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 -#include -#include -#include -#include -#include +#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 +#include +#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 +#include +#include +#include +#include +#include + +#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