git.sesse.net Git - bcachefs-tools-debian/blob - libbcachefs/acl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #ifdef CONFIG_BCACHEFS_POSIX_ACL
   3
   4 #include "bcachefs.h"
   5
   6 #include <linux/fs.h>
   7 #include <linux/posix_acl.h>
   8 #include <linux/posix_acl_xattr.h>
   9 #include <linux/sched.h>
  10 #include <linux/slab.h>
  11
  12 #include "acl.h"
  13 #include "fs.h"
  14 #include "xattr.h"
  15
  16 static inline size_t bch2_acl_size(unsigned nr_short, unsigned nr_long)
  17 {
  18         return sizeof(bch_acl_header) +
  19                 sizeof(bch_acl_entry_short) * nr_short +
  20                 sizeof(bch_acl_entry) * nr_long;
  21 }
  22
  23 static inline int acl_to_xattr_type(int type)
  24 {
  25         switch (type) {
  26         case ACL_TYPE_ACCESS:
  27                 return KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS;
  28         case ACL_TYPE_DEFAULT:
  29                 return KEY_TYPE_XATTR_INDEX_POSIX_ACL_DEFAULT;
  30         default:
  31                 BUG();
  32         }
  33 }
  34
  35 /*
  36  * Convert from filesystem to in-memory representation.
  37  */
  38 static struct posix_acl *bch2_acl_from_disk(const void *value, size_t size)
  39 {
  40         const void *p, *end = value + size;
  41         struct posix_acl *acl;
  42         struct posix_acl_entry *out;
  43         unsigned count = 0;
  44
  45         if (!value)
  46                 return NULL;
  47         if (size < sizeof(bch_acl_header))
  48                 goto invalid;
  49         if (((bch_acl_header *)value)->a_version !=
  50             cpu_to_le32(BCH_ACL_VERSION))
  51                 goto invalid;
  52
  53         p = value + sizeof(bch_acl_header);
  54         while (p < end) {
  55                 const bch_acl_entry *entry = p;
  56
  57                 if (p + sizeof(bch_acl_entry_short) > end)
  58                         goto invalid;
  59
  60                 switch (le16_to_cpu(entry->e_tag)) {
  61                 case ACL_USER_OBJ:
  62                 case ACL_GROUP_OBJ:
  63                 case ACL_MASK:
  64                 case ACL_OTHER:
  65                         p += sizeof(bch_acl_entry_short);
  66                         break;
  67                 case ACL_USER:
  68                 case ACL_GROUP:
  69                         p += sizeof(bch_acl_entry);
  70                         break;
  71                 default:
  72                         goto invalid;
  73                 }
  74
  75                 count++;
  76         }
  77
  78         if (p > end)
  79                 goto invalid;
  80
  81         if (!count)
  82                 return NULL;
  83
  84         acl = posix_acl_alloc(count, GFP_KERNEL);
  85         if (!acl)
  86                 return ERR_PTR(-ENOMEM);
  87
  88         out = acl->a_entries;
  89
  90         p = value + sizeof(bch_acl_header);
  91         while (p < end) {
  92                 const bch_acl_entry *in = p;
  93
  94                 out->e_tag  = le16_to_cpu(in->e_tag);
  95                 out->e_perm = le16_to_cpu(in->e_perm);
  96
  97                 switch (out->e_tag) {
  98                 case ACL_USER_OBJ:
  99                 case ACL_GROUP_OBJ:
 100                 case ACL_MASK:
 101                 case ACL_OTHER:
 102                         p += sizeof(bch_acl_entry_short);
 103                         break;
 104                 case ACL_USER:
 105                         out->e_uid = make_kuid(&init_user_ns,
 106                                                le32_to_cpu(in->e_id));
 107                         p += sizeof(bch_acl_entry);
 108                         break;
 109                 case ACL_GROUP:
 110                         out->e_gid = make_kgid(&init_user_ns,
 111                                                le32_to_cpu(in->e_id));
 112                         p += sizeof(bch_acl_entry);
 113                         break;
 114                 }
 115
 116                 out++;
 117         }
 118
 119         BUG_ON(out != acl->a_entries + acl->a_count);
 120
 121         return acl;
 122 invalid:
 123         pr_err("invalid acl entry");
 124         return ERR_PTR(-EINVAL);
 125 }
 126
 127 #define acl_for_each_entry(acl, acl_e)                  \
 128         for (acl_e = acl->a_entries;                    \
 129              acl_e < acl->a_entries + acl->a_count;     \
 130              acl_e++)
 131
 132 /*
 133  * Convert from in-memory to filesystem representation.
 134  */
 135 static struct bkey_i_xattr *
 136 bch2_acl_to_xattr(struct btree_trans *trans,
 137                   const struct posix_acl *acl,
 138                   int type)
 139 {
 140         struct bkey_i_xattr *xattr;
 141         bch_acl_header *acl_header;
 142         const struct posix_acl_entry *acl_e;
 143         void *outptr;
 144         unsigned nr_short = 0, nr_long = 0, acl_len, u64s;
 145
 146         acl_for_each_entry(acl, acl_e) {
 147                 switch (acl_e->e_tag) {
 148                 case ACL_USER:
 149                 case ACL_GROUP:
 150                         nr_long++;
 151                         break;
 152                 case ACL_USER_OBJ:
 153                 case ACL_GROUP_OBJ:
 154                 case ACL_MASK:
 155                 case ACL_OTHER:
 156                         nr_short++;
 157                         break;
 158                 default:
 159                         return ERR_PTR(-EINVAL);
 160                 }
 161         }
 162
 163         acl_len = bch2_acl_size(nr_short, nr_long);
 164         u64s = BKEY_U64s + xattr_val_u64s(0, acl_len);
 165
 166         if (u64s > U8_MAX)
 167                 return ERR_PTR(-E2BIG);
 168
 169         xattr = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
 170         if (IS_ERR(xattr))
 171                 return xattr;
 172
 173         bkey_xattr_init(&xattr->k_i);
 174         xattr->k.u64s           = u64s;
 175         xattr->v.x_type         = acl_to_xattr_type(type);
 176         xattr->v.x_name_len     = 0;
 177         xattr->v.x_val_len      = cpu_to_le16(acl_len);
 178
 179         acl_header = xattr_val(&xattr->v);
 180         acl_header->a_version = cpu_to_le32(BCH_ACL_VERSION);
 181
 182         outptr = (void *) acl_header + sizeof(*acl_header);
 183
 184         acl_for_each_entry(acl, acl_e) {
 185                 bch_acl_entry *entry = outptr;
 186
 187                 entry->e_tag = cpu_to_le16(acl_e->e_tag);
 188                 entry->e_perm = cpu_to_le16(acl_e->e_perm);
 189                 switch (acl_e->e_tag) {
 190                 case ACL_USER:
 191                         entry->e_id = cpu_to_le32(
 192                                 from_kuid(&init_user_ns, acl_e->e_uid));
 193                         outptr += sizeof(bch_acl_entry);
 194                         break;
 195                 case ACL_GROUP:
 196                         entry->e_id = cpu_to_le32(
 197                                 from_kgid(&init_user_ns, acl_e->e_gid));
 198                         outptr += sizeof(bch_acl_entry);
 199                         break;
 200
 201                 case ACL_USER_OBJ:
 202                 case ACL_GROUP_OBJ:
 203                 case ACL_MASK:
 204                 case ACL_OTHER:
 205                         outptr += sizeof(bch_acl_entry_short);
 206                         break;
 207                 }
 208         }
 209
 210         BUG_ON(outptr != xattr_val(&xattr->v) + acl_len);
 211
 212         return xattr;
 213 }
 214
 215 struct posix_acl *bch2_get_acl(struct inode *vinode, int type, bool rcu)
 216 {
 217         struct bch_inode_info *inode = to_bch_ei(vinode);
 218         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 219         struct bch_hash_info hash = bch2_hash_info_init(c, &inode->ei_inode);
 220         struct btree_trans trans;
 221         struct btree_iter iter = { NULL };
 222         struct bkey_s_c_xattr xattr;
 223         struct posix_acl *acl = NULL;
 224         struct bkey_s_c k;
 225         int ret;
 226
 227         if (rcu)
 228                 return ERR_PTR(-ECHILD);
 229
 230         bch2_trans_init(&trans, c, 0, 0);
 231 retry:
 232         bch2_trans_begin(&trans);
 233
 234         ret = bch2_hash_lookup(&trans, &iter, bch2_xattr_hash_desc,
 235                         &hash, inode_inum(inode),
 236                         &X_SEARCH(acl_to_xattr_type(type), "", 0),
 237                         0);
 238         if (ret) {
 239                 if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 240                         goto retry;
 241                 if (ret != -ENOENT)
 242                         acl = ERR_PTR(ret);
 243                 goto out;
 244         }
 245
 246         k = bch2_btree_iter_peek_slot(&iter);
 247         ret = bkey_err(k);
 248         if (ret) {
 249                 acl = ERR_PTR(ret);
 250                 goto out;
 251         }
 252
 253         xattr = bkey_s_c_to_xattr(k);
 254         acl = bch2_acl_from_disk(xattr_val(xattr.v),
 255                         le16_to_cpu(xattr.v->x_val_len));
 256
 257         if (!IS_ERR(acl))
 258                 set_cached_acl(&inode->v, type, acl);
 259 out:
 260         bch2_trans_iter_exit(&trans, &iter);
 261         bch2_trans_exit(&trans);
 262         return acl;
 263 }
 264
 265 int bch2_set_acl_trans(struct btree_trans *trans, subvol_inum inum,
 266                        struct bch_inode_unpacked *inode_u,
 267                        struct posix_acl *acl, int type)
 268 {
 269         struct bch_hash_info hash_info = bch2_hash_info_init(trans->c, inode_u);
 270         int ret;
 271
 272         if (type == ACL_TYPE_DEFAULT &&
 273             !S_ISDIR(inode_u->bi_mode))
 274                 return acl ? -EACCES : 0;
 275
 276         if (acl) {
 277                 struct bkey_i_xattr *xattr =
 278                         bch2_acl_to_xattr(trans, acl, type);
 279                 if (IS_ERR(xattr))
 280                         return PTR_ERR(xattr);
 281
 282                 ret = bch2_hash_set(trans, bch2_xattr_hash_desc, &hash_info,
 283                                     inum, &xattr->k_i, 0);
 284         } else {
 285                 struct xattr_search_key search =
 286                         X_SEARCH(acl_to_xattr_type(type), "", 0);
 287
 288                 ret = bch2_hash_delete(trans, bch2_xattr_hash_desc, &hash_info,
 289                                        inum, &search);
 290         }
 291
 292         return ret == -ENOENT ? 0 : ret;
 293 }
 294
 295 int bch2_set_acl(struct user_namespace *mnt_userns,
 296                  struct inode *vinode, struct posix_acl *_acl, int type)
 297 {
 298         struct bch_inode_info *inode = to_bch_ei(vinode);
 299         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 300         struct btree_trans trans;
 301         struct btree_iter inode_iter = { NULL };
 302         struct bch_inode_unpacked inode_u;
 303         struct posix_acl *acl;
 304         umode_t mode;
 305         int ret;
 306
 307         mutex_lock(&inode->ei_update_lock);
 308         bch2_trans_init(&trans, c, 0, 0);
 309 retry:
 310         bch2_trans_begin(&trans);
 311         acl = _acl;
 312
 313         ret = bch2_inode_peek(&trans, &inode_iter, &inode_u, inode_inum(inode),
 314                               BTREE_ITER_INTENT);
 315         if (ret)
 316                 goto btree_err;
 317
 318         mode = inode_u.bi_mode;
 319
 320         if (type == ACL_TYPE_ACCESS) {
 321                 ret = posix_acl_update_mode(mnt_userns, &inode->v, &mode, &acl);
 322                 if (ret)
 323                         goto btree_err;
 324         }
 325
 326         ret = bch2_set_acl_trans(&trans, inode_inum(inode), &inode_u, acl, type);
 327         if (ret)
 328                 goto btree_err;
 329
 330         inode_u.bi_ctime        = bch2_current_time(c);
 331         inode_u.bi_mode         = mode;
 332
 333         ret =   bch2_inode_write(&trans, &inode_iter, &inode_u) ?:
 334                 bch2_trans_commit(&trans, NULL, NULL, 0);
 335 btree_err:
 336         bch2_trans_iter_exit(&trans, &inode_iter);
 337
 338         if (bch2_err_matches(ret, BCH_ERR_transaction_restart))
 339                 goto retry;
 340         if (unlikely(ret))
 341                 goto err;
 342
 343         bch2_inode_update_after_write(&trans, inode, &inode_u,
 344                                       ATTR_CTIME|ATTR_MODE);
 345
 346         set_cached_acl(&inode->v, type, acl);
 347 err:
 348         bch2_trans_exit(&trans);
 349         mutex_unlock(&inode->ei_update_lock);
 350
 351         return ret;
 352 }
 353
 354 int bch2_acl_chmod(struct btree_trans *trans, subvol_inum inum,
 355                    struct bch_inode_unpacked *inode,
 356                    umode_t mode,
 357                    struct posix_acl **new_acl)
 358 {
 359         struct bch_hash_info hash_info = bch2_hash_info_init(trans->c, inode);
 360         struct btree_iter iter;
 361         struct bkey_s_c_xattr xattr;
 362         struct bkey_i_xattr *new;
 363         struct posix_acl *acl;
 364         struct bkey_s_c k;
 365         int ret;
 366
 367         ret = bch2_hash_lookup(trans, &iter, bch2_xattr_hash_desc,
 368                                &hash_info, inum,
 369                         &X_SEARCH(KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS, "", 0),
 370                         BTREE_ITER_INTENT);
 371         if (ret)
 372                 return ret == -ENOENT ? 0 : ret;
 373
 374         k = bch2_btree_iter_peek_slot(&iter);
 375         xattr = bkey_s_c_to_xattr(k);
 376         if (ret)
 377                 goto err;
 378
 379         acl = bch2_acl_from_disk(xattr_val(xattr.v),
 380                         le16_to_cpu(xattr.v->x_val_len));
 381         ret = PTR_ERR_OR_ZERO(acl);
 382         if (IS_ERR_OR_NULL(acl))
 383                 goto err;
 384
 385         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 386         if (ret)
 387                 goto err;
 388
 389         new = bch2_acl_to_xattr(trans, acl, ACL_TYPE_ACCESS);
 390         if (IS_ERR(new)) {
 391                 ret = PTR_ERR(new);
 392                 goto err;
 393         }
 394
 395         new->k.p = iter.pos;
 396         ret = bch2_trans_update(trans, &iter, &new->k_i, 0);
 397         *new_acl = acl;
 398         acl = NULL;
 399 err:
 400         bch2_trans_iter_exit(trans, &iter);
 401         if (!IS_ERR_OR_NULL(acl))
 402                 kfree(acl);
 403         return ret;
 404 }
 405
 406 #endif /* CONFIG_BCACHEFS_POSIX_ACL */