Return to ocspcheck.c CVS log

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Convert libressl to use the BoringSSL style time conversions

This gets rid of our last uses of timegm and gmtime in the
library and things that ship with it. It includes a bit
of refactoring in ocsp_cl.c to remove some obvious ugly.

ok tb@

/* $OpenBSD: ocspcheck.c,v 1.33 2024/03/24 11:30:12 beck Exp $ */

/*
 * Copyright (c) 2017,2020 Bob Beck <beck@openbsd.org>
 *
 * 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 <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/stat.h>

#include <err.h>
#include <fcntl.h>
#include <limits.h>
#include <netdb.h>
#include <poll.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include <openssl/err.h>
#include <openssl/ocsp.h>
#include <openssl/posix_time.h>
#include <openssl/ssl.h>

#include "http.h"

#define MAXAGE_SEC (14*24*60*60)
#define JITTER_SEC (60)
#define OCSP_MAX_RESPONSE_SIZE (20480)

typedef struct ocsp_request {
	STACK_OF(X509) *fullchain;
	OCSP_REQUEST *req;
	char *url;
	unsigned char *data;
	size_t size;
	int nonce;
} ocsp_request;

int verbose;
#define vspew(fmt, ...) \
	do { if (verbose >= 1) fprintf(stderr, fmt, __VA_ARGS__); } while (0)
#define dspew(fmt, ...) \
	do { if (verbose >= 2) fprintf(stderr, fmt, __VA_ARGS__); } while (0)

#define MAX_SERVERS_DNS 8

struct addr {
	int	 family; /* 4 for PF_INET, 6 for PF_INET6 */
	char	 ip[INET6_ADDRSTRLEN];
};

static ssize_t
host_dns(const char *s, struct addr vec[MAX_SERVERS_DNS])
{
	struct addrinfo		 hints, *res0, *res;
	int			 error;
	ssize_t			 vecsz;
	struct sockaddr		*sa;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM; /* DUMMY */

	error = getaddrinfo(s, NULL, &hints, &res0);

	if (error == EAI_AGAIN ||
#ifdef EAI_NODATA
	    error == EAI_NODATA ||
#endif
	    error == EAI_NONAME)
		return 0;

	if (error) {
		warnx("%s: parse error: %s", s, gai_strerror(error));
		return -1;
	}

	for (vecsz = 0, res = res0;
	    res != NULL && vecsz < MAX_SERVERS_DNS;
	    res = res->ai_next) {
		if (res->ai_family != AF_INET &&
		    res->ai_family != AF_INET6)
			continue;

		sa = res->ai_addr;

		if (res->ai_family == AF_INET) {
			vec[vecsz].family = 4;
			inet_ntop(AF_INET,
			    &(((struct sockaddr_in *)sa)->sin_addr),
				vec[vecsz].ip, INET6_ADDRSTRLEN);
		} else {
			vec[vecsz].family = 6;
			inet_ntop(AF_INET6,
			    &(((struct sockaddr_in6 *)sa)->sin6_addr),
			    vec[vecsz].ip, INET6_ADDRSTRLEN);
		}

		dspew("DNS returns %s for %s\n", vec[vecsz].ip, s);
		vecsz++;
	}

	freeaddrinfo(res0);
	return vecsz;
}

/*
 * Extract the domain and port from a URL.
 * The url must be formatted as schema://address[/stuff].
 * This returns NULL on failure.
 */
static char *
url2host(const char *host, short *port, char **path)
{
	char	*url, *ep;

	/* We only understand HTTP and HTTPS. */

	if (strncmp(host, "https://", 8) == 0) {
		*port = 443;
		if ((url = strdup(host + 8)) == NULL) {
			warn("strdup");
			return (NULL);
		}
	} else if (strncmp(host, "http://", 7) == 0) {
		*port = 80;
		if ((url = strdup(host + 7)) == NULL) {
			warn("strdup");
			return (NULL);
		}
	} else {
		warnx("%s: unknown schema", host);
		return (NULL);
	}

	/* Terminate path part. */

	if ((ep = strchr(url, '/')) != NULL) {
		*path = strdup(ep);
		*ep = '\0';
	} else
		*path = strdup("/");

	if (*path == NULL) {
		warn("strdup");
		free(url);
		return (NULL);
	}

	/* Check to see if there is a port in the url */
	if ((ep = strchr(url, ':')) != NULL) {
		const char *errstr;
		short pp;
		pp = strtonum(ep + 1, 1, SHRT_MAX, &errstr);
		if (errstr != NULL) {
			warnx("error parsing port from '%s': %s", url, errstr);
			free(url);
			free(*path);
			return NULL;
		}
		*port = pp;
		*ep = '\0';
	}

	return (url);
}

static time_t
parse_ocsp_time(ASN1_GENERALIZEDTIME *gt)
{
	struct tm tm;
	time_t rv = -1;

	if (gt == NULL)
		return -1;
	/* RFC 6960 specifies that all times in OCSP must be GENERALIZEDTIME */
	if (!ASN1_GENERALIZEDTIME_check(gt))
		return -1;
	if (!ASN1_TIME_to_tm(gt, &tm))
		return -1;
	if (!OPENSSL_timegm(&tm, &rv))
		return -1;
	return rv;
}

static X509_STORE *
read_cacerts(const char *file, const char *dir)
{
	X509_STORE *store = NULL;
	X509_LOOKUP *lookup;

	if (file == NULL && dir == NULL) {
		warnx("No CA certs to load");
		goto end;
	}
	if ((store = X509_STORE_new()) == NULL) {
		warnx("Malloc failed");
		goto end;
	}
	if (file != NULL) {
		if ((lookup = X509_STORE_add_lookup(store,
		    X509_LOOKUP_file())) == NULL) {
			warnx("Unable to load CA cert file");
			goto end;
		}
		if (!X509_LOOKUP_load_file(lookup, file, X509_FILETYPE_PEM)) {
			warnx("Unable to load CA certs from file %s", file);
			goto end;
		}
	}
	if (dir != NULL) {
		if ((lookup = X509_STORE_add_lookup(store,
		    X509_LOOKUP_hash_dir())) == NULL) {
			warnx("Unable to load CA cert directory");
			goto end;
		}
		if (!X509_LOOKUP_add_dir(lookup, dir, X509_FILETYPE_PEM)) {
			warnx("Unable to load CA certs from directory %s", dir);
			goto end;
		}
	}
	return store;

 end:
	X509_STORE_free(store);
	return NULL;
}

static STACK_OF(X509) *
read_fullchain(const char *file, int *count)
{
	int i;
	BIO *bio;
	STACK_OF(X509_INFO) *xis = NULL;
	X509_INFO *xi;
	STACK_OF(X509) *rv = NULL;

	*count = 0;

	if ((bio = BIO_new_file(file, "r")) == NULL) {
		warn("Unable to read a certificate from %s", file);
		goto end;
	}
	if ((xis = PEM_X509_INFO_read_bio(bio, NULL, NULL, NULL)) == NULL) {
		warnx("Unable to read PEM format from %s", file);
		goto end;
	}
	if (sk_X509_INFO_num(xis) <= 0) {
		warnx("No certificates in file %s", file);
		goto end;
	}
	if ((rv = sk_X509_new_null()) == NULL) {
		warnx("malloc failed");
		goto end;
	}

	for (i = 0; i < sk_X509_INFO_num(xis); i++) {
		xi = sk_X509_INFO_value(xis, i);
		if (xi->x509 == NULL)
			continue;
		if (!sk_X509_push(rv, xi->x509)) {
			warnx("unable to build x509 chain");
			sk_X509_pop_free(rv, X509_free);
			rv = NULL;
			goto end;
		}
		xi->x509 = NULL;
		(*count)++;
	}
 end:
	BIO_free(bio);
	sk_X509_INFO_pop_free(xis, X509_INFO_free);
	return rv;
}

static inline X509 *
cert_from_chain(STACK_OF(X509) *fullchain)
{
	return sk_X509_value(fullchain, 0);
}

static const X509 *
issuer_from_chain(STACK_OF(X509) *fullchain)
{
	const X509 *cert;
	X509_NAME *issuer_name;

	cert = cert_from_chain(fullchain);
	if ((issuer_name = X509_get_issuer_name(cert)) == NULL)
		return NULL;

	return X509_find_by_subject(fullchain, issuer_name);
}

static ocsp_request *
ocsp_request_new_from_cert(const char *cadir, char *file, int nonce)
{
	X509 *cert;
	int count = 0;
	OCSP_CERTID *id = NULL;
	ocsp_request *request = NULL;
	const EVP_MD *cert_id_md = NULL;
	const X509 *issuer;
	STACK_OF(OPENSSL_STRING) *urls = NULL;

	if ((request = calloc(1, sizeof(ocsp_request))) == NULL) {
		warn("malloc");
		goto err;
	}

	if ((request->req = OCSP_REQUEST_new()) == NULL)
		goto err;

	request->fullchain = read_fullchain(file, &count);
	if (cadir == NULL) {
		/* Drop rpath from pledge, we don't need to read anymore */
		if (pledge("stdio inet dns", NULL) == -1)
			err(1, "pledge");
	}
	if (request->fullchain == NULL) {
		warnx("Unable to read cert chain from file %s", file);
		goto err;
	}
	if (count <= 1) {
		warnx("File %s does not contain a cert chain", file);
		goto err;
	}
	if ((cert = cert_from_chain(request->fullchain)) == NULL) {
		warnx("No certificate found in %s", file);
		goto err;
	}
	if ((issuer = issuer_from_chain(request->fullchain)) == NULL) {
		warnx("Unable to find issuer for cert in %s", file);
		goto err;
	}

	urls = X509_get1_ocsp(cert);
	if (urls == NULL || sk_OPENSSL_STRING_num(urls) <= 0) {
		warnx("Certificate in %s contains no OCSP url", file);
		goto err;
	}
	if ((request->url = strdup(sk_OPENSSL_STRING_value(urls, 0))) == NULL)
		goto err;
	X509_email_free(urls);
	urls = NULL;

	cert_id_md = EVP_sha1(); /* XXX. This sucks but OCSP is poopy */
	if ((id = OCSP_cert_to_id(cert_id_md, cert, issuer)) == NULL) {
		warnx("Unable to get certificate id from cert in %s", file);
		goto err;
	}
	if (OCSP_request_add0_id(request->req, id) == NULL) {
		warnx("Unable to add certificate id to request");
		goto err;
	}
	id = NULL;

	request->nonce = nonce;
	if (request->nonce)
		OCSP_request_add1_nonce(request->req, NULL, -1);

	if ((request->size = i2d_OCSP_REQUEST(request->req,
	    &request->data)) <= 0) {
		warnx("Unable to encode ocsp request");
		goto err;
	}
	if (request->data == NULL) {
		warnx("Unable to allocate memory");
		goto err;
	}
	return request;

 err:
	if (request != NULL) {
		sk_X509_pop_free(request->fullchain, X509_free);
		free(request->url);
		OCSP_REQUEST_free(request->req);
		free(request->data);
	}
	X509_email_free(urls);
	OCSP_CERTID_free(id);
	free(request);
	return NULL;
}


int
validate_response(char *buf, size_t size, ocsp_request *request,
    X509_STORE *store, char *host, char *file)
{
	ASN1_GENERALIZEDTIME *revtime = NULL, *thisupd = NULL, *nextupd = NULL;
	const unsigned char **p = (const unsigned char **)&buf;
	int status, cert_status = 0, crl_reason = 0;
	time_t now, rev_t = -1, this_t, next_t;
	OCSP_RESPONSE *resp = NULL;
	OCSP_BASICRESP *bresp = NULL;
	OCSP_CERTID *cid = NULL;
	const X509 *cert, *issuer;
	int ret = 0;

	if ((cert = cert_from_chain(request->fullchain)) == NULL) {
		warnx("No certificate found in %s", file);
		goto err;
	}
	if ((issuer = issuer_from_chain(request->fullchain)) == NULL) {
		warnx("Unable to find certificate issuer for cert in %s", file);
		goto err;
	}
	if ((cid = OCSP_cert_to_id(NULL, cert, issuer)) == NULL) {
		warnx("Unable to get issuer cert/CID in %s", file);
		goto err;
	}

	if ((resp = d2i_OCSP_RESPONSE(NULL, p, size)) == NULL) {
		warnx("OCSP response unserializable from host %s", host);
		goto err;
	}

	if ((bresp = OCSP_response_get1_basic(resp)) == NULL) {
		warnx("Failed to load OCSP response from %s", host);
		goto err;
	}

	if (OCSP_basic_verify(bresp, request->fullchain, store,
		OCSP_TRUSTOTHER) != 1) {
		warnx("OCSP verify failed from %s", host);
		goto err;
	}
	dspew("OCSP response signature validated from %s\n", host);

	status = OCSP_response_status(resp);
	if (status != OCSP_RESPONSE_STATUS_SUCCESSFUL) {
		warnx("OCSP Failure: code %d (%s) from host %s",
		    status, OCSP_response_status_str(status), host);
		goto err;
	}
	dspew("OCSP response status %d from host %s\n", status, host);

	/* Check the nonce if we sent one */

	if (request->nonce) {
		if (OCSP_check_nonce(request->req, bresp) <= 0) {
			warnx("No OCSP nonce, or mismatch, from host %s", host);
			goto err;
		}
	}

	if (OCSP_resp_find_status(bresp, cid, &cert_status, &crl_reason,
	    &revtime, &thisupd, &nextupd) != 1) {
		warnx("OCSP verify failed: no result for cert");
		goto err;
	}

	if (revtime && (rev_t = parse_ocsp_time(revtime)) == -1) {
		warnx("Unable to parse revocation time in OCSP reply");
		goto err;
	}
	/*
	 * Belt and suspenders, Treat it as revoked if there is either
	 * a revocation time, or status revoked.
	 */
	if (rev_t != -1 || cert_status == V_OCSP_CERTSTATUS_REVOKED) {
		warnx("Invalid OCSP reply: certificate is revoked");
		if (rev_t != -1)
			warnx("Certificate revoked at: %s", ctime(&rev_t));
		goto err;
	}
	if ((this_t = parse_ocsp_time(thisupd)) == -1) {
		warnx("unable to parse this update time in OCSP reply");
		goto err;
	}
	if ((next_t = parse_ocsp_time(nextupd)) == -1) {
		warnx("unable to parse next update time in OCSP reply");
		goto err;
	}

	/* Don't allow this update to precede next update */
	if (this_t >= next_t) {
		warnx("Invalid OCSP reply: this update >= next update");
		goto err;
	}

	now = time(NULL);
	/*
	 * Check that this update is not more than JITTER seconds
	 * in the future.
	 */
	if (this_t > now + JITTER_SEC) {
		warnx("Invalid OCSP reply: this update is in the future at %s",
		    ctime(&this_t));
		goto err;
	}

	/*
	 * Check that this update is not more than MAXSEC
	 * in the past.
	 */
	if (this_t < now - MAXAGE_SEC) {
		warnx("Invalid OCSP reply: this update is too old %s",
		    ctime(&this_t));
		goto err;
	}

	/*
	 * Check that next update is still valid
	 */
	if (next_t < now - JITTER_SEC) {
		warnx("Invalid OCSP reply: reply has expired at %s",
		    ctime(&next_t));
		goto err;
	}

	vspew("OCSP response validated from %s\n", host);
	vspew("	   This Update: %s", ctime(&this_t));
	vspew("	   Next Update: %s", ctime(&next_t));
	ret = 1;
 err:
	OCSP_RESPONSE_free(resp);
	OCSP_BASICRESP_free(bresp);
	OCSP_CERTID_free(cid);
	return ret;
}

static void
usage(void)
{
	fprintf(stderr,
	    "usage: ocspcheck [-Nv] [-C CAfile] [-i staplefile] "
	    "[-o staplefile] file\n");
	exit(1);
}

int
main(int argc, char **argv)
{
	const char *cafile = NULL, *cadir = NULL;
	char *host = NULL, *path = NULL, *certfile = NULL, *outfile = NULL,
	    *instaple = NULL, *infile = NULL;
	struct addr addrs[MAX_SERVERS_DNS] = {{0}};
	struct source sources[MAX_SERVERS_DNS];
	int i, ch, staplefd = -1, infd = -1, nonce = 1;
	ocsp_request *request = NULL;
	size_t rescount, httphsz = 0, instaplesz = 0;
	struct httphead	*httph = NULL;
	struct httpget *hget;
	X509_STORE *castore;
	ssize_t written, w;
	short port;

	while ((ch = getopt(argc, argv, "C:i:No:v")) != -1) {
		switch (ch) {
		case 'C':
			cafile = optarg;
			break;
		case 'N':
			nonce = 0;
			break;
		case 'o':
			outfile = optarg;
			break;
		case 'i':
			infile = optarg;
			break;
		case 'v':
			verbose++;
			break;
		default:
			usage();
		}
	}
	argc -= optind;
	argv += optind;

	if (argc != 1 || (certfile = argv[0]) == NULL)
		usage();

	if (outfile != NULL) {
		if (strcmp(outfile, "-") == 0)
			staplefd = STDOUT_FILENO;
		else
			staplefd = open(outfile, O_WRONLY|O_CREAT,
			    S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH);
		if (staplefd < 0)
			err(1, "Unable to open output file %s", outfile);
	}

	if (infile != NULL) {
		if (strcmp(infile, "-") == 0)
			infd = STDIN_FILENO;
		else
			infd = open(infile, O_RDONLY);
		if (infd < 0)
			err(1, "Unable to open input file %s", infile);
		nonce = 0; /* Can't validate a nonce on a saved reply */
	}

	if (cafile == NULL) {
		if (access(X509_get_default_cert_file(), R_OK) == 0)
			cafile = X509_get_default_cert_file();
		if (access(X509_get_default_cert_dir(), F_OK) == 0)
			cadir = X509_get_default_cert_dir();
	}

	if (cafile != NULL) {
		if (unveil(cafile, "r") == -1)
			err(1, "unveil %s", cafile);
	}
	if (cadir != NULL) {
		if (unveil(cadir, "r") == -1)
			err(1, "unveil %s", cadir);
	}
	if (unveil(certfile, "r") == -1)
		err(1, "unveil %s", certfile);

	if (pledge("stdio inet rpath dns", NULL) == -1)
		err(1, "pledge");

	/*
	 * Load our certificate and keystore, and build up an
	 * OCSP request based on the full certificate chain
	 * we have been given to check.
	 */
	if ((castore = read_cacerts(cafile, cadir)) == NULL)
		exit(1);
	if ((request = ocsp_request_new_from_cert(cadir, certfile, nonce))
	    == NULL)
		exit(1);

	dspew("Built an %zu byte ocsp request\n", request->size);

	if ((host = url2host(request->url, &port, &path)) == NULL)
		errx(1, "Invalid OCSP url %s from %s", request->url,
		    certfile);

	if (infd == -1) {
		/* Get a new OCSP response from the indicated server */

		vspew("Using %s to host %s, port %d, path %s\n",
		    port == 443 ? "https" : "http", host, port, path);

		rescount = host_dns(host, addrs);
		for (i = 0; i < rescount; i++) {
			sources[i].ip = addrs[i].ip;
			sources[i].family = addrs[i].family;
		}

		/*
		 * Do an HTTP post to send our request to the OCSP
		 * server, and hopefully get an answer back
		 */
		hget = http_get(sources, rescount, host, port, path,
		    request->data, request->size);
		if (hget == NULL)
			errx(1, "http_get");
		/*
		 * Pledge minimally before fiddling with libcrypto init
		 * routines and parsing untrusted input from someone's OCSP
		 * server.
		 */
		if (cadir == NULL) {
			if (pledge("stdio", NULL) == -1)
				err(1, "pledge");
		} else {
			if (pledge("stdio rpath", NULL) == -1)
				err(1, "pledge");
		}

		dspew("Server at %s returns:\n", host);
		for (i = 0; i < httphsz; i++)
			dspew("	  [%s]=[%s]\n", httph[i].key, httph[i].val);
		dspew("	  [Body]=[%zu bytes]\n", hget->bodypartsz);
		if (hget->bodypartsz <= 0)
			errx(1, "No body in reply from %s", host);

		if (hget->code != 200)
			errx(1, "http reply code %d from %s", hget->code, host);

		/*
		 * Validate the OCSP response we got back
		 */
		OPENSSL_add_all_algorithms_noconf();
		if (!validate_response(hget->bodypart, hget->bodypartsz,
			request, castore, host, certfile))
			exit(1);
		instaple = hget->bodypart;
		instaplesz = hget->bodypartsz;
	} else {
		size_t nr = 0;
		instaplesz = 0;

		/*
		 * Pledge minimally before fiddling with libcrypto init
		 */
		if (cadir == NULL) {
			if (pledge("stdio", NULL) == -1)
				err(1, "pledge");
		} else {
			if (pledge("stdio rpath", NULL) == -1)
				err(1, "pledge");
		}

		dspew("Using ocsp response saved in %s:\n", infile);

		/* Use the existing OCSP response saved in infd */
		instaple = calloc(OCSP_MAX_RESPONSE_SIZE, 1);
		if (instaple) {
			while ((nr = read(infd, instaple + instaplesz,
			    OCSP_MAX_RESPONSE_SIZE - instaplesz)) != -1 &&
			    nr != 0)
				instaplesz += nr;
		}
		if (instaplesz == 0)
			exit(1);
		/*
		 * Validate the OCSP staple we read in.
		 */
		OPENSSL_add_all_algorithms_noconf();
		if (!validate_response(instaple, instaplesz,
			request, castore, host, certfile))
			exit(1);
	}

	/*
	 * If we have been given a place to save a staple,
	 * write out the DER format response to the staplefd
	 */
	if (staplefd >= 0) {
		while (ftruncate(staplefd, 0) < 0) {
			if (errno == EINVAL)
				break;
			if (errno != EINTR && errno != EAGAIN)
				err(1, "Write of OCSP response failed");
		}
		written = 0;
		while (written < instaplesz) {
			w = write(staplefd, instaple + written,
			    instaplesz - written);
			if (w == -1) {
				if (errno != EINTR && errno != EAGAIN)
					err(1, "Write of OCSP response failed");
			} else
				written += w;
		}
		close(staplefd);
	}
	exit(0);
}