MEDIUM: http: restrict the HTTP version token to 1 digit as per RFC7230

While RFC2616 used to allow an undeterminate amount of digits for the
major and minor components of the HTTP version, RFC7230 has reduced
that to a single digit for each.

If a server can't properly parse the version string and falls back to 0.9,
it could then send a head-less response whose payload would be taken for
headers, which could confuse downstream agents.

Since there's no more reason for supporting a version scheme that was
never used, let's upgrade to the updated version of the standard. It is
still possible to enforce support for the old behaviour using options
accept-invalid-http-request and accept-invalid-http-response.

It would be wise to backport this to 1.5 as well just in case.

diff --git a/doc/configuration.txt b/doc/configuration.txt
index 780d6b5054088780306cb45b1a882c228773036c..67286440b23da781cd55932d8c7f2888f644e589 100644 (file)
--- a/doc/configuration.txt
+++ b/doc/configuration.txt
@@ -4108,7 +4108,7 @@ no option accept-invalid-http-request
                                  yes   |    yes   |   yes  |   no
   Arguments : none
 
-  By default, HAProxy complies with RFC2616 in terms of message parsing. This
+  By default, HAProxy complies with RFC7230 in terms of message parsing. This
   means that invalid characters in header names are not permitted and cause an
   error to be returned to the client. This is the desired behaviour as such
   forbidden characters are essentially used to build attacks exploiting server
@@ -4121,7 +4121,9 @@ no option accept-invalid-http-request
   chars 0-31, 32 (space), 34 ('"'), 60 ('<'), 62 ('>'), 92 ('\'), 94 ('^'), 96
   ('`'), 123 ('{'), 124 ('|'), 125 ('}'), 127 (delete) and anything above are
   not allowed at all. Haproxy always blocks a number of them (0..32, 127). The
-  remaining ones are blocked by default unless this option is enabled.
+  remaining ones are blocked by default unless this option is enabled. This
+  option also relaxes the test on the HTTP version format, it allows multiple
+  digits for both the major and the minor version.
 
   This option should never be enabled by default as it hides application bugs
   and open security breaches. It should only be deployed after a problem has
@@ -4147,7 +4149,7 @@ no option accept-invalid-http-response
                                  yes   |     no   |   yes  |   yes
   Arguments : none
 
-  By default, HAProxy complies with RFC2616 in terms of message parsing. This
+  By default, HAProxy complies with RFC7230 in terms of message parsing. This
   means that invalid characters in header names are not permitted and cause an
   error to be returned to the client. This is the desired behaviour as such
   forbidden characters are essentially used to build attacks exploiting server
@@ -4155,7 +4157,9 @@ no option accept-invalid-http-response
   server will emit invalid header names for whatever reason (configuration,
   implementation) and the issue will not be immediately fixed. In such a case,
   it is possible to relax HAProxy's header name parser to accept any character
-  even if that does not make sense, by specifying this option.
+  even if that does not make sense, by specifying this option. This option also
+  relaxes the test on the HTTP version format, it allows multiple digits for
+  both the major and the minor version.
 
   This option should never be enabled by default as it hides application bugs
   and open security breaches. It should only be deployed after a problem has

diff --git a/src/proto_http.c b/src/proto_http.c
index a34c11036a172300f8fe221390d9e6fec90fa0b3..a0c9e1ce608b6c1b9c3a0aa0cca0a594922044ff 100644 (file)
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -2943,6 +2943,25 @@ int http_wait_for_request(struct stream *s, struct channel *req, int an_bit)
        if (unlikely(msg->sl.rq.v_l == 0) && !http_upgrade_v09_to_v10(txn))
                goto return_bad_req;
 
+       /* RFC7230#2.6 has enforced the format of the HTTP version string to be
+        * exactly one digit "." one digit. This check may be disabled using
+        * option accept-invalid-http-request.
+        */
+       if (!(sess->fe->options2 & PR_O2_REQBUG_OK)) {
+               if (msg->sl.rq.v_l != 8) {
+                       msg->err_pos = msg->sl.rq.v;
+                       goto return_bad_req;
+               }
+
+               if (req->buf->p[msg->sl.rq.v + 4] != '/' ||
+                   !isdigit((unsigned char)req->buf->p[msg->sl.rq.v + 5]) ||
+                   req->buf->p[msg->sl.rq.v + 6] != '.' ||
+                   !isdigit((unsigned char)req->buf->p[msg->sl.rq.v + 7])) {
+                       msg->err_pos = msg->sl.rq.v + 4;
+                       goto return_bad_req;
+               }
+       }
+
        /* ... and check if the request is HTTP/1.1 or above */
        if ((msg->sl.rq.v_l == 8) &&
            ((req->buf->p[msg->sl.rq.v + 5] > '1') ||
@@ -6061,6 +6080,25 @@ int http_wait_for_response(struct stream *s, struct channel *rep, int an_bit)
        if (objt_server(s->target))
                objt_server(s->target)->counters.p.http.rsp[n]++;
 
+       /* RFC7230#2.6 has enforced the format of the HTTP version string to be
+        * exactly one digit "." one digit. This check may be disabled using
+        * option accept-invalid-http-response.
+        */
+       if (!(s->be->options2 & PR_O2_RSPBUG_OK)) {
+               if (msg->sl.st.v_l != 8) {
+                       msg->err_pos = 0;
+                       goto hdr_response_bad;
+               }
+
+               if (rep->buf->p[4] != '/' ||
+                   !isdigit((unsigned char)rep->buf->p[5]) ||
+                   rep->buf->p[6] != '.' ||
+                   !isdigit((unsigned char)rep->buf->p[7])) {
+                       msg->err_pos = 4;
+                       goto hdr_response_bad;
+               }
+       }
+
        /* check if the response is HTTP/1.1 or above */
        if ((msg->sl.st.v_l == 8) &&
            ((rep->buf->p[5] > '1') ||