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imap-send: the subject of SSL certificate must match the host

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We did not check a valid certificate's subject at all, and would
have happily talked with a wrong host after connecting to an
incorrect address and getting a valid certificate that does not
belong to the host we intended to talk to.

Signed-off-by: Oswald Buddenhagen <ossi@kde.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Oswald Buddenhagen
2013-02-15 12:50:35 -08:00
committed by Junio C Hamano
parent 1e1fe52923
commit b62fb077d5
1 changed files with 39 additions and 0 deletions
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39
imap-send.c
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@ -275,6 +275,35 @@ static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int ve
#else #else
static int host_matches(const char *host, const char *pattern)
{
if (pattern[0] == '*' && pattern[1] == '.') {
pattern += 2;
if (!(host = strchr(host, '.')))
return 0;
host++;
}
return *host && *pattern && !strcasecmp(host, pattern);
}
static int verify_hostname(X509 *cert, const char *hostname)
{
int len;
X509_NAME *subj;
char cname[1000];
/* try the common name */
if (!(subj = X509_get_subject_name(cert)))
return error("cannot get certificate subject");
if ((len = X509_NAME_get_text_by_NID(subj, NID_commonName, cname, sizeof(cname))) < 0)
return error("cannot get certificate common name");
if (strlen(cname) == (size_t)len && host_matches(hostname, cname))
return 0;
return error("certificate owner '%s' does not match hostname '%s'",
cname, hostname);
}
static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int verify) static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int verify)
{ {
#if (OPENSSL_VERSION_NUMBER >= 0x10000000L) #if (OPENSSL_VERSION_NUMBER >= 0x10000000L)
@ -284,6 +313,7 @@ static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int ve
#endif #endif
SSL_CTX *ctx; SSL_CTX *ctx;
int ret; int ret;
X509 *cert;
SSL_library_init(); SSL_library_init();
SSL_load_error_strings(); SSL_load_error_strings();
@ -327,6 +357,15 @@ static int ssl_socket_connect(struct imap_socket *sock, int use_tls_only, int ve
return -1; return -1;
} }
if (verify) {
/* make sure the hostname matches that of the certificate */
cert = SSL_get_peer_certificate(sock->ssl);
if (!cert)
return error("unable to get peer certificate.");
if (verify_hostname(cert, server.host) < 0)
return -1;
}
return 0; return 0;
} }
#endif #endif