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Bugfix/unarchive course external symlinks #3037

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Bugfix/unarchive course external symlinks #3037

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727f184
Recreate course template symlinks after unarchiving
drdrew42 Jul 3, 2026
fdeefdf
Remove the partial course directory when unarchiving fails
drdrew42 Jul 3, 2026
b29b201
Recreate symbolic links when extracting an archive in the File Manager
drdrew42 Jul 3, 2026
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10 changes: 9 additions & 1 deletion lib/WeBWorK/ContentGenerator/Instructor/FileManager.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -578,7 +578,15 @@ sub unpack_archive ($c, $archive) {
next;
}

unless ($tar->extract_file($_)) {
my ($member) = $tar->get_files($_);
if ($member && $member->is_symlink) {
# Secure extract mode refuses links whose targets leave the directory;
# recreate them directly (location already validated above).
unless (symlink($member->linkname, $out_file->to_string)) {
$c->addbadmessage($c->maketext(q{Unable to extract "[_1]": [_2]}, $_, $!));
next;
}
} elsif (!$tar->extract_file($_)) {
$c->addbadmessage($tar->error);
next;
}
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13 changes: 13 additions & 0 deletions lib/WeBWorK/Utils/CourseManagement.pm
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Expand Up @@ -972,13 +972,26 @@ sub unarchiveCourse {
my $arch = Archive::Tar->new($archivePath);
die "The tar file $archivePath is not valid." unless $arch;
$arch->setcwd($coursesDir);

# Secure extract mode refuses symbolic/hard links whose targets leave the
# course directory (CVE-2026-42496/-42497), which the standard template links
# do. Extract the files under secure mode, then recreate the symbolic links.
my @symlinks = grep { $_->is_symlink } $arch->get_files;
$arch->remove(map { $_->full_path } grep { $_->is_symlink || $_->is_hardlink } $arch->get_files);
$arch->extract();

if ($arch->error) {
# Remove the partial extraction so move_back can restore a displaced course.
path("$coursesDir/$currCourseID")->remove_tree if -e "$coursesDir/$currCourseID";
_unarchiveCourse_move_back($restoreCourseData);
die "Failed to unarchive course directory for course $newCourseID: $arch->error";
}

for my $symlink (@symlinks) {
my $link_path = "$coursesDir/" . $symlink->full_path;
symlink($symlink->linkname, $link_path) unless -e $link_path;
}

##### step 3: read the course environment for this course #####

my $ce2 = WeBWorK::CourseEnvironment->new({ get_SeedCE($ce), courseName => $currCourseID });
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