commit:     590e32d05fce225dfdab6308555f4a7668378d79
Author:     Mike Gilbert <floppym <AT> gentoo <DOT> org>
AuthorDate: Wed Jul 31 19:51:34 2019 +0000
Commit:     Mike Gilbert <floppym <AT> gentoo <DOT> org>
CommitDate: Thu Aug  1 19:01:21 2019 +0000
URL:        https://gitweb.gentoo.org/proj/portage.git/commit/?id=590e32d0

Configure additional addresses on the lo interface for network-sandbox

This works around some strange behavior in glibc's getaddrinfo()
implementation when the AI_ADDRCONFIG flag is set.

For example:

  struct addrinfo *res, hints = { .ai_family = AF_INET, .ai_flags = 
AI_ADDRCONFIG };
  getaddrinfo("localhost", NULL, &hints, &res);

This returns no results if there are no non-loopback addresses configured.

Bug: https://bugs.gentoo.org/690758
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=12377#c13
Reviewed-by: Zac Medico <zmedico <AT> gentoo.org>
Signed-off-by: Mike Gilbert <floppym <AT> gentoo.org>

 lib/portage/process.py | 50 +++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 37 insertions(+), 13 deletions(-)

diff --git a/lib/portage/process.py b/lib/portage/process.py
index dfbda75de..77f7fac02 100644
--- a/lib/portage/process.py
+++ b/lib/portage/process.py
@@ -446,6 +446,42 @@ def spawn(mycommand, env=None, opt_name=None, 
fd_pipes=None, returnpid=False,
        # Everything succeeded
        return 0
 
+def _configure_loopback_interface():
+       """
+       Configure the loopback interface.
+       """
+
+       IFF_UP = 0x1
+       ifreq = struct.pack('16sh', b'lo', IFF_UP)
+       SIOCSIFFLAGS = 0x8914
+
+       sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
+       try:
+               fcntl.ioctl(sock, SIOCSIFFLAGS, ifreq)
+       except IOError as e:
+               writemsg("Unable to enable loopback interface: %s\n" % 
e.strerror, noiselevel=-1)
+       sock.close()
+
+       # We add some additional addresses to work around odd behavior in 
glibc's
+       # getaddrinfo() implementation when the AI_ADDRCONFIG flag is set.
+       #
+       # For example:
+       #
+       #   struct addrinfo *res, hints = { .ai_family = AF_INET, .ai_flags = 
AI_ADDRCONFIG };
+       #   getaddrinfo("localhost", NULL, &hints, &res);
+       #
+       # This returns no results if there are no non-loopback addresses
+       # configured for a given address family.
+       #
+       # Bug: https://bugs.gentoo.org/690758
+       # Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=12377#c13
+
+       try:
+               subprocess.call(['ip', 'address', 'add', '10.0.0.1/8', 'dev', 
'lo'])
+               subprocess.call(['ip', 'address', 'add', 'fd00::1/8', 'dev', 
'lo'])
+       except OSError as e:
+               writemsg("Error calling 'ip': %s\n" % e.strerror, noiselevel=-1)
+
 def _exec(binary, mycommand, opt_name, fd_pipes,
        env, gid, groups, uid, umask, cwd,
        pre_exec, close_fds, unshare_net, unshare_ipc, unshare_mount, 
unshare_pid,
@@ -624,19 +660,7 @@ def _exec(binary, mycommand, opt_name, fd_pipes,
                                                                        
noiselevel=-1)
                                                                os._exit(1)
                                                if unshare_net:
-                                                       # 'up' the loopback
-                                                       IFF_UP = 0x1
-                                                       ifreq = 
struct.pack('16sh', b'lo', IFF_UP)
-                                                       SIOCSIFFLAGS = 0x8914
-
-                                                       sock = 
socket.socket(socket.AF_INET, socket.SOCK_DGRAM, 0)
-                                                       try:
-                                                               
fcntl.ioctl(sock, SIOCSIFFLAGS, ifreq)
-                                                       except IOError as e:
-                                                               
writemsg("Unable to enable loopback interface: %s\n" % (
-                                                                       
errno.errorcode.get(e.errno, '?')),
-                                                                       
noiselevel=-1)
-                                                       sock.close()
+                                                       
_configure_loopback_interface()
                                except AttributeError:
                                        # unshare() not supported by libc
                                        pass

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