path: root/tools/net/ynl/lib/ynl.c

// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
#include <errno.h>
#include <poll.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <linux/types.h>
#include <linux/genetlink.h>
#include <sys/socket.h>

#include "ynl.h"

#define ARRAY_SIZE(arr)		(sizeof(arr) / sizeof(*arr))

#define __yerr_msg(yse, _msg...)					\
	({								\
		struct ynl_error *_yse = (yse);				\
									\
		if (_yse) {						\
			snprintf(_yse->msg, sizeof(_yse->msg) - 1,  _msg); \
			_yse->msg[sizeof(_yse->msg) - 1] = 0;		\
		}							\
	})

#define __yerr_code(yse, _code...)		\
	({					\
		struct ynl_error *_yse = (yse);	\
						\
		if (_yse) {			\
			_yse->code = _code;	\
		}				\
	})

#define __yerr(yse, _code, _msg...)		\
	({					\
		__yerr_msg(yse, _msg);		\
		__yerr_code(yse, _code);	\
	})

#define __perr(yse, _msg)		__yerr(yse, errno, _msg)

#define yerr_msg(_ys, _msg...)		__yerr_msg(&(_ys)->err, _msg)
#define yerr(_ys, _code, _msg...)	__yerr(&(_ys)->err, _code, _msg)
#define perr(_ys, _msg)			__yerr(&(_ys)->err, errno, _msg)

/* -- Netlink boiler plate */
static int
ynl_err_walk_report_one(const struct ynl_policy_nest *policy, unsigned int type,
			char *str, int str_sz, int *n)
{
	if (!policy) {
		if (*n < str_sz)
			*n += snprintf(str, str_sz, "!policy");
		return 1;
	}

	if (type > policy->max_attr) {
		if (*n < str_sz)
			*n += snprintf(str, str_sz, "!oob");
		return 1;
	}

	if (!policy->table[type].name) {
		if (*n < str_sz)
			*n += snprintf(str, str_sz, "!name");
		return 1;
	}

	if (*n < str_sz)
		*n += snprintf(str, str_sz - *n,
			       ".%s", policy->table[type].name);
	return 0;
}

static int
ynl_err_walk(struct ynl_sock *ys, void *start, void *end, unsigned int off,
	     const struct ynl_policy_nest *policy, char *str, int str_sz,
	     const struct ynl_policy_nest **nest_pol)
{
	unsigned int astart_off, aend_off;
	const struct nlattr *attr;
	unsigned int data_len;
	unsigned int type;
	bool found = false;
	int n = 0;

	if (!policy) {
		if (n < str_sz)
			n += snprintf(str, str_sz, "!policy");
		return n;
	}

	data_len = end - start;

	ynl_attr_for_each_payload(start, data_len, attr) {
		astart_off = (char *)attr - (char *)start;
		aend_off = astart_off + ynl_attr_data_len(attr);
		if (aend_off <= off)
			continue;

		found = true;
		break;
	}
	if (!found)
		return 0;

	off -= astart_off;

	type = ynl_attr_type(attr);

	if (ynl_err_walk_report_one(policy, type, str, str_sz, &n))
		return n;

	if (!off) {
		if (nest_pol)
			*nest_pol = policy->table[type].nest;
		return n;
	}

	if (!policy->table[type].nest) {
		if (n < str_sz)
			n += snprintf(str, str_sz, "!nest");
		return n;
	}

	off -= sizeof(struct nlattr);
	start =  ynl_attr_data(attr);
	end = start + ynl_attr_data_len(attr);

	return n + ynl_err_walk(ys, start, end, off, policy->table[type].nest,
				&str[n], str_sz - n, nest_pol);
}

#define NLMSGERR_ATTR_MISS_TYPE (NLMSGERR_ATTR_POLICY + 1)
#define NLMSGERR_ATTR_MISS_NEST (NLMSGERR_ATTR_POLICY + 2)
#define NLMSGERR_ATTR_MAX (NLMSGERR_ATTR_MAX + 2)

static int
ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
		  unsigned int hlen)
{
	const struct nlattr *tb[NLMSGERR_ATTR_MAX + 1] = {};
	char miss_attr[sizeof(ys->err.msg)];
	char bad_attr[sizeof(ys->err.msg)];
	const struct nlattr *attr;
	const char *str = NULL;

	if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS)) {
		yerr_msg(ys, "%s", strerror(ys->err.code));
		return YNL_PARSE_CB_OK;
	}

	ynl_attr_for_each(attr, nlh, hlen) {
		unsigned int len, type;

		len = ynl_attr_data_len(attr);
		type = ynl_attr_type(attr);

		if (type > NLMSGERR_ATTR_MAX)
			continue;

		tb[type] = attr;

		switch (type) {
		case NLMSGERR_ATTR_OFFS:
		case NLMSGERR_ATTR_MISS_TYPE:
		case NLMSGERR_ATTR_MISS_NEST:
			if (len != sizeof(__u32))
				return YNL_PARSE_CB_ERROR;
			break;
		case NLMSGERR_ATTR_MSG:
			str = ynl_attr_get_str(attr);
			if (str[len - 1])
				return YNL_PARSE_CB_ERROR;
			break;
		default:
			break;
		}
	}

	bad_attr[0] = '\0';
	miss_attr[0] = '\0';

	if (tb[NLMSGERR_ATTR_OFFS]) {
		unsigned int n, off;
		void *start, *end;

		ys->err.attr_offs = ynl_attr_get_u32(tb[NLMSGERR_ATTR_OFFS]);

		n = snprintf(bad_attr, sizeof(bad_attr), "%sbad attribute: ",
			     str ? " (" : "");

		start = ynl_nlmsg_data_offset(ys->nlh, ys->family->hdr_len);
		end = ynl_nlmsg_end_addr(ys->nlh);

		off = ys->err.attr_offs;
		off -= sizeof(struct nlmsghdr);
		off -= ys->family->hdr_len;

		n += ynl_err_walk(ys, start, end, off, ys->