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/*
* (C) 2005 Andreas Gruenbacher <agruen@suse.de>
*
* This file is released under the GPL.
*
* Generic ACL support for in-memory filesystems.
*/

#include <linux/sched.h>
#include <linux/gfp.h>
#include <linux/fs.h>
#include <linux/generic_acl.h>
#include <linux/posix_acl.h>
#include <linux/posix_acl_xattr.h>


static size_t
generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
const char *name, size_t name_len, int type)
{
struct posix_acl *acl;
const char *xname;
size_t size;

acl = get_cached_acl(dentry->d_inode, type);
if (!acl)
return 0;
posix_acl_release(acl);

switch (type) {
case ACL_TYPE_ACCESS:
xname = POSIX_ACL_XATTR_ACCESS;
break;
case ACL_TYPE_DEFAULT:
xname = POSIX_ACL_XATTR_DEFAULT;
break;
default:
return 0;
}
size = strlen(xname) + 1;
if (list && size <= list_size)
memcpy(list, xname, size);
return size;
}

static int
generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
size_t size, int type)
{
struct posix_acl *acl;
int error;

if (strcmp(name, "") != 0)
return -EINVAL;

acl = get_cached_acl(dentry->d_inode, type);
if (!acl)
return -ENODATA;
error = posix_acl_to_xattr(acl, buffer, size);
posix_acl_release(acl);

return error;
}

static int
generic_acl_set(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags, int type)
{
struct inode *inode = dentry->d_inode;
struct posix_acl *acl = NULL;
int error;

if (strcmp(name, "") != 0)
return -EINVAL;
if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
if (!inode_owner_or_capable(inode))
return -EPERM;
if (value) {
acl = posix_acl_from_xattr(value, size);
if (IS_ERR(acl))
return PTR_ERR(acl);
}
if (acl) {
mode_t mode;

error = posix_acl_valid(acl);
if (error)
goto failed;
switch (type) {
case ACL_TYPE_ACCESS:
mode = inode->i_mode;
error = posix_acl_equiv_mode(acl, &mode);
if (error < 0)
goto failed;
inode->i_mode = mode;
inode->i_ctime = CURRENT_TIME;
if (error == 0) {
posix_acl_release(acl);
acl = NULL;
}
break;
case ACL_TYPE_DEFAULT:
if (!S_ISDIR(inode->i_mode)) {
error = -EINVAL;
goto failed;
}
break;
}
}
set_cached_acl(inode, type, acl);
error = 0;
failed:
posix_acl_release(acl);
return error;
}

/**
* generic_acl_init - Take care of acl inheritance at @inode create time
*
* Files created inside a directory with a default ACL inherit the
* directory's default ACL.
*/
int
generic_acl_init(struct inode *inode, struct inode *dir)
{
struct posix_acl *acl = NULL;
mode_t mode = inode->i_mode;
int error;

inode->i_mode = mode & ~current_umask();
if (!S_ISLNK(inode->i_mode))
acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
if (acl) {
struct posix_acl *clone;

if (S_ISDIR(inode->i_mode)) {
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto cleanup;
set_cached_acl(inode, ACL_TYPE_DEFAULT, clone);
posix_acl_release(clone);
}
clone = posix_acl_clone(acl, GFP_KERNEL);
error = -ENOMEM;
if (!clone)
goto cleanup;
error = posix_acl_create_masq(clone, &mode);
if (error >= 0) {
inode->i_mode = mode;
if (error > 0)
set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
}
posix_acl_release(clone);
}
error = 0;

cleanup:
posix_acl_release(acl);
return error;
}

/**
* generic_acl_chmod - change the access acl of @inode upon chmod()
*
* A chmod also changes the permissions of the owner, group/mask, and
* other ACL entries.
*/
int
generic_acl_chmod(struct inode *inode)
{
struct posix_acl *acl, *clone;
int error = 0;

if (S_ISLNK(inode->i_mode))
return -EOPNOTSUPP;
acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
if (acl) {
clone = posix_acl_clone(acl, GFP_KERNEL);
posix_acl_release(acl);
if (!clone)
return -ENOMEM;
error = posix_acl_chmod_masq(clone, inode->i_mode);
if (!error)
set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
posix_acl_release(clone);
}
return error;
}

int
generic_check_acl(struct inode *inode, int mask, unsigned int flags)
{
if (flags & IPERM_FLAG_RCU) {
if (!negative_cached_acl(inode, ACL_TYPE_ACCESS))
return -ECHILD;
} else {
struct posix_acl *acl;

acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
if (acl) {
int error = posix_acl_permission(inode, acl, mask);
posix_acl_release(acl);
return error;
}
}
return -EAGAIN;
}

const struct xattr_handler generic_acl_access_handler = {
.prefix = POSIX_ACL_XATTR_ACCESS,
.flags = ACL_TYPE_ACCESS,
.list = generic_acl_list,
.get = generic_acl_get,
.set = generic_acl_set,
};

const struct xattr_handler generic_acl_default_handler = {
.prefix = POSIX_ACL_XATTR_DEFAULT,
.flags = ACL_TYPE_DEFAULT,
.list = generic_acl_list,
.get = generic_acl_get,
.set = generic_acl_set,
};
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