diff options
Diffstat (limited to 'src/openssl.c')
| -rw-r--r-- | src/openssl.c | 1056 |
1 files changed, 1056 insertions, 0 deletions
diff --git a/src/openssl.c b/src/openssl.c new file mode 100644 index 0000000..73e7f0f --- /dev/null +++ b/src/openssl.c @@ -0,0 +1,1056 @@ +/* SSL support via OpenSSL library. + Copyright (C) 2000-2012, 2015, 2018 Free Software Foundation, Inc. + Originally contributed by Christian Fraenkel. + +This file is part of GNU Wget. + +GNU Wget is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 3 of the License, or +(at your option) any later version. + +GNU Wget is distributed in the hope that it will be useful, +but WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +GNU General Public License for more details. + +You should have received a copy of the GNU General Public License +along with Wget. If not, see <http://www.gnu.org/licenses/>. + +Additional permission under GNU GPL version 3 section 7 + +If you modify this program, or any covered work, by linking or +combining it with the OpenSSL project's OpenSSL library (or a +modified version of that library), containing parts covered by the +terms of the OpenSSL or SSLeay licenses, the Free Software Foundation +grants you additional permission to convey the resulting work. +Corresponding Source for a non-source form of such a combination +shall include the source code for the parts of OpenSSL used as well +as that of the covered work. */ + +#include "wget.h" + +#include <assert.h> +#include <errno.h> +#include <unistd.h> +#include <string.h> +#include <xalloc.h> + +#include <openssl/ssl.h> +#include <openssl/x509v3.h> +#include <openssl/err.h> +#include <openssl/rand.h> +#include <openssl/bio.h> +#if OPENSSL_VERSION_NUMBER >= 0x00907000 +#include <openssl/conf.h> +#ifndef OPENSSL_NO_ENGINE +#include <openssl/engine.h> +#endif +#endif + +#include "utils.h" +#include "connect.h" +#include "url.h" +#include "ssl.h" + +#ifdef WINDOWS +# include <w32sock.h> +#endif + +/* Application-wide SSL context. This is common to all SSL + connections. */ +static SSL_CTX *ssl_ctx; + +/* Initialize the SSL's PRNG using various methods. */ + +static void +init_prng (void) +{ + char namebuf[256]; + const char *random_file; + + /* Seed from a file specified by the user. This will be the file + specified with --random-file, $RANDFILE, if set, or ~/.rnd, if it + exists. */ + if (opt.random_file) + random_file = opt.random_file; + else + { + /* Get the random file name using RAND_file_name. */ + namebuf[0] = '\0'; + random_file = RAND_file_name (namebuf, sizeof (namebuf)); + } + + if (random_file && *random_file) + /* Seed at most 16k (apparently arbitrary value borrowed from + curl) from random file. */ + RAND_load_file (random_file, 16384); + +#ifdef HAVE_RAND_EGD + /* Get random data from EGD if opt.egd_file was used. */ + if (opt.egd_file && *opt.egd_file) + RAND_egd (opt.egd_file); +#endif + +#ifdef WINDOWS + /* Under Windows, we can try to seed the PRNG using screen content. + This may or may not work, depending on whether we'll calling Wget + interactively. */ + + RAND_screen (); + if (RAND_status ()) + return; +#endif + +#if 0 /* don't do this by default */ + { + int maxrand = 500; + + /* Still not random enough, presumably because neither /dev/random + nor EGD were available. Try to seed OpenSSL's PRNG with libc + PRNG. This is cryptographically weak and defeats the purpose + of using OpenSSL, which is why it is highly discouraged. */ + + logprintf (LOG_NOTQUIET, _("WARNING: using a weak random seed.\n")); + + while (RAND_status () == 0 && maxrand-- > 0) + { + unsigned char rnd = random_number (256); + RAND_seed (&rnd, sizeof (rnd)); + } + } +#endif +} + +/* Print errors in the OpenSSL error stack. */ + +static void +print_errors (void) +{ + unsigned long err; + while ((err = ERR_get_error ()) != 0) + logprintf (LOG_NOTQUIET, "OpenSSL: %s\n", ERR_error_string (err, NULL)); +} + +/* Convert keyfile type as used by options.h to a type as accepted by + SSL_CTX_use_certificate_file and SSL_CTX_use_PrivateKey_file. + + (options.h intentionally doesn't use values from openssl/ssl.h so + it doesn't depend specifically on OpenSSL for SSL functionality.) */ + +static int +key_type_to_ssl_type (enum keyfile_type type) +{ + switch (type) + { + case keyfile_pem: + return SSL_FILETYPE_PEM; + case keyfile_asn1: + return SSL_FILETYPE_ASN1; + default: + abort (); + } +} + +/* SSL has been initialized */ +static int ssl_true_initialized = 0; + +/* Create an SSL Context and set default paths etc. Called the first + time an HTTP download is attempted. + + Returns true on success, false otherwise. */ + +bool +ssl_init (void) +{ + SSL_METHOD const *meth; + long ssl_options = 0; + char *ciphers_string = NULL; +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) + int ssl_proto_version = 0; +#endif + +#if OPENSSL_VERSION_NUMBER >= 0x00907000 + if (ssl_true_initialized == 0) + { +#if OPENSSL_API_COMPAT < 0x10100000L + OPENSSL_config (NULL); +#endif + ssl_true_initialized = 1; + } +#endif + + if (ssl_ctx) + /* The SSL has already been initialized. */ + return true; + + /* Init the PRNG. If that fails, bail out. */ + init_prng (); + if (RAND_status () != 1) + { + logprintf (LOG_NOTQUIET, + _("Could not seed PRNG; consider using --random-file.\n")); + goto error; + } + +#if OPENSSL_VERSION_NUMBER >= 0x00907000 + OPENSSL_load_builtin_modules(); +#ifndef OPENSSL_NO_ENGINE + ENGINE_load_builtin_engines(); +#endif + CONF_modules_load_file(NULL, NULL, + CONF_MFLAGS_DEFAULT_SECTION|CONF_MFLAGS_IGNORE_MISSING_FILE); +#endif +#if OPENSSL_API_COMPAT >= 0x10100000L + OPENSSL_init_ssl(0, NULL); +#else + SSL_library_init (); + SSL_load_error_strings (); +#endif +#if OPENSSL_VERSION_NUMBER < 0x10100000L + SSLeay_add_all_algorithms (); + SSLeay_add_ssl_algorithms (); +#endif + + switch (opt.secure_protocol) + { +#if !defined OPENSSL_NO_SSL2 && OPENSSL_VERSION_NUMBER < 0x10100000L + case secure_protocol_sslv2: + meth = SSLv2_client_method (); + break; +#endif + +#ifndef OPENSSL_NO_SSL3_METHOD + case secure_protocol_sslv3: + meth = SSLv3_client_method (); + break; +#endif + + case secure_protocol_auto: + case secure_protocol_pfs: + meth = SSLv23_client_method (); + ssl_options |= SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; + break; + case secure_protocol_tlsv1: +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) + meth = TLS_client_method(); + ssl_proto_version = TLS1_VERSION; +#else + meth = TLSv1_client_method (); +#endif + break; + +#if OPENSSL_VERSION_NUMBER >= 0x10001000 + case secure_protocol_tlsv1_1: +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) + meth = TLS_client_method(); + ssl_proto_version = TLS1_1_VERSION; +#else + meth = TLSv1_1_client_method (); +#endif + break; + + case secure_protocol_tlsv1_2: +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) + meth = TLS_client_method(); + ssl_proto_version = TLS1_2_VERSION; +#else + meth = TLSv1_2_client_method (); +#endif + break; + + case secure_protocol_tlsv1_3: +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) && defined TLS1_3_VERSION + meth = TLS_client_method(); + ssl_proto_version = TLS1_3_VERSION; +#else + logprintf (LOG_NOTQUIET, _("Your OpenSSL version is too old to support TLS 1.3\n")); + goto error; +#endif + break; +#else + case secure_protocol_tlsv1_1: + logprintf (LOG_NOTQUIET, _("Your OpenSSL version is too old to support TLSv1.1\n")); + goto error; + + case secure_protocol_tlsv1_2: + logprintf (LOG_NOTQUIET, _("Your OpenSSL version is too old to support TLSv1.2\n")); + goto error; + +#endif + + default: + logprintf (LOG_NOTQUIET, _("OpenSSL: unimplemented 'secure-protocol' option value %d\n"), opt.secure_protocol); + logprintf (LOG_NOTQUIET, _("Please report this issue to bug-wget@gnu.org\n")); + abort (); + } + + /* The type cast below accommodates older OpenSSL versions (0.9.8) + where SSL_CTX_new() is declared without a "const" argument. */ + ssl_ctx = SSL_CTX_new ((SSL_METHOD *)meth); + if (!ssl_ctx) + goto error; + + if (ssl_options) + SSL_CTX_set_options (ssl_ctx, ssl_options); + +#if !defined(LIBRESSL_VERSION_NUMBER) && (OPENSSL_VERSION_NUMBER >= 0x10100000L) + if (ssl_proto_version) + SSL_CTX_set_min_proto_version(ssl_ctx, ssl_proto_version); +#endif + + /* OpenSSL ciphers: https://www.openssl.org/docs/apps/ciphers.html + * + * Rules: + * 1. --ciphers overrides everything + * 2. We allow RSA key exchange by default (secure_protocol_auto) + * 3. We disallow RSA key exchange if PFS was requested (secure_protocol_pfs) + */ + if (!opt.tls_ciphers_string) + { + if (opt.secure_protocol == secure_protocol_auto) + ciphers_string = "HIGH:!aNULL:!RC4:!MD5:!SRP:!PSK"; + else if (opt.secure_protocol == secure_protocol_pfs) + ciphers_string = "HIGH:!aNULL:!RC4:!MD5:!SRP:!PSK:!kRSA"; + } + else + { + ciphers_string = opt.tls_ciphers_string; + } + + if (ciphers_string && !SSL_CTX_set_cipher_list(ssl_ctx, ciphers_string)) + { + logprintf(LOG_NOTQUIET, _("OpenSSL: Invalid cipher list: %s\n"), ciphers_string); + goto error; + } + + SSL_CTX_set_default_verify_paths (ssl_ctx); + SSL_CTX_load_verify_locations (ssl_ctx, opt.ca_cert, opt.ca_directory); + + if (opt.crl_file) + { + X509_STORE *store = SSL_CTX_get_cert_store (ssl_ctx); + X509_LOOKUP *lookup; + + if (!(lookup = X509_STORE_add_lookup (store, X509_LOOKUP_file ())) + || (!X509_load_crl_file (lookup, opt.crl_file, X509_FILETYPE_PEM))) + goto error; + + X509_STORE_set_flags (store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL); + } + + /* SSL_VERIFY_NONE instructs OpenSSL not to abort SSL_connect if the + certificate is invalid. We verify the certificate separately in + ssl_check_certificate, which provides much better diagnostics + than examining the error stack after a failed SSL_connect. */ + SSL_CTX_set_verify (ssl_ctx, SSL_VERIFY_NONE, NULL); + + /* Use the private key from the cert file unless otherwise specified. */ + if (opt.cert_file && !opt.private_key) + { + opt.private_key = xstrdup (opt.cert_file); + opt.private_key_type = opt.cert_type; + } + + /* Use cert from private key file unless otherwise specified. */ + if (opt.private_key && !opt.cert_file) + { + opt.cert_file = xstrdup (opt.private_key); + opt.cert_type = opt.private_key_type; + } + + if (opt.cert_file) + if (SSL_CTX_use_certificate_file (ssl_ctx, opt.cert_file, + key_type_to_ssl_type (opt.cert_type)) + != 1) + goto error; + if (opt.private_key) + if (SSL_CTX_use_PrivateKey_file (ssl_ctx, opt.private_key, + key_type_to_ssl_type (opt.private_key_type)) + != 1) + goto error; + + /* Since fd_write unconditionally assumes partial writes (and + handles them correctly), allow them in OpenSSL. */ + SSL_CTX_set_mode (ssl_ctx, SSL_MODE_ENABLE_PARTIAL_WRITE); + + /* The OpenSSL library can handle renegotiations automatically, so + tell it to do so. */ + SSL_CTX_set_mode (ssl_ctx, SSL_MODE_AUTO_RETRY); + + return true; + + error: + if (ssl_ctx) + SSL_CTX_free (ssl_ctx); + print_errors (); + return false; +} + +struct openssl_transport_context +{ + SSL *conn; /* SSL connection handle */ + SSL_SESSION *sess; /* SSL session info */ + char *last_error; /* last error printed with openssl_errstr */ +}; + +struct openssl_read_args +{ + int fd; + struct openssl_transport_context *ctx; + char *buf; + int bufsize; + int retval; +}; + +static void openssl_read_callback(void *arg) +{ + struct openssl_read_args *args = (struct openssl_read_args *) arg; + struct openssl_transport_context *ctx = args->ctx; + SSL *conn = ctx->conn; + char *buf = args->buf; + int bufsize = args->bufsize; + int ret; + + do + ret = SSL_read (conn, buf, bufsize); + while (ret == -1 && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL + && errno == EINTR); + args->retval = ret; +} + +static int +openssl_read (int fd, char *buf, int bufsize, void *arg) +{ + struct openssl_read_args args; + args.fd = fd; + args.buf = buf; + args.bufsize = bufsize; + args.ctx = (struct openssl_transport_context*) arg; + + if (run_with_timeout(opt.read_timeout, openssl_read_callback, &args)) { + return -1; + } + return args.retval; +} + +static int +openssl_write (int fd _GL_UNUSED, char *buf, int bufsize, void *arg) +{ + int ret = 0; + struct openssl_transport_context *ctx = arg; + SSL *conn = ctx->conn; + do + ret = SSL_write (conn, buf, bufsize); + while (ret == -1 + && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL + && errno == EINTR); + return ret; +} + +static int +openssl_poll (int fd, double timeout, int wait_for, void *arg) +{ + struct openssl_transport_context *ctx = arg; + SSL *conn = ctx->conn; + if (SSL_pending (conn)) + return 1; + if (timeout == 0) + return 1; + return select_fd (fd, timeout, wait_for); +} + +static int +openssl_peek (int fd, char *buf, int bufsize, void *arg) +{ + int ret; + struct openssl_transport_context *ctx = arg; + SSL *conn = ctx->conn; + if (! openssl_poll (fd, 0.0, WAIT_FOR_READ, arg)) + return 0; + do + ret = SSL_peek (conn, buf, bufsize); + while (ret == -1 + && SSL_get_error (conn, ret) == SSL_ERROR_SYSCALL + && errno == EINTR); + return ret; +} + +static const char * +openssl_errstr (int fd _GL_UNUSED, void *arg) +{ + struct openssl_transport_context *ctx = arg; + unsigned long errcode; + char *errmsg = NULL; + int msglen = 0; + + /* If there are no SSL-specific errors, just return NULL. */ + if ((errcode = ERR_get_error ()) == 0) + return NULL; + + /* Get rid of previous contents of ctx->last_error, if any. */ + xfree (ctx->last_error); + + /* Iterate over OpenSSL's error stack and accumulate errors in the + last_error buffer, separated by "; ". This is better than using + a static buffer, which *always* takes up space (and has to be + large, to fit more than one error message), whereas these + allocations are only performed when there is an actual error. */ + + for (;;) + { + const char *str = ERR_error_string (errcode, NULL); + int len = strlen (str); + + /* Allocate space for the existing message, plus two more chars + for the "; " separator and one for the terminating \0. */ + errmsg = xrealloc (errmsg, msglen + len + 2 + 1); + memcpy (errmsg + msglen, str, len); + msglen += len; + + /* Get next error and bail out if there are no more. */ + errcode = ERR_get_error (); + if (errcode == 0) + break; + + errmsg[msglen++] = ';'; + errmsg[msglen++] = ' '; + } + errmsg[msglen] = '\0'; + + /* Store the error in ctx->last_error where openssl_close will + eventually find it and free it. */ + ctx->last_error = errmsg; + + return errmsg; +} + +static void +openssl_close (int fd, void *arg) +{ + struct openssl_transport_context *ctx = arg; + SSL *conn = ctx->conn; + + SSL_shutdown (conn); + SSL_free (conn); + xfree (ctx->last_error); + xfree (ctx); + + close (fd); + + DEBUGP (("Closed %d/SSL 0x%0*lx\n", fd, PTR_FORMAT (conn))); +} + +/* openssl_transport is the singleton that describes the SSL transport + methods provided by this file. */ + +static struct transport_implementation openssl_transport = { + openssl_read, openssl_write, openssl_poll, + openssl_peek, openssl_errstr, openssl_close +}; + +struct scwt_context +{ + SSL *ssl; + int result; +}; + +static void +ssl_connect_with_timeout_callback(void *arg) +{ + struct scwt_context *ctx = (struct scwt_context *)arg; + ctx->result = SSL_connect(ctx->ssl); +} + +static const char * +_sni_hostname(const char *hostname) +{ + size_t len = strlen(hostname); + + char *sni_hostname = xmemdup(hostname, len + 1); + + /* Remove trailing dot(s) to fix #47408. + * Regarding RFC 6066 (SNI): The hostname is represented as a byte + * string using ASCII encoding without a trailing dot. */ + while (len && sni_hostname[--len] == '.') + sni_hostname[len] = 0; + + return sni_hostname; +} + +/* Perform the SSL handshake on file descriptor FD, which is assumed + to be connected to an SSL server. The SSL handle provided by + OpenSSL is registered with the file descriptor FD using + fd_register_transport, so that subsequent calls to fd_read, + fd_write, etc., will use the corresponding SSL functions. + + Returns true on success, false on failure. */ + +bool +ssl_connect_wget (int fd, const char *hostname, int *continue_session) +{ + SSL *conn; + struct scwt_context scwt_ctx; + struct openssl_transport_context *ctx; + + DEBUGP (("Initiating SSL handshake.\n")); + + assert (ssl_ctx != NULL); + conn = SSL_new (ssl_ctx); + if (!conn) + goto error; +#if OPENSSL_VERSION_NUMBER >= 0x0090806fL && !defined(OPENSSL_NO_TLSEXT) + /* If the SSL library was built with support for ServerNameIndication + then use it whenever we have a hostname. If not, don't, ever. */ + if (! is_valid_ip_address (hostname)) + { + const char *sni_hostname = _sni_hostname(hostname); + + long rc = SSL_set_tlsext_host_name (conn, sni_hostname); + xfree(sni_hostname); + + if (rc == 0) + { + DEBUGP (("Failed to set TLS server-name indication.")); + goto error; + } + } +#endif + + if (continue_session) + { + /* attempt to resume a previous SSL session */ + ctx = (struct openssl_transport_context *) fd_transport_context (*continue_session); + if (!ctx || !ctx->sess || !SSL_set_session (conn, ctx->sess)) + goto error; + } + +#ifndef FD_TO_SOCKET +# define FD_TO_SOCKET(X) (X) +#endif + if (!SSL_set_fd (conn, FD_TO_SOCKET (fd))) + goto error; + SSL_set_connect_state (conn); + + /* Re-seed the PRNG before the SSL handshake */ + init_prng (); + if (RAND_status () != 1) + { + logprintf(LOG_NOTQUIET, + _("WARNING: Could not seed PRNG. Consider using --random-file.\n")); + goto error; + } + + scwt_ctx.ssl = conn; + if (run_with_timeout(opt.read_timeout, ssl_connect_with_timeout_callback, + &scwt_ctx)) { + DEBUGP (("SSL handshake timed out.\n")); + goto timeout; + } + if (scwt_ctx.result <= 0 || !SSL_is_init_finished(conn)) + goto error; + + ctx = xnew0 (struct openssl_transport_context); + ctx->conn = conn; + ctx->sess = SSL_get0_session (conn); + if (!ctx->sess) + logprintf (LOG_NOTQUIET, "WARNING: Could not save SSL session data for socket %d\n", fd); + + /* Register FD with Wget's transport layer, i.e. arrange that our + functions are used for reading, writing, and polling. */ + fd_register_transport (fd, &openssl_transport, ctx); + DEBUGP (("Handshake successful; connected socket %d to SSL handle 0x%0*lx\n", + fd, PTR_FORMAT (conn))); + return true; + + error: + DEBUGP (("SSL handshake failed.\n")); + print_errors (); + timeout: + if (conn) + SSL_free (conn); + return false; +} + +#define ASTERISK_EXCLUDES_DOT /* mandated by rfc2818 */ + +/* Return true is STRING (case-insensitively) matches PATTERN, false + otherwise. The recognized wildcard character is "*", which matches + any character in STRING except ".". Any number of the "*" wildcard + may be present in the pattern. + + This is used to match of hosts as indicated in rfc2818: "Names may + contain the wildcard character * which is considered to match any + single domain name component or component fragment. E.g., *.a.com + matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com but + not bar.com [or foo.bar.com]." + + If the pattern contain no wildcards, pattern_match(a, b) is + equivalent to !strcasecmp(a, b). */ + +static bool +pattern_match (const char *pattern, const char *string) +{ + const char *p = pattern, *n = string; + char c; + for (; (c = c_tolower (*p++)) != '\0'; n++) + if (c == '*') + { + for (c = c_tolower (*p); c == '*'; c = c_tolower (*++p)) + ; + for (; *n != '\0'; n++) + if (c_tolower (*n) == c && pattern_match (p, n)) + return true; +#ifdef ASTERISK_EXCLUDES_DOT + else if (*n == '.') + return false; +#endif + return c == '\0'; + } + else + { + if (c != c_tolower (*n)) + return false; + } + return *n == '\0'; +} + +static char *_get_rfc2253_formatted (X509_NAME *name) +{ + int len; + char *out = NULL; + BIO* b; + + if ((b = BIO_new (BIO_s_mem ()))) + { + if (X509_NAME_print_ex (b, name, 0, XN_FLAG_RFC2253) >= 0 + && (len = BIO_number_written (b)) > 0) + { + out = xmalloc (len + 1); + BIO_read (b, out, len); + out[len] = 0; + } + BIO_free (b); + } + + return out ? out : xstrdup(""); +} + +/* + * Heavily modified from: + * https://www.owasp.org/index.php/Certificate_and_Public_Key_Pinning#OpenSSL + */ +static bool +pkp_pin_peer_pubkey (X509* cert, const char *pinnedpubkey) +{ + /* Scratch */ + int len1 = 0, len2 = 0; + char *buff1 = NULL, *temp = NULL; + + /* Result is returned to caller */ + bool result = false; + + /* if a path wasn't specified, don't pin */ + if (!pinnedpubkey) + return true; + + if (!cert) + return result; + + /* Begin Gyrations to get the subjectPublicKeyInfo */ + /* Thanks to Viktor Dukhovni on the OpenSSL mailing list */ + + /* https://groups.google.com/group/mailing.openssl.users/browse_thread + /thread/d61858dae102c6c7 */ + len1 = i2d_X509_PUBKEY (X509_get_X509_PUBKEY (cert), NULL); + if (len1 < 1) + goto cleanup; /* failed */ + + /* https://www.openssl.org/docs/crypto/buffer.html */ + buff1 = temp = OPENSSL_malloc (len1); + if (!buff1) + goto cleanup; /* failed */ + + /* https://www.openssl.org/docs/crypto/d2i_X509.html */ + len2 = i2d_X509_PUBKEY (X509_get_X509_PUBKEY (cert), (unsigned char **) &temp); + + /* + * These checks are verifying we got back the same values as when we + * sized the buffer. It's pretty weak since they should always be the + * same. But it gives us something to test. + */ + if ((len1 != len2) || !temp || ((temp - buff1) != len1)) + goto cleanup; /* failed */ + + /* End Gyrations */ + + /* The one good exit point */ + result = wg_pin_peer_pubkey (pinnedpubkey, buff1, len1); + + cleanup: + /* https://www.openssl.org/docs/crypto/buffer.html */ + if (NULL != buff1) + OPENSSL_free (buff1); + + return result; +} + +/* Verify the validity of the certificate presented by the server. + Also check that the "common name" of the server, as presented by + its certificate, corresponds to HOST. (HOST typically comes from + the URL and is what the user thinks he's connecting to.) + + This assumes that ssl_connect_wget has successfully finished, i.e. that + the SSL handshake has been performed and that FD is connected to an + SSL handle. + + If opt.check_cert is true (the default), this returns 1 if the + certificate is valid, 0 otherwise. If opt.check_cert is 0, the + function always returns 1, but should still be called because it + warns the user about any problems with the certificate. */ + +bool +ssl_check_certificate (int fd, const char *host) +{ + X509 *cert; + GENERAL_NAMES *subjectAltNames; + char common_name[256]; + long vresult; + bool success = true; + bool alt_name_checked = false; + bool pinsuccess = opt.pinnedpubkey == NULL; + + /* If the user has specified --no-check-cert, we still want to warn + him about problems with the server's certificate. */ + const char *severity = opt.check_cert ? _("ERROR") : _("WARNING"); + + struct openssl_transport_context *ctx = fd_transport_context (fd); + SSL *conn = ctx->conn; + assert (conn != NULL); + + /* The user explicitly said to not check for the certificate. */ + if (opt.check_cert == CHECK_CERT_QUIET && pinsuccess) + return success; + + cert = SSL_get_peer_certificate (conn); + if (!cert) + { + logprintf (LOG_NOTQUIET, _("%s: No certificate presented by %s.\n"), + severity, quotearg_style (escape_quoting_style, host)); + success = false; + goto no_cert; /* must bail out since CERT is NULL */ + } + + IF_DEBUG + { + char *subject = _get_rfc2253_formatted (X509_get_subject_name (cert)); + char *issuer = _get_rfc2253_formatted (X509_get_issuer_name (cert)); + DEBUGP (("certificate:\n subject: %s\n issuer: %s\n", + quotearg_n_style (0, escape_quoting_style, subject), + quotearg_n_style (1, escape_quoting_style, issuer))); + xfree (subject); + xfree (issuer); + } + + vresult = SSL_get_verify_result (conn); + if (vresult != X509_V_OK) + { + char *issuer = _get_rfc2253_formatted (X509_get_issuer_name (cert)); + logprintf (LOG_NOTQUIET, + _("%s: cannot verify %s's certificate, issued by %s:\n"), + severity, quotearg_n_style (0, escape_quoting_style, host), + quote_n (1, issuer)); + xfree(issuer); + + /* Try to print more user-friendly (and translated) messages for + the frequent verification errors. */ + switch (vresult) + { + case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY: + logprintf (LOG_NOTQUIET, + _(" Unable to locally verify the issuer's authority.\n")); + break; + case X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: + case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT: + logprintf (LOG_NOTQUIET, + _(" Self-signed certificate encountered.\n")); + break; + case X509_V_ERR_CERT_NOT_YET_VALID: + logprintf (LOG_NOTQUIET, _(" Issued certificate not yet valid.\n")); + break; + case X509_V_ERR_CERT_HAS_EXPIRED: + logprintf (LOG_NOTQUIET, _(" Issued certificate has expired.\n")); + break; + default: + /* For the less frequent error strings, simply provide the + OpenSSL error message. */ + logprintf (LOG_NOTQUIET, " %s\n", + X509_verify_cert_error_string (vresult)); + } + success = false; + /* Fall through, so that the user is warned about *all* issues + with the cert (important with --no-check-certificate.) */ + } + + /* Check that HOST matches the common name in the certificate. + #### The following remains to be done: + + - When matching against common names, it should loop over all + common names and choose the most specific one, i.e. the last + one, not the first one, which the current code picks. + + - Ensure that ASN1 strings from the certificate are encoded as + UTF-8 which can be meaningfully compared to HOST. */ + + subjectAltNames = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL); + + if (subjectAltNames) + { + /* Test subject alternative names */ + + /* SNI hostname must not have a trailing dot */ + const char *sni_hostname = _sni_hostname(host); + + /* Do we want to check for dNSNAmes or ipAddresses (see RFC 2818)? + * Signal it by host_in_octet_string. */ + ASN1_OCTET_STRING *host_in_octet_string = a2i_IPADDRESS (sni_hostname); + + int numaltnames = sk_GENERAL_NAME_num (subjectAltNames); + int i; + for (i=0; i < numaltnames; i++) + { + const GENERAL_NAME *name = + sk_GENERAL_NAME_value (subjectAltNames, i); + if (name) + { + if (host_in_octet_string) + { + if (name->type == GEN_IPADD) + { + /* Check for ipAddress */ + /* TODO: Should we convert between IPv4-mapped IPv6 + * addresses and IPv4 addresses? */ + alt_name_checked = true; + if (!ASN1_STRING_cmp (host_in_octet_string, + name->d.iPAddress)) + break; + } + } + else if (name->type == GEN_DNS) + { + /* dNSName should be IA5String (i.e. ASCII), however who + * does trust CA? Convert it into UTF-8 for sure. */ + unsigned char *name_in_utf8 = NULL; + + /* Check for dNSName */ + alt_name_checked = true; + + if (0 <= ASN1_STRING_to_UTF8 (&name_in_utf8, name->d.dNSName)) + { + /* Compare and check for NULL attack in ASN1_STRING */ + if (pattern_match ((char *)name_in_utf8, sni_hostname) && + (strlen ((char *)name_in_utf8) == + (size_t) ASN1_STRING_length (name->d.dNSName))) + { + OPENSSL_free (name_in_utf8); + break; + } + OPENSSL_free (name_in_utf8); + } + } + } + } + sk_GENERAL_NAME_pop_free(subjectAltNames, GENERAL_NAME_free); + if (host_in_octet_string) + ASN1_OCTET_STRING_free(host_in_octet_string); + + if (alt_name_checked == true && i >= numaltnames) + { + logprintf (LOG_NOTQUIET, + _("%s: no certificate subject alternative name matches\n" + "\trequested host name %s.\n"), + severity, quote_n (1, sni_hostname)); + success = false; + } + + xfree(sni_hostname); + } + + if (alt_name_checked == false) + { + /* Test commomName */ + X509_NAME *xname = X509_get_subject_name(cert); + common_name[0] = '\0'; + X509_NAME_get_text_by_NID (xname, NID_commonName, common_name, + sizeof (common_name)); + + if (!pattern_match (common_name, host)) + { + logprintf (LOG_NOTQUIET, _("\ + %s: certificate common name %s doesn't match requested host name %s.\n"), + severity, quote_n (0, common_name), quote_n (1, host)); + success = false; + } + else + { + /* We now determine the length of the ASN1 string. If it + * differs from common_name's length, then there is a \0 + * before the string terminates. This can be an instance of a + * null-prefix attack. + * + * https://www.blackhat.com/html/bh-usa-09/bh-usa-09-archives.html#Marlinspike + * */ + + int i = -1, j; + X509_NAME_ENTRY *xentry; + ASN1_STRING *sdata; + + if (xname) { + for (;;) + { + j = X509_NAME_get_index_by_NID (xname, NID_commonName, i); + if (j == -1) break; + i = j; + } + } + + xentry = X509_NAME_get_entry(xname,i); + sdata = X509_NAME_ENTRY_get_data(xentry); + if (strlen (common_name) != (size_t) ASN1_STRING_length (sdata)) + { + logprintf (LOG_NOTQUIET, _("\ + %s: certificate common name is invalid (contains a NUL character).\n\ + This may be an indication that the host is not who it claims to be\n\ + (that is, it is not the real %s).\n"), + severity, quote (host)); + success = false; + } + } + } + + pinsuccess = pkp_pin_peer_pubkey (cert, opt.pinnedpubkey); + if (!pinsuccess) + { + logprintf (LOG_ALWAYS, _("The public key does not match pinned public key!\n")); + success = false; + } + + + if (success) + DEBUGP (("X509 certificate successfully verified and matches host %s\n", + quotearg_style (escape_quoting_style, host))); + X509_free (cert); + + no_cert: + if (opt.check_cert == CHECK_CERT_ON && !success) + logprintf (LOG_NOTQUIET, _("\ +To connect to %s insecurely, use `--no-check-certificate'.\n"), + quotearg_style (escape_quoting_style, host)); + + /* never return true if pinsuccess fails */ + return !pinsuccess ? false : (opt.check_cert == CHECK_CERT_ON ? success : true); +} + +/* + * vim: tabstop=2 shiftwidth=2 softtabstop=2 + */ |