linux/fs/gfs2/acl.c
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   1/*
   2 * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3 * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
   4 *
   5 * This copyrighted material is made available to anyone wishing to use,
   6 * modify, copy, or redistribute it subject to the terms and conditions
   7 * of the GNU General Public License version 2.
   8 */
   9
  10#include <linux/sched.h>
  11#include <linux/slab.h>
  12#include <linux/spinlock.h>
  13#include <linux/completion.h>
  14#include <linux/buffer_head.h>
  15#include <linux/xattr.h>
  16#include <linux/posix_acl.h>
  17#include <linux/posix_acl_xattr.h>
  18#include <linux/gfs2_ondisk.h>
  19
  20#include "gfs2.h"
  21#include "incore.h"
  22#include "acl.h"
  23#include "xattr.h"
  24#include "glock.h"
  25#include "inode.h"
  26#include "meta_io.h"
  27#include "trans.h"
  28#include "util.h"
  29
  30static const char *gfs2_acl_name(int type)
  31{
  32        switch (type) {
  33        case ACL_TYPE_ACCESS:
  34                return GFS2_POSIX_ACL_ACCESS;
  35        case ACL_TYPE_DEFAULT:
  36                return GFS2_POSIX_ACL_DEFAULT;
  37        }
  38        return NULL;
  39}
  40
  41struct posix_acl *gfs2_get_acl(struct inode *inode, int type)
  42{
  43        struct gfs2_inode *ip = GFS2_I(inode);
  44        struct posix_acl *acl;
  45        const char *name;
  46        char *data;
  47        int len;
  48
  49        if (!ip->i_eattr)
  50                return NULL;
  51
  52        acl = get_cached_acl(&ip->i_inode, type);
  53        if (acl != ACL_NOT_CACHED)
  54                return acl;
  55
  56        name = gfs2_acl_name(type);
  57        if (name == NULL)
  58                return ERR_PTR(-EINVAL);
  59
  60        len = gfs2_xattr_acl_get(ip, name, &data);
  61        if (len < 0)
  62                return ERR_PTR(len);
  63        if (len == 0)
  64                return NULL;
  65
  66        acl = posix_acl_from_xattr(&init_user_ns, data, len);
  67        kfree(data);
  68        return acl;
  69}
  70
  71static int gfs2_set_mode(struct inode *inode, umode_t mode)
  72{
  73        int error = 0;
  74
  75        if (mode != inode->i_mode) {
  76                inode->i_mode = mode;
  77                mark_inode_dirty(inode);
  78        }
  79
  80        return error;
  81}
  82
  83static int gfs2_acl_set(struct inode *inode, int type, struct posix_acl *acl)
  84{
  85        int error;
  86        int len;
  87        char *data;
  88        const char *name = gfs2_acl_name(type);
  89
  90        BUG_ON(name == NULL);
  91        len = posix_acl_to_xattr(&init_user_ns, acl, NULL, 0);
  92        if (len == 0)
  93                return 0;
  94        data = kmalloc(len, GFP_NOFS);
  95        if (data == NULL)
  96                return -ENOMEM;
  97        error = posix_acl_to_xattr(&init_user_ns, acl, data, len);
  98        if (error < 0)
  99                goto out;
 100        error = __gfs2_xattr_set(inode, name, data, len, 0, GFS2_EATYPE_SYS);
 101        if (!error)
 102                set_cached_acl(inode, type, acl);
 103out:
 104        kfree(data);
 105        return error;
 106}
 107
 108int gfs2_acl_create(struct gfs2_inode *dip, struct inode *inode)
 109{
 110        struct gfs2_sbd *sdp = GFS2_SB(&dip->i_inode);
 111        struct posix_acl *acl;
 112        umode_t mode = inode->i_mode;
 113        int error = 0;
 114
 115        if (!sdp->sd_args.ar_posix_acl)
 116                return 0;
 117        if (S_ISLNK(inode->i_mode))
 118                return 0;
 119
 120        acl = gfs2_get_acl(&dip->i_inode, ACL_TYPE_DEFAULT);
 121        if (IS_ERR(acl))
 122                return PTR_ERR(acl);
 123        if (!acl) {
 124                mode &= ~current_umask();
 125                return gfs2_set_mode(inode, mode);
 126        }
 127
 128        if (S_ISDIR(inode->i_mode)) {
 129                error = gfs2_acl_set(inode, ACL_TYPE_DEFAULT, acl);
 130                if (error)
 131                        goto out;
 132        }
 133
 134        error = posix_acl_create(&acl, GFP_NOFS, &mode);
 135        if (error < 0)
 136                return error;
 137
 138        if (error == 0)
 139                goto munge;
 140
 141        error = gfs2_acl_set(inode, ACL_TYPE_ACCESS, acl);
 142        if (error)
 143                goto out;
 144munge:
 145        error = gfs2_set_mode(inode, mode);
 146out:
 147        posix_acl_release(acl);
 148        return error;
 149}
 150
 151int gfs2_acl_chmod(struct gfs2_inode *ip, struct iattr *attr)
 152{
 153        struct inode *inode = &ip->i_inode;
 154        struct posix_acl *acl;
 155        char *data;
 156        unsigned int len;
 157        int error;
 158
 159        acl = gfs2_get_acl(&ip->i_inode, ACL_TYPE_ACCESS);
 160        if (IS_ERR(acl))
 161                return PTR_ERR(acl);
 162        if (!acl)
 163                return gfs2_setattr_simple(inode, attr);
 164
 165        error = posix_acl_chmod(&acl, GFP_NOFS, attr->ia_mode);
 166        if (error)
 167                return error;
 168
 169        len = posix_acl_to_xattr(&init_user_ns, acl, NULL, 0);
 170        data = kmalloc(len, GFP_NOFS);
 171        error = -ENOMEM;
 172        if (data == NULL)
 173                goto out;
 174        posix_acl_to_xattr(&init_user_ns, acl, data, len);
 175        error = gfs2_xattr_acl_chmod(ip, attr, data);
 176        kfree(data);
 177        set_cached_acl(&ip->i_inode, ACL_TYPE_ACCESS, acl);
 178
 179out:
 180        posix_acl_release(acl);
 181        return error;
 182}
 183
 184static int gfs2_acl_type(const char *name)
 185{
 186        if (strcmp(name, GFS2_POSIX_ACL_ACCESS) == 0)
 187                return ACL_TYPE_ACCESS;
 188        if (strcmp(name, GFS2_POSIX_ACL_DEFAULT) == 0)
 189                return ACL_TYPE_DEFAULT;
 190        return -EINVAL;
 191}
 192
 193static int gfs2_xattr_system_get(struct dentry *dentry, const char *name,
 194                                 void *buffer, size_t size, int xtype)
 195{
 196        struct inode *inode = dentry->d_inode;
 197        struct gfs2_sbd *sdp = GFS2_SB(inode);
 198        struct posix_acl *acl;
 199        int type;
 200        int error;
 201
 202        if (!sdp->sd_args.ar_posix_acl)
 203                return -EOPNOTSUPP;
 204
 205        type = gfs2_acl_type(name);
 206        if (type < 0)
 207                return type;
 208
 209        acl = gfs2_get_acl(inode, type);
 210        if (IS_ERR(acl))
 211                return PTR_ERR(acl);
 212        if (acl == NULL)
 213                return -ENODATA;
 214
 215        error = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);
 216        posix_acl_release(acl);
 217
 218        return error;
 219}
 220
 221static int gfs2_xattr_system_set(struct dentry *dentry, const char *name,
 222                                 const void *value, size_t size, int flags,
 223                                 int xtype)
 224{
 225        struct inode *inode = dentry->d_inode;
 226        struct gfs2_sbd *sdp = GFS2_SB(inode);
 227        struct posix_acl *acl = NULL;
 228        int error = 0, type;
 229
 230        if (!sdp->sd_args.ar_posix_acl)
 231                return -EOPNOTSUPP;
 232
 233        type = gfs2_acl_type(name);
 234        if (type < 0)
 235                return type;
 236        if (flags & XATTR_CREATE)
 237                return -EINVAL;
 238        if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
 239                return value ? -EACCES : 0;
 240        if (!uid_eq(current_fsuid(), inode->i_uid) && !capable(CAP_FOWNER))
 241                return -EPERM;
 242        if (S_ISLNK(inode->i_mode))
 243                return -EOPNOTSUPP;
 244
 245        if (!value)
 246                goto set_acl;
 247
 248        acl = posix_acl_from_xattr(&init_user_ns, value, size);
 249        if (!acl) {
 250                /*
 251                 * acl_set_file(3) may request that we set default ACLs with
 252                 * zero length -- defend (gracefully) against that here.
 253                 */
 254                goto out;
 255        }
 256        if (IS_ERR(acl)) {
 257                error = PTR_ERR(acl);
 258                goto out;
 259        }
 260
 261        error = posix_acl_valid(acl);
 262        if (error)
 263                goto out_release;
 264
 265        error = -EINVAL;
 266        if (acl->a_count > GFS2_ACL_MAX_ENTRIES)
 267                goto out_release;
 268
 269        if (type == ACL_TYPE_ACCESS) {
 270                umode_t mode = inode->i_mode;
 271                error = posix_acl_equiv_mode(acl, &mode);
 272
 273                if (error <= 0) {
 274                        posix_acl_release(acl);
 275                        acl = NULL;
 276
 277                        if (error < 0)
 278                                return error;
 279                }
 280
 281                error = gfs2_set_mode(inode, mode);
 282                if (error)
 283                        goto out_release;
 284        }
 285
 286set_acl:
 287        error = __gfs2_xattr_set(inode, name, value, size, 0, GFS2_EATYPE_SYS);
 288        if (!error) {
 289                if (acl)
 290                        set_cached_acl(inode, type, acl);
 291                else
 292                        forget_cached_acl(inode, type);
 293        }
 294out_release:
 295        posix_acl_release(acl);
 296out:
 297        return error;
 298}
 299
 300const struct xattr_handler gfs2_xattr_system_handler = {
 301        .prefix = XATTR_SYSTEM_PREFIX,
 302        .flags  = GFS2_EATYPE_SYS,
 303        .get    = gfs2_xattr_system_get,
 304        .set    = gfs2_xattr_system_set,
 305};
 306
 307
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