1/*
  2 * (C) 2005 Andreas Gruenbacher <agruen@suse.de>
  3 *
  4 * This file is released under the GPL.
  5 *
  6 * Generic ACL support for in-memory filesystems.
  7 */
  8
  9#include <linux/sched.h>
 10#include <linux/gfp.h>
 11#include <linux/fs.h>
 12#include <linux/generic_acl.h>
 13#include <linux/posix_acl.h>
 14#include <linux/posix_acl_xattr.h>
 15
 16
 17static size_t
 18generic_acl_list(struct dentry *dentry, char *list, size_t list_size,
 19		const char *name, size_t name_len, int type)
 20{
 21	struct posix_acl *acl;
 22	const char *xname;
 23	size_t size;
 24
 25	acl = get_cached_acl(dentry->d_inode, type);
 26	if (!acl)
 27		return 0;
 28	posix_acl_release(acl);
 29
 30	switch (type) {
 31	case ACL_TYPE_ACCESS:
 32		xname = POSIX_ACL_XATTR_ACCESS;
 33		break;
 34	case ACL_TYPE_DEFAULT:
 35		xname = POSIX_ACL_XATTR_DEFAULT;
 36		break;
 37	default:
 38		return 0;
 39	}
 40	size = strlen(xname) + 1;
 41	if (list && size <= list_size)
 42		memcpy(list, xname, size);
 43	return size;
 44}
 45
 46static int
 47generic_acl_get(struct dentry *dentry, const char *name, void *buffer,
 48		     size_t size, int type)
 49{
 50	struct posix_acl *acl;
 51	int error;
 52
 53	if (strcmp(name, "") != 0)
 54		return -EINVAL;
 55
 56	acl = get_cached_acl(dentry->d_inode, type);
 57	if (!acl)
 58		return -ENODATA;
 59	error = posix_acl_to_xattr(acl, buffer, size);
 60	posix_acl_release(acl);
 61
 62	return error;
 63}
 64
 65static int
 66generic_acl_set(struct dentry *dentry, const char *name, const void *value,
 67		     size_t size, int flags, int type)
 68{
 69	struct inode *inode = dentry->d_inode;
 70	struct posix_acl *acl = NULL;
 71	int error;
 72
 73	if (strcmp(name, "") != 0)
 74		return -EINVAL;
 75	if (S_ISLNK(inode->i_mode))
 76		return -EOPNOTSUPP;
 77	if (!inode_owner_or_capable(inode))
 78		return -EPERM;
 79	if (value) {
 80		acl = posix_acl_from_xattr(value, size);
 81		if (IS_ERR(acl))
 82			return PTR_ERR(acl);
 83	}
 84	if (acl) {
 85		error = posix_acl_valid(acl);
 86		if (error)
 87			goto failed;
 88		switch (type) {
 89		case ACL_TYPE_ACCESS:
 90			error = posix_acl_equiv_mode(acl, &inode->i_mode);
 91			if (error < 0)
 92				goto failed;
 93			inode->i_ctime = CURRENT_TIME;
 94			if (error == 0) {
 95				posix_acl_release(acl);
 96				acl = NULL;
 97			}
 98			break;
 99		case ACL_TYPE_DEFAULT:
100			if (!S_ISDIR(inode->i_mode)) {
101				error = -EINVAL;
102				goto failed;
103			}
104			break;
105		}
106	}
107	set_cached_acl(inode, type, acl);
108	error = 0;
109failed:
110	posix_acl_release(acl);
111	return error;
112}
113
114/**
115 * generic_acl_init  -  Take care of acl inheritance at @inode create time
116 *
117 * Files created inside a directory with a default ACL inherit the
118 * directory's default ACL.
119 */
120int
121generic_acl_init(struct inode *inode, struct inode *dir)
122{
123	struct posix_acl *acl = NULL;
124	int error;
125
126	if (!S_ISLNK(inode->i_mode))
127		acl = get_cached_acl(dir, ACL_TYPE_DEFAULT);
128	if (acl) {
129		if (S_ISDIR(inode->i_mode))
130			set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
131		error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);
132		if (error < 0)
133			return error;
134		if (error > 0)
135			set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
136	} else {
137		inode->i_mode &= ~current_umask();
138	}
139	error = 0;
140
141	posix_acl_release(acl);
142	return error;
143}
144
145/**
146 * generic_acl_chmod  -  change the access acl of @inode upon chmod()
147 *
148 * A chmod also changes the permissions of the owner, group/mask, and
149 * other ACL entries.
150 */
151int
152generic_acl_chmod(struct inode *inode)
153{
154	struct posix_acl *acl;
155	int error = 0;
156
157	if (S_ISLNK(inode->i_mode))
158		return -EOPNOTSUPP;
159	acl = get_cached_acl(inode, ACL_TYPE_ACCESS);
160	if (acl) {
161		error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
162		if (error)
163			return error;
164		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
165		posix_acl_release(acl);
166	}
167	return error;
168}
169
170const struct xattr_handler generic_acl_access_handler = {
171	.prefix = POSIX_ACL_XATTR_ACCESS,
172	.flags	= ACL_TYPE_ACCESS,
173	.list	= generic_acl_list,
174	.get	= generic_acl_get,
175	.set	= generic_acl_set,
176};
177
178const struct xattr_handler generic_acl_default_handler = {
179	.prefix = POSIX_ACL_XATTR_DEFAULT,
180	.flags	= ACL_TYPE_DEFAULT,
181	.list	= generic_acl_list,
182	.get	= generic_acl_get,
183	.set	= generic_acl_set,
184};