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))