bitbake: fetch2/wget: fetch securely by default

The days of broken certificates are behind us now, so instead of always
passing --no-check-certificate to wget, don't pass it by default and
instead only pass it BB_CHECK_SSL_CERTS = "0".

[ YOCTO #14108 ]

(Bitbake rev: 4104850dd36096a9ff01836c5fca9ac0e452bcf8)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/doc/bitbake-user-manual/bitbake-user-manual-fetching.rst

@@ -144,6 +144,10 @@ download without a checksum triggers an error message. The
 make any attempted network access a fatal error, which is useful for
 checking that mirrors are complete as well as other things.
 
+If :term:`BB_CHECK_SSL_CERTS` is set to ``0`` then SSL certificate checking will
+be disabled. This variable defaults to ``1`` so SSL certificates are normally
+checked.
+
 .. _bb-the-unpack:
 
 The Unpack

bitbake/doc/bitbake-user-manual/bitbake-user-manual-ref-variables.rst

@@ -93,6 +93,10 @@ overview of their function and contents.
       fetcher does not attempt to use the host listed in :term:`SRC_URI` after
       a successful fetch from the :term:`PREMIRRORS` occurs.
 
+   :term:`BB_CHECK_SSL_CERTS`
+      Specifies if SSL certificates should be checked when fetching. The default
+      value is ``1`` and certificates are not checked if the value is set to ``0``.
+
    :term:`BB_CONSOLELOG`
       Specifies the path to a log file into which BitBake's user interface
       writes output during the build.

bitbake/lib/bb/fetch2/wget.py

@@ -52,13 +52,19 @@ class WgetProgressHandler(bb.progress.LineFilterProgressHandler):
 
 
 class Wget(FetchMethod):
+    """Class to fetch urls via 'wget'"""
 
     # CDNs like CloudFlare may do a 'browser integrity test' which can fail
     # with the standard wget/urllib User-Agent, so pretend to be a modern
     # browser.
     user_agent = "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:84.0) Gecko/20100101 Firefox/84.0"
 
-    """Class to fetch urls via 'wget'"""
+    def check_certs(self, d):
+        """
+        Should certificates be checked?
+        """
+        return (d.getVar("BB_CHECK_SSL_CERTS") or "1") != "0"
+
     def supports(self, ud, d):
         """
         Check to see if a given url can be fetched with wget.
@@ -82,7 +88,10 @@ class Wget(FetchMethod):
         if not ud.localfile:
             ud.localfile = d.expand(urllib.parse.unquote(ud.host + ud.path).replace("/", "."))
 
-        self.basecmd = d.getVar("FETCHCMD_wget") or "/usr/bin/env wget -t 2 -T 30 --passive-ftp --no-check-certificate"
+        self.basecmd = d.getVar("FETCHCMD_wget") or "/usr/bin/env wget -t 2 -T 30 --passive-ftp"
+
+        if not self.check_certs(d):
+            self.basecmd += " --no-check-certificate"
 
     def _runwget(self, ud, d, command, quiet, workdir=None):
 
@@ -309,7 +318,11 @@ class Wget(FetchMethod):
         with bb.utils.environment(**newenv):
             import ssl
 
-            context = ssl._create_unverified_context()
+            if self.check_certs(d):
+                context = ssl.create_default_context()
+            else:
+                context = ssl._create_unverified_context()
+
             handlers = [FixedHTTPRedirectHandler,
                         HTTPMethodFallback,
                         urllib.request.ProxyHandler(),