[PATCH 2/2] tests: check decoding of NETLINK_SELINUX protocol

[Dmitry V. Levin]

On Sat, Jul 15, 2017 at 08:02:24AM +0800, JingPiao Chen wrote:
> On Sat, Jul 15, 2017 at 02:45:01AM +0300, Dmitry V. Levin wrote:
> > On Sat, Jul 15, 2017 at 12:22:57AM +0800, JingPiao Chen wrote:
> > > On Fri, Jul 14, 2017 at 01:16:37PM +0800, JingPiao Chen wrote:
> > > [...]
> > > > +static void
> > > > +test_selnl_msg_setenforce(const int fd)
> > > > +{
> > > > +	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
> > > > +	static char pattern[4096];
> > > > +	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
> > > > +
> > > > +	static const struct selnl_msg_setenforce msg = {
> > > > +		.val = 0xfbdcdfab
> > > > +	};
> > > > +	TEST_NETLINK_OBJECT(fd, nlh0,
> > > > +			    SELNL_MSG_SETENFORCE, NLM_F_REQUEST,
> > > > +			    pattern, msg,
> > > > +			    PRINT_FIELD_D("{", msg, val);
> > > > +			    printf("}"));
> > > > +}
> > > > +
> > > > +static void
> > > > +test_selnl_msg_policyload(const int fd)
> > > > +{
> > > > +	void *const nlh0 = tail_alloc(NLMSG_HDRLEN);
> > > > +	static char pattern[4096];
> > > > +	fill_memory_ex(pattern, sizeof(pattern), 'a', 'z' - 'a' + 1);
> > > 
> > > Move ...
> > > 
> > > > +
> > > > +	static const struct selnl_msg_policyload msg = {
> > > > +		.seqno = 0xabdcfabc
> > > > +	};
> > > > +	TEST_NETLINK_OBJECT(fd, nlh0,
> > > > +			    SELNL_MSG_POLICYLOAD, NLM_F_REQUEST,
> > > > +			    pattern, msg,
> > > > +			    PRINT_FIELD_U("{", msg, seqno);
> > > > +			    printf("}"));
> > > > +}
> > > > +
> > > >  int main(void)
> > > >  {
> > > >  	skip_if_unavailable("/proc/self/fd/");
> > > > @@ -57,6 +103,9 @@ int main(void)
> > > >  	int fd = create_nl_socket(NETLINK_SELINUX);
> > > >  
> > > >  	test_nlmsg_type(fd);
> > > > +	test_selnl_msg_unspec(fd);
> > > > +	test_selnl_msg_setenforce(fd);
> > > > +	test_selnl_msg_policyload(fd);
> > > >  
> > > >  	printf("+++ exited with 0 +++\n");
> > > >  
> > > > diff --git a/tests/test_netlink.h b/tests/test_netlink.h
> > > > index 7049128..b6f6ac9 100644
> > > > --- a/tests/test_netlink.h
> > > > +++ b/tests/test_netlink.h
> > > > @@ -45,3 +45,33 @@
> > > >  		      (type_), #type_,					\
> > > >  		      (flags_), #flags_,				\
> > > >  		      (data_len_), (src_), (slen_), __VA_ARGS__)
> > > > +
> > > > +#define TEST_NETLINK_OBJECT(fd_, nlh0_,					\
> > > > +			    type_, flags_,				\
> > > > +			    pattern_, obj_, ...)			\
> > > > +	do {								\
> > > > +		const unsigned int plen =				\
> > > > +			sizeof(obj_) - 1 > DEFAULT_STRLEN		\
> > > > +			? DEFAULT_STRLEN : (int) sizeof(obj_) - 1;	\
> > > 
> > > ... here. The template of TEST_NETLINK_OBJECT is TEST_NLATTR_OBJECT.
> > > I think pattern can declare here instead of in the caller.
> > > If this thought is ok, I will send version 2.
> > 
> > Do you want to create a private pattern[4096] in every invocation
> > of TEST_NETLINK_OBJECT macro?
> 
> Yes, Is that ok? I hope you can give me some advice. Thank you.

If you want to create a local pattern[], no need to create it that big.
Assuming that you never read more than plen bytes from the pattern,
pattern[DEFAULT_STRLEN] should be enough.


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