[PATCH v6 07/18] tests: check decoding of inet_diag_msg attributes

[Dmitry V. Levin]

On Tue, Jun 27, 2017 at 06:10:09PM +0800, JingPiao Chen wrote:
[...]
> +static void
> +init_inet_diag_msg(struct nlmsghdr *nlh, unsigned int msg_len,
> +		   const char *address)
> +{
> +	struct inet_diag_msg *msg;
> +
> +	SET_STRUCT(struct nlmsghdr, nlh,
> +		.nlmsg_len = msg_len,
> +		.nlmsg_type = SOCK_DIAG_BY_FAMILY,
> +		.nlmsg_flags = NLM_F_DUMP
> +	);
> +
> +	msg = NLMSG_DATA(nlh);
> +	SET_STRUCT(struct inet_diag_msg, msg,
> +		.idiag_family = AF_INET,
> +		.idiag_state = TCP_LISTEN
> +	);
> +
> +	if (!inet_pton(AF_INET, address, msg->id.idiag_src))
> +		perror_msg_and_skip("inet_pton");
> +	if (!inet_pton(AF_INET, address, msg->id.idiag_dst))
> +		perror_msg_and_skip("inet_pton");
> +}

This can be shortened to

	if (!inet_pton(AF_INET, address, msg->id.idiag_src) ||
	    !inet_pton(AF_INET, address, msg->id.idiag_dst))
		perror_msg_and_skip("inet_pton");

[...]
> +static void
> +test_inet_diag_skmeminfo(const int fd)
> +{
> +	const int hdrlen = sizeof(struct inet_diag_msg);
> +	const char address[] = "87.65.43.21";
> +	struct nlmsghdr *nlh;
> +	struct nlattr *nla;
> +	uint32_t *mem;
> +	unsigned int nla_len;
> +	unsigned int msg_len;
> +	void *const nlh0 = tail_alloc(NLMSG_SPACE(hdrlen));
> +	long rc;
> +
> +	/* len < sizeof(uint32_t) */
> +	nla_len = NLA_HDRLEN + 2;
> +	msg_len = NLMSG_SPACE(hdrlen) + nla_len;
> +	nlh = nlh0 - nla_len;
> +	init_inet_diag_msg(nlh, msg_len, address);
> +
> +	nla = NLMSG_ATTR(nlh, hdrlen);
> +	SET_STRUCT(struct nlattr, nla,
> +		.nla_len = nla_len,
> +		.nla_type = INET_DIAG_SKMEMINFO
> +	);
> +	memcpy(RTA_DATA(nla), "12", 2);
> +
> +	rc = sendto(fd, nlh, msg_len, MSG_DONTWAIT, NULL, 0);
> +
> +	printf("sendto(%d, {{len=%u, type=SOCK_DIAG_BY_FAMILY"
> +	       ", flags=NLM_F_DUMP, seq=0, pid=0}, {idiag_family=AF_INET"
> +	       ", idiag_state=TCP_LISTEN, idiag_timer=0, idiag_retrans=0"
> +	       ", id={idiag_sport=htons(0), idiag_dport=htons(0)"
> +	       ", inet_pton(AF_INET, \"%s\", &idiag_src)"
> +	       ", inet_pton(AF_INET, \"%s\", &idiag_dst)"
> +	       ", idiag_if=0, idiag_cookie=[0, 0]}, idiag_expires=0"
> +	       ", idiag_rqueue=0, idiag_wqueue=0, idiag_uid=0"
> +	       ", idiag_inode=0}, {{nla_len=%u"
> +	       ", nla_type=INET_DIAG_SKMEMINFO}, \"12\"}}"
> +	       ", %u, MSG_DONTWAIT, NULL, 0) = %s\n",
> +	       fd, msg_len, address, address, nla_len,
> +	       msg_len, sprintrc(rc));
> +	
> +	/* len = sizeof(uint32_t) * 2 - 1 */
> +	nla_len = NLA_HDRLEN + sizeof(*mem) * 2 - 1;
> +	msg_len = NLMSG_SPACE(hdrlen) + nla_len;
> +	nlh = nlh0 - nla_len;
> +	init_inet_diag_msg(nlh, msg_len, address);
> +
> +	nla = NLMSG_ATTR(nlh, hdrlen);
> +	SET_STRUCT(struct nlattr, nla,
> +		.nla_len = nla_len,
> +		.nla_type = INET_DIAG_SKMEMINFO
> +	);
> +	mem = RTA_DATA(nla);
> +	mem[0] = 0xaffacbad;

This is unaligned access.  I suggest to do the same trick with mem[] array
as you did with structures:  create a static array and call memcpy.

> +
> +	rc = sendto(fd, nlh, msg_len, MSG_DONTWAIT, NULL, 0);
> +
> +	printf("sendto(%d, {{len=%u, type=SOCK_DIAG_BY_FAMILY"
> +	       ", flags=NLM_F_DUMP, seq=0, pid=0}, {idiag_family=AF_INET"
> +	       ", idiag_state=TCP_LISTEN, idiag_timer=0, idiag_retrans=0"
> +	       ", id={idiag_sport=htons(0), idiag_dport=htons(0)"
> +	       ", inet_pton(AF_INET, \"%s\", &idiag_src)"
> +	       ", inet_pton(AF_INET, \"%s\", &idiag_dst)"
> +	       ", idiag_if=0, idiag_cookie=[0, 0]}, idiag_expires=0"
> +	       ", idiag_rqueue=0, idiag_wqueue=0, idiag_uid=0"
> +	       ", idiag_inode=0}, {{nla_len=%u, nla_type=INET_DIAG_SKMEMINFO}"
> +	       ", [%u]}}, %u, MSG_DONTWAIT, NULL, 0) = %s\n",
> +	       fd, msg_len, address, address, nla_len,
> +	       mem[0], msg_len, sprintrc(rc));
> +
> +	/* len = sizeof(uint32_t) * 2 */
> +	nla_len = NLA_HDRLEN + sizeof(*mem) * 2;
> +	msg_len = NLMSG_SPACE(hdrlen) + nla_len;
> +	nlh = nlh0 - nla_len;
> +	init_inet_diag_msg(nlh, msg_len, address);
> +
> +	nla = NLMSG_ATTR(nlh, hdrlen);
> +	SET_STRUCT(struct nlattr, nla,
> +		.nla_len = nla_len,
> +		.nla_type = INET_DIAG_SKMEMINFO
> +	);
> +	mem = RTA_DATA(nla);
> +	mem[0] = 0xaffacbad;
> +	mem[1] = 0xffadbcab;

There is no unaligned access here, but I suggest to use memcpy here as well.


-- 
ldv
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