.flags);
+ error = path_permission(&nd.path, MAY_READ | MAY_EXEC, 0);
if (error)
goto exit;

@@ -664,7 +664,7 @@ struct file *open_exec(const char *name)
struct inode *inode = nd.path.dentry->d_inode;
file = ERR_PTR(-EACCES);
if (S_ISREG(inode->i_mode)) {
- int err = path_permission(&nd.path, MAY_EXEC, nd.flags);
+ int err = path_permission(&nd.path, MAY_EXEC, 0);
file = ERR_PTR(err);
if (!err) {
file = nameidata_to_filp(&nd,
Index: linux-2.6/fs/inotify_user.c
===================================================================
--- linux-2.6.orig/fs/inotify_user.c 2008-05-21 18:15:02.000000000 +0200
+++ linux-2.6/fs/inotify_user.c 2008-05-21 18:30:34.000000000 +0200
@@ -365,7 +365,7 @@ static int find_inode(const char __user
if (error)
return error;
/* you can only watch an inode if you have read permissions on it */
- error = path_permission(&nd->path, MAY_READ, nd->flags);
+ error = path_permission(&nd->path, MAY_READ, 0);
if (error)
path_put(&nd->path);
return error;
Index: linux-2.6/fs/namei.c
===================================================================
--- linux-2.6.orig/fs/namei.c 2008-05-21 18:17:08.000000000 +0200
+++ linux-2.6/fs/namei.c 2008-05-21 18:36:27.000000000 +0200
@@ -899,7 +899,7 @@ static int __link_path_walk(const char *
nd->flags |= LOOKUP_CONTINUE;
err = exec_permission_lite(inode, nd);
if (err == -EAGAIN)
- err = path_permission(&nd->path, MAY_EXEC, nd->flags);
+ err = path_permission(&nd->path, MAY_EXEC, 0);
if (err)
break;

@@ -1180,7 +1180,6 @@ static int do_path_lookup(int dfd, const

nd->path = file->f_path;
path_get(&file->f_path);
-
fput_light(file, fput_needed);
}

@@ -1347,7 +1346,7 @@ static struct dentry *lookup_hash(struct
{
int err;

- err = path_permission(&nd->path, MAY_EXEC, nd->flags);
+ err = path_permission(&nd->path, MAY_EXEC, 0);
if (err)
return ERR_PTR(err);
return __lookup_hash(&nd->last, nd->path.dentry, nd);
@@ -1517,15 +1516,13 @@ static int may_delete(struct dentry *dir
* 3. We should have write and exec permissions on dir
* 4. We can't do it if dir is immutable (done in permission())
*/
-static inline int may_create(struct dentry *dir_dentry, struct dentry *child,
- struct nameidata *nd)
+static inline int may_create(struct dentry *dir_dentry, struct dentry *child)
{
if (child->d_inode)
return -EEXIST;
if (IS_DEADDIR(dir_dentry->d_inode))
return -ENOENT;
- return dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC,
- nd ? nd->flags : 0);
+ return dentry_permission(dir_dentry, MAY_WRITE | MAY_EXEC, 0);
}

/*
@@ -1592,7 +1589,7 @@ static int vfs_create(struct dentry *dir
int mode, struct nameidata *nd)
{
struct inode *dir = dir_dentry->d_inode;
- int error = may_create(dir_dentry, dentry, nd);
+ int error = may_create(dir_dentry, dentry);

if (error)
return error;
@@ -1654,7 +1651,7 @@ int may_open(struct nameidata *nd, int a
flag &= ~O_TRUNC;
}

- error = path_permission(&nd->path, acc_mode, nd->flags);
+ error = path_permission(&nd->path, acc_mode, nd->flags & LOOKUP_OPEN);
if (error)
return error;
/*
@@ -2048,7 +2045,7 @@ static int vfs_mknod(struct dentry *dir_
int mode, dev_t dev)
{
struct inode *dir = dir_dentry->d_inode;
- int error = may_create(dir_dentry, dentry, NULL);
+ int error = may_create(dir_dentry, dentry);

if (error)
return error;
@@ -2146,7 +2143,7 @@ asmlinkage long sys_mknod(const char __u
static int vfs_mkdir(struct dentry *dir_dentry, struct dentry *dentry, int mode)
{
struct inode *dir = dir_dentry->d_inode;
- int error = may_create(dir_dentry, dentry, NULL);
+ int error = may_create(dir_dentry, dentry);

if (error)
return error;
@@ -2456,7 +2453,7 @@ static int vfs_symlink(struct dentry *di
const char *oldname)
{
struct inode *dir = dir_dentry->d_inode;
- int error = may_create(dir_dentry, dentry, NULL);
+ int error = may_create(dir_dentry, dentry);

if (error)
return error;
@@ -2541,7 +2538,7 @@ static int vfs_link(struct dentry *old_d
if (!inode)
return -ENOENT;

- error = may_create(new_dir_dentry, new_dentry, NULL);
+ error = may_create(new_dir_dentry, new_dentry);
if (error)
return error;

@@ -2764,7 +2761,7 @@ static int vfs_rename(struct dentry *old
return error;

if (!new_dentry->d_inode)
- error = may_create(new_dir_dentry, new_dentry, NULL);
+ error = may_create(new_dir_dentry, new_dentry);
else
error = may_delete(new_dir_dentry, new_dentry, is_dir);
if (error)
Index: linux-2.6/fs/open.c
===================================================================
--- linux-2.6.orig/fs/open.c 2008-05-21 18:15:02.000000000 +0200
+++ linux-2.6/fs/open.c 2008-05-21 18:30:34.000000000 +0200
@@ -267,7 +267,7 @@ static long do_sys_truncate(const char _
if (error)
goto dput_and_out;

- error = path_permission(&nd.path, MAY_WRITE, nd.flags);
+ error = path_permission(&nd.path, MAY_WRITE, 0);
if (error)
goto mnt_drop_write_and_out;

@@ -467,11 +467,11 @@ asmlinkage long sys_faccessat(int dfd, c
else
current->cap_effective = current->cap_permitted;

- res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
+ res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
if (res)
goto out;

- res = path_permission(&nd.path, mode, nd.flags);
+ res = path_permission(&nd.path, mode, LOOKUP_ACCESS);
/* SuS v2 requires we report a read only fs too */
if(res || !(mode & S_IWOTH) ||
special_file(nd.path.dentry->d_inode->i_mode))
@@ -509,12 +509,11 @@ asmlinkage long sys_chdir(const char __u
struct nameidata nd;
int error;

- error = __user_walk(filename,
- LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
+ error = __user_walk(filename, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, &nd);
if (error)
goto out;

- error = path_permission(&nd.path, MAY_EXEC, nd.flags);
+ error = path_permission(&nd.path, MAY_EXEC, LOOKUP_CHDIR);
if (error)
goto dput_and_out;

@@ -543,7 +542,7 @@ asmlinkage long sys_fchdir(unsigned int
if (!S_ISDIR(inode->i_mode))
goto out_putf;

- error = file_permission(file, MAY_EXEC);
+ error = path_permission(&file->f_path, MAY_EXEC, LOOKUP_CHDIR);
if (!error)
set_fs_pwd(current->fs, &file->f_path);
out_putf:
@@ -561,7 +560,7 @@ asmlinkage long sys_chroot(const char __
if (error)
goto out;

- error = path_permission(&nd.path, MAY_EXEC, nd.flags);
+ error = path_permission(&nd.path, MAY_EXEC, 0);
if (error)
goto dput_and_out;

Index: linux-2.6/net/unix/af_unix.c
===================================================================
--- linux-2.6.orig/net/unix/af_unix.c 2008-05-21 18:15:02.000000000 +0200
+++ linux-2.6/net/unix/af_unix.c 2008-05-21 18:30:34.000000000 +0200
@@ -713,7 +713,7 @@ static struct sock *unix_find_other(stru
err = path_lookup(sunname->sun_path, LOOKUP_FOLLOW, &nd);
if (err)
goto fail;
- err = path_permission(&nd.path, MAY_WRITE, nd.flags);
+ err = path_permission(&nd.path, MAY_WRITE, 0);
if (err)
goto put_fail;

Index: linux-2.6/fs/utimes.c
===================================================================
--- linux-2.6.orig/fs/utimes.c 2008-05-21 18:15:02.000000000 +0200
+++ linux-2.6/fs/utimes.c 2008-05-21 18:30:34.000000000 +0200
@@ -141,7 +141,7 @@ static int do_utimes_name(int dfd, char
goto out_path_put;

if (!is_owner_or_cap(inode)) {
- error = path_permission(&nd.path, MAY_WRITE, nd.flags);
+ error = path_permission(&nd.path, MAY_WRITE, 0);
if (error)
goto out_path_put;
}
--


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