[nginx] Disabled control characters in URIs.

[Maxim Dounin]

details:   https://hg.nginx.org/nginx/rev/b4073527be81
branches:  
changeset: 7882:b4073527be81
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Mon Jun 28 18:01:15 2021 +0300
description:
Disabled control characters in URIs.

Control characters (0x00-0x1f, 0x7f) were never allowed in URIs, and must
be percent-encoded by clients.  Further, these are not believed to appear
in practice.  On the other hand, passing such characters might make various
attacks possible or easier, despite the fact that currently allowed control
characters are not significant for HTTP request parsing.

diffstat:

 src/http/ngx_http_parse.c |  42 ++++++++++++++++++++++++++++--------------
 1 files changed, 28 insertions(+), 14 deletions(-)

diffs (119 lines):

diff -r 52338ddf9e2f -r b4073527be81 src/http/ngx_http_parse.c
--- a/src/http/ngx_http_parse.c	Mon Jun 28 18:01:13 2021 +0300
+++ b/src/http/ngx_http_parse.c	Mon Jun 28 18:01:15 2021 +0300
@@ -11,7 +11,7 @@
 
 
 static uint32_t  usual[] = {
-    0xffffdbfe, /* 1111 1111 1111 1111  1101 1011 1111 1110 */
+    0x00000000, /* 0000 0000 0000 0000  0000 0000 0000 0000 */
 
                 /* ?>=< ;:98 7654 3210  /.-, +*)( '&%$ #"!  */
     0x7fff37d6, /* 0111 1111 1111 1111  0011 0111 1101 0110 */
@@ -24,7 +24,7 @@ static uint32_t  usual[] = {
 #endif
 
                 /*  ~}| {zyx wvut srqp  onml kjih gfed cba` */
-    0xffffffff, /* 1111 1111 1111 1111  1111 1111 1111 1111 */
+    0x7fffffff, /* 0111 1111 1111 1111  1111 1111 1111 1111 */
 
     0xffffffff, /* 1111 1111 1111 1111  1111 1111 1111 1111 */
     0xffffffff, /* 1111 1111 1111 1111  1111 1111 1111 1111 */
@@ -528,9 +528,10 @@ ngx_http_parse_request_line(ngx_http_req
             case '+':
                 r->plus_in_uri = 1;
                 break;
-            case '\0':
-                return NGX_HTTP_PARSE_INVALID_REQUEST;
             default:
+                if (ch < 0x20 || ch == 0x7f) {
+                    return NGX_HTTP_PARSE_INVALID_REQUEST;
+                }
                 state = sw_check_uri;
                 break;
             }
@@ -592,8 +593,11 @@ ngx_http_parse_request_line(ngx_http_req
             case '+':
                 r->plus_in_uri = 1;
                 break;
-            case '\0':
-                return NGX_HTTP_PARSE_INVALID_REQUEST;
+            default:
+                if (ch < 0x20 || ch == 0x7f) {
+                    return NGX_HTTP_PARSE_INVALID_REQUEST;
+                }
+                break;
             }
             break;
 
@@ -621,8 +625,11 @@ ngx_http_parse_request_line(ngx_http_req
             case '#':
                 r->complex_uri = 1;
                 break;
-            case '\0':
-                return NGX_HTTP_PARSE_INVALID_REQUEST;
+            default:
+                if (ch < 0x20 || ch == 0x7f) {
+                    return NGX_HTTP_PARSE_INVALID_REQUEST;
+                }
+                break;
             }
             break;
 
@@ -1118,8 +1125,6 @@ ngx_http_parse_uri(ngx_http_request_t *r
             }
 
             switch (ch) {
-            case ' ':
-                return NGX_ERROR;
             case '.':
                 r->complex_uri = 1;
                 state = sw_uri;
@@ -1150,6 +1155,9 @@ ngx_http_parse_uri(ngx_http_request_t *r
                 r->plus_in_uri = 1;
                 break;
             default:
+                if (ch <= 0x20 || ch == 0x7f) {
+                    return NGX_ERROR;
+                }
                 state = sw_check_uri;
                 break;
             }
@@ -1177,8 +1185,6 @@ ngx_http_parse_uri(ngx_http_request_t *r
             case '.':
                 r->uri_ext = p + 1;
                 break;
-            case ' ':
-                return NGX_ERROR;
 #if (NGX_WIN32)
             case '\\':
                 r->complex_uri = 1;
@@ -1200,6 +1206,11 @@ ngx_http_parse_uri(ngx_http_request_t *r
             case '+':
                 r->plus_in_uri = 1;
                 break;
+            default:
+                if (ch <= 0x20 || ch == 0x7f) {
+                    return NGX_ERROR;
+                }
+                break;
             }
             break;
 
@@ -1211,11 +1222,14 @@ ngx_http_parse_uri(ngx_http_request_t *r
             }
 
             switch (ch) {
-            case ' ':
-                return NGX_ERROR;
             case '#':
                 r->complex_uri = 1;
                 break;
+            default:
+                if (ch <= 0x20 || ch == 0x7f) {
+                    return NGX_ERROR;
+                }
+                break;
             }
             break;
         }