tools/testing/selftests/exec/binfmt_script.py - linux - Git at Google

 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
 #
 # Test that truncation of bprm->buf doesn't cause unexpected execs paths, along
 # with various other pathological cases.
 import os, subprocess

 # Relevant commits
 #
 # b5372fe5dc84 ("exec: load_script: Do not exec truncated interpreter path")
 # 6eb3c3d0a52d ("exec: increase BINPRM_BUF_SIZE to 256")

 # BINPRM_BUF_SIZE
 SIZE=256

 NAME_MAX=int(subprocess.check_output(["getconf", "NAME_MAX", "."]))

 test_num=0
 pass_num=0
 fail_num=0

 code='''#!/usr/bin/perl
 print "Executed interpreter! Args:\n";
 print "0 : '$0'\n";
 $counter = 1;
 foreach my $a (@ARGV) {
     print "$counter : '$a'\n";
     $counter++;
 }
 '''

 ##
 # test - produce a binfmt_script hashbang line for testing
 #
 # @size:     bytes for bprm->buf line, including hashbang but not newline
 # @good:     whether this script is expected to execute correctly
 # @hashbang: the special 2 bytes for running binfmt_script
 # @leading:  any leading whitespace before the executable path
 # @root:     start of executable pathname
 # @target:   end of executable pathname
 # @arg:      bytes following the executable pathname
 # @fill:     character to fill between @root and @target to reach @size bytes
 # @newline:  character to use as newline, not counted towards @size
 # ...
 def test(name, size, good=True, leading="", root="./", target="/perl",
                      fill="A", arg="", newline="\n", hashbang="#!"):
     global test_num, pass_num, fail_num, tests, NAME_MAX
     test_num += 1
     if test_num > tests:
         raise ValueError("more binfmt_script tests than expected! (want %d, expected %d)"
                          % (test_num, tests))

     middle = ""
     remaining = size - len(hashbang) - len(leading) - len(root) - len(target) - len(arg)
     # The middle of the pathname must not exceed NAME_MAX
     while remaining >= NAME_MAX:
         middle += fill * (NAME_MAX - 1)
         middle += '/'
         remaining -= NAME_MAX
     middle += fill * remaining

     dirpath = root + middle
     binary = dirpath + target
     if len(target):
         os.makedirs(dirpath, mode=0o755, exist_ok=True)
         open(binary, "w").write(code)
         os.chmod(binary, 0o755)

     buf=hashbang + leading + root + middle + target + arg + newline
     if len(newline) > 0:
         buf += 'echo this is not really perl\n'

     script = "binfmt_script-%s" % (name)
     open(script, "w").write(buf)
     os.chmod(script, 0o755)

     proc = subprocess.Popen(["./%s" % (script)], shell=True,
                             stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
     stdout = proc.communicate()[0]

     if proc.returncode == 0 and b'Executed interpreter' in stdout:
         if good:
             print("ok %d - binfmt_script %s (successful good exec)"
                   % (test_num, name))
             pass_num += 1
         else:
             print("not ok %d - binfmt_script %s succeeded when it should have failed"
                   % (test_num, name))
             fail_num = 1
     else:
         if good:
             print("not ok %d - binfmt_script %s failed when it should have succeeded (rc:%d)"
                   % (test_num, name, proc.returncode))
             fail_num = 1
         else:
             print("ok %d - binfmt_script %s (correctly failed bad exec)"
                   % (test_num, name))
             pass_num += 1

     # Clean up crazy binaries
     os.unlink(script)
     if len(target):
         elements = binary.split('/')
         os.unlink(binary)
         elements.pop()
         while len(elements) > 1:
             os.rmdir("/".join(elements))
             elements.pop()

 tests=27
 print("TAP version 1.3")
 print("1..%d" % (tests))

 ### FAIL (8 tests)

 # Entire path is well past the BINFMT_BUF_SIZE.
 test(name="too-big",        size=SIZE+80, good=False)
 # Path is right at max size, making it impossible to tell if it was truncated.
 test(name="exact",          size=SIZE,    good=False)
 # Same as above, but with leading whitespace.
 test(name="exact-space",    size=SIZE,    good=False, leading=" ")
 # Huge buffer of only whitespace.
 test(name="whitespace-too-big", size=SIZE+71, good=False, root="",
                                               fill=" ", target="")
 # A good path, but it gets truncated due to leading whitespace.
 test(name="truncated",      size=SIZE+17, good=False, leading=" " * 19)
 # Entirely empty except for #!
 test(name="empty",          size=2,       good=False, root="",
                                           fill="", target="", newline="")
 # Within size, but entirely spaces
 test(name="spaces",         size=SIZE-1,  good=False, root="", fill=" ",
                                           target="", newline="")
 # Newline before binary.
 test(name="newline-prefix", size=SIZE-1,  good=False, leading="\n",
                                           root="", fill=" ", target="")

 ### ok (19 tests)

 # The original test case that was broken by commit:
 # 8099b047ecc4 ("exec: load_script: don't blindly truncate shebang string")
 test(name="test.pl",        size=439, leading=" ",
      root="./nix/store/bwav8kz8b3y471wjsybgzw84mrh4js9-perl-5.28.1/bin",
      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")
 # One byte under size, leaving newline visible.
 test(name="one-under",           size=SIZE-1)
 # Two bytes under size, leaving newline visible.
 test(name="two-under",           size=SIZE-2)
 # Exact size, but trailing whitespace visible instead of newline
 test(name="exact-trunc-whitespace", size=SIZE, arg=" ")
 # Exact size, but trailing space and first arg char visible instead of newline.
 test(name="exact-trunc-arg",     size=SIZE, arg=" f")
 # One bute under, with confirmed non-truncated arg since newline now visible.
 test(name="one-under-full-arg",  size=SIZE-1, arg=" f")
 # Short read buffer by one byte.
 test(name="one-under-no-nl",     size=SIZE-1, newline="")
 # Short read buffer by half buffer size.
 test(name="half-under-no-nl",    size=int(SIZE/2), newline="")
 # One byte under with whitespace arg. leaving wenline visible.
 test(name="one-under-trunc-arg", size=SIZE-1, arg=" ")
 # One byte under with whitespace leading. leaving wenline visible.
 test(name="one-under-leading",   size=SIZE-1, leading=" ")
 # One byte under with whitespace leading and as arg. leaving newline visible.
 test(name="one-under-leading-trunc-arg",  size=SIZE-1, leading=" ", arg=" ")
 # Same as above, but with 2 bytes under
 test(name="two-under-no-nl",     size=SIZE-2, newline="")
 test(name="two-under-trunc-arg", size=SIZE-2, arg=" ")
 test(name="two-under-leading",   size=SIZE-2, leading=" ")
 test(name="two-under-leading-trunc-arg",   size=SIZE-2, leading=" ", arg=" ")
 # Same as above, but with buffer half filled
 test(name="two-under-no-nl",     size=int(SIZE/2), newline="")
 test(name="two-under-trunc-arg", size=int(SIZE/2), arg=" ")
 test(name="two-under-leading",   size=int(SIZE/2), leading=" ")
 test(name="two-under-lead-trunc-arg", size=int(SIZE/2), leading=" ", arg=" ")

 print("# Totals: pass:%d fail:%d xfail:0 xpass:0 skip:0 error:0" % (pass_num, fail_num))

 if test_num != tests:
     raise ValueError("fewer binfmt_script tests than expected! (ran %d, expected %d"
                      % (test_num, tests))
	#!/usr/bin/env python3
	# SPDX-License-Identifier: GPL-2.0
	#
	# Test that truncation of bprm->buf doesn't cause unexpected execs paths, along
	# with various other pathological cases.
	import os, subprocess

	# Relevant commits
	#
	# b5372fe5dc84 ("exec: load_script: Do not exec truncated interpreter path")
	# 6eb3c3d0a52d ("exec: increase BINPRM_BUF_SIZE to 256")

	# BINPRM_BUF_SIZE
	SIZE=256

	NAME_MAX=int(subprocess.check_output(["getconf", "NAME_MAX", "."]))

	test_num=0
	pass_num=0
	fail_num=0

	code='''#!/usr/bin/perl
	print "Executed interpreter! Args:\n";
	print "0 : '$0'\n";
	$counter = 1;
	foreach my $a (@ARGV) {
	print "$counter : '$a'\n";
	$counter++;
	}
	'''

	##
	# test - produce a binfmt_script hashbang line for testing
	#
	# @size: bytes for bprm->buf line, including hashbang but not newline
	# @good: whether this script is expected to execute correctly
	# @hashbang: the special 2 bytes for running binfmt_script
	# @leading: any leading whitespace before the executable path
	# @root: start of executable pathname
	# @target: end of executable pathname
	# @arg: bytes following the executable pathname
	# @fill: character to fill between @root and @target to reach @size bytes
	# @newline: character to use as newline, not counted towards @size
	# ...
	def test(name, size, good=True, leading="", root="./", target="/perl",
	fill="A", arg="", newline="\n", hashbang="#!"):
	global test_num, pass_num, fail_num, tests, NAME_MAX
	test_num += 1
	if test_num > tests:
	raise ValueError("more binfmt_script tests than expected! (want %d, expected %d)"
	% (test_num, tests))

	middle = ""
	remaining = size - len(hashbang) - len(leading) - len(root) - len(target) - len(arg)
	# The middle of the pathname must not exceed NAME_MAX
	while remaining >= NAME_MAX:
	middle += fill * (NAME_MAX - 1)
	middle += '/'
	remaining -= NAME_MAX
	middle += fill * remaining

	dirpath = root + middle
	binary = dirpath + target
	if len(target):
	os.makedirs(dirpath, mode=0o755, exist_ok=True)
	open(binary, "w").write(code)
	os.chmod(binary, 0o755)

	buf=hashbang + leading + root + middle + target + arg + newline
	if len(newline) > 0:
	buf += 'echo this is not really perl\n'

	script = "binfmt_script-%s" % (name)
	open(script, "w").write(buf)
	os.chmod(script, 0o755)

	proc = subprocess.Popen(["./%s" % (script)], shell=True,
	stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
	stdout = proc.communicate()[0]

	if proc.returncode == 0 and b'Executed interpreter' in stdout:
	if good:
	print("ok %d - binfmt_script %s (successful good exec)"
	% (test_num, name))
	pass_num += 1
	else:
	print("not ok %d - binfmt_script %s succeeded when it should have failed"
	% (test_num, name))
	fail_num = 1
	else:
	if good:
	print("not ok %d - binfmt_script %s failed when it should have succeeded (rc:%d)"
	% (test_num, name, proc.returncode))
	fail_num = 1
	else:
	print("ok %d - binfmt_script %s (correctly failed bad exec)"
	% (test_num, name))
	pass_num += 1

	# Clean up crazy binaries
	os.unlink(script)
	if len(target):
	elements = binary.split('/')
	os.unlink(binary)
	elements.pop()
	while len(elements) > 1:
	os.rmdir("/".join(elements))
	elements.pop()

	tests=27
	print("TAP version 1.3")
	print("1..%d" % (tests))

	### FAIL (8 tests)

	# Entire path is well past the BINFMT_BUF_SIZE.
	test(name="too-big", size=SIZE+80, good=False)
	# Path is right at max size, making it impossible to tell if it was truncated.
	test(name="exact", size=SIZE, good=False)
	# Same as above, but with leading whitespace.
	test(name="exact-space", size=SIZE, good=False, leading=" ")
	# Huge buffer of only whitespace.
	test(name="whitespace-too-big", size=SIZE+71, good=False, root="",
	fill=" ", target="")
	# A good path, but it gets truncated due to leading whitespace.
	test(name="truncated", size=SIZE+17, good=False, leading=" " * 19)
	# Entirely empty except for #!
	test(name="empty", size=2, good=False, root="",
	fill="", target="", newline="")
	# Within size, but entirely spaces
	test(name="spaces", size=SIZE-1, good=False, root="", fill=" ",
	target="", newline="")
	# Newline before binary.
	test(name="newline-prefix", size=SIZE-1, good=False, leading="\n",
	root="", fill=" ", target="")

	### ok (19 tests)

	# The original test case that was broken by commit:
	# 8099b047ecc4 ("exec: load_script: don't blindly truncate shebang string")
	test(name="test.pl", size=439, leading=" ",
	root="./nix/store/bwav8kz8b3y471wjsybgzw84mrh4js9-perl-5.28.1/bin",
	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")
	# One byte under size, leaving newline visible.
	test(name="one-under", size=SIZE-1)
	# Two bytes under size, leaving newline visible.
	test(name="two-under", size=SIZE-2)
	# Exact size, but trailing whitespace visible instead of newline
	test(name="exact-trunc-whitespace", size=SIZE, arg=" ")
	# Exact size, but trailing space and first arg char visible instead of newline.
	test(name="exact-trunc-arg", size=SIZE, arg=" f")
	# One bute under, with confirmed non-truncated arg since newline now visible.
	test(name="one-under-full-arg", size=SIZE-1, arg=" f")
	# Short read buffer by one byte.
	test(name="one-under-no-nl", size=SIZE-1, newline="")
	# Short read buffer by half buffer size.
	test(name="half-under-no-nl", size=int(SIZE/2), newline="")
	# One byte under with whitespace arg. leaving wenline visible.
	test(name="one-under-trunc-arg", size=SIZE-1, arg=" ")
	# One byte under with whitespace leading. leaving wenline visible.
	test(name="one-under-leading", size=SIZE-1, leading=" ")
	# One byte under with whitespace leading and as arg. leaving newline visible.
	test(name="one-under-leading-trunc-arg", size=SIZE-1, leading=" ", arg=" ")
	# Same as above, but with 2 bytes under
	test(name="two-under-no-nl", size=SIZE-2, newline="")
	test(name="two-under-trunc-arg", size=SIZE-2, arg=" ")
	test(name="two-under-leading", size=SIZE-2, leading=" ")
	test(name="two-under-leading-trunc-arg", size=SIZE-2, leading=" ", arg=" ")
	# Same as above, but with buffer half filled
	test(name="two-under-no-nl", size=int(SIZE/2), newline="")
	test(name="two-under-trunc-arg", size=int(SIZE/2), arg=" ")
	test(name="two-under-leading", size=int(SIZE/2), leading=" ")
	test(name="two-under-lead-trunc-arg", size=int(SIZE/2), leading=" ", arg=" ")

	print("# Totals: pass:%d fail:%d xfail:0 xpass:0 skip:0 error:0" % (pass_num, fail_num))

	if test_num != tests:
	raise ValueError("fewer binfmt_script tests than expected! (ran %d, expected %d"
	% (test_num, tests))