ref: 3bc748078a135fc3b31a611c4074f1f416c3e758
parent: 3f54b9ddde0cc11327887c6c207b5c48b3af451d
author: Timothy B. Terriberry <tterribe@xiph.org>
date: Sat Oct 27 02:52:11 EDT 2012
A few small updates to the hostname verification. Fixes the case where a raw IPv6 address would be rejected as not looking like a FQDN. Also simplifies the wildcard comparison a little.
--- a/src/http.c
+++ b/src/http.c
@@ -1428,9 +1428,11 @@
ASN1_STRING *_pattern){const char *pattern;
size_t host_label_len;
+ size_t host_suffix_len;
size_t pattern_len;
size_t pattern_label_len;
size_t pattern_prefix_len;
+ size_t pattern_suffix_len;
pattern=(const char *)ASN1_STRING_data(_pattern);
pattern_len=strlen(pattern);
/*Check the pattern for embedded NULs.*/
@@ -1450,9 +1452,9 @@
the ASCII range.*/
return _host_len==pattern_len&&op_strncasecmp(_host,pattern,_host_len)==0;
}
- /*"However, the client SHOULD NOT attempt to match a presented identifier where
- the wildcard character is embedded within an A-label or U-label of an
- internationalized domain name.*/
+ /*"However, the client SHOULD NOT attempt to match a presented identifier
+ where the wildcard character is embedded within an A-label or U-label of
+ an internationalized domain name.*/
if(op_strncasecmp(pattern,"xn--",4)==0)return 0;
host_label_len=strcspn(_host,".");
/*Make sure the host has at least two dots, to prevent the wildcard match
@@ -1472,12 +1474,7 @@
We also use the fact that the wildcard must match at least one character,
so the left-most label of the hostname must be at least as large as the
left-most label of the pattern.*/
- if(host_label_len<pattern_label_len
- ||pattern_len-pattern_label_len!=_host_len-host_label_len
- ||op_strncasecmp(_host+host_label_len,pattern+pattern_label_len,
- _host_len-host_label_len)!=0){- return 0;
- }
+ if(host_label_len<pattern_label_len)return 0;
OP_ASSERT(pattern[pattern_prefix_len]=='*');
/*"The client MAY match a presented identifier in which the wildcard
character is not the only character of the label (e.g., baz*.example.net
@@ -1484,9 +1481,13 @@
and *baz.example.net and b*z.example.net would be taken to match
baz1.example.net and foobaz.example.net and buzz.example.net,
respectively)."*/
- return op_strncasecmp(_host,pattern,pattern_prefix_len)==0&&
- op_strncasecmp(_host+host_label_len-(pattern_label_len-pattern_prefix_len-1),
- pattern+pattern_prefix_len+1,pattern_label_len-pattern_prefix_len-1)==0;
+ pattern_suffix_len=pattern_len-pattern_prefix_len-1;
+ host_suffix_len=_host_len-host_label_len
+ +pattern_label_len-pattern_prefix_len-1;
+ return pattern_suffix_len==host_suffix_len
+ &&op_strncasecmp(_host,pattern,pattern_prefix_len)==0
+ &&op_strncasecmp(_host+_host_len-host_suffix_len,
+ pattern+pattern_prefix_len+1,host_suffix_len)==0;
}
/*Convert a host to a numeric address, if possible.
@@ -1498,7 +1499,7 @@
memset(&hints,0,sizeof(hints));
hints.ai_socktype=SOCK_STREAM;
hints.ai_flags=AI_NUMERICHOST;
- if(OP_LIKELY(!getaddrinfo(_host,NULL,&hints,&addrs)))return addrs;
+ if(!getaddrinfo(_host,NULL,&hints,&addrs))return addrs;
return NULL;
}
@@ -1514,26 +1515,6 @@
int ret;
host=_stream->url.host;
host_len=strlen(host);
- /*We can only verify fully-qualified domain names.
- To quote RFC 6125: "The extracted data MUST include only information that
- can be securely parsed out of the inputs (e.g., parsing the fully
- qualified DNS domain name out of the "host" component (or its equivalent)
- of a URI or deriving the application service type from the scheme of a
- URI) ..."
- We don't have a way to check (without relying on DNS records, which might
- be subverted), if this address is fully-qualified.
- This is particularly problematic when using a CONNECT tunnel, as it is the
- server that does DNS lookup, not us.
- However, we are certain that if the hostname has no '.', it is definitely
- not a fully-qualified domain name (with the exception of crazy TLDs that
- actually resolve, like "uz", but I am willing to ignore those).
- RFC 1535 says "...in any event where a '.' exists in a specified name it
- should be assumed to be a fully qualified domain name (FQDN) and SHOULD be
- tried as a rooted name first."
- That doesn't give us any security guarantees, of course (a subverted DNS
- could fail the original query and our resolver might still retry with a
- local domain appended).*/
- if(strchr(host,'.')==NULL)return 0;
peer_cert=SSL_get_peer_certificate(_ssl_conn);
/*We set VERIFY_PEER, so we shouldn't get here without a certificate.*/
if(OP_UNLIKELY(peer_cert==NULL))return 0;
@@ -1587,6 +1568,26 @@
}break;
}
}
+ /*We can only verify fully-qualified domain names.
+ To quote RFC 6125: "The extracted data MUST include only information that
+ can be securely parsed out of the inputs (e.g., parsing the fully
+ qualified DNS domain name out of the "host" component (or its
+ equivalent) of a URI or deriving the application service type from the
+ scheme of a URI) ..."
+ We don't have a way to check (without relying on DNS records, which might
+ be subverted), if this address is fully-qualified.
+ This is particularly problematic when using a CONNECT tunnel, as it is
+ the server that does DNS lookup, not us.
+ However, we are certain that if the hostname has no '.', it is definitely
+ not a fully-qualified domain name (with the exception of crazy TLDs that
+ actually resolve, like "uz", but I am willing to ignore those).
+ RFC 1535 says "...in any event where a '.' exists in a specified name it
+ should be assumed to be a fully qualified domain name (FQDN) and SHOULD
+ be tried as a rooted name first."
+ That doesn't give us any security guarantees, of course (a subverted DNS
+ could fail the original query and our resolver might still retry with a
+ local domain appended).*/
+ if(ip==NULL&&strchr(host,'.')==NULL)return 0;
/*RFC 2459 says there MUST be at least one, but we don't depend on it.*/
nsan_names=sk_GENERAL_NAME_num(san_names);
for(sni=0;sni<nsan_names;sni++){@@ -1627,6 +1628,10 @@
else{int last_cn_loc;
int cn_loc;
+ /*Do the same FQDN check we did above.
+ We don't do this once in advance for both cases, because in the
+ subjectAltName case we might have an IPv6 address without a dot.*/
+ if(strchr(host,'.')==NULL)return 0;
/*If there is no subjectAltName, match against commonName.
RFC 6125 says that at least one significant CA is known to issue certs
with multiple CNs, although it SHOULD NOT.