diff options
Diffstat (limited to 'utils/perldoc.PL')
| -rw-r--r-- | utils/perldoc.PL | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/utils/perldoc.PL b/utils/perldoc.PL index 62a82f381f..2f60c6ed2e 100644 --- a/utils/perldoc.PL +++ b/utils/perldoc.PL @@ -169,13 +169,27 @@ if (!($Is_VMS || $Is_MSWin32 || $Is_Dos || $Is_OS2) && ($> == 0 || $< == 0) my $id = eval { getpwnam("nobody") }; $id = eval { getpwnam("nouser") } unless defined $id; $id = -2 unless defined $id; + # + # According to Stevens' APUE and various + # (BSD, Solaris, HP-UX) man pages setting + # the real uid first and effective uid second + # is the way to go if one wants to drop privileges, + # because if one changes into an effective uid of + # non-zero, one cannot change the real uid any more. + # + # Actually, it gets even messier. There is + # a third uid, called the saved uid, and as + # long as that is zero, one can get back to + # uid of zero. Setting the real-effective *twice* + # helps in *most* systems (FreeBSD and Solaris) + # but apparently in HP-UX even this doesn't help: + # the saved uid stays zero (apparently the only way + # in HP-UX to change saved uid is to call setuid() + # when the effective uid is zero). + # eval { - # According to Stevens' APUE and various - # (BSD, Solaris, HP-UX) man pages setting - # the real uid first and effective uid second - # is the way to go if one wants to drop privileges, - # because if one changes into an effective uid of - # non-zero, one cannot change the real uid any more. + $< = $id; # real uid + $> = $id; # effective uid $< = $id; # real uid $> = $id; # effective uid }; |