1 /* $Id: keyproc.c,v 1.7 2016/09/13 17:13:37 deraadt Exp $ */ 2 /* 3 * Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <sys/stat.h> 19 20 #include <err.h> 21 #include <stdio.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include <unistd.h> 25 26 #include <openssl/pem.h> 27 #include <openssl/err.h> 28 #include <openssl/rand.h> 29 #include <openssl/x509.h> 30 #include <openssl/x509v3.h> 31 32 #include "extern.h" 33 #include "rsa.h" 34 35 /* 36 * This was lifted more or less directly from demos/x509/mkreq.c of the 37 * OpenSSL source code. 38 */ 39 static int 40 add_ext(STACK_OF(X509_EXTENSION) *sk, int nid, const char *value) 41 { 42 X509_EXTENSION *ex; 43 char *cp; 44 45 /* 46 * XXX: I don't like this at all. 47 * There's no documentation for X509V3_EXT_conf_nid, so I'm not 48 * sure if the "value" parameter is ever written to, touched, 49 * etc. 50 * The 'official' examples suggest not (they use a string 51 * literal as the input), but to be safe, I'm doing an 52 * allocation here and just letting it go. 53 * This leaks memory, but bounded to the number of SANs. 54 */ 55 56 if (NULL == (cp = strdup(value))) { 57 warn("strdup"); 58 return (0); 59 } 60 ex = X509V3_EXT_conf_nid(NULL, NULL, nid, cp); 61 if (NULL == ex) { 62 warnx("X509V3_EXT_conf_nid"); 63 free(cp); 64 return (0); 65 } 66 sk_X509_EXTENSION_push(sk, ex); 67 return (1); 68 } 69 70 /* 71 * Create an X509 certificate from the private key we have on file. 72 * To do this, we first open the key file, then jail ourselves. 73 * We then use the crypto library to create the certificate within the 74 * jail and, on success, ship it to "netsock" as an X509 request. 75 */ 76 int 77 keyproc(int netsock, const char *keyfile, 78 const char **alts, size_t altsz, int newkey) 79 { 80 char *der64 = NULL, *der = NULL, *dercp; 81 char *sans = NULL, *san = NULL; 82 FILE *f; 83 size_t i, sansz; 84 void *pp; 85 EVP_PKEY *pkey = NULL; 86 X509_REQ *x = NULL; 87 X509_NAME *name = NULL; 88 int len, rc = 0, cc, nid; 89 mode_t prev; 90 STACK_OF(X509_EXTENSION) *exts = NULL; 91 92 /* 93 * First, open our private key file read-only or write-only if 94 * we're creating from scratch. 95 * Set our umask to be maximally restrictive. 96 */ 97 98 prev = umask((S_IWUSR | S_IXUSR) | S_IRWXG | S_IRWXO); 99 f = fopen(keyfile, newkey ? "wx" : "r"); 100 umask(prev); 101 102 if (NULL == f) { 103 warn("%s", keyfile); 104 goto out; 105 } 106 107 /* File-system, user, and sandbox jail. */ 108 109 ERR_load_crypto_strings(); 110 111 if (pledge("stdio", NULL) == -1) { 112 warn("pledge"); 113 goto out; 114 } 115 116 if (newkey) { 117 if (NULL == (pkey = rsa_key_create(f, keyfile))) 118 goto out; 119 dodbg("%s: generated RSA domain key", keyfile); 120 } else { 121 if (NULL == (pkey = rsa_key_load(f, keyfile))) 122 goto out; 123 doddbg("%s: loaded RSA domain key", keyfile); 124 } 125 126 fclose(f); 127 f = NULL; 128 129 /* 130 * Generate our certificate from the EVP public key. 131 * Then set it as the X509 requester's key. 132 */ 133 134 if (NULL == (x = X509_REQ_new())) { 135 warnx("X509_new"); 136 goto out; 137 } else if (!X509_REQ_set_pubkey(x, pkey)) { 138 warnx("X509_set_pubkey"); 139 goto out; 140 } 141 142 /* Now specify the common name that we'll request. */ 143 144 if (NULL == (name = X509_NAME_new())) { 145 warnx("X509_NAME_new"); 146 goto out; 147 } else if (!X509_NAME_add_entry_by_txt(name, "CN", 148 MBSTRING_ASC, (u_char *)alts[0], -1, -1, 0)) { 149 warnx("X509_NAME_add_entry_by_txt: CN=%s", alts[0]); 150 goto out; 151 } else if (!X509_REQ_set_subject_name(x, name)) { 152 warnx("X509_req_set_issuer_name"); 153 goto out; 154 } 155 156 /* 157 * Now add the SAN extensions. 158 * This was lifted more or less directly from demos/x509/mkreq.c 159 * of the OpenSSL source code. 160 * (The zeroth altname is the domain name.) 161 * TODO: is this the best way of doing this? 162 */ 163 164 if (altsz > 1) { 165 nid = NID_subject_alt_name; 166 if (NULL == (exts = sk_X509_EXTENSION_new_null())) { 167 warnx("sk_X509_EXTENSION_new_null"); 168 goto out; 169 } 170 /* Initialise to empty string. */ 171 if (NULL == (sans = strdup(""))) { 172 warn("strdup"); 173 goto out; 174 } 175 sansz = strlen(sans) + 1; 176 177 /* 178 * For each SAN entry, append it to the string. 179 * We need a single SAN entry for all of the SAN 180 * domains: NOT an entry per domain! 181 */ 182 183 for (i = 1; i < altsz; i++) { 184 cc = asprintf(&san, "%sDNS:%s", 185 i > 1 ? "," : "", alts[i]); 186 if (-1 == cc) { 187 warn("asprintf"); 188 goto out; 189 } 190 pp = realloc(sans, sansz + strlen(san)); 191 if (NULL == pp) { 192 warn("realloc"); 193 goto out; 194 } 195 sans = pp; 196 sansz += strlen(san); 197 strlcat(sans, san, sansz); 198 free(san); 199 san = NULL; 200 } 201 202 if (!add_ext(exts, nid, sans)) { 203 warnx("add_ext"); 204 goto out; 205 } else if (!X509_REQ_add_extensions(x, exts)) { 206 warnx("X509_REQ_add_extensions"); 207 goto out; 208 } 209 sk_X509_EXTENSION_pop_free(exts, X509_EXTENSION_free); 210 } 211 212 /* Sign the X509 request using SHA256. */ 213 214 if (!X509_REQ_sign(x, pkey, EVP_sha256())) { 215 warnx("X509_sign"); 216 goto out; 217 } 218 219 /* Now, serialise to DER, then base64. */ 220 221 if ((len = i2d_X509_REQ(x, NULL)) < 0) { 222 warnx("i2d_X509"); 223 goto out; 224 } else if (NULL == (der = dercp = malloc(len))) { 225 warn("malloc"); 226 goto out; 227 } else if (len != i2d_X509_REQ(x, (u_char **)&dercp)) { 228 warnx("i2d_X509"); 229 goto out; 230 } else if (NULL == (der64 = base64buf_url(der, len))) { 231 warnx("base64buf_url"); 232 goto out; 233 } 234 235 /* 236 * Write that we're ready, then write. 237 * We ignore reader-closed failure, as we're just going to roll 238 * into the exit case anyway. 239 */ 240 241 if (writeop(netsock, COMM_KEY_STAT, KEY_READY) < 0) 242 goto out; 243 if (writestr(netsock, COMM_CERT, der64) < 0) 244 goto out; 245 246 rc = 1; 247 out: 248 close(netsock); 249 if (NULL != f) 250 fclose(f); 251 free(der); 252 free(der64); 253 free(sans); 254 free(san); 255 if (NULL != x) 256 X509_REQ_free(x); 257 if (NULL != name) 258 X509_NAME_free(name); 259 if (NULL != pkey) 260 EVP_PKEY_free(pkey); 261 ERR_print_errors_fp(stderr); 262 ERR_free_strings(); 263 return (rc); 264 } 265