fs/bcachefs/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 mnt_idmap *idmap,
 216                                struct dentry *dentry, int type)
 217 {
 218         struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
 219         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 220         struct bch_hash_info hash = bch2_hash_info_init(c, &inode->ei_inode);
 221         struct btree_trans trans;
 222         struct btree_iter *iter;
 223         struct bkey_s_c_xattr xattr;
 224         struct posix_acl *acl = NULL;
 225
 226         bch2_trans_init(&trans, c, 0, 0);
 227 retry:
 228         bch2_trans_begin(&trans);
 229
 230         iter = bch2_hash_lookup(&trans, bch2_xattr_hash_desc,
 231                         &hash, inode->v.i_ino,
 232                         &X_SEARCH(acl_to_xattr_type(type), "", 0),
 233                         0);
 234         if (IS_ERR(iter)) {
 235                 if (PTR_ERR(iter) == -EINTR)
 236                         goto retry;
 237
 238                 if (PTR_ERR(iter) != -ENOENT)
 239                         acl = ERR_CAST(iter);
 240                 goto out;
 241         }
 242
 243         xattr = bkey_s_c_to_xattr(bch2_btree_iter_peek_slot(iter));
 244         acl = bch2_acl_from_disk(xattr_val(xattr.v),
 245                         le16_to_cpu(xattr.v->x_val_len));
 246
 247         if (!IS_ERR(acl))
 248                 set_cached_acl(&inode->v, type, acl);
 249         bch2_trans_iter_put(&trans, iter);
 250 out:
 251         bch2_trans_exit(&trans);
 252         return acl;
 253 }
 254
 255 int bch2_set_acl_trans(struct btree_trans *trans,
 256                        struct bch_inode_unpacked *inode_u,
 257                        const struct bch_hash_info *hash_info,
 258                        struct posix_acl *acl, int type)
 259 {
 260         int ret;
 261
 262         if (type == ACL_TYPE_DEFAULT &&
 263             !S_ISDIR(inode_u->bi_mode))
 264                 return acl ? -EACCES : 0;
 265
 266         if (acl) {
 267                 struct bkey_i_xattr *xattr =
 268                         bch2_acl_to_xattr(trans, acl, type);
 269                 if (IS_ERR(xattr))
 270                         return PTR_ERR(xattr);
 271
 272                 ret = bch2_hash_set(trans, bch2_xattr_hash_desc, hash_info,
 273                                     inode_u->bi_inum, &xattr->k_i, 0);
 274         } else {
 275                 struct xattr_search_key search =
 276                         X_SEARCH(acl_to_xattr_type(type), "", 0);
 277
 278                 ret = bch2_hash_delete(trans, bch2_xattr_hash_desc, hash_info,
 279                                        inode_u->bi_inum, &search);
 280         }
 281
 282         return ret == -ENOENT ? 0 : ret;
 283 }
 284
 285 int bch2_set_acl(struct mnt_idmap *idmap,
 286                  struct dentry *dentry,
 287                  struct posix_acl *_acl, int type)
 288 {
 289         struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
 290         struct bch_fs *c = inode->v.i_sb->s_fs_info;
 291         struct btree_trans trans;
 292         struct btree_iter *inode_iter;
 293         struct bch_inode_unpacked inode_u;
 294         struct bch_hash_info hash_info;
 295         struct posix_acl *acl;
 296         umode_t mode;
 297         int ret;
 298
 299         mutex_lock(&inode->ei_update_lock);
 300         bch2_trans_init(&trans, c, 0, 0);
 301 retry:
 302         bch2_trans_begin(&trans);
 303         acl = _acl;
 304
 305         inode_iter = bch2_inode_peek(&trans, &inode_u, inode->v.i_ino,
 306                                      BTREE_ITER_INTENT);
 307         ret = PTR_ERR_OR_ZERO(inode_iter);
 308         if (ret)
 309                 goto btree_err;
 310
 311         mode = inode_u.bi_mode;
 312
 313         if (type == ACL_TYPE_ACCESS) {
 314                 ret = posix_acl_update_mode(idmap, &inode->v, &mode, &acl);
 315                 if (ret)
 316                         goto btree_err;
 317         }
 318
 319         hash_info = bch2_hash_info_init(c, &inode_u);
 320
 321         ret = bch2_set_acl_trans(&trans, &inode_u, &hash_info, acl, type);
 322         if (ret)
 323                 goto btree_err;
 324
 325         inode_u.bi_ctime        = bch2_current_time(c);
 326         inode_u.bi_mode         = mode;
 327
 328         ret =   bch2_inode_write(&trans, inode_iter, &inode_u) ?:
 329                 bch2_trans_commit(&trans, NULL,
 330                                   &inode->ei_journal_seq,
 331                                   BTREE_INSERT_NOUNLOCK);
 332 btree_err:
 333         bch2_trans_iter_put(&trans, inode_iter);
 334
 335         if (ret == -EINTR)
 336                 goto retry;
 337         if (unlikely(ret))
 338                 goto err;
 339
 340         bch2_inode_update_after_write(c, inode, &inode_u,
 341                                       ATTR_CTIME|ATTR_MODE);
 342
 343         set_cached_acl(&inode->v, type, acl);
 344 err:
 345         bch2_trans_exit(&trans);
 346         mutex_unlock(&inode->ei_update_lock);
 347
 348         return ret;
 349 }
 350
 351 int bch2_acl_chmod(struct btree_trans *trans,
 352                    struct bch_inode_unpacked *inode,
 353                    umode_t mode,
 354                    struct posix_acl **new_acl)
 355 {
 356         struct bch_hash_info hash_info = bch2_hash_info_init(trans->c, inode);
 357         struct btree_iter *iter;
 358         struct bkey_s_c_xattr xattr;
 359         struct bkey_i_xattr *new;
 360         struct posix_acl *acl;
 361         int ret;
 362
 363         iter = bch2_hash_lookup(trans, bch2_xattr_hash_desc,
 364                         &hash_info, inode->bi_inum,
 365                         &X_SEARCH(KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS, "", 0),
 366                         BTREE_ITER_INTENT);
 367         ret = PTR_ERR_OR_ZERO(iter);
 368         if (ret)
 369                 return ret == -ENOENT ? 0 : ret;
 370
 371         xattr = bkey_s_c_to_xattr(bch2_btree_iter_peek_slot(iter));
 372         acl = bch2_acl_from_disk(xattr_val(xattr.v),
 373                         le16_to_cpu(xattr.v->x_val_len));
 374         ret = PTR_ERR_OR_ZERO(acl);
 375         if (ret || !acl)
 376                 goto err;
 377
 378         ret = __posix_acl_chmod(&acl, GFP_KERNEL, mode);
 379         if (ret)
 380                 goto err;
 381
 382         new = bch2_acl_to_xattr(trans, acl, ACL_TYPE_ACCESS);
 383         if (IS_ERR(new)) {
 384                 ret = PTR_ERR(new);
 385                 goto err;
 386         }
 387
 388         new->k.p = iter->pos;
 389         bch2_trans_update(trans, iter, &new->k_i, 0);
 390         *new_acl = acl;
 391         acl = NULL;
 392 err:
 393         bch2_trans_iter_put(trans, iter);
 394         kfree(acl);
 395         return ret;
 396 }
 397
 398 #endif /* CONFIG_BCACHEFS_POSIX_ACL */