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 <linux/crypto.h> 8 9 #ifdef RPC_DEBUG 10 # define RPCDBG_FACILITY RPCDBG_AUTH 11 #endif 12 13 static inline int 14 gss_krb5_padding(int blocksize, int length) 15 { 16 /* Most of the code is block-size independent but currently we 17 * use only 8: */ 18 BUG_ON(blocksize != 8); 19 return 8 - (length & 7); 20 } 21 22 static inline void 23 gss_krb5_add_padding(struct xdr_buf *buf, int offset, int blocksize) 24 { 25 int padding = gss_krb5_padding(blocksize, buf->len - offset); 26 char *p; 27 struct kvec *iov; 28 29 if (buf->page_len || buf->tail[0].iov_len) 30 iov = &buf->tail[0]; 31 else 32 iov = &buf->head[0]; 33 p = iov->iov_base + iov->iov_len; 34 iov->iov_len += padding; 35 buf->len += padding; 36 memset(p, padding, padding); 37 } 38 39 static inline int 40 gss_krb5_remove_padding(struct xdr_buf *buf, int blocksize) 41 { 42 u8 *ptr; 43 u8 pad; 44 size_t len = buf->len; 45 46 if (len <= buf->head[0].iov_len) { 47 pad = *(u8 *)(buf->head[0].iov_base + len - 1); 48 if (pad > buf->head[0].iov_len) 49 return -EINVAL; 50 buf->head[0].iov_len -= pad; 51 goto out; 52 } else 53 len -= buf->head[0].iov_len; 54 if (len <= buf->page_len) { 55 unsigned int last = (buf->page_base + len - 1) 56 >>PAGE_CACHE_SHIFT; 57 unsigned int offset = (buf->page_base + len - 1) 58 & (PAGE_CACHE_SIZE - 1); 59 ptr = kmap_atomic(buf->pages[last], KM_USER0); 60 pad = *(ptr + offset); 61 kunmap_atomic(ptr, KM_USER0); 62 goto out; 63 } else 64 len -= buf->page_len; 65 BUG_ON(len > buf->tail[0].iov_len); 66 pad = *(u8 *)(buf->tail[0].iov_base + len - 1); 67 out: 68 /* XXX: NOTE: we do not adjust the page lengths--they represent 69 * a range of data in the real filesystem page cache, and we need 70 * to know that range so the xdr code can properly place read data. 71 * However adjusting the head length, as we do above, is harmless. 72 * In the case of a request that fits into a single page, the server 73 * also uses length and head length together to determine the original 74 * start of the request to copy the request for deferal; so it's 75 * easier on the server if we adjust head and tail length in tandem. 76 * It's not really a problem that we don't fool with the page and 77 * tail lengths, though--at worst badly formed xdr might lead the 78 * server to attempt to parse the padding. 79 * XXX: Document all these weird requirements for gss mechanism 80 * wrap/unwrap functions. */ 81 if (pad > blocksize) 82 return -EINVAL; 83 if (buf->len > pad) 84 buf->len -= pad; 85 else 86 return -EINVAL; 87 return 0; 88 } 89 90 static void 91 make_confounder(char *p, u32 conflen) 92 { 93 static u64 i = 0; 94 u64 *q = (u64 *)p; 95 96 /* rfc1964 claims this should be "random". But all that's really 97 * necessary is that it be unique. And not even that is necessary in 98 * our case since our "gssapi" implementation exists only to support 99 * rpcsec_gss, so we know that the only buffers we will ever encrypt 100 * already begin with a unique sequence number. Just to hedge my bets 101 * I'll make a half-hearted attempt at something unique, but ensuring 102 * uniqueness would mean worrying about atomicity and rollover, and I 103 * don't care enough. */ 104 105 /* initialize to random value */ 106 if (i == 0) { 107 i = random32(); 108 i = (i << 32) | random32(); 109 } 110 111 switch (conflen) { 112 case 16: 113 *q++ = i++; 114 /* fall through */ 115 case 8: 116 *q++ = i++; 117 break; 118 default: 119 BUG(); 120 } 121 } 122 123 /* Assumptions: the head and tail of inbuf are ours to play with. 124 * The pages, however, may be real pages in the page cache and we replace 125 * them with scratch pages from **pages before writing to them. */ 126 /* XXX: obviously the above should be documentation of wrap interface, 127 * and shouldn't be in this kerberos-specific file. */ 128 129 /* XXX factor out common code with seal/unseal. */ 130 131 u32 132 gss_wrap_kerberos(struct gss_ctx *ctx, int offset, 133 struct xdr_buf *buf, struct page **pages) 134 { 135 struct krb5_ctx *kctx = ctx->internal_ctx_id; 136 char cksumdata[16]; 137 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 138 int blocksize = 0, plainlen; 139 unsigned char *ptr, *msg_start; 140 s32 now; 141 int headlen; 142 struct page **tmp_pages; 143 u32 seq_send; 144 145 dprintk("RPC: gss_wrap_kerberos\n"); 146 147 now = get_seconds(); 148 149 blocksize = crypto_blkcipher_blocksize(kctx->enc); 150 gss_krb5_add_padding(buf, offset, blocksize); 151 BUG_ON((buf->len - offset) % blocksize); 152 plainlen = blocksize + buf->len - offset; 153 154 headlen = g_token_size(&kctx->mech_used, 24 + plainlen) - 155 (buf->len - offset); 156 157 ptr = buf->head[0].iov_base + offset; 158 /* shift data to make room for header. */ 159 /* XXX Would be cleverer to encrypt while copying. */ 160 /* XXX bounds checking, slack, etc. */ 161 memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); 162 buf->head[0].iov_len += headlen; 163 buf->len += headlen; 164 BUG_ON((buf->len - offset - headlen) % blocksize); 165 166 g_make_token_header(&kctx->mech_used, 167 GSS_KRB5_TOK_HDR_LEN + 8 + plainlen, &ptr); 168 169 170 /* ptr now at header described in rfc 1964, section 1.2.1: */ 171 ptr[0] = (unsigned char) ((KG_TOK_WRAP_MSG >> 8) & 0xff); 172 ptr[1] = (unsigned char) (KG_TOK_WRAP_MSG & 0xff); 173 174 msg_start = ptr + 24; 175 176 *(__be16 *)(ptr + 2) = htons(SGN_ALG_DES_MAC_MD5); 177 memset(ptr + 4, 0xff, 4); 178 *(__be16 *)(ptr + 4) = htons(SEAL_ALG_DES); 179 180 make_confounder(msg_start, blocksize); 181 182 /* XXXJBF: UGH!: */ 183 tmp_pages = buf->pages; 184 buf->pages = pages; 185 if (make_checksum("md5", ptr, 8, buf, 186 offset + headlen - blocksize, &md5cksum)) 187 return GSS_S_FAILURE; 188 buf->pages = tmp_pages; 189 190 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 191 md5cksum.data, md5cksum.len)) 192 return GSS_S_FAILURE; 193 memcpy(ptr + GSS_KRB5_TOK_HDR_LEN, md5cksum.data + md5cksum.len - 8, 8); 194 195 spin_lock(&krb5_seq_lock); 196 seq_send = kctx->seq_send++; 197 spin_unlock(&krb5_seq_lock); 198 199 /* XXX would probably be more efficient to compute checksum 200 * and encrypt at the same time: */ 201 if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, 202 seq_send, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8))) 203 return GSS_S_FAILURE; 204 205 if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, 206 pages)) 207 return GSS_S_FAILURE; 208 209 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 210 } 211 212 u32 213 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) 214 { 215 struct krb5_ctx *kctx = ctx->internal_ctx_id; 216 int signalg; 217 int sealalg; 218 char cksumdata[16]; 219 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 220 s32 now; 221 int direction; 222 s32 seqnum; 223 unsigned char *ptr; 224 int bodysize; 225 void *data_start, *orig_start; 226 int data_len; 227 int blocksize; 228 229 dprintk("RPC: gss_unwrap_kerberos\n"); 230 231 ptr = (u8 *)buf->head[0].iov_base + offset; 232 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 233 buf->len - offset)) 234 return GSS_S_DEFECTIVE_TOKEN; 235 236 if ((ptr[0] != ((KG_TOK_WRAP_MSG >> 8) & 0xff)) || 237 (ptr[1] != (KG_TOK_WRAP_MSG & 0xff))) 238 return GSS_S_DEFECTIVE_TOKEN; 239 240 /* XXX sanity-check bodysize?? */ 241 242 /* get the sign and seal algorithms */ 243 244 signalg = ptr[2] + (ptr[3] << 8); 245 if (signalg != SGN_ALG_DES_MAC_MD5) 246 return GSS_S_DEFECTIVE_TOKEN; 247 248 sealalg = ptr[4] + (ptr[5] << 8); 249 if (sealalg != SEAL_ALG_DES) 250 return GSS_S_DEFECTIVE_TOKEN; 251 252 if ((ptr[6] != 0xff) || (ptr[7] != 0xff)) 253 return GSS_S_DEFECTIVE_TOKEN; 254 255 if (gss_decrypt_xdr_buf(kctx->enc, buf, 256 ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base)) 257 return GSS_S_DEFECTIVE_TOKEN; 258 259 if (make_checksum("md5", ptr, 8, buf, 260 ptr + GSS_KRB5_TOK_HDR_LEN + 8 - (unsigned char *)buf->head[0].iov_base, &md5cksum)) 261 return GSS_S_FAILURE; 262 263 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 264 md5cksum.data, md5cksum.len)) 265 return GSS_S_FAILURE; 266 267 if (memcmp(md5cksum.data + 8, ptr + GSS_KRB5_TOK_HDR_LEN, 8)) 268 return GSS_S_BAD_SIG; 269 270 /* it got through unscathed. Make sure the context is unexpired */ 271 272 now = get_seconds(); 273 274 if (now > kctx->endtime) 275 return GSS_S_CONTEXT_EXPIRED; 276 277 /* do sequencing checks */ 278 279 if (krb5_get_seq_num(kctx->seq, ptr + GSS_KRB5_TOK_HDR_LEN, ptr + 8, 280 &direction, &seqnum)) 281 return GSS_S_BAD_SIG; 282 283 if ((kctx->initiate && direction != 0xff) || 284 (!kctx->initiate && direction != 0)) 285 return GSS_S_BAD_SIG; 286 287 /* Copy the data back to the right position. XXX: Would probably be 288 * better to copy and encrypt at the same time. */ 289 290 blocksize = crypto_blkcipher_blocksize(kctx->enc); 291 data_start = ptr + GSS_KRB5_TOK_HDR_LEN + 8 + blocksize; 292 orig_start = buf->head[0].iov_base + offset; 293 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 294 memmove(orig_start, data_start, data_len); 295 buf->head[0].iov_len -= (data_start - orig_start); 296 buf->len -= (data_start - orig_start); 297 298 if (gss_krb5_remove_padding(buf, blocksize)) 299 return GSS_S_DEFECTIVE_TOKEN; 300 301 return GSS_S_COMPLETE; 302 } 303