[nginx] Fixed handling of unix sockets in $binary_remote_addr.

[Maxim Dounin]

details:   http://hg.nginx.org/nginx/rev/0800444254e8
branches:  stable-1.12
changeset: 7147:0800444254e8
user:      Maxim Dounin <mdounin at mdounin.ru>
date:      Wed Oct 04 21:19:42 2017 +0300
description:
Fixed handling of unix sockets in $binary_remote_addr.

Previously, unix sockets were treated as AF_INET ones, and this may
result in buffer overread on Linux, where unbound unix sockets have
2-byte addresses.

Note that it is not correct to use just sun_path as a binary representation
for unix sockets.  This will result in an empty string for unbound unix
sockets, and thus behaviour of limit_req and limit_conn will change when
switching from $remote_addr to $binary_remote_addr.  As such, normal text
representation is used.

Reported by Stephan Dollberg.

diffstat:

 src/http/ngx_http_variables.c     |  12 ++++++++++++
 src/stream/ngx_stream_variables.c |  12 ++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)

diffs (44 lines):

diff --git a/src/http/ngx_http_variables.c b/src/http/ngx_http_variables.c
--- a/src/http/ngx_http_variables.c
+++ b/src/http/ngx_http_variables.c
@@ -1225,6 +1225,18 @@ ngx_http_variable_binary_remote_addr(ngx
         break;
 #endif
 
+#if (NGX_HAVE_UNIX_DOMAIN)
+    case AF_UNIX:
+
+        v->len = r->connection->addr_text.len;
+        v->valid = 1;
+        v->no_cacheable = 0;
+        v->not_found = 0;
+        v->data = r->connection->addr_text.data;
+
+        break;
+#endif
+
     default: /* AF_INET */
         sin = (struct sockaddr_in *) r->connection->sockaddr;
 
diff --git a/src/stream/ngx_stream_variables.c b/src/stream/ngx_stream_variables.c
--- a/src/stream/ngx_stream_variables.c
+++ b/src/stream/ngx_stream_variables.c
@@ -481,6 +481,18 @@ ngx_stream_variable_binary_remote_addr(n
         break;
 #endif
 
+#if (NGX_HAVE_UNIX_DOMAIN)
+    case AF_UNIX:
+
+        v->len = s->connection->addr_text.len;
+        v->valid = 1;
+        v->no_cacheable = 0;
+        v->not_found = 0;
+        v->data = s->connection->addr_text.data;
+
+        break;
+#endif
+
     default: /* AF_INET */
         sin = (struct sockaddr_in *) s->connection->sockaddr;