gitolite/src/gl-auth-command

#!/usr/bin/perl

use strict;
use warnings;

# === auth-command ===
# the command that GL users actually run

# part of the gitolite (GL) suite

# how run:      via sshd, being listed in "command=" in ssh authkeys
# when:         every login by a GL user
# input:        $1 is GL username, plus $SSH_ORIGINAL_COMMAND
# output:
# security:
#     - currently, we just make some basic checks, copied from gitosis

# robustness:

# other notes:

# ----------------------------------------------------------------------------
#       common definitions
# ----------------------------------------------------------------------------

# these are set by the "rc" file
our ($GL_LOGT, $GL_CONF_COMPILED, $REPO_BASE, $GIT_PATH, $REPO_UMASK, $GL_ADMINDIR, $RSYNC_BASE);
# and these are set by gitolite.pm
our ($R_COMMANDS, $W_COMMANDS, $REPONAME_PATT);
our %repos;

# the common setup module is in the same directory as this running program is
my $bindir = $0;
$bindir =~ s/\/[^\/]+$//;
require "$bindir/gitolite.pm";

# ask where the rc file is, get it, and "do" it
&where_is_rc();
die "parse $ENV{GL_RC} failed: "       . ($! or $@) unless do $ENV{GL_RC};

# we need to pass GL_ADMINDIR and the bindir to the child hooks
$ENV{GL_ADMINDIR} = $GL_ADMINDIR;
$ENV{GL_BINDIR} = $bindir;

# add a custom path for git binaries, if specified
$ENV{PATH} .= ":$GIT_PATH" if $GIT_PATH;

# set the umask before creating any files
umask($REPO_UMASK);

# ----------------------------------------------------------------------------
#       start...
# ----------------------------------------------------------------------------

# if the first argument is a "-s", this user is allowed to get a shell using
# this key
my $shell_allowed = 0;
if ($ARGV[0] eq '-s') {
    $shell_allowed = 1;
    shift;
}

# first, fix the biggest gripe I have with gitosis, a 1-line change
my $user=$ENV{GL_USER}=shift;       # there; now that's available everywhere!

# ----------------------------------------------------------------------------
#       logging, timestamp env vars
# ----------------------------------------------------------------------------

# timestamp
my ($s, $min, $h, $d, $m, $y) = (localtime)[0..5];
$y += 1900; $m++;               # usual adjustments
for ($s, $min, $h, $d, $m) {
    $_ = "0$_" if $_ < 10;
}
$ENV{GL_TS} = "$y-$m-$d.$h:$min:$s";

# substitute template parameters and set the logfile name
$GL_LOGT =~ s/%y/$y/g;
$GL_LOGT =~ s/%m/$m/g;
$GL_LOGT =~ s/%d/$d/g;
$ENV{GL_LOG} = $GL_LOGT;

# ----------------------------------------------------------------------------
#       sanity checks on SSH_ORIGINAL_COMMAND
# ----------------------------------------------------------------------------

# no SSH_ORIGINAL_COMMAND given...
unless ($ENV{SSH_ORIGINAL_COMMAND}) {
    # if the user is allowed to use a shell, give him one
    if ($shell_allowed) {
        my $shell = $ENV{SHELL};
        $shell =~ s/.*\//-/;    # change "/bin/bash" to "-bash"
        exec { $ENV{SHELL} } $shell;
    }
    # otherwise, pretend he typed in "info" and carry on...
    $ENV{SSH_ORIGINAL_COMMAND} = 'info';
}

my $cmd = $ENV{SSH_ORIGINAL_COMMAND};
# people allowed to get a shell can get basic access info by asking nicely
if ($cmd eq 'info') {
    &report_basic($GL_ADMINDIR, $GL_CONF_COMPILED, $user);
    print "you also have shell access\n\r" if $shell_allowed;
    exit 1;
}

# split into command and arguments; the pattern allows old style as well as
# new style: "git-subcommand arg" or "git subcommand arg", just like gitosis
# does, although I'm not sure how necessary that is
#
# keep in mind this is how git sends across the command:
#   git-receive-pack 'reponame.git'
# including the single quotes

my ($verb, $repo) = ($cmd =~ /^\s*(git\s+\S+|\S+)\s+'\/?(.*?)(?:\.git)?'/);
unless ( $verb and ( $verb =~ $R_COMMANDS or $verb =~ $W_COMMANDS ) and $repo and $repo =~ $REPONAME_PATT ) {
    # if the user is allowed a shell, just run the command
    exec $ENV{SHELL}, "-c", $ENV{SSH_ORIGINAL_COMMAND} if $shell_allowed;
    # otherwise, call the external command helper
    &ext_cmd($GL_CONF_COMPILED, $RSYNC_BASE, $cmd);
    exit;   # in case the external command helper forgot :-)
}

# ----------------------------------------------------------------------------
#       first level permissions check
# ----------------------------------------------------------------------------

$ENV{GL_REPO}=$repo;

# parse the compiled acl; goes into %repos (global)
&parse_acl($GL_CONF_COMPILED);

# we know the user and repo; we just need to know what perm he's trying
my $perm = ($verb =~ $R_COMMANDS ? 'R' : 'W');

die "$perm access for $repo DENIED to $user\n"
    unless $repos{$repo}{$perm}{$user}
        or $repos{$repo}{$perm}{'@all'};

# create the repo if it doesn't already exist and the user has "W" access
my $repo_base_abs = ( $REPO_BASE =~ m(^/) ? $REPO_BASE : "$ENV{HOME}/$REPO_BASE" );
if ( not -d "$repo_base_abs/$repo.git" ) {
    if ( $repos{$repo}{W}{$user} or $repos{$repo}{W}{'@all'} ) {
        wrap_chdir("$repo_base_abs");
        new_repo($repo, "$GL_ADMINDIR/src/hooks");
        wrap_chdir($ENV{HOME});
    }
}

# ----------------------------------------------------------------------------
#       over to git now
# ----------------------------------------------------------------------------

&log_it("$ENV{GL_TS}\t$ENV{SSH_ORIGINAL_COMMAND}\t$user\n");

$repo = "'$REPO_BASE/$repo.git'";
exec("git", "shell", "-c", "$verb $repo");