fs/nfs_common/nfsacl.c

   1 /*
   2  * fs/nfs_common/nfsacl.c
   3  *
   4  *  Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
   5  */
   6
   7 /*
   8  * The Solaris nfsacl protocol represents some ACLs slightly differently
   9  * than POSIX 1003.1e draft 17 does (and we do):
  10  *
  11  *  - Minimal ACLs always have an ACL_MASK entry, so they have
  12  *    four instead of three entries.
  13  *  - The ACL_MASK entry in such minimal ACLs always has the same
  14  *    permissions as the ACL_GROUP_OBJ entry. (In extended ACLs
  15  *    the ACL_MASK and ACL_GROUP_OBJ entries may differ.)
  16  *  - The identifier fields of the ACL_USER_OBJ and ACL_GROUP_OBJ
  17  *    entries contain the identifiers of the owner and owning group.
  18  *    (In POSIX ACLs we always set them to ACL_UNDEFINED_ID).
  19  *  - ACL entries in the kernel are kept sorted in ascending order
  20  *    of (e_tag, e_id). Solaris ACLs are unsorted.
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/fs.h>
  25 #include <linux/gfp.h>
  26 #include <linux/sunrpc/xdr.h>
  27 #include <linux/nfsacl.h>
  28 #include <linux/nfs3.h>
  29 #include <linux/sort.h>
  30
  31 MODULE_LICENSE("GPL");
  32
  33 EXPORT_SYMBOL_GPL(nfsacl_encode);
  34 EXPORT_SYMBOL_GPL(nfsacl_decode);
  35
  36 struct nfsacl_encode_desc {
  37         struct xdr_array2_desc desc;
  38         unsigned int count;
  39         struct posix_acl *acl;
  40         int typeflag;
  41         uid_t uid;
  42         gid_t gid;
  43 };
  44
  45 static int
  46 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
  47 {
  48         struct nfsacl_encode_desc *nfsacl_desc =
  49                 (struct nfsacl_encode_desc *) desc;
  50         __be32 *p = elem;
  51
  52         struct posix_acl_entry *entry =
  53                 &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
  54
  55         *p++ = htonl(entry->e_tag | nfsacl_desc->typeflag);
  56         switch(entry->e_tag) {
  57                 case ACL_USER_OBJ:
  58                         *p++ = htonl(nfsacl_desc->uid);
  59                         break;
  60                 case ACL_GROUP_OBJ:
  61                         *p++ = htonl(nfsacl_desc->gid);
  62                         break;
  63                 case ACL_USER:
  64                 case ACL_GROUP:
  65                         *p++ = htonl(entry->e_id);
  66                         break;
  67                 default:  /* Solaris depends on that! */
  68                         *p++ = 0;
  69                         break;
  70         }
  71         *p++ = htonl(entry->e_perm & S_IRWXO);
  72         return 0;
  73 }
  74
  75 unsigned int
  76 nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
  77               struct posix_acl *acl, int encode_entries, int typeflag)
  78 {
  79         int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
  80         struct nfsacl_encode_desc nfsacl_desc = {
  81                 .desc = {
  82                         .elem_size = 12,
  83                         .array_len = encode_entries ? entries : 0,
  84                         .xcode = xdr_nfsace_encode,
  85                 },
  86                 .acl = acl,
  87                 .typeflag = typeflag,
  88                 .uid = inode->i_uid,
  89                 .gid = inode->i_gid,
  90         };
  91         int err;
  92         struct posix_acl *acl2 = NULL;
  93
  94         if (entries > NFS_ACL_MAX_ENTRIES ||
  95             xdr_encode_word(buf, base, entries))
  96                 return -EINVAL;
  97         if (encode_entries && acl && acl->a_count == 3) {
  98                 /* Fake up an ACL_MASK entry. */
  99                 acl2 = posix_acl_alloc(4, GFP_KERNEL);
 100                 if (!acl2)
 101                         return -ENOMEM;
 102                 /* Insert entries in canonical order: other orders seem
 103                  to confuse Solaris VxFS. */
 104                 acl2->a_entries[0] = acl->a_entries[0];  /* ACL_USER_OBJ */
 105                 acl2->a_entries[1] = acl->a_entries[1];  /* ACL_GROUP_OBJ */
 106                 acl2->a_entries[2] = acl->a_entries[1];  /* ACL_MASK */
 107                 acl2->a_entries[2].e_tag = ACL_MASK;
 108                 acl2->a_entries[3] = acl->a_entries[2];  /* ACL_OTHER */
 109                 nfsacl_desc.acl = acl2;
 110         }
 111         err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
 112         if (acl2)
 113                 posix_acl_release(acl2);
 114         if (!err)
 115                 err = 8 + nfsacl_desc.desc.elem_size *
 116                           nfsacl_desc.desc.array_len;
 117         return err;
 118 }
 119
 120 struct nfsacl_decode_desc {
 121         struct xdr_array2_desc desc;
 122         unsigned int count;
 123         struct posix_acl *acl;
 124 };
 125
 126 static int
 127 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
 128 {
 129         struct nfsacl_decode_desc *nfsacl_desc =
 130                 (struct nfsacl_decode_desc *) desc;
 131         __be32 *p = elem;
 132         struct posix_acl_entry *entry;
 133
 134         if (!nfsacl_desc->acl) {
 135                 if (desc->array_len > NFS_ACL_MAX_ENTRIES)
 136                         return -EINVAL;
 137                 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
 138                 if (!nfsacl_desc->acl)
 139                         return -ENOMEM;
 140                 nfsacl_desc->count = 0;
 141         }
 142
 143         entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
 144         entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
 145         entry->e_id = ntohl(*p++);
 146         entry->e_perm = ntohl(*p++);
 147
 148         switch(entry->e_tag) {
 149                 case ACL_USER_OBJ:
 150                 case ACL_USER:
 151                 case ACL_GROUP_OBJ:
 152                 case ACL_GROUP:
 153                 case ACL_OTHER:
 154                         if (entry->e_perm & ~S_IRWXO)
 155                                 return -EINVAL;
 156                         break;
 157                 case ACL_MASK:
 158                         /* Solaris sometimes sets additonal bits in the mask */
 159                         entry->e_perm &= S_IRWXO;
 160                         break;
 161                 default:
 162                         return -EINVAL;
 163         }
 164
 165         return 0;
 166 }
 167
 168 static int
 169 cmp_acl_entry(const void *x, const void *y)
 170 {
 171         const struct posix_acl_entry *a = x, *b = y;
 172
 173         if (a->e_tag != b->e_tag)
 174                 return a->e_tag - b->e_tag;
 175         else if (a->e_id > b->e_id)
 176                 return 1;
 177         else if (a->e_id < b->e_id)
 178                 return -1;
 179         else
 180                 return 0;
 181 }
 182
 183 /*
 184  * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
 185  */
 186 static int
 187 posix_acl_from_nfsacl(struct posix_acl *acl)
 188 {
 189         struct posix_acl_entry *pa, *pe,
 190                *group_obj = NULL, *mask = NULL;
 191
 192         if (!acl)
 193                 return 0;
 194
 195         sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
 196              cmp_acl_entry, NULL);
 197
 198         /* Clear undefined identifier fields and find the ACL_GROUP_OBJ
 199            and ACL_MASK entries. */
 200         FOREACH_ACL_ENTRY(pa, acl, pe) {
 201                 switch(pa->e_tag) {
 202                         case ACL_USER_OBJ:
 203                                 pa->e_id = ACL_UNDEFINED_ID;
 204                                 break;
 205                         case ACL_GROUP_OBJ:
 206                                 pa->e_id = ACL_UNDEFINED_ID;
 207                                 group_obj = pa;
 208                                 break;
 209                         case ACL_MASK:
 210                                 mask = pa;
 211                                 /* fall through */
 212                         case ACL_OTHER:
 213                                 pa->e_id = ACL_UNDEFINED_ID;
 214                                 break;
 215                 }
 216         }
 217         if (acl->a_count == 4 && group_obj && mask &&
 218             mask->e_perm == group_obj->e_perm) {
 219                 /* remove bogus ACL_MASK entry */
 220                 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
 221                                       sizeof(struct posix_acl_entry));
 222                 acl->a_count = 3;
 223         }
 224         return 0;
 225 }
 226
 227 unsigned int
 228 nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
 229               struct posix_acl **pacl)
 230 {
 231         struct nfsacl_decode_desc nfsacl_desc = {
 232                 .desc = {
 233                         .elem_size = 12,
 234                         .xcode = pacl ? xdr_nfsace_decode : NULL,
 235                 },
 236         };
 237         u32 entries;
 238         int err;
 239
 240         if (xdr_decode_word(buf, base, &entries) ||
 241             entries > NFS_ACL_MAX_ENTRIES)
 242                 return -EINVAL;
 243         nfsacl_desc.desc.array_maxlen = entries;
 244         err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
 245         if (err)
 246                 return err;
 247         if (pacl) {
 248                 if (entries != nfsacl_desc.desc.array_len ||
 249                     posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
 250                         posix_acl_release(nfsacl_desc.acl);
 251                         return -EINVAL;
 252                 }
 253                 *pacl = nfsacl_desc.acl;
 254         }
 255         if (aclcnt)
 256                 *aclcnt = entries;
 257         return 8 + nfsacl_desc.desc.elem_size *
 258                    nfsacl_desc.desc.array_len;
 259 }