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 char cksumdata[16]; 125 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 126 int blocksize = 0, plainlen; 127 unsigned char *ptr, *krb5_hdr, *msg_start; 128 s32 now; 129 int headlen; 130 struct page **tmp_pages; 131 u32 seq_send; 132 133 dprintk("RPC: gss_wrap_kerberos\n"); 134 135 now = get_seconds(); 136 137 switch (kctx->signalg) { 138 case SGN_ALG_DES_MAC_MD5: 139 checksum_type = CKSUMTYPE_RSA_MD5; 140 break; 141 default: 142 dprintk("RPC: gss_krb5_seal: kctx->signalg %d not" 143 " supported\n", kctx->signalg); 144 goto out_err; 145 } 146 if (kctx->sealalg != SEAL_ALG_NONE && kctx->sealalg != SEAL_ALG_DES) { 147 dprintk("RPC: gss_krb5_seal: kctx->sealalg %d not supported\n", 148 kctx->sealalg); 149 goto out_err; 150 } 151 152 blocksize = crypto_tfm_alg_blocksize(kctx->enc); 153 gss_krb5_add_padding(buf, offset, blocksize); 154 BUG_ON((buf->len - offset) % blocksize); 155 plainlen = blocksize + buf->len - offset; 156 157 headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - 158 (buf->len - offset); 159 160 ptr = buf->head[0].iov_base + offset; 161 /* shift data to make room for header. */ 162 /* XXX Would be cleverer to encrypt while copying. */ 163 /* XXX bounds checking, slack, etc. */ 164 memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); 165 buf->head[0].iov_len += headlen; 166 buf->len += headlen; 167 BUG_ON((buf->len - offset - headlen) % blocksize); 168 169 g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr); 170 171 172 *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); 173 *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); 174 175 /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ 176 krb5_hdr = ptr - 2; 177 msg_start = krb5_hdr + 24; 178 /* XXXJBF: */ BUG_ON(buf->head[0].iov_base + offset + headlen != msg_start + blocksize); 179 180 *(u16 *)(krb5_hdr + 2) = htons(kctx->signalg); 181 memset(krb5_hdr + 4, 0xff, 4); 182 *(u16 *)(krb5_hdr + 4) = htons(kctx->sealalg); 183 184 make_confounder(msg_start, blocksize); 185 186 /* XXXJBF: UGH!: */ 187 tmp_pages = buf->pages; 188 buf->pages = pages; 189 if (make_checksum(checksum_type, krb5_hdr, 8, buf, 190 offset + headlen - blocksize, &md5cksum)) 191 goto out_err; 192 buf->pages = tmp_pages; 193 194 switch (kctx->signalg) { 195 case SGN_ALG_DES_MAC_MD5: 196 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 197 md5cksum.data, md5cksum.len)) 198 goto out_err; 199 memcpy(krb5_hdr + 16, 200 md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, 201 KRB5_CKSUM_LENGTH); 202 203 dprintk("RPC: make_seal_token: cksum data: \n"); 204 print_hexl((u32 *) (krb5_hdr + 16), KRB5_CKSUM_LENGTH, 0); 205 break; 206 default: 207 BUG(); 208 } 209 210 spin_lock(&krb5_seq_lock); 211 seq_send = kctx->seq_send++; 212 spin_unlock(&krb5_seq_lock); 213 214 /* XXX would probably be more efficient to compute checksum 215 * and encrypt at the same time: */ 216 if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, 217 seq_send, krb5_hdr + 16, krb5_hdr + 8))) 218 goto out_err; 219 220 if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, 221 pages)) 222 goto out_err; 223 224 return ((kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE); 225 out_err: 226 return GSS_S_FAILURE; 227 } 228 229 u32 230 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) 231 { 232 struct krb5_ctx *kctx = ctx->internal_ctx_id; 233 int signalg; 234 int sealalg; 235 s32 checksum_type; 236 char cksumdata[16]; 237 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 238 s32 now; 239 int direction; 240 s32 seqnum; 241 unsigned char *ptr; 242 int bodysize; 243 u32 ret = GSS_S_DEFECTIVE_TOKEN; 244 void *data_start, *orig_start; 245 int data_len; 246 int blocksize; 247 248 dprintk("RPC: gss_unwrap_kerberos\n"); 249 250 ptr = (u8 *)buf->head[0].iov_base + offset; 251 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 252 buf->len - offset)) 253 goto out; 254 255 if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || 256 (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) 257 goto out; 258 259 /* XXX sanity-check bodysize?? */ 260 261 /* get the sign and seal algorithms */ 262 263 signalg = ptr[0] + (ptr[1] << 8); 264 sealalg = ptr[2] + (ptr[3] << 8); 265 266 /* Sanity checks */ 267 268 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 269 goto out; 270 271 if (sealalg == 0xffff) 272 goto out; 273 274 /* in the current spec, there is only one valid seal algorithm per 275 key type, so a simple comparison is ok */ 276 277 if (sealalg != kctx->sealalg) 278 goto out; 279 280 /* there are several mappings of seal algorithms to sign algorithms, 281 but few enough that we can try them all. */ 282 283 if ((kctx->sealalg == SEAL_ALG_NONE && signalg > 1) || 284 (kctx->sealalg == SEAL_ALG_1 && signalg != SGN_ALG_3) || 285 (kctx->sealalg == SEAL_ALG_DES3KD && 286 signalg != SGN_ALG_HMAC_SHA1_DES3_KD)) 287 goto out; 288 289 if (gss_decrypt_xdr_buf(kctx->enc, buf, 290 ptr + 22 - (unsigned char *)buf->head[0].iov_base)) 291 goto out; 292 293 /* compute the checksum of the message */ 294 295 /* initialize the the cksum */ 296 switch (signalg) { 297 case SGN_ALG_DES_MAC_MD5: 298 checksum_type = CKSUMTYPE_RSA_MD5; 299 break; 300 default: 301 ret = GSS_S_DEFECTIVE_TOKEN; 302 goto out; 303 } 304 305 switch (signalg) { 306 case SGN_ALG_DES_MAC_MD5: 307 ret = make_checksum(checksum_type, ptr - 2, 8, buf, 308 ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum); 309 if (ret) 310 goto out; 311 312 ret = krb5_encrypt(kctx->seq, NULL, md5cksum.data, 313 md5cksum.data, md5cksum.len); 314 if (ret) 315 goto out; 316 317 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) { 318 ret = GSS_S_BAD_SIG; 319 goto out; 320 } 321 break; 322 default: 323 ret = GSS_S_DEFECTIVE_TOKEN; 324 goto out; 325 } 326 327 /* it got through unscathed. Make sure the context is unexpired */ 328 329 now = get_seconds(); 330 331 ret = GSS_S_CONTEXT_EXPIRED; 332 if (now > kctx->endtime) 333 goto out; 334 335 /* do sequencing checks */ 336 337 ret = GSS_S_BAD_SIG; 338 if ((ret = krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, 339 &seqnum))) 340 goto out; 341 342 if ((kctx->initiate && direction != 0xff) || 343 (!kctx->initiate && direction != 0)) 344 goto out; 345 346 /* Copy the data back to the right position. XXX: Would probably be 347 * better to copy and encrypt at the same time. */ 348 349 blocksize = crypto_tfm_alg_blocksize(kctx->enc); 350 data_start = ptr + 22 + blocksize; 351 orig_start = buf->head[0].iov_base + offset; 352 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 353 memmove(orig_start, data_start, data_len); 354 buf->head[0].iov_len -= (data_start - orig_start); 355 buf->len -= (data_start - orig_start); 356 357 ret = GSS_S_DEFECTIVE_TOKEN; 358 if (gss_krb5_remove_padding(buf, blocksize)) 359 goto out; 360 361 ret = GSS_S_COMPLETE; 362 out: 363 return ret; 364 } 365