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fix: add parent-dir permission checks to symlink() and link() #341

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fix: add parent-dir permission checks to symlink() and link() #341

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14 changes: 14 additions & 0 deletions lib/Test/MockFile.pm
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Original file line number Diff line number Diff line change
Expand Up @@ -3752,6 +3752,13 @@ sub __symlink ($$) {
return 0;
}

# Permission check: symlink needs write+execute on parent dir
if ( defined $_mock_uid && !_check_parent_perms( $mock->{'path'}, 2 | 1 ) ) {
$! = EACCES;
_maybe_throw_autodie( 'symlink', @_ );
return 0;
}

# Convert the mock to a symlink pointing to $oldname
$mock->{'readlink'} = $oldname;
$mock->{'mode'} = 07777 | S_IFLNK;
Expand Down Expand Up @@ -3842,6 +3849,13 @@ sub __link ($$) {
return 0;
}

# Permission check: link needs write+execute on parent dir of destination
if ( defined $_mock_uid && !_check_parent_perms( $new_mock->{'path'}, 2 | 1 ) ) {
$! = EACCES;
_maybe_throw_autodie( 'link', @_ );
return 0;
}

# Copy file attributes from source to destination
$new_mock->{'contents'} = $source_mock->{'contents'};
$new_mock->{'has_content'} = 1;
Expand Down
44 changes: 44 additions & 0 deletions t/perms.t
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Expand Up @@ -336,4 +336,48 @@ subtest 'open > on new file checks parent directory perms' => sub {
} 1000, 1000;
};

# =========================================================================
# symlink permission checks (needs write+exec on parent)
# =========================================================================

subtest 'symlink permission checks on parent directory' => sub {
my $parent = Test::MockFile->new_dir( '/perms/sdir', { mode => 0555, uid => 1000, gid => 1000 } );
my $target = Test::MockFile->file('/perms/sdir/mylink');

with_user {
ok( !symlink( '/some/target', '/perms/sdir/mylink' ), 'cannot symlink in read-only parent dir' );
is( $! + 0, EACCES, 'symlink errno is EACCES' );
} 1000, 1000;

my $parent2 = Test::MockFile->new_dir( '/perms/sdir2', { mode => 0755, uid => 1000, gid => 1000 } );
my $target2 = Test::MockFile->file('/perms/sdir2/mylink2');

with_user {
ok( symlink( '/some/target', '/perms/sdir2/mylink2' ), 'can symlink in writable parent dir' );
} 1000, 1000;
};

# =========================================================================
# link permission checks (needs write+exec on parent of destination)
# =========================================================================

subtest 'link permission checks on parent directory' => sub {
my $parent = Test::MockFile->new_dir( '/perms/ldir', { mode => 0555, uid => 1000, gid => 1000 } );
my $source = Test::MockFile->file( '/perms/ldir/src', 'data' );
my $dest = Test::MockFile->file('/perms/ldir/hardlink');

with_user {
ok( !link( '/perms/ldir/src', '/perms/ldir/hardlink' ), 'cannot link in read-only parent dir' );
is( $! + 0, EACCES, 'link errno is EACCES' );
} 1000, 1000;

my $parent2 = Test::MockFile->new_dir( '/perms/ldir2', { mode => 0755, uid => 1000, gid => 1000 } );
my $source2 = Test::MockFile->file( '/perms/ldir2/src2', 'data' );
my $dest2 = Test::MockFile->file('/perms/ldir2/hardlink2');

with_user {
ok( link( '/perms/ldir2/src2', '/perms/ldir2/hardlink2' ), 'can link in writable parent dir' );
} 1000, 1000;
};

done_testing();
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