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_USER0); 61 pad = *(ptr + offset); 62 kunmap_atomic(ptr, KM_USER0); 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 char cksumdata[16]; 124 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 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 u32 seq_send; 131 132 dprintk("RPC: gss_wrap_kerberos\n"); 133 134 now = get_seconds(); 135 136 blocksize = crypto_blkcipher_blocksize(kctx->enc); 137 gss_krb5_add_padding(buf, offset, blocksize); 138 BUG_ON((buf->len - offset) % blocksize); 139 plainlen = blocksize + buf->len - offset; 140 141 headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - 142 (buf->len - offset); 143 144 ptr = buf->head[0].iov_base + offset; 145 /* shift data to make room for header. */ 146 /* XXX Would be cleverer to encrypt while copying. */ 147 /* XXX bounds checking, slack, etc. */ 148 memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); 149 buf->head[0].iov_len += headlen; 150 buf->len += headlen; 151 BUG_ON((buf->len - offset - headlen) % blocksize); 152 153 g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr); 154 155 156 *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); 157 *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); 158 159 /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ 160 krb5_hdr = ptr - 2; 161 msg_start = krb5_hdr + 24; 162 163 *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5); 164 memset(krb5_hdr + 4, 0xff, 4); 165 *(__be16 *)(krb5_hdr + 4) = htons(SEAL_ALG_DES); 166 167 make_confounder(msg_start, blocksize); 168 169 /* XXXJBF: UGH!: */ 170 tmp_pages = buf->pages; 171 buf->pages = pages; 172 if (make_checksum("md5", krb5_hdr, 8, buf, 173 offset + headlen - blocksize, &md5cksum)) 174 return GSS_S_FAILURE; 175 buf->pages = tmp_pages; 176 177 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 178 md5cksum.data, md5cksum.len)) 179 return GSS_S_FAILURE; 180 memcpy(krb5_hdr + 16, 181 md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, 182 KRB5_CKSUM_LENGTH); 183 184 spin_lock(&krb5_seq_lock); 185 seq_send = kctx->seq_send++; 186 spin_unlock(&krb5_seq_lock); 187 188 /* XXX would probably be more efficient to compute checksum 189 * and encrypt at the same time: */ 190 if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, 191 seq_send, krb5_hdr + 16, krb5_hdr + 8))) 192 return GSS_S_FAILURE; 193 194 if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, 195 pages)) 196 return GSS_S_FAILURE; 197 198 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 199 } 200 201 u32 202 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) 203 { 204 struct krb5_ctx *kctx = ctx->internal_ctx_id; 205 int signalg; 206 int sealalg; 207 char cksumdata[16]; 208 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 209 s32 now; 210 int direction; 211 s32 seqnum; 212 unsigned char *ptr; 213 int bodysize; 214 void *data_start, *orig_start; 215 int data_len; 216 int blocksize; 217 218 dprintk("RPC: gss_unwrap_kerberos\n"); 219 220 ptr = (u8 *)buf->head[0].iov_base + offset; 221 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 222 buf->len - offset)) 223 return GSS_S_DEFECTIVE_TOKEN; 224 225 if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || 226 (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) 227 return GSS_S_DEFECTIVE_TOKEN; 228 229 /* XXX sanity-check bodysize?? */ 230 231 /* get the sign and seal algorithms */ 232 233 signalg = ptr[0] + (ptr[1] << 8); 234 if (signalg != SGN_ALG_DES_MAC_MD5) 235 return GSS_S_DEFECTIVE_TOKEN; 236 237 sealalg = ptr[2] + (ptr[3] << 8); 238 if (sealalg != SEAL_ALG_DES) 239 return GSS_S_DEFECTIVE_TOKEN; 240 241 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 242 return GSS_S_DEFECTIVE_TOKEN; 243 244 if (gss_decrypt_xdr_buf(kctx->enc, buf, 245 ptr + 22 - (unsigned char *)buf->head[0].iov_base)) 246 return GSS_S_DEFECTIVE_TOKEN; 247 248 if (make_checksum("md5", ptr - 2, 8, buf, 249 ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum)) 250 return GSS_S_FAILURE; 251 252 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 253 md5cksum.data, md5cksum.len)) 254 return GSS_S_FAILURE; 255 256 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) 257 return GSS_S_BAD_SIG; 258 259 /* it got through unscathed. Make sure the context is unexpired */ 260 261 now = get_seconds(); 262 263 if (now > kctx->endtime) 264 return GSS_S_CONTEXT_EXPIRED; 265 266 /* do sequencing checks */ 267 268 if (krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, 269 &seqnum)) 270 return GSS_S_BAD_SIG; 271 272 if ((kctx->initiate && direction != 0xff) || 273 (!kctx->initiate && direction != 0)) 274 return GSS_S_BAD_SIG; 275 276 /* Copy the data back to the right position. XXX: Would probably be 277 * better to copy and encrypt at the same time. */ 278 279 blocksize = crypto_blkcipher_blocksize(kctx->enc); 280 data_start = ptr + 22 + blocksize; 281 orig_start = buf->head[0].iov_base + offset; 282 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 283 memmove(orig_start, data_start, data_len); 284 buf->head[0].iov_len -= (data_start - orig_start); 285 buf->len -= (data_start - orig_start); 286 287 if (gss_krb5_remove_padding(buf, blocksize)) 288 return GSS_S_DEFECTIVE_TOKEN; 289 290 return GSS_S_COMPLETE; 291 } 292