1 #include <linux/types.h> 2 #include <linux/slab.h> 3 #include <linux/jiffies.h> 4 #include <linux/sunrpc/gss_krb5.h> 5 #include <linux/random.h> 6 #include <linux/pagemap.h> 7 #include <asm/scatterlist.h> 8 #include <linux/crypto.h> 9 10 #ifdef RPC_DEBUG 11 # define RPCDBG_FACILITY RPCDBG_AUTH 12 #endif 13 14 static inline int 15 gss_krb5_padding(int blocksize, int length) 16 { 17 /* Most of the code is block-size independent but currently we 18 * use only 8: */ 19 BUG_ON(blocksize != 8); 20 return 8 - (length & 7); 21 } 22 23 static inline void 24 gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize) 25 { 26 int padding = gss_krb5_padding(blocksize, buf->len - offset); 27 char *p; 28 struct kvec *iov; 29 30 if (buf->page_len || buf->tail[0].iov_len) 31 iov = &buf->tail[0]; 32 else 33 iov = &buf->head[0]; 34 p = iov->iov_base + iov->iov_len; 35 iov->iov_len += padding; 36 buf->len += padding; 37 memset(p, padding, padding); 38 } 39 40 static inline int 41 gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize) 42 { 43 u8 *ptr; 44 u8 pad; 45 int len = buf->len; 46 47 if (len <= buf->head[0].iov_len) { 48 pad = *(u8 *)(buf->head[0].iov_base + len - 1); 49 if (pad > buf->head[0].iov_len) 50 return -EINVAL; 51 buf->head[0].iov_len -= pad; 52 goto out; 53 } else 54 len -= buf->head[0].iov_len; 55 if (len <= buf->page_len) { 56 int last = (buf->page_base + len - 1) 57 >>PAGE_CACHE_SHIFT; 58 int offset = (buf->page_base + len - 1) 59 & (PAGE_CACHE_SIZE - 1); 60 ptr = kmap_atomic(buf->pages[last], KM_SKB_SUNRPC_DATA); 61 pad = *(ptr + offset); 62 kunmap_atomic(ptr, KM_SKB_SUNRPC_DATA); 63 goto out; 64 } else 65 len -= buf->page_len; 66 BUG_ON(len > buf->tail[0].iov_len); 67 pad = *(u8 *)(buf->tail[0].iov_base + len - 1); 68 out: 69 /* XXX: NOTE: we do not adjust the page lengths--they represent 70 * a range of data in the real filesystem page cache, and we need 71 * to know that range so the xdr code can properly place read data. 72 * However adjusting the head length, as we do above, is harmless. 73 * In the case of a request that fits into a single page, the server 74 * also uses length and head length together to determine the original 75 * start of the request to copy the request for deferal; so it's 76 * easier on the server if we adjust head and tail length in tandem. 77 * It's not really a problem that we don't fool with the page and 78 * tail lengths, though--at worst badly formed xdr might lead the 79 * server to attempt to parse the padding. 80 * XXX: Document all these weird requirements for gss mechanism 81 * wrap/unwrap functions. */ 82 if (pad > blocksize) 83 return -EINVAL; 84 if (buf->len > pad) 85 buf->len -= pad; 86 else 87 return -EINVAL; 88 return 0; 89 } 90 91 static inline void 92 make_confounder(char *p, int blocksize) 93 { 94 static u64 i = 0; 95 u64 *q = (u64 *)p; 96 97 /* rfc1964 claims this should be "random". But all that's really 98 * necessary is that it be unique. And not even that is necessary in 99 * our case since our "gssapi" implementation exists only to support 100 * rpcsec_gss, so we know that the only buffers we will ever encrypt 101 * already begin with a unique sequence number. Just to hedge my bets 102 * I'll make a half-hearted attempt at something unique, but ensuring 103 * uniqueness would mean worrying about atomicity and rollover, and I 104 * don't care enough. */ 105 106 BUG_ON(blocksize != 8); 107 *q = i++; 108 } 109 110 /* Assumptions: the head and tail of inbuf are ours to play with. 111 * The pages, however, may be real pages in the page cache and we replace 112 * them with scratch pages from **pages before writing to them. */ 113 /* XXX: obviously the above should be documentation of wrap interface, 114 * and shouldn't be in this kerberos-specific file. */ 115 116 /* XXX factor out common code with seal/unseal. */ 117 118 u32 119 gss_wrap_kerberos(struct gss_ctx *ctx, int offset, 120 struct xdr_buf *buf, struct page **pages) 121 { 122 struct krb5_ctx *kctx = ctx->internal_ctx_id; 123 s32 checksum_type; 124 struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; 125 int blocksize = 0, plainlen; 126 unsigned char *ptr, *krb5_hdr, *msg_start; 127 s32 now; 128 int headlen; 129 struct page **tmp_pages; 130 131 dprintk("RPC: gss_wrap_kerberos\n"); 132 133 now = get_seconds(); 134 135 switch (kctx->signalg) { 136 case SGN_ALG_DES_MAC_MD5: 137 checksum_type = CKSUMTYPE_RSA_MD5; 138 break; 139 default: 140 dprintk("RPC: gss_krb5_seal: kctx->signalg %d not" 141 " supported\n", kctx->signalg); 142 goto out_err; 143 } 144 if (kctx->sealalg != SEAL_ALG_NONE && kctx->sealalg != SEAL_ALG_DES) { 145 dprintk("RPC: gss_krb5_seal: kctx->sealalg %d not supported\n", 146 kctx->sealalg); 147 goto out_err; 148 } 149 150 blocksize = crypto_tfm_alg_blocksize(kctx->enc); 151 gss_krb5_add_padding(buf, offset, blocksize); 152 BUG_ON((buf->len - offset) % blocksize); 153 plainlen = blocksize + buf->len - offset; 154 155 headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - 156 (buf->len - offset); 157 158 ptr = buf->head[0].iov_base + offset; 159 /* shift data to make room for header. */ 160 /* XXX Would be cleverer to encrypt while copying. */ 161 /* XXX bounds checking, slack, etc. */ 162 memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); 163 buf->head[0].iov_len += headlen; 164 buf->len += headlen; 165 BUG_ON((buf->len - offset - headlen) % blocksize); 166 167 g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr); 168 169 170 *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); 171 *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); 172 173 /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ 174 krb5_hdr = ptr - 2; 175 msg_start = krb5_hdr + 24; 176 /* XXXJBF: */ BUG_ON(buf->head[0].iov_base + offset + headlen != msg_start + blocksize); 177 178 *(u16 *)(krb5_hdr + 2) = htons(kctx->signalg); 179 memset(krb5_hdr + 4, 0xff, 4); 180 *(u16 *)(krb5_hdr + 4) = htons(kctx->sealalg); 181 182 make_confounder(msg_start, blocksize); 183 184 /* XXXJBF: UGH!: */ 185 tmp_pages = buf->pages; 186 buf->pages = pages; 187 if (make_checksum(checksum_type, krb5_hdr, 8, buf, 188 offset + headlen - blocksize, &md5cksum)) 189 goto out_err; 190 buf->pages = tmp_pages; 191 192 switch (kctx->signalg) { 193 case SGN_ALG_DES_MAC_MD5: 194 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 195 md5cksum.data, md5cksum.len)) 196 goto out_err; 197 memcpy(krb5_hdr + 16, 198 md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, 199 KRB5_CKSUM_LENGTH); 200 201 dprintk("RPC: make_seal_token: cksum data: \n"); 202 print_hexl((u32 *) (krb5_hdr + 16), KRB5_CKSUM_LENGTH, 0); 203 break; 204 default: 205 BUG(); 206 } 207 208 kfree(md5cksum.data); 209 210 /* XXX would probably be more efficient to compute checksum 211 * and encrypt at the same time: */ 212 if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, 213 kctx->seq_send, krb5_hdr + 16, krb5_hdr + 8))) 214 goto out_err; 215 216 if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, 217 pages)) 218 goto out_err; 219 220 kctx->seq_send++; 221 222 return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE); 223 out_err: 224 if (md5cksum.data) kfree(md5cksum.data); 225 return GSS_S_FAILURE; 226 } 227 228 u32 229 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) 230 { 231 struct krb5_ctx *kctx = ctx->internal_ctx_id; 232 int signalg; 233 int sealalg; 234 s32 checksum_type; 235 struct xdr_netobj md5cksum = {.len = 0, .data = NULL}; 236 s32 now; 237 int direction; 238 s32 seqnum; 239 unsigned char *ptr; 240 int bodysize; 241 u32 ret = GSS_S_DEFECTIVE_TOKEN; 242 void *data_start, *orig_start; 243 int data_len; 244 int blocksize; 245 246 dprintk("RPC: gss_unwrap_kerberos\n"); 247 248 ptr = (u8 *)buf->head[0].iov_base + offset; 249 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 250 buf->len - offset)) 251 goto out; 252 253 if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || 254 (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) 255 goto out; 256 257 /* XXX sanity-check bodysize?? */ 258 259 /* get the sign and seal algorithms */ 260 261 signalg = ptr[0] + (ptr[1] << 8); 262 sealalg = ptr[2] + (ptr[3] << 8); 263 264 /* Sanity checks */ 265 266 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 267 goto out; 268 269 if (sealalg == 0xffff) 270 goto out; 271 272 /* in the current spec, there is only one valid seal algorithm per 273 key type, so a simple comparison is ok */ 274 275 if (sealalg != kctx->sealalg) 276 goto out; 277 278 /* there are several mappings of seal algorithms to sign algorithms, 279 but few enough that we can try them all. */ 280 281 if ((kctx->sealalg == SEAL_ALG_NONE && signalg > 1) || 282 (kctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || 283 (kctx->sealalg == SEAL_ALG_DES3KD && 284 signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) 285 goto out; 286 287 if (gss_decrypt_xdr_buf(kctx->enc, buf, 288 ptr + 22 - (unsigned char *)buf->head[0].iov_base)) 289 goto out; 290 291 /* compute the checksum of the message */ 292 293 /* initialize the the cksum */ 294 switch (signalg) { 295 case SGN_ALG_DES_MAC_MD5: 296 checksum_type = CKSUMTYPE_RSA_MD5; 297 break; 298 default: 299 ret = GSS_S_DEFECTIVE_TOKEN; 300 goto out; 301 } 302 303 switch (signalg) { 304 case SGN_ALG_DES_MAC_MD5: 305 ret = make_checksum(checksum_type, ptr - 2, 8, buf, 306 ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum); 307 if (ret) 308 goto out; 309 310 ret = krb5_encrypt(kctx->seq, NULL, md5cksum.data, 311 md5cksum.data, md5cksum.len); 312 if (ret) 313 goto out; 314 315 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { 316 ret = GSS_S_BAD_SIG; 317 goto out; 318 } 319 break; 320 default: 321 ret = GSS_S_DEFECTIVE_TOKEN; 322 goto out; 323 } 324 325 /* it got through unscathed. Make sure the context is unexpired */ 326 327 now = get_seconds(); 328 329 ret = GSS_S_CONTEXT_EXPIRED; 330 if (now > kctx->endtime) 331 goto out; 332 333 /* do sequencing checks */ 334 335 ret = GSS_S_BAD_SIG; 336 if ((ret = krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, 337 &seqnum))) 338 goto out; 339 340 if ((kctx->initiate && direction != 0xff) || 341 (!kctx->initiate && direction != 0)) 342 goto out; 343 344 /* Copy the data back to the right position. XXX: Would probably be 345 * better to copy and encrypt at the same time. */ 346 347 blocksize = crypto_tfm_alg_blocksize(kctx->enc); 348 data_start = ptr + 22 + blocksize; 349 orig_start = buf->head[0].iov_base + offset; 350 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 351 memmove(orig_start, data_start, data_len); 352 buf->head[0].iov_len -= (data_start - orig_start); 353 buf->len -= (data_start - orig_start); 354 355 ret = GSS_S_DEFECTIVE_TOKEN; 356 if (gss_krb5_remove_padding(buf, blocksize)) 357 goto out; 358 359 ret = GSS_S_COMPLETE; 360 out: 361 if (md5cksum.data) kfree(md5cksum.data); 362 return ret; 363 } 364