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 inline void 91 make_confounder(char *p, int blocksize) 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 BUG_ON(blocksize != 8); 106 *q = i++; 107 } 108 109 /* Assumptions: the head and tail of inbuf are ours to play with. 110 * The pages, however, may be real pages in the page cache and we replace 111 * them with scratch pages from **pages before writing to them. */ 112 /* XXX: obviously the above should be documentation of wrap interface, 113 * and shouldn't be in this kerberos-specific file. */ 114 115 /* XXX factor out common code with seal/unseal. */ 116 117 u32 118 gss_wrap_kerberos(struct gss_ctx *ctx, int offset, 119 struct xdr_buf *buf, struct page **pages) 120 { 121 struct krb5_ctx *kctx = ctx->internal_ctx_id; 122 char cksumdata[16]; 123 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 124 int blocksize = 0, plainlen; 125 unsigned char *ptr, *krb5_hdr, *msg_start; 126 s32 now; 127 int headlen; 128 struct page **tmp_pages; 129 u32 seq_send; 130 131 dprintk("RPC: gss_wrap_kerberos\n"); 132 133 now = get_seconds(); 134 135 blocksize = crypto_blkcipher_blocksize(kctx->enc); 136 gss_krb5_add_padding(buf, offset, blocksize); 137 BUG_ON((buf->len - offset) % blocksize); 138 plainlen = blocksize + buf->len - offset; 139 140 headlen = g_token_size(&kctx->mech_used, 22 + plainlen) - 141 (buf->len - offset); 142 143 ptr = buf->head[0].iov_base + offset; 144 /* shift data to make room for header. */ 145 /* XXX Would be cleverer to encrypt while copying. */ 146 /* XXX bounds checking, slack, etc. */ 147 memmove(ptr + headlen, ptr, buf->head[0].iov_len - offset); 148 buf->head[0].iov_len += headlen; 149 buf->len += headlen; 150 BUG_ON((buf->len - offset - headlen) % blocksize); 151 152 g_make_token_header(&kctx->mech_used, 22 + plainlen, &ptr); 153 154 155 *ptr++ = (unsigned char) ((KG_TOK_WRAP_MSG>>8)&0xff); 156 *ptr++ = (unsigned char) (KG_TOK_WRAP_MSG&0xff); 157 158 /* ptr now at byte 2 of header described in rfc 1964, section 1.2.1: */ 159 krb5_hdr = ptr - 2; 160 msg_start = krb5_hdr + 24; 161 162 *(__be16 *)(krb5_hdr + 2) = htons(SGN_ALG_DES_MAC_MD5); 163 memset(krb5_hdr + 4, 0xff, 4); 164 *(__be16 *)(krb5_hdr + 4) = htons(SEAL_ALG_DES); 165 166 make_confounder(msg_start, blocksize); 167 168 /* XXXJBF: UGH!: */ 169 tmp_pages = buf->pages; 170 buf->pages = pages; 171 if (make_checksum("md5", krb5_hdr, 8, buf, 172 offset + headlen - blocksize, &md5cksum)) 173 return GSS_S_FAILURE; 174 buf->pages = tmp_pages; 175 176 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 177 md5cksum.data, md5cksum.len)) 178 return GSS_S_FAILURE; 179 memcpy(krb5_hdr + 16, 180 md5cksum.data + md5cksum.len - KRB5_CKSUM_LENGTH, 181 KRB5_CKSUM_LENGTH); 182 183 spin_lock(&krb5_seq_lock); 184 seq_send = kctx->seq_send++; 185 spin_unlock(&krb5_seq_lock); 186 187 /* XXX would probably be more efficient to compute checksum 188 * and encrypt at the same time: */ 189 if ((krb5_make_seq_num(kctx->seq, kctx->initiate ? 0 : 0xff, 190 seq_send, krb5_hdr + 16, krb5_hdr + 8))) 191 return GSS_S_FAILURE; 192 193 if (gss_encrypt_xdr_buf(kctx->enc, buf, offset + headlen - blocksize, 194 pages)) 195 return GSS_S_FAILURE; 196 197 return (kctx->endtime < now) ? GSS_S_CONTEXT_EXPIRED : GSS_S_COMPLETE; 198 } 199 200 u32 201 gss_unwrap_kerberos(struct gss_ctx *ctx, int offset, struct xdr_buf *buf) 202 { 203 struct krb5_ctx *kctx = ctx->internal_ctx_id; 204 int signalg; 205 int sealalg; 206 char cksumdata[16]; 207 struct xdr_netobj md5cksum = {.len = 0, .data = cksumdata}; 208 s32 now; 209 int direction; 210 s32 seqnum; 211 unsigned char *ptr; 212 int bodysize; 213 void *data_start, *orig_start; 214 int data_len; 215 int blocksize; 216 217 dprintk("RPC: gss_unwrap_kerberos\n"); 218 219 ptr = (u8 *)buf->head[0].iov_base + offset; 220 if (g_verify_token_header(&kctx->mech_used, &bodysize, &ptr, 221 buf->len - offset)) 222 return GSS_S_DEFECTIVE_TOKEN; 223 224 if ((*ptr++ != ((KG_TOK_WRAP_MSG>>8)&0xff)) || 225 (*ptr++ != (KG_TOK_WRAP_MSG &0xff)) ) 226 return GSS_S_DEFECTIVE_TOKEN; 227 228 /* XXX sanity-check bodysize?? */ 229 230 /* get the sign and seal algorithms */ 231 232 signalg = ptr[0] + (ptr[1] << 8); 233 if (signalg != SGN_ALG_DES_MAC_MD5) 234 return GSS_S_DEFECTIVE_TOKEN; 235 236 sealalg = ptr[2] + (ptr[3] << 8); 237 if (sealalg != SEAL_ALG_DES) 238 return GSS_S_DEFECTIVE_TOKEN; 239 240 if ((ptr[4] != 0xff) || (ptr[5] != 0xff)) 241 return GSS_S_DEFECTIVE_TOKEN; 242 243 if (gss_decrypt_xdr_buf(kctx->enc, buf, 244 ptr + 22 - (unsigned char *)buf->head[0].iov_base)) 245 return GSS_S_DEFECTIVE_TOKEN; 246 247 if (make_checksum("md5", ptr - 2, 8, buf, 248 ptr + 22 - (unsigned char *)buf->head[0].iov_base, &md5cksum)) 249 return GSS_S_FAILURE; 250 251 if (krb5_encrypt(kctx->seq, NULL, md5cksum.data, 252 md5cksum.data, md5cksum.len)) 253 return GSS_S_FAILURE; 254 255 if (memcmp(md5cksum.data + 8, ptr + 14, 8)) 256 return GSS_S_BAD_SIG; 257 258 /* it got through unscathed. Make sure the context is unexpired */ 259 260 now = get_seconds(); 261 262 if (now > kctx->endtime) 263 return GSS_S_CONTEXT_EXPIRED; 264 265 /* do sequencing checks */ 266 267 if (krb5_get_seq_num(kctx->seq, ptr + 14, ptr + 6, &direction, 268 &seqnum)) 269 return GSS_S_BAD_SIG; 270 271 if ((kctx->initiate && direction != 0xff) || 272 (!kctx->initiate && direction != 0)) 273 return GSS_S_BAD_SIG; 274 275 /* Copy the data back to the right position. XXX: Would probably be 276 * better to copy and encrypt at the same time. */ 277 278 blocksize = crypto_blkcipher_blocksize(kctx->enc); 279 data_start = ptr + 22 + blocksize; 280 orig_start = buf->head[0].iov_base + offset; 281 data_len = (buf->head[0].iov_base + buf->head[0].iov_len) - data_start; 282 memmove(orig_start, data_start, data_len); 283 buf->head[0].iov_len -= (data_start - orig_start); 284 buf->len -= (data_start - orig_start); 285 286 if (gss_krb5_remove_padding(buf, blocksize)) 287 return GSS_S_DEFECTIVE_TOKEN; 288 289 return GSS_S_COMPLETE; 290 } 291