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authorTimo Teräs <timo.teras@iki.fi>2017-10-06 13:23:54 +0300
committerTimo Teräs <timo.teras@iki.fi>2017-10-06 13:25:27 +0300
commiteb8f44d629aca3a780f7feedfee11794f14082ad (patch)
treec6e198874a9063881e6bba27d1e48d755e8e240c
parent52fd85a8dcfee9c93522d80693673bc95cc1caaf (diff)
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libfetch: improve openssl/libressl compatibility
X509_check_host() is introduced in libressl-2.5.0 and openssl-1.0.2 which are not yet universally available. Add support for building against the older versions.
-rw-r--r--libfetch/Makefile2
-rw-r--r--libfetch/common.h7
-rw-r--r--libfetch/openssl-compat.c401
-rw-r--r--libfetch/openssl-compat.h33
4 files changed, 436 insertions, 7 deletions
diff --git a/libfetch/Makefile b/libfetch/Makefile
index 618348d..12fead9 100644
--- a/libfetch/Makefile
+++ b/libfetch/Makefile
@@ -1,5 +1,5 @@
libs-y += libfetch.a
-libfetch.a-objs := common.o fetch.o file.o ftp.o http.o
+libfetch.a-objs := common.o fetch.o file.o ftp.o http.o openssl-compat.o
generate-y += ftperr.h httperr.h
CFLAGS_common.o += -DCA_CERT_FILE=\"$(CONFDIR)/ca.pem\" -DCA_CRL_FILE=\"$(CONFDIR)/crl.pem\"
CFLAGS_common.o += -DCLIENT_CERT_FILE=\"$(CONFDIR)/cert.pem\" -DCLIENT_KEY_FILE=\"$(CONFDIR)/cert.key\"
diff --git a/libfetch/common.h b/libfetch/common.h
index b643a34..d7ad1d6 100644
--- a/libfetch/common.h
+++ b/libfetch/common.h
@@ -37,12 +37,7 @@
#define FTP_DEFAULT_PROXY_PORT 21
#define HTTP_DEFAULT_PROXY_PORT 3128
-#include <openssl/crypto.h>
-#include <openssl/x509.h>
-#include <openssl/x509v3.h>
-#include <openssl/pem.h>
-#include <openssl/ssl.h>
-#include <openssl/err.h>
+#include "openssl-compat.h"
#if defined(__GNUC__) && __GNUC__ >= 3
#define LIBFETCH_PRINTFLIKE(fmtarg, firstvararg) \
diff --git a/libfetch/openssl-compat.c b/libfetch/openssl-compat.c
new file mode 100644
index 0000000..3228d17
--- /dev/null
+++ b/libfetch/openssl-compat.c
@@ -0,0 +1,401 @@
+#include <string.h>
+#include <strings.h>
+#include "openssl-compat.h"
+
+#ifdef OSSL_COMPAT_NEED_X509_CHECK
+
+/* libressl 2.5.5 implementation of X509_check_host() */
+
+typedef int (*equal_fn) (const unsigned char *pattern, size_t pattern_len,
+ const unsigned char *subject, size_t subject_len, unsigned int flags);
+
+/* Skip pattern prefix to match "wildcard" subject */
+static void skip_prefix(const unsigned char **p, size_t *plen,
+ const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+ const unsigned char *pattern = *p;
+ size_t pattern_len = *plen;
+
+ /*
+ * If subject starts with a leading '.' followed by more octets, and
+ * pattern is longer, compare just an equal-length suffix with the
+ * full subject (starting at the '.'), provided the prefix contains
+ * no NULs.
+ */
+ if ((flags & _X509_CHECK_FLAG_DOT_SUBDOMAINS) == 0)
+ return;
+
+ while (pattern_len > subject_len && *pattern) {
+ if ((flags & X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS) &&
+ *pattern == '.')
+ break;
+ ++pattern;
+ --pattern_len;
+ }
+
+ /* Skip if entire prefix acceptable */
+ if (pattern_len == subject_len) {
+ *p = pattern;
+ *plen = pattern_len;
+ }
+}
+
+/*
+ * Open/BoringSSL uses memcmp for "equal_case" while their
+ * "equal_nocase" function is a hand-rolled strncasecmp that does not
+ * allow \0 in the pattern. Since an embedded \0 is likely a sign of
+ * problems, we simply don't allow it in either case, and then we use
+ * standard libc funcitons.
+ */
+
+/* Compare using strncasecmp */
+static int equal_nocase(const unsigned char *pattern, size_t pattern_len,
+ const unsigned char *subject, size_t subject_len,
+ unsigned int flags)
+{
+ if (memchr(pattern, '\0', pattern_len) != NULL)
+ return 0;
+ if (memchr(subject, '\0', subject_len) != NULL)
+ return 0;
+ skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
+ if (pattern_len != subject_len)
+ return 0;
+ return (strncasecmp((const char *)pattern, (const char *)subject, pattern_len) == 0);
+}
+
+/* Compare using strncmp. */
+static int equal_case(const unsigned char *pattern, size_t pattern_len,
+ const unsigned char *subject, size_t subject_len,
+ unsigned int flags)
+{
+ if (memchr(pattern, 0, pattern_len) != NULL)
+ return 0;
+ if (memchr(subject, 0, subject_len) != NULL)
+ return 0;
+ skip_prefix(&pattern, &pattern_len, subject, subject_len, flags);
+ if (pattern_len != subject_len)
+ return 0;
+ return (strncmp((const char *)pattern, (const char *)subject, pattern_len) == 0);
+}
+
+/*
+ * RFC 5280, section 7.5, requires that only the domain is compared in a
+ * case-insensitive manner.
+ */
+static int equal_email(const unsigned char *a, size_t a_len,
+ const unsigned char *b, size_t b_len,
+ unsigned int unused_flags)
+{
+ size_t pos = a_len;
+ if (a_len != b_len)
+ return 0;
+ /*
+ * We search backwards for the '@' character, so that we do not have to
+ * deal with quoted local-parts. The domain part is compared in a
+ * case-insensitive manner.
+ */
+ while (pos > 0) {
+ pos--;
+ if (a[pos] == '@' || b[pos] == '@') {
+ if (!equal_nocase(a + pos, a_len - pos, b + pos, a_len - pos, 0))
+ return 0;
+ break;
+ }
+ }
+ if (pos == 0)
+ pos = a_len;
+ return equal_case(a, pos, b, pos, 0);
+}
+
+/*
+ * Compare the prefix and suffix with the subject, and check that the
+ * characters in-between are valid.
+ */
+static int wildcard_match(const unsigned char *prefix, size_t prefix_len,
+ const unsigned char *suffix, size_t suffix_len,
+ const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+ const unsigned char *wildcard_start;
+ const unsigned char *wildcard_end;
+ const unsigned char *p;
+ int allow_multi = 0;
+ int allow_idna = 0;
+
+ if (subject_len < prefix_len + suffix_len)
+ return 0;
+ if (!equal_nocase(prefix, prefix_len, subject, prefix_len, flags))
+ return 0;
+ wildcard_start = subject + prefix_len;
+ wildcard_end = subject + (subject_len - suffix_len);
+ if (!equal_nocase(wildcard_end, suffix_len, suffix, suffix_len, flags))
+ return 0;
+ /*
+ * If the wildcard makes up the entire first label, it must match at
+ * least one character.
+ */
+ if (prefix_len == 0 && *suffix == '.') {
+ if (wildcard_start == wildcard_end)
+ return 0;
+ allow_idna = 1;
+ if (flags & X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS)
+ allow_multi = 1;
+ }
+ /* IDNA labels cannot match partial wildcards */
+ if (!allow_idna &&
+ subject_len >= 4
+ && strncasecmp((const char *)subject, "xn--", 4) == 0)
+ return 0;
+ /* The wildcard may match a literal '*' */
+ if (wildcard_end == wildcard_start + 1 && *wildcard_start == '*')
+ return 1;
+ /*
+ * Check that the part matched by the wildcard contains only
+ * permitted characters and only matches a single label unless
+ * allow_multi is set.
+ */
+ for (p = wildcard_start; p != wildcard_end; ++p)
+ if (!(('0' <= *p && *p <= '9') || ('A' <= *p && *p <= 'Z') ||
+ ('a' <= *p && *p <= 'z') || *p == '-' ||
+ (allow_multi && *p == '.')))
+ return 0;
+ return 1;
+}
+
+#define LABEL_START (1 << 0)
+#define LABEL_END (1 << 1)
+#define LABEL_HYPHEN (1 << 2)
+#define LABEL_IDNA (1 << 3)
+
+static const unsigned char *valid_star(const unsigned char *p, size_t len,
+ unsigned int flags)
+{
+ const unsigned char *star = 0;
+ size_t i;
+ int state = LABEL_START;
+ int dots = 0;
+ for (i = 0; i < len; ++i) {
+ /*
+ * Locate first and only legal wildcard, either at the start
+ * or end of a non-IDNA first and not final label.
+ */
+ if (p[i] == '*') {
+ int atstart = (state & LABEL_START);
+ int atend = (i == len - 1 || p[i + 1] == '.');
+ /*
+ * At most one wildcard per pattern.
+ * No wildcards in IDNA labels.
+ * No wildcards after the first label.
+ */
+ if (star != NULL || (state & LABEL_IDNA) != 0 || dots)
+ return NULL;
+ /* Only full-label '*.example.com' wildcards? */
+ if ((flags & X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS)
+ && (!atstart || !atend))
+ return NULL;
+ /* No 'foo*bar' wildcards */
+ if (!atstart && !atend)
+ return NULL;
+ star = &p[i];
+ state &= ~LABEL_START;
+ } else if ((state & LABEL_START) != 0) {
+ /*
+ * At the start of a label, skip any "xn--" and
+ * remain in the LABEL_START state, but set the
+ * IDNA label state
+ */
+ if ((state & LABEL_IDNA) == 0 && len - i >= 4
+ && strncasecmp((const char *)&p[i], "xn--", 4) == 0) {
+ i += 3;
+ state |= LABEL_IDNA;
+ continue;
+ }
+ /* Labels must start with a letter or digit */
+ state &= ~LABEL_START;
+ if (('a' <= p[i] && p[i] <= 'z')
+ || ('A' <= p[i] && p[i] <= 'Z')
+ || ('0' <= p[i] && p[i] <= '9'))
+ continue;
+ return NULL;
+ } else if (('a' <= p[i] && p[i] <= 'z')
+ || ('A' <= p[i] && p[i] <= 'Z')
+ || ('0' <= p[i] && p[i] <= '9')) {
+ state &= LABEL_IDNA;
+ continue;
+ } else if (p[i] == '.') {
+ if (state & (LABEL_HYPHEN | LABEL_START))
+ return NULL;
+ state = LABEL_START;
+ ++dots;
+ } else if (p[i] == '-') {
+ /* no domain/subdomain starts with '-' */
+ if ((state & LABEL_START) != 0)
+ return NULL;
+ state |= LABEL_HYPHEN;
+ } else
+ return NULL;
+ }
+
+ /*
+ * The final label must not end in a hyphen or ".", and
+ * there must be at least two dots after the star.
+ */
+ if ((state & (LABEL_START | LABEL_HYPHEN)) != 0 || dots < 2)
+ return NULL;
+ return star;
+}
+
+/* Compare using wildcards. */
+static int equal_wildcard(const unsigned char *pattern, size_t pattern_len,
+ const unsigned char *subject, size_t subject_len, unsigned int flags)
+{
+ const unsigned char *star = NULL;
+
+ /*
+ * Subject names starting with '.' can only match a wildcard pattern
+ * via a subject sub-domain pattern suffix match.
+ */
+ if (!(subject_len > 1 && subject[0] == '.'))
+ star = valid_star(pattern, pattern_len, flags);
+ if (star == NULL)
+ return equal_nocase(pattern, pattern_len,
+ subject, subject_len, flags);
+ return wildcard_match(pattern, star - pattern,
+ star + 1, (pattern + pattern_len) - star - 1,
+ subject, subject_len, flags);
+}
+
+/*
+ * Compare an ASN1_STRING to a supplied string. If they match return 1. If
+ * cmp_type > 0 only compare if string matches the type, otherwise convert it
+ * to UTF8.
+ */
+
+static int
+do_check_string(ASN1_STRING *a, int cmp_type, equal_fn equal,
+ unsigned int flags, const char *b, size_t blen, char **peername)
+{
+ int rv = 0;
+
+ if (!a->data || !a->length)
+ return 0;
+ if (cmp_type > 0) {
+ if (cmp_type != a->type)
+ return 0;
+ if (cmp_type == V_ASN1_IA5STRING)
+ rv = equal(a->data, a->length, (unsigned char *)b,
+ blen, flags);
+ else if (a->length == (int)blen && !memcmp(a->data, b, blen))
+ rv = 1;
+ if (rv > 0 && peername &&
+ (*peername = strndup((char *)a->data, a->length)) == NULL)
+ rv = -1;
+ } else {
+ int astrlen;
+ unsigned char *astr;
+ astrlen = ASN1_STRING_to_UTF8(&astr, a);
+ if (astrlen < 0)
+ return -1;
+ rv = equal(astr, astrlen, (unsigned char *)b, blen, flags);
+ if (rv > 0 && peername &&
+ (*peername = strndup((char *)astr, astrlen)) == NULL)
+ rv = -1;
+ free(astr);
+ }
+ return rv;
+}
+
+static int do_x509_check(X509 *x, const char *chk, size_t chklen,
+ unsigned int flags, int check_type, char **peername)
+{
+ GENERAL_NAMES *gens = NULL;
+ X509_NAME *name = NULL;
+ size_t i;
+ int j;
+ int cnid = NID_undef;
+ int alt_type;
+ int san_present = 0;
+ int rv = 0;
+ equal_fn equal;
+
+ /* See below, this flag is internal-only */
+ flags &= ~_X509_CHECK_FLAG_DOT_SUBDOMAINS;
+ if (check_type == GEN_EMAIL) {
+ cnid = NID_pkcs9_emailAddress;
+ alt_type = V_ASN1_IA5STRING;
+ equal = equal_email;
+ } else if (check_type == GEN_DNS) {
+ cnid = NID_commonName;
+ /* Implicit client-side DNS sub-domain pattern */
+ if (chklen > 1 && chk[0] == '.')
+ flags |= _X509_CHECK_FLAG_DOT_SUBDOMAINS;
+ alt_type = V_ASN1_IA5STRING;
+ if (flags & X509_CHECK_FLAG_NO_WILDCARDS)
+ equal = equal_nocase;
+ else
+ equal = equal_wildcard;
+ } else {
+ alt_type = V_ASN1_OCTET_STRING;
+ equal = equal_case;
+ }
+
+ gens = X509_get_ext_d2i(x, NID_subject_alt_name, NULL, NULL);
+ if (gens != NULL) {
+ for (i = 0; i < sk_GENERAL_NAME_num(gens); i++) {
+ GENERAL_NAME *gen;
+ ASN1_STRING *cstr;
+ gen = sk_GENERAL_NAME_value(gens, i);
+ if (gen->type != check_type)
+ continue;
+ san_present = 1;
+ if (check_type == GEN_EMAIL)
+ cstr = gen->d.rfc822Name;
+ else if (check_type == GEN_DNS)
+ cstr = gen->d.dNSName;
+ else
+ cstr = gen->d.iPAddress;
+ /* Positive on success, negative on error! */
+ if ((rv = do_check_string(cstr, alt_type, equal, flags,
+ chk, chklen, peername)) != 0)
+ break;
+ }
+ GENERAL_NAMES_free(gens);
+ if (rv != 0)
+ return rv;
+ if (cnid == NID_undef ||
+ (san_present &&
+ !(flags & X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT)))
+ return 0;
+ }
+
+ /* We're done if CN-ID is not pertinent */
+ if (cnid == NID_undef)
+ return 0;
+
+ j = -1;
+ name = X509_get_subject_name(x);
+ while ((j = X509_NAME_get_index_by_NID(name, cnid, j)) >= 0) {
+ X509_NAME_ENTRY *ne;
+ ASN1_STRING *str;
+ if ((ne = X509_NAME_get_entry(name, j)) == NULL)
+ return -1;
+ if ((str = X509_NAME_ENTRY_get_data(ne)) == NULL)
+ return -1;
+ /* Positive on success, negative on error! */
+ if ((rv = do_check_string(str, -1, equal, flags,
+ chk, chklen, peername)) != 0)
+ return rv;
+ }
+ return 0;
+}
+
+int X509_check_host(X509 *x, const char *chk, size_t chklen,
+ unsigned int flags, char **peername)
+{
+ if (chk == NULL)
+ return -2;
+ if (memchr(chk, '\0', chklen))
+ return -2;
+ return do_x509_check(x, chk, chklen, flags, GEN_DNS, peername);
+}
+
+#endif
diff --git a/libfetch/openssl-compat.h b/libfetch/openssl-compat.h
new file mode 100644
index 0000000..6b72fda
--- /dev/null
+++ b/libfetch/openssl-compat.h
@@ -0,0 +1,33 @@
+#include <openssl/crypto.h>
+#include <openssl/x509.h>
+#include <openssl/x509v3.h>
+#include <openssl/pem.h>
+#include <openssl/ssl.h>
+#include <openssl/err.h>
+
+#ifndef X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT
+#define OSSL_COMPAT_NEED_X509_CHECK 1
+
+/* Flags for X509_check_* functions */
+/* Always check subject name for host match even if subject alt names present */
+#define X509_CHECK_FLAG_ALWAYS_CHECK_SUBJECT 0x1
+/* Disable wildcard matching for dnsName fields and common name. */
+#define X509_CHECK_FLAG_NO_WILDCARDS 0x2
+/* Wildcards must not match a partial label. */
+#define X509_CHECK_FLAG_NO_PARTIAL_WILDCARDS 0x4
+/* Allow (non-partial) wildcards to match multiple labels. */
+#define X509_CHECK_FLAG_MULTI_LABEL_WILDCARDS 0x8
+/* Constraint verifier subdomain patterns to match a single labels. */
+#define X509_CHECK_FLAG_SINGLE_LABEL_SUBDOMAINS 0x10
+
+/*
+ * Match reference identifiers starting with "." to any sub-domain.
+ * This is a non-public flag, turned on implicitly when the subject
+ * reference identity is a DNS name.
+ */
+#define _X509_CHECK_FLAG_DOT_SUBDOMAINS 0x8000
+
+int X509_check_host(X509 *x, const char *chk, size_t chklen,
+ unsigned int flags, char **peername);
+
+#endif