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/sunrpc/xdr.h>
  26 #include <linux/nfsacl.h>
  27 #include <linux/nfs3.h>
  28 #include <linux/sort.h>
  29
  30 MODULE_LICENSE("GPL");
  31
  32 EXPORT_SYMBOL(nfsacl_encode);
  33 EXPORT_SYMBOL(nfsacl_decode);
  34
  35 struct nfsacl_encode_desc {
  36         struct xdr_array2_desc desc;
  37         unsigned int count;
  38         struct posix_acl *acl;
  39         int typeflag;
  40         uid_t uid;
  41         gid_t gid;
  42 };
  43
  44 static int
  45 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem)
  46 {
  47         struct nfsacl_encode_desc *nfsacl_desc =
  48                 (struct nfsacl_encode_desc *) desc;
  49         u32 *p = (u32 *) elem;
  50
  51         if (nfsacl_desc->count < nfsacl_desc->acl->a_count) {
  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         } else {
  73                 const struct posix_acl_entry *pa, *pe;
  74                 int group_obj_perm = ACL_READ|ACL_WRITE|ACL_EXECUTE;
  75
  76                 FOREACH_ACL_ENTRY(pa, nfsacl_desc->acl, pe) {
  77                         if (pa->e_tag == ACL_GROUP_OBJ) {
  78                                 group_obj_perm = pa->e_perm & S_IRWXO;
  79                                 break;
  80                         }
  81                 }
  82                 /* fake up ACL_MASK entry */
  83                 *p++ = htonl(ACL_MASK | nfsacl_desc->typeflag);
  84                 *p++ = htonl(0);
  85                 *p++ = htonl(group_obj_perm);
  86         }
  87
  88         return 0;
  89 }
  90
  91 unsigned int
  92 nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode,
  93               struct posix_acl *acl, int encode_entries, int typeflag)
  94 {
  95         int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0;
  96         struct nfsacl_encode_desc nfsacl_desc = {
  97                 .desc = {
  98                         .elem_size = 12,
  99                         .array_len = encode_entries ? entries : 0,
 100                         .xcode = xdr_nfsace_encode,
 101                 },
 102                 .acl = acl,
 103                 .typeflag = typeflag,
 104                 .uid = inode->i_uid,
 105                 .gid = inode->i_gid,
 106         };
 107         int err;
 108
 109         if (entries > NFS_ACL_MAX_ENTRIES ||
 110             xdr_encode_word(buf, base, entries))
 111                 return -EINVAL;
 112         err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc);
 113         if (!err)
 114                 err = 8 + nfsacl_desc.desc.elem_size *
 115                           nfsacl_desc.desc.array_len;
 116         return err;
 117 }
 118
 119 struct nfsacl_decode_desc {
 120         struct xdr_array2_desc desc;
 121         unsigned int count;
 122         struct posix_acl *acl;
 123 };
 124
 125 static int
 126 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem)
 127 {
 128         struct nfsacl_decode_desc *nfsacl_desc =
 129                 (struct nfsacl_decode_desc *) desc;
 130         u32 *p = (u32 *) elem;
 131         struct posix_acl_entry *entry;
 132
 133         if (!nfsacl_desc->acl) {
 134                 if (desc->array_len > NFS_ACL_MAX_ENTRIES)
 135                         return -EINVAL;
 136                 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL);
 137                 if (!nfsacl_desc->acl)
 138                         return -ENOMEM;
 139                 nfsacl_desc->count = 0;
 140         }
 141
 142         entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++];
 143         entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT;
 144         entry->e_id = ntohl(*p++);
 145         entry->e_perm = ntohl(*p++);
 146
 147         switch(entry->e_tag) {
 148                 case ACL_USER_OBJ:
 149                 case ACL_USER:
 150                 case ACL_GROUP_OBJ:
 151                 case ACL_GROUP:
 152                 case ACL_OTHER:
 153                         if (entry->e_perm & ~S_IRWXO)
 154                                 return -EINVAL;
 155                         break;
 156                 case ACL_MASK:
 157                         /* Solaris sometimes sets additonal bits in the mask */
 158                         entry->e_perm &= S_IRWXO;
 159                         break;
 160                 default:
 161                         return -EINVAL;
 162         }
 163
 164         return 0;
 165 }
 166
 167 static int
 168 cmp_acl_entry(const void *x, const void *y)
 169 {
 170         const struct posix_acl_entry *a = x, *b = y;
 171
 172         if (a->e_tag != b->e_tag)
 173                 return a->e_tag - b->e_tag;
 174         else if (a->e_id > b->e_id)
 175                 return 1;
 176         else if (a->e_id < b->e_id)
 177                 return -1;
 178         else
 179                 return 0;
 180 }
 181
 182 /*
 183  * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL.
 184  */
 185 static int
 186 posix_acl_from_nfsacl(struct posix_acl *acl)
 187 {
 188         struct posix_acl_entry *pa, *pe,
 189                *group_obj = NULL, *mask = NULL;
 190
 191         if (!acl)
 192                 return 0;
 193
 194         sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry),
 195              cmp_acl_entry, NULL);
 196
 197         /* Clear undefined identifier fields and find the ACL_GROUP_OBJ
 198            and ACL_MASK entries. */
 199         FOREACH_ACL_ENTRY(pa, acl, pe) {
 200                 switch(pa->e_tag) {
 201                         case ACL_USER_OBJ:
 202                                 pa->e_id = ACL_UNDEFINED_ID;
 203                                 break;
 204                         case ACL_GROUP_OBJ:
 205                                 pa->e_id = ACL_UNDEFINED_ID;
 206                                 group_obj = pa;
 207                                 break;
 208                         case ACL_MASK:
 209                                 mask = pa;
 210                                 /* fall through */
 211                         case ACL_OTHER:
 212                                 pa->e_id = ACL_UNDEFINED_ID;
 213                                 break;
 214                 }
 215         }
 216         if (acl->a_count == 4 && group_obj && mask &&
 217             mask->e_perm == group_obj->e_perm) {
 218                 /* remove bogus ACL_MASK entry */
 219                 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) *
 220                                       sizeof(struct posix_acl_entry));
 221                 acl->a_count = 3;
 222         }
 223         return 0;
 224 }
 225
 226 unsigned int
 227 nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt,
 228               struct posix_acl **pacl)
 229 {
 230         struct nfsacl_decode_desc nfsacl_desc = {
 231                 .desc = {
 232                         .elem_size = 12,
 233                         .xcode = pacl ? xdr_nfsace_decode : NULL,
 234                 },
 235         };
 236         u32 entries;
 237         int err;
 238
 239         if (xdr_decode_word(buf, base, &entries) ||
 240             entries > NFS_ACL_MAX_ENTRIES)
 241                 return -EINVAL;
 242         nfsacl_desc.desc.array_maxlen = entries;
 243         err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
 244         if (err)
 245                 return err;
 246         if (pacl) {
 247                 if (entries != nfsacl_desc.desc.array_len ||
 248                     posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) {
 249                         posix_acl_release(nfsacl_desc.acl);
 250                         return -EINVAL;
 251                 }
 252                 *pacl = nfsacl_desc.acl;
 253         }
 254         if (aclcnt)
 255                 *aclcnt = entries;
 256         return 8 + nfsacl_desc.desc.elem_size *
 257                    nfsacl_desc.desc.array_len;
 258 }