180 lines · python
1#!/usr/bin/env python32# SPDX-License-Identifier: GPL-2.03#4# Test that truncation of bprm->buf doesn't cause unexpected execs paths, along5# with various other pathological cases.6import os, subprocess7 8# Relevant commits9#10# b5372fe5dc84 ("exec: load_script: Do not exec truncated interpreter path")11# 6eb3c3d0a52d ("exec: increase BINPRM_BUF_SIZE to 256")12 13# BINPRM_BUF_SIZE14SIZE=25615 16NAME_MAX=int(subprocess.check_output(["getconf", "NAME_MAX", "."]))17 18test_num=019pass_num=020fail_num=021 22code='''#!/usr/bin/perl23print "Executed interpreter! Args:\n";24print "0 : '$0'\n";25$counter = 1;26foreach my $a (@ARGV) {27 print "$counter : '$a'\n";28 $counter++;29}30'''31 32##33# test - produce a binfmt_script hashbang line for testing34#35# @size: bytes for bprm->buf line, including hashbang but not newline36# @good: whether this script is expected to execute correctly37# @hashbang: the special 2 bytes for running binfmt_script38# @leading: any leading whitespace before the executable path39# @root: start of executable pathname40# @target: end of executable pathname41# @arg: bytes following the executable pathname42# @fill: character to fill between @root and @target to reach @size bytes43# @newline: character to use as newline, not counted towards @size44# ...45def test(name, size, good=True, leading="", root="./", target="/perl",46 fill="A", arg="", newline="\n", hashbang="#!"):47 global test_num, pass_num, fail_num, tests, NAME_MAX48 test_num += 149 if test_num > tests:50 raise ValueError("more binfmt_script tests than expected! (want %d, expected %d)"51 % (test_num, tests))52 53 middle = ""54 remaining = size - len(hashbang) - len(leading) - len(root) - len(target) - len(arg)55 # The middle of the pathname must not exceed NAME_MAX56 while remaining >= NAME_MAX:57 middle += fill * (NAME_MAX - 1)58 middle += '/'59 remaining -= NAME_MAX60 middle += fill * remaining61 62 dirpath = root + middle63 binary = dirpath + target64 if len(target):65 os.makedirs(dirpath, mode=0o755, exist_ok=True)66 open(binary, "w").write(code)67 os.chmod(binary, 0o755)68 69 buf=hashbang + leading + root + middle + target + arg + newline70 if len(newline) > 0:71 buf += 'echo this is not really perl\n'72 73 script = "binfmt_script-%s" % (name)74 open(script, "w").write(buf)75 os.chmod(script, 0o755)76 77 proc = subprocess.Popen(["./%s" % (script)], shell=True,78 stdout=subprocess.PIPE, stderr=subprocess.STDOUT)79 stdout = proc.communicate()[0]80 81 if proc.returncode == 0 and b'Executed interpreter' in stdout:82 if good:83 print("ok %d - binfmt_script %s (successful good exec)"84 % (test_num, name))85 pass_num += 186 else:87 print("not ok %d - binfmt_script %s succeeded when it should have failed"88 % (test_num, name))89 fail_num = 190 else:91 if good:92 print("not ok %d - binfmt_script %s failed when it should have succeeded (rc:%d)"93 % (test_num, name, proc.returncode))94 fail_num = 195 else:96 print("ok %d - binfmt_script %s (correctly failed bad exec)"97 % (test_num, name))98 pass_num += 199 100 # Clean up crazy binaries101 os.unlink(script)102 if len(target):103 elements = binary.split('/')104 os.unlink(binary)105 elements.pop()106 while len(elements) > 1:107 os.rmdir("/".join(elements))108 elements.pop()109 110tests=27111print("TAP version 1.3")112print("1..%d" % (tests))113 114### FAIL (8 tests)115 116# Entire path is well past the BINFMT_BUF_SIZE.117test(name="too-big", size=SIZE+80, good=False)118# Path is right at max size, making it impossible to tell if it was truncated.119test(name="exact", size=SIZE, good=False)120# Same as above, but with leading whitespace.121test(name="exact-space", size=SIZE, good=False, leading=" ")122# Huge buffer of only whitespace.123test(name="whitespace-too-big", size=SIZE+71, good=False, root="",124 fill=" ", target="")125# A good path, but it gets truncated due to leading whitespace.126test(name="truncated", size=SIZE+17, good=False, leading=" " * 19)127# Entirely empty except for #!128test(name="empty", size=2, good=False, root="",129 fill="", target="", newline="")130# Within size, but entirely spaces131test(name="spaces", size=SIZE-1, good=False, root="", fill=" ",132 target="", newline="")133# Newline before binary.134test(name="newline-prefix", size=SIZE-1, good=False, leading="\n",135 root="", fill=" ", target="")136 137### ok (19 tests)138 139# The original test case that was broken by commit:140# 8099b047ecc4 ("exec: load_script: don't blindly truncate shebang string")141test(name="test.pl", size=439, leading=" ",142 root="./nix/store/bwav8kz8b3y471wjsybgzw84mrh4js9-perl-5.28.1/bin",143 arg=" -I/nix/store/x6yyav38jgr924nkna62q3pkp0dgmzlx-perl5.28.1-File-Slurp-9999.25/lib/perl5/site_perl -I/nix/store/ha8v67sl8dac92r9z07vzr4gv1y9nwqz-perl5.28.1-Net-DBus-1.1.0/lib/perl5/site_perl -I/nix/store/dcrkvnjmwh69ljsvpbdjjdnqgwx90a9d-perl5.28.1-XML-Parser-2.44/lib/perl5/site_perl -I/nix/store/rmji88k2zz7h4zg97385bygcydrf2q8h-perl5.28.1-XML-Twig-3.52/lib/perl5/site_perl")144# One byte under size, leaving newline visible.145test(name="one-under", size=SIZE-1)146# Two bytes under size, leaving newline visible.147test(name="two-under", size=SIZE-2)148# Exact size, but trailing whitespace visible instead of newline149test(name="exact-trunc-whitespace", size=SIZE, arg=" ")150# Exact size, but trailing space and first arg char visible instead of newline.151test(name="exact-trunc-arg", size=SIZE, arg=" f")152# One bute under, with confirmed non-truncated arg since newline now visible.153test(name="one-under-full-arg", size=SIZE-1, arg=" f")154# Short read buffer by one byte.155test(name="one-under-no-nl", size=SIZE-1, newline="")156# Short read buffer by half buffer size.157test(name="half-under-no-nl", size=int(SIZE/2), newline="")158# One byte under with whitespace arg. leaving wenline visible.159test(name="one-under-trunc-arg", size=SIZE-1, arg=" ")160# One byte under with whitespace leading. leaving wenline visible.161test(name="one-under-leading", size=SIZE-1, leading=" ")162# One byte under with whitespace leading and as arg. leaving newline visible.163test(name="one-under-leading-trunc-arg", size=SIZE-1, leading=" ", arg=" ")164# Same as above, but with 2 bytes under165test(name="two-under-no-nl", size=SIZE-2, newline="")166test(name="two-under-trunc-arg", size=SIZE-2, arg=" ")167test(name="two-under-leading", size=SIZE-2, leading=" ")168test(name="two-under-leading-trunc-arg", size=SIZE-2, leading=" ", arg=" ")169# Same as above, but with buffer half filled170test(name="two-under-no-nl", size=int(SIZE/2), newline="")171test(name="two-under-trunc-arg", size=int(SIZE/2), arg=" ")172test(name="two-under-leading", size=int(SIZE/2), leading=" ")173test(name="two-under-lead-trunc-arg", size=int(SIZE/2), leading=" ", arg=" ")174 175print("# Totals: pass:%d fail:%d xfail:0 xpass:0 skip:0 error:0" % (pass_num, fail_num))176 177if test_num != tests:178 raise ValueError("fewer binfmt_script tests than expected! (ran %d, expected %d"179 % (test_num, tests))180