[pkg-gnupg-maint] Bug#835629: gnupg2: “unsafe ownership” is based on uid instead of euid

[Valentin Lorentz]

Package: gnupg2
Version: 2.1.11-7

When running gnupg2 from an executable with a SUID, gnupg2 wrongly warns
about “unsafe ownership on homedir”.

Here is how to reproduce the bug:

 val at particle:/tmp $ cat foo.c
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>

void main(int argc, char* argv[]) {
    system("gpg2 --list-secret-keys --homedir=/home/dev-misc/.gnupg");
}
 val at particle:/tmp $ sudo gcc foo.c && sudo chown dev-misc:dev-misc
a.out && sudo chmod u+s a.out
 val at particle:/tmp $ LANG=C ./a.out
gpg: WARNING: unsafe ownership on homedir '/home/dev-misc/.gnupg'
gpg: keybox '/home/dev-misc/.gnupg/pubring.kbx' created
 val at particle:/tmp $ sudo ls -la /home/dev-misc/ | grep gnupg
drwx------  2 dev-misc dev-misc    4096 août  27 20:22 .gnupg

Best regards,
Valentin