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 kuid_t uid; 42 kgid_t gid; 43 }; 44 45 struct nfsacl_simple_acl { 46 struct posix_acl acl; 47 struct posix_acl_entry ace[4]; 48 }; 49 50 static int 51 xdr_nfsace_encode(struct xdr_array2_desc *desc, void *elem) 52 { 53 struct nfsacl_encode_desc *nfsacl_desc = 54 (struct nfsacl_encode_desc *) desc; 55 __be32 *p = elem; 56 57 struct posix_acl_entry *entry = 58 &nfsacl_desc->acl->a_entries[nfsacl_desc->count++]; 59 60 *p++ = htonl(entry->e_tag | nfsacl_desc->typeflag); 61 switch(entry->e_tag) { 62 case ACL_USER_OBJ: 63 *p++ = htonl(from_kuid(&init_user_ns, nfsacl_desc->uid)); 64 break; 65 case ACL_GROUP_OBJ: 66 *p++ = htonl(from_kgid(&init_user_ns, nfsacl_desc->gid)); 67 break; 68 case ACL_USER: 69 *p++ = htonl(from_kuid(&init_user_ns, entry->e_uid)); 70 break; 71 case ACL_GROUP: 72 *p++ = htonl(from_kgid(&init_user_ns, entry->e_gid)); 73 break; 74 default: /* Solaris depends on that! */ 75 *p++ = 0; 76 break; 77 } 78 *p++ = htonl(entry->e_perm & S_IRWXO); 79 return 0; 80 } 81 82 /** 83 * nfsacl_encode - Encode an NFSv3 ACL 84 * 85 * @buf: destination xdr_buf to contain XDR encoded ACL 86 * @base: byte offset in xdr_buf where XDR'd ACL begins 87 * @inode: inode of file whose ACL this is 88 * @acl: posix_acl to encode 89 * @encode_entries: whether to encode ACEs as well 90 * @typeflag: ACL type: NFS_ACL_DEFAULT or zero 91 * 92 * Returns size of encoded ACL in bytes or a negative errno value. 93 */ 94 int nfsacl_encode(struct xdr_buf *buf, unsigned int base, struct inode *inode, 95 struct posix_acl *acl, int encode_entries, int typeflag) 96 { 97 int entries = (acl && acl->a_count) ? max_t(int, acl->a_count, 4) : 0; 98 struct nfsacl_encode_desc nfsacl_desc = { 99 .desc = { 100 .elem_size = 12, 101 .array_len = encode_entries ? entries : 0, 102 .xcode = xdr_nfsace_encode, 103 }, 104 .acl = acl, 105 .typeflag = typeflag, 106 .uid = inode->i_uid, 107 .gid = inode->i_gid, 108 }; 109 struct nfsacl_simple_acl aclbuf; 110 int err; 111 112 if (entries > NFS_ACL_MAX_ENTRIES || 113 xdr_encode_word(buf, base, entries)) 114 return -EINVAL; 115 if (encode_entries && acl && acl->a_count == 3) { 116 struct posix_acl *acl2 = &aclbuf.acl; 117 118 /* Avoid the use of posix_acl_alloc(). nfsacl_encode() is 119 * invoked in contexts where a memory allocation failure is 120 * fatal. Fortunately this fake ACL is small enough to 121 * construct on the stack. */ 122 posix_acl_init(acl2, 4); 123 124 /* Insert entries in canonical order: other orders seem 125 to confuse Solaris VxFS. */ 126 acl2->a_entries[0] = acl->a_entries[0]; /* ACL_USER_OBJ */ 127 acl2->a_entries[1] = acl->a_entries[1]; /* ACL_GROUP_OBJ */ 128 acl2->a_entries[2] = acl->a_entries[1]; /* ACL_MASK */ 129 acl2->a_entries[2].e_tag = ACL_MASK; 130 acl2->a_entries[3] = acl->a_entries[2]; /* ACL_OTHER */ 131 nfsacl_desc.acl = acl2; 132 } 133 err = xdr_encode_array2(buf, base + 4, &nfsacl_desc.desc); 134 if (!err) 135 err = 8 + nfsacl_desc.desc.elem_size * 136 nfsacl_desc.desc.array_len; 137 return err; 138 } 139 140 struct nfsacl_decode_desc { 141 struct xdr_array2_desc desc; 142 unsigned int count; 143 struct posix_acl *acl; 144 }; 145 146 static int 147 xdr_nfsace_decode(struct xdr_array2_desc *desc, void *elem) 148 { 149 struct nfsacl_decode_desc *nfsacl_desc = 150 (struct nfsacl_decode_desc *) desc; 151 __be32 *p = elem; 152 struct posix_acl_entry *entry; 153 unsigned int id; 154 155 if (!nfsacl_desc->acl) { 156 if (desc->array_len > NFS_ACL_MAX_ENTRIES) 157 return -EINVAL; 158 nfsacl_desc->acl = posix_acl_alloc(desc->array_len, GFP_KERNEL); 159 if (!nfsacl_desc->acl) 160 return -ENOMEM; 161 nfsacl_desc->count = 0; 162 } 163 164 entry = &nfsacl_desc->acl->a_entries[nfsacl_desc->count++]; 165 entry->e_tag = ntohl(*p++) & ~NFS_ACL_DEFAULT; 166 id = ntohl(*p++); 167 entry->e_perm = ntohl(*p++); 168 169 switch(entry->e_tag) { 170 case ACL_USER: 171 entry->e_uid = make_kuid(&init_user_ns, id); 172 if (!uid_valid(entry->e_uid)) 173 return -EINVAL; 174 break; 175 case ACL_GROUP: 176 entry->e_gid = make_kgid(&init_user_ns, id); 177 if (!gid_valid(entry->e_gid)) 178 return -EINVAL; 179 break; 180 case ACL_USER_OBJ: 181 case ACL_GROUP_OBJ: 182 case ACL_OTHER: 183 if (entry->e_perm & ~S_IRWXO) 184 return -EINVAL; 185 break; 186 case ACL_MASK: 187 /* Solaris sometimes sets additional bits in the mask */ 188 entry->e_perm &= S_IRWXO; 189 break; 190 default: 191 return -EINVAL; 192 } 193 194 return 0; 195 } 196 197 static int 198 cmp_acl_entry(const void *x, const void *y) 199 { 200 const struct posix_acl_entry *a = x, *b = y; 201 202 if (a->e_tag != b->e_tag) 203 return a->e_tag - b->e_tag; 204 else if ((a->e_tag == ACL_USER) && uid_gt(a->e_uid, b->e_uid)) 205 return 1; 206 else if ((a->e_tag == ACL_USER) && uid_lt(a->e_uid, b->e_uid)) 207 return -1; 208 else if ((a->e_tag == ACL_GROUP) && gid_gt(a->e_gid, b->e_gid)) 209 return 1; 210 else if ((a->e_tag == ACL_GROUP) && gid_lt(a->e_gid, b->e_gid)) 211 return -1; 212 else 213 return 0; 214 } 215 216 /* 217 * Convert from a Solaris ACL to a POSIX 1003.1e draft 17 ACL. 218 */ 219 static int 220 posix_acl_from_nfsacl(struct posix_acl *acl) 221 { 222 struct posix_acl_entry *pa, *pe, 223 *group_obj = NULL, *mask = NULL; 224 225 if (!acl) 226 return 0; 227 228 sort(acl->a_entries, acl->a_count, sizeof(struct posix_acl_entry), 229 cmp_acl_entry, NULL); 230 231 /* Find the ACL_GROUP_OBJ and ACL_MASK entries. */ 232 FOREACH_ACL_ENTRY(pa, acl, pe) { 233 switch(pa->e_tag) { 234 case ACL_USER_OBJ: 235 break; 236 case ACL_GROUP_OBJ: 237 group_obj = pa; 238 break; 239 case ACL_MASK: 240 mask = pa; 241 /* fall through */ 242 case ACL_OTHER: 243 break; 244 } 245 } 246 if (acl->a_count == 4 && group_obj && mask && 247 mask->e_perm == group_obj->e_perm) { 248 /* remove bogus ACL_MASK entry */ 249 memmove(mask, mask+1, (3 - (mask - acl->a_entries)) * 250 sizeof(struct posix_acl_entry)); 251 acl->a_count = 3; 252 } 253 return 0; 254 } 255 256 /** 257 * nfsacl_decode - Decode an NFSv3 ACL 258 * 259 * @buf: xdr_buf containing XDR'd ACL data to decode 260 * @base: byte offset in xdr_buf where XDR'd ACL begins 261 * @aclcnt: count of ACEs in decoded posix_acl 262 * @pacl: buffer in which to place decoded posix_acl 263 * 264 * Returns the length of the decoded ACL in bytes, or a negative errno value. 265 */ 266 int nfsacl_decode(struct xdr_buf *buf, unsigned int base, unsigned int *aclcnt, 267 struct posix_acl **pacl) 268 { 269 struct nfsacl_decode_desc nfsacl_desc = { 270 .desc = { 271 .elem_size = 12, 272 .xcode = pacl ? xdr_nfsace_decode : NULL, 273 }, 274 }; 275 u32 entries; 276 int err; 277 278 if (xdr_decode_word(buf, base, &entries) || 279 entries > NFS_ACL_MAX_ENTRIES) 280 return -EINVAL; 281 nfsacl_desc.desc.array_maxlen = entries; 282 err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc); 283 if (err) 284 return err; 285 if (pacl) { 286 if (entries != nfsacl_desc.desc.array_len || 287 posix_acl_from_nfsacl(nfsacl_desc.acl) != 0) { 288 posix_acl_release(nfsacl_desc.acl); 289 return -EINVAL; 290 } 291 *pacl = nfsacl_desc.acl; 292 } 293 if (aclcnt) 294 *aclcnt = entries; 295 return 8 + nfsacl_desc.desc.elem_size * 296 nfsacl_desc.desc.array_len; 297 } 298