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/* $Id: keyproc.c,v 1.18 2022/08/28 18:30:29 tb Exp $ */
/*
* Copyright (c) 2016 Kristaps Dzonsons <kristaps@bsd.lv>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/stat.h>
#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <openssl/pem.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include "extern.h"
#include "key.h"
/*
* This was lifted more or less directly from demos/x509/mkreq.c of the
* OpenSSL source code.
*/
static int
add_ext(STACK_OF(X509_EXTENSION) *sk, int nid, const char *value)
{
X509_EXTENSION *ex;
char *cp;
/*
* XXX: I don't like this at all.
* There's no documentation for X509V3_EXT_conf_nid, so I'm not
* sure if the "value" parameter is ever written to, touched,
* etc.
* The 'official' examples suggest not (they use a string
* literal as the input), but to be safe, I'm doing an
* allocation here and just letting it go.
* This leaks memory, but bounded to the number of SANs.
*/
if ((cp = strdup(value)) == NULL) {
warn("strdup");
return (0);
}
ex = X509V3_EXT_conf_nid(NULL, NULL, nid, cp);
if (ex == NULL) {
warnx("X509V3_EXT_conf_nid");
free(cp);
return (0);
}
sk_X509_EXTENSION_push(sk, ex);
return (1);
}
/*
* Create an X509 certificate from the private key we have on file.
* To do this, we first open the key file, then jail ourselves.
* We then use the crypto library to create the certificate within the
* jail and, on success, ship it to "netsock" as an X509 request.
*/
int
keyproc(int netsock, const char *keyfile, const char **alts, size_t altsz,
enum keytype keytype)
{
char *der64 = NULL, *der = NULL, *dercp;
char *sans = NULL, *san = NULL;
FILE *f;
size_t i, sansz;
void *pp;
EVP_PKEY *pkey = NULL;
X509_REQ *x = NULL;
X509_NAME *name = NULL;
int len, rc = 0, cc, nid, newkey = 0;
mode_t prev;
STACK_OF(X509_EXTENSION) *exts = NULL;
/*
* First, open our private key file read-only or write-only if
* we're creating from scratch.
* Set our umask to be maximally restrictive.
*/
prev = umask((S_IWUSR | S_IXUSR) | S_IRWXG | S_IRWXO);
if ((f = fopen(keyfile, "r")) == NULL && errno == ENOENT) {
f = fopen(keyfile, "wx");
newkey = 1;
}
umask(prev);
if (f == NULL) {
warn("%s", keyfile);
goto out;
}
/* File-system, user, and sandbox jail. */
ERR_load_crypto_strings();
if (pledge("stdio", NULL) == -1) {
warn("pledge");
goto out;
}
if (newkey) {
switch (keytype) {
case KT_ECDSA:
if ((pkey = ec_key_create(f, keyfile)) == NULL)
goto out;
dodbg("%s: generated ECDSA domain key", keyfile);
break;
case KT_RSA:
if ((pkey = rsa_key_create(f, keyfile)) == NULL)
goto out;
dodbg("%s: generated RSA domain key", keyfile);
break;
}
} else {
if ((pkey = key_load(f, keyfile)) == NULL)
goto out;
/* XXX check if domain key type equals configured key type */
doddbg("%s: loaded domain key", keyfile);
}
fclose(f);
f = NULL;
/*
* Generate our certificate from the EVP public key.
* Then set it as the X509 requester's key.
*/
if ((x = X509_REQ_new()) == NULL) {
warnx("X509_REQ_new");
goto out;
} else if (!X509_REQ_set_version(x, 0)) {
warnx("X509_REQ_set_version");
goto out;
} else if (!X509_REQ_set_pubkey(x, pkey)) {
warnx("X509_REQ_set_pubkey");
goto out;
}
/* Now specify the common name that we'll request. */
if ((name = X509_NAME_new()) == NULL) {
warnx("X509_NAME_new");
goto out;
} else if (!X509_NAME_add_entry_by_txt(name, "CN",
MBSTRING_ASC, (u_char *)alts[0], -1, -1, 0)) {
warnx("X509_NAME_add_entry_by_txt: CN=%s", alts[0]);
goto out;
} else if (!X509_REQ_set_subject_name(x, name)) {
warnx("X509_req_set_issuer_name");
goto out;
}
/*
* Now add the SAN extensions.
* This was lifted more or less directly from demos/x509/mkreq.c
* of the OpenSSL source code.
* (The zeroth altname is the domain name.)
* TODO: is this the best way of doing this?
*/
nid = NID_subject_alt_name;
if ((exts = sk_X509_EXTENSION_new_null()) == NULL) {
warnx("sk_X509_EXTENSION_new_null");
goto out;
}
/* Initialise to empty string. */
if ((sans = strdup("")) == NULL) {
warn("strdup");
goto out;
}
sansz = strlen(sans) + 1;
/*
* For each SAN entry, append it to the string.
* We need a single SAN entry for all of the SAN
* domains: NOT an entry per domain!
*/
for (i = 0; i < altsz; i++) {
cc = asprintf(&san, "%sDNS:%s",
i ? "," : "", alts[i]);
if (cc == -1) {
warn("asprintf");
goto out;
}
pp = recallocarray(sans, sansz, sansz + strlen(san), 1);
if (pp == NULL) {
warn("recallocarray");
goto out;
}
sans = pp;
sansz += strlen(san);
strlcat(sans, san, sansz);
free(san);
san = NULL;
}
if (!add_ext(exts, nid, sans)) {
warnx("add_ext");
goto out;
} else if (!X509_REQ_add_extensions(x, exts)) {
warnx("X509_REQ_add_extensions");
goto out;
}
sk_X509_EXTENSION_pop_free(exts, X509_EXTENSION_free);
/* Sign the X509 request using SHA256. */
if (!X509_REQ_sign(x, pkey, EVP_sha256())) {
warnx("X509_sign");
goto out;
}
/* Now, serialise to DER, then base64. */
if ((len = i2d_X509_REQ(x, NULL)) < 0) {
warnx("i2d_X509_REQ");
goto out;
} else if ((der = dercp = malloc(len)) == NULL) {
warn("malloc");
goto out;
} else if (len != i2d_X509_REQ(x, (u_char **)&dercp)) {
warnx("i2d_X509_REQ");
goto out;
} else if ((der64 = base64buf_url(der, len)) == NULL) {
warnx("base64buf_url");
goto out;
}
/*
* Write that we're ready, then write.
* We ignore reader-closed failure, as we're just going to roll
* into the exit case anyway.
*/
if (writeop(netsock, COMM_KEY_STAT, KEY_READY) < 0)
goto out;
if (writestr(netsock, COMM_CERT, der64) < 0)
goto out;
rc = 1;
out:
close(netsock);
if (f != NULL)
fclose(f);
free(der);
free(der64);
free(sans);
free(san);
X509_REQ_free(x);
X509_NAME_free(name);
EVP_PKEY_free(pkey);
ERR_print_errors_fp(stderr);
ERR_free_strings();
return rc;
}
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