scripts: always check certificates

Remove flags from wget and curl instructing them to ignore bad server
certificates. Although other mechanisms can protect against malicious
modifications of downloads, other vectors of attack may be available
to an adversary.

TLS certificate verification can be disabled by turning oof the
"Enable TLS certificate verification during package download" option
enabled by default in the "Global build settings" in "make menuconfig"

Signed-off-by: Josh Roys <[email protected]>
[ add additional info on how to disable this option ]
Signed-off-by: Christian Marangi <[email protected]>

config/Config-build.in

@@ -58,6 +58,10 @@ menu "Global build settings"
 		bool "Enable signature checking in opkg"
 		default SIGNED_PACKAGES
 
+	config DOWNLOAD_CHECK_CERTIFICATE
+		bool "Enable TLS certificate verification during package download"
+		default y
+
 	comment "General build options"
 
 	config TESTING_KERNEL

rules.mk

@@ -257,6 +257,9 @@ ESED:=$(STAGING_DIR_HOST)/bin/sed -E -i -e
 MKHASH:=$(STAGING_DIR_HOST)/bin/mkhash
 # MKHASH is used in /scripts, so we export it here.
 export MKHASH
+# DOWNLOAD_CHECK_CERTIFICATE is used in /scripts, so we export it here.
+DOWNLOAD_CHECK_CERTIFICATE:=$(CONFIG_DOWNLOAD_CHECK_CERTIFICATE)
+export DOWNLOAD_CHECK_CERTIFICATE
 CP:=cp -fpR
 LN:=ln -sf
 XARGS:=xargs -r

scripts/download.pl

@@ -24,6 +24,8 @@ my $scriptdir = dirname($0);
 my @mirrors;
 my $ok;
 
+my $check_certificate = $ENV{DOWNLOAD_CHECK_CERTIFICATE} eq "y";
+
 $url_filename or $url_filename = $filename;
 
 sub localmirrors {
@@ -80,8 +82,8 @@ sub download_cmd($) {
 	}
 
 	return $have_curl
-		? (qw(curl -f --connect-timeout 20 --retry 5 --location --insecure), shellwords($ENV{CURL_OPTIONS} || ''), $url)
-		: (qw(wget --tries=5 --timeout=20 --no-check-certificate --output-document=-), shellwords($ENV{WGET_OPTIONS} || ''), $url)
+		? (qw(curl -f --connect-timeout 20 --retry 5 --location), $check_certificate ? '' : '--insecure', shellwords($ENV{CURL_OPTIONS} || ''), $url)
+		: (qw(wget --tries=5 --timeout=20 --output-document=-), $check_certificate ? '' : '--no-check-certificate', shellwords($ENV{WGET_OPTIONS} || ''), $url)
 	;
 }