Adding upstream version 3.8.5.upstream/3.8.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 435 insertions, 0 deletions

diff --git a/src/tls/tls_fprint.c b/src/tls/tls_fprint.c
new file mode 100644
index 0000000..39b5a52
--- /dev/null
+++ b/src/tls/tls_fprint.c
@@ -0,0 +1,435 @@
+/*++
+/* NAME
+/*	tls_fprint 3
+/* SUMMARY
+/*	Digests fingerprints and all that.
+/* SYNOPSIS
+/*	#include <tls.h>
+/*
+/*	EVP_MD *tls_digest_byname(const char *mdalg, EVP_MD_CTX **mdctxPtr)
+/*	const char *mdalg;
+/*	EVP_MD_CTX **mdctxPtr;
+/*
+/*	char	*tls_serverid_digest(TLScontext, props, ciphers)
+/*	TLS_SESS_STATE *TLScontext;
+/*	const TLS_CLIENT_START_PROPS *props;
+/*	const char *ciphers;
+/*
+/*	char	*tls_digest_encode(md_buf, md_len)
+/*	const unsigned char *md_buf;
+/*	const char *md_len;
+/*
+/*	char	*tls_cert_fprint(peercert, mdalg)
+/*	X509	*peercert;
+/*	const char *mdalg;
+/*
+/*	char	*tls_pkey_fprint(peercert, mdalg)
+/*	X509	*peercert;
+/*	const char *mdalg;
+/* DESCRIPTION
+/*	tls_digest_byname() constructs, and optionally returns, an EVP_MD_CTX
+/*	handle for performing digest operations with the algorithm named by the
+/*	mdalg parameter.  The return value is non-null on success, and holds a
+/*	digest algorithm handle.  If the mdctxPtr argument is non-null the
+/*	created context is returned to the caller, who is then responsible for
+/*	deleting it by calling EVP_MD_ctx_free() once it is no longer needed.
+/*
+/*	tls_digest_encode() converts a binary message digest to a hex ASCII
+/*	format with ':' separators between each pair of hex digits.
+/*	The return value is dynamically allocated with mymalloc(),
+/*	and the caller must eventually free it with myfree().
+/*
+/*	tls_cert_fprint() returns a fingerprint of the given
+/*	certificate using the requested message digest, formatted
+/*	with tls_digest_encode(). Panics if the
+/*	(previously verified) digest algorithm is not found. The return
+/*	value is dynamically allocated with mymalloc(), and the caller
+/*	must eventually free it with myfree().
+/*
+/*	tls_pkey_fprint() returns a public-key fingerprint; in all
+/*	other respects the function behaves as tls_cert_fprint().
+/*	The var_tls_bc_pkey_fprint variable enables an incorrect
+/*	algorithm that was used in Postfix versions 2.9.[0-5].
+/*	The return value is dynamically allocated with mymalloc(),
+/*	and the caller must eventually free it with myfree().
+/*
+/*	tls_serverid_digest() suffixes props->serverid computed by the SMTP
+/*	client with "&" plus a digest of additional parameters needed to ensure
+/*	that re-used sessions are more likely to be reused and that they will
+/*	satisfy all protocol and security requirements.  The return value is
+/*	dynamically allocated with mymalloc(), and the caller must eventually
+/*	free it with myfree().
+/*
+/*	Arguments:
+/* .IP mdalg
+/*	A digest algorithm name, such as "sha256".
+/* .IP peercert
+/*	Server or client X.509 certificate.
+/* .IP md_buf
+/*	The raw binary digest.
+/* .IP md_len
+/*	The digest length in bytes.
+/* .IP mdalg
+/*	Name of a message digest algorithm suitable for computing secure
+/*	(1st pre-image resistant) message digests of certificates. For now,
+/*	md5, sha1, or member of SHA-2 family if supported by OpenSSL.
+/* .IP mdctxPtr
+/*	Pointer to an (EVP_MD_CTX *) handle, or NULL if only probing for
+/*	algorithm support without immediate use in mind.
+/* .IP buf
+/*	Input data for the message digest algorithm mdalg.
+/* .IP len
+/*	The length of the input data.
+/* .IP props
+/*	The client start properties for the session, which contains the
+/*	initial serverid from the SMTP client and the DANE verification
+/*	parameters.
+/* .IP protomask
+/*	The mask of protocol exclusions.
+/* .IP ciphers
+/*	The SSL client cipherlist.
+/* LICENSE
+/* .ad
+/* .fi
+/*	This software is free. You can do with it whatever you want.
+/*	The original author kindly requests that you acknowledge
+/*	the use of his software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Viktor Dukhovni
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <ctype.h>
+
+#ifdef USE_TLS
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <stringops.h>
+
+/* Global library. */
+
+#include <mail_params.h>
+
+/* TLS library. */
+
+#define TLS_INTERNAL
+#include <tls.h>
+
+/* Application-specific. */
+
+static const char hexcodes[] = "0123456789ABCDEF";
+
+#define CHECK_OK_AND(stillok) (ok = ok && (stillok))
+#define CHECK_OK_AND_DIGEST_OBJECT(m, p) \
+	CHECK_OK_AND_DIGEST_DATA((m), (unsigned char *)(p), sizeof(*(p)))
+#define CHECK_OK_AND_DIGEST_DATA(m, p, l) CHECK_OK_AND(digest_bytes((m), (p), (l)))
+#define CHECK_OK_AND_DIGEST_CHARS(m, s) CHECK_OK_AND(digest_chars((m), (s)))
+
+/* digest_bytes - hash octet string of given length */
+
+static int digest_bytes(EVP_MD_CTX *ctx, const unsigned char *buf, size_t len)
+{
+    return (EVP_DigestUpdate(ctx, buf, len));
+}
+
+/* digest_chars - hash string including trailing NUL */
+
+static int digest_chars(EVP_MD_CTX *ctx, const char *s)
+{
+    return (EVP_DigestUpdate(ctx, s, strlen(s) + 1));
+}
+
+/* tlsa_cmp - compare TLSA RRs for sorting to canonical order */
+
+static int tlsa_cmp(const void *a, const void *b)
+{
+    TLS_TLSA *p = *(TLS_TLSA **) a;
+    TLS_TLSA *q = *(TLS_TLSA **) b;
+    int     d;
+
+    if ((d = (int) p->usage - (int) q->usage) != 0)
+	return d;
+    if ((d = (int) p->selector - (int) q->selector) != 0)
+	return d;
+    if ((d = (int) p->mtype - (int) q->mtype) != 0)
+	return d;
+    if ((d = (int) p->length - (int) q->length) != 0)
+	return d;
+    return (memcmp(p->data, q->data, p->length));
+}
+
+/* tls_digest_tlsa - fold in digest of TLSA records */
+
+static int tls_digest_tlsa(EVP_MD_CTX *mdctx, TLS_TLSA *tlsa)
+{
+    TLS_TLSA *p;
+    TLS_TLSA **arr;
+    int     ok = 1;
+    int     n;
+    int     i;
+
+    for (n = 0, p = tlsa; p != 0; p = p->next)
+	++n;
+    arr = (TLS_TLSA **) mymalloc(n * sizeof(*arr));
+    for (i = 0, p = tlsa; p; p = p->next)
+	arr[i++] = (void *) p;
+    qsort(arr, n, sizeof(arr[0]), tlsa_cmp);
+
+    CHECK_OK_AND_DIGEST_OBJECT(mdctx, &n);
+    for (i = 0; i < n; ++i) {
+	CHECK_OK_AND_DIGEST_OBJECT(mdctx, &arr[i]->usage);
+	CHECK_OK_AND_DIGEST_OBJECT(mdctx, &arr[i]->selector);
+	CHECK_OK_AND_DIGEST_OBJECT(mdctx, &arr[i]->mtype);
+	CHECK_OK_AND_DIGEST_OBJECT(mdctx, &arr[i]->length);
+	CHECK_OK_AND_DIGEST_DATA(mdctx, arr[i]->data, arr[i]->length);
+    }
+    myfree((void *) arr);
+    return (ok);
+}
+
+/* tls_digest_byname - test availability or prepare to use digest */
+
+const EVP_MD *tls_digest_byname(const char *mdalg, EVP_MD_CTX **mdctxPtr)
+{
+    const EVP_MD *md;
+    EVP_MD_CTX *mdctx = NULL;
+    int     ok = 1;
+
+    /*
+     * In OpenSSL 3.0, because of dynamically variable algorithm providers,
+     * there is a time-of-check/time-of-use issue that means that abstract
+     * algorithm handles returned by EVP_get_digestbyname() can (and not
+     * infrequently do) return ultimately unusable algorithms, to check for
+     * actual availability, one needs to use the new EVP_MD_fetch() API, or
+     * indirectly check usability by creating a concrete context. We take the
+     * latter approach here (works for 1.1.1 without #ifdef).
+     * 
+     * Note that EVP_MD_CTX_{create,destroy} were renamed to, respectively,
+     * EVP_MD_CTX_{new,free} in OpenSSL 1.1.0.
+     */
+    CHECK_OK_AND(md = EVP_get_digestbyname(mdalg));
+
+    /*
+     * Sanity check: Newer shared libraries could (hypothetical ABI break)
+     * allow larger digests, we avoid such poison algorithms.
+     */
+    CHECK_OK_AND(EVP_MD_size(md) <= EVP_MAX_MD_SIZE);
+    CHECK_OK_AND(mdctx = EVP_MD_CTX_new());
+    CHECK_OK_AND(EVP_DigestInit_ex(mdctx, md, NULL));
+
+
+    if (ok && mdctxPtr != 0)
+	*mdctxPtr = mdctx;
+    else
+	EVP_MD_CTX_free(mdctx);
+    return (ok ? md : 0);
+}
+
+/* tls_serverid_digest - suffix props->serverid with parameter digest */
+
+char   *tls_serverid_digest(TLS_SESS_STATE *TLScontext,
+			            const TLS_CLIENT_START_PROPS *props,
+			            const char *ciphers)
+{
+    EVP_MD_CTX *mdctx;
+    const char *mdalg;
+    unsigned char md_buf[EVP_MAX_MD_SIZE];
+    unsigned int md_len;
+    int     ok = 1;
+    int     i;
+    long    sslversion;
+    VSTRING *result;
+
+    /*
+     * Try to use sha256: our serverid choice should be strong enough to
+     * resist 2nd-preimage attacks with a difficulty comparable to that of
+     * DANE TLSA digests.  Failing that, we compute serverid digests with the
+     * default digest, but DANE requires sha256 and sha512, so if we must
+     * fall back to our default digest, DANE support won't be available.  We
+     * panic if the fallback algorithm is not available, as it was verified
+     * available in tls_client_init() and must not simply vanish.  Our
+     * provider set is not expected to change once the OpenSSL library is
+     * initialized.
+     */
+    if (tls_digest_byname(mdalg = LN_sha256, &mdctx) == 0
+	&& tls_digest_byname(mdalg = props->mdalg, &mdctx) == 0)
+	msg_panic("digest algorithm \"%s\" not found", props->mdalg);
+
+    /* Salt the session lookup key with the OpenSSL runtime version. */
+    sslversion = OpenSSL_version_num();
+
+    CHECK_OK_AND_DIGEST_CHARS(mdctx, props->helo ? props->helo : "");
+    CHECK_OK_AND_DIGEST_OBJECT(mdctx, &sslversion);
+    CHECK_OK_AND_DIGEST_CHARS(mdctx, props->protocols);
+    CHECK_OK_AND_DIGEST_CHARS(mdctx, ciphers);
+
+    /*
+     * Ensure separation of caches for sessions where DANE trust
+     * configuration succeeded from those where it did not.  The latter
+     * should always see a certificate validation failure, both on initial
+     * handshake and on resumption.
+     */
+    CHECK_OK_AND_DIGEST_OBJECT(mdctx, &TLScontext->must_fail);
+
+    /*
+     * DNS-based or synthetic DANE trust settings are potentially used at all
+     * levels above "encrypt".
+     */
+    if (TLScontext->level > TLS_LEV_ENCRYPT
+	&& props->dane && props->dane->tlsa) {
+	CHECK_OK_AND(tls_digest_tlsa(mdctx, props->dane->tlsa));
+    } else {
+	int     none = 0;		/* Record a TLSA RR count of zero */
+
+	CHECK_OK_AND_DIGEST_OBJECT(mdctx, &none);
+    }
+
+    /*
+     * Include the chosen SNI name, which can affect server certificate
+     * selection.
+     */
+    if (TLScontext->level > TLS_LEV_ENCRYPT && TLScontext->peer_sni)
+	CHECK_OK_AND_DIGEST_CHARS(mdctx, TLScontext->peer_sni);
+    else
+	CHECK_OK_AND_DIGEST_CHARS(mdctx, "");
+
+    CHECK_OK_AND(EVP_DigestFinal_ex(mdctx, md_buf, &md_len));
+    EVP_MD_CTX_destroy(mdctx);
+    if (!ok)
+	msg_fatal("error computing %s message digest", mdalg);
+
+    /* Check for OpenSSL contract violation */
+    if (md_len > EVP_MAX_MD_SIZE)
+	msg_panic("unexpectedly large %s digest size: %u", mdalg, md_len);
+
+    /*
+     * Append the digest to the serverid.  We don't compare this digest to
+     * any user-specified fingerprints.  Therefore, we don't need to use a
+     * colon-separated format, which saves space in the TLS session cache and
+     * makes logging of session cache lookup keys more readable.
+     * 
+     * This does however duplicate a few lines of code from the digest encoder
+     * for colon-separated cert and pkey fingerprints. If that is a
+     * compelling reason to consolidate, we could use that and append the
+     * result.
+     */
+    result = vstring_alloc(strlen(props->serverid) + 1 + 2 * md_len);
+    vstring_strcpy(result, props->serverid);
+    VSTRING_ADDCH(result, '&');
+    for (i = 0; i < md_len; i++) {
+	VSTRING_ADDCH(result, hexcodes[(md_buf[i] & 0xf0) >> 4U]);
+	VSTRING_ADDCH(result, hexcodes[(md_buf[i] & 0x0f)]);
+    }
+    VSTRING_TERMINATE(result);
+    return (vstring_export(result));
+}
+
+/* tls_digest_encode - encode message digest binary blob as xx:xx:... */
+
+char   *tls_digest_encode(const unsigned char *md_buf, int md_len)
+{
+    int     i;
+    char   *result = mymalloc(md_len * 3);
+
+    /* Check for contract violation */
+    if (md_len > EVP_MAX_MD_SIZE || md_len >= INT_MAX / 3)
+	msg_panic("unexpectedly large message digest size: %u", md_len);
+
+    /* No risk of overruns, len is bounded by OpenSSL digest length */
+    for (i = 0; i < md_len; i++) {
+	result[i * 3] = hexcodes[(md_buf[i] & 0xf0) >> 4U];
+	result[(i * 3) + 1] = hexcodes[(md_buf[i] & 0x0f)];
+	result[(i * 3) + 2] = (i + 1 != md_len) ? ':' : '\0';
+    }
+    return (result);
+}
+
+/* tls_data_fprint - compute and encode digest of binary object */
+
+static char *tls_data_fprint(const unsigned char *buf, int len, const char *mdalg)
+{
+    EVP_MD_CTX *mdctx = NULL;
+    unsigned char md_buf[EVP_MAX_MD_SIZE];
+    unsigned int md_len;
+    int     ok = 1;
+
+    /* Previously available in "init" routine. */
+    if (tls_digest_byname(mdalg, &mdctx) == 0)
+	msg_panic("digest algorithm \"%s\" not found", mdalg);
+
+    CHECK_OK_AND_DIGEST_DATA(mdctx, buf, len);
+    CHECK_OK_AND(EVP_DigestFinal_ex(mdctx, md_buf, &md_len));
+    EVP_MD_CTX_destroy(mdctx);
+    if (!ok)
+	msg_fatal("error computing %s message digest", mdalg);
+
+    return (tls_digest_encode(md_buf, md_len));
+}
+
+/* tls_cert_fprint - extract certificate fingerprint */
+
+char   *tls_cert_fprint(X509 *peercert, const char *mdalg)
+{
+    int     len;
+    unsigned char *buf;
+    unsigned char *buf2;
+    char   *result;
+
+    len = i2d_X509(peercert, NULL);
+    buf2 = buf = mymalloc(len);
+    i2d_X509(peercert, &buf2);
+    if (buf2 - buf != len)
+	msg_panic("i2d_X509 invalid result length");
+
+    result = tls_data_fprint(buf, len, mdalg);
+    myfree(buf);
+
+    return (result);
+}
+
+/* tls_pkey_fprint - extract public key fingerprint from certificate */
+
+char   *tls_pkey_fprint(X509 *peercert, const char *mdalg)
+{
+    if (var_tls_bc_pkey_fprint) {
+	const char *myname = "tls_pkey_fprint";
+	ASN1_BIT_STRING *key;
+	char   *result;
+
+	key = X509_get0_pubkey_bitstr(peercert);
+	if (key == 0)
+	    msg_fatal("%s: error extracting legacy public-key fingerprint: %m",
+		      myname);
+
+	result = tls_data_fprint(key->data, key->length, mdalg);
+	return (result);
+    } else {
+	int     len;
+	unsigned char *buf;
+	unsigned char *buf2;
+	char   *result;
+
+	len = i2d_X509_PUBKEY(X509_get_X509_PUBKEY(peercert), NULL);
+	buf2 = buf = mymalloc(len);
+	i2d_X509_PUBKEY(X509_get_X509_PUBKEY(peercert), &buf2);
+	if (buf2 - buf != len)
+	    msg_panic("i2d_X509_PUBKEY invalid result length");
+
+	result = tls_data_fprint(buf, len, mdalg);
+	myfree(buf);
+	return (result);
+    }
+}
+
+#endif