1 /* SPDX-License-Identifier: GPL-2.0 */
12  * ------------------------------------------------------------------------
14  * ------------------------------------------------------------------------
17  *    <--- nlmsg_total_size(payload)  --->
18  *    <-- nlmsg_msg_size(payload) ->
19  *   +----------+- - -+-------------+- - -+-------- - -
21  *   +----------+- - -+-------------+- - -+-------- - -
22  *   nlmsg_data(nlh)---^                   ^
23  *   nlmsg_next(nlh)-----------------------+
26  *    <---------------------- nlmsg_len(nlh) --------------------->
27  *    <------ hdrlen ------>       <- nlmsg_attrlen(nlh, hdrlen) ->
28  *   +----------------------+- - -+--------------------------------+
30  *   +----------------------+- - -+--------------------------------+
31  *   nlmsg_attrdata(nlh, hdrlen)---^
67  *   nlmsg_find_attr()			find an attribute in a message
75  * ------------------------------------------------------------------------
77  * ------------------------------------------------------------------------
79  * Attribute Format:
80  *    <------- nla_total_size(payload) ------->
81  *    <---- nla_attr_size(payload) ----->
82  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
84  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
85  *                     <- nla_len(nla) ->      ^
86  *   nla_data(nla)----^                        |
87  *   nla_next(nla)-----------------------------'
90  *   struct nlattr			netlink attribute header
92  * Attribute Construction:
93  *   nla_reserve(skb, type, len)	reserve room for an attribute
94  *   nla_reserve_nohdr(skb, len)	reserve room for an attribute w/o hdr
95  *   nla_put(skb, type, len, data)	add attribute to skb
96  *   nla_put_nohdr(skb, len, data)	add attribute w/o hdr
99  * Attribute Construction for Basic Types:
100  *   nla_put_u8(skb, type, value)	add u8 attribute to skb
101  *   nla_put_u16(skb, type, value)	add u16 attribute to skb
102  *   nla_put_u32(skb, type, value)	add u32 attribute to skb
104  *                     value, padattr)	add u64 attribute to skb
105  *   nla_put_s8(skb, type, value)	add s8 attribute to skb
106  *   nla_put_s16(skb, type, value)	add s16 attribute to skb
107  *   nla_put_s32(skb, type, value)	add s32 attribute to skb
109  *               padattr)		add s64 attribute to skb
110  *   nla_put_string(skb, type, str)	add string attribute to skb
111  *   nla_put_flag(skb, type)		add flag attribute to skb
113  *                 padattr)		add msecs attribute to skb
114  *   nla_put_in_addr(skb, type, addr)	add IPv4 address attribute to skb
115  *   nla_put_in6_addr(skb, type, addr)	add IPv6 address attribute to skb
118  *   nla_nest_start(skb, type)		start a nested attribute
119  *   nla_nest_end(skb, nla)		finalize a nested attribute
120  *   nla_nest_cancel(skb, nla)		cancel nested attribute construction
122  * Attribute Length Calculations:
123  *   nla_attr_size(payload)		length of attribute w/o padding
124  *   nla_total_size(payload)		length of attribute w/ padding
127  * Attribute Payload Access:
128  *   nla_data(nla)			head of attribute payload
129  *   nla_len(nla)			length of attribute payload
131  * Attribute Payload Access for Basic Types:
132  *   nla_get_uint(nla)			get payload for a uint attribute
133  *   nla_get_sint(nla)			get payload for a sint attribute
134  *   nla_get_u8(nla)			get payload for a u8 attribute
135  *   nla_get_u16(nla)			get payload for a u16 attribute
136  *   nla_get_u32(nla)			get payload for a u32 attribute
137  *   nla_get_u64(nla)			get payload for a u64 attribute
138  *   nla_get_s8(nla)			get payload for a s8 attribute
139  *   nla_get_s16(nla)			get payload for a s16 attribute
140  *   nla_get_s32(nla)			get payload for a s32 attribute
141  *   nla_get_s64(nla)			get payload for a s64 attribute
143  *   nla_get_msecs(nla)			get payload for a msecs attribute
145  * Attribute Misc:
146  *   nla_memcpy(dest, nla, count)	copy attribute into memory
147  *   nla_memcmp(nla, data, size)	compare attribute with memory area
148  *   nla_strscpy(dst, nla, size)	copy attribute to a sized string
149  *   nla_strcmp(nla, str)		compare attribute with string
151  * Attribute Parsing:
153  *   nla_next(nla, remaining)		get next netlink attribute
156  *   nla_find()				find attribute in stream of attributes
157  *   nla_find_nested()			find attribute in nested attributes
170   * Standard attribute types to specify validation policy
198 #define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
220  * struct nla_policy - attribute validation policy
221  * @type: Type of attribute or NLA_UNSPEC
222  * @validation_type: type of attribute validation done in addition to
223  *	type-specific validation (e.g. range, function call), see
228  * accessible by attribute type up to the highest identifier to be expected.
234  *    NLA_BINARY           Maximum length of attribute payload
252  *    All other            Minimum length of attribute payload
255  *    NLA_BITFIELD32       This is a 32-bit bitmap/bitselector attribute and
257  *    NLA_REJECT           This attribute is always rejected and `reject_message'
261  *                         also set `len' to the max attribute number. Use the
264  *                         parse, the nested sub-policies.
266  *                         must also set `len' to the max attribute number. Use
271  *                         level down and the attribute types directly in the
287  *                         the value of the integer attribute.
291  *                         of s16 - do that using the NLA_POLICY_FULL_RANGE()
299  *    NLA_U64              If the validation_type field instead is set to
308  *    NLA_S64              If the validation_type field instead is set to
316  *                         integers) of the attribute is enforced.
318  *    All other            Unused - but note that it's a union
321  *    NLA_BINARY           Validation function called for the attribute.
322  *    All other            Unused - but note that it's a union
341 		 * @strict_start_type: first attribute to validate strictly
343 		 * This entry is special, and used for the attribute at index 0
346 		 * starts for any attribute types >= this value, also, strict
355 		 * For completely new families it should be set to 1 so that the
357 		 * it should be set at least when new attributes are added to
358 		 * the enum used by the policy, and be set to the new value that
363 		/* private: use NLA_POLICY_*() to set */
386 	_NLA_POLICY_NESTED(ARRAY_SIZE(policy) - 1, policy)
388 	_NLA_POLICY_NESTED_ARRAY(ARRAY_SIZE(policy) - 1, policy)
474  * struct nl_info - netlink source information
479  * @skip_notify_kernel: Skip selected in-kernel notifications
490  * enum netlink_validation - netlink message/attribute validation levels
491  * @NL_VALIDATE_LIBERAL: Old-style "be liberal" validation, not caring about
494  * @NL_VALIDATE_TRAILING: Reject junk data encountered after attribute parsing.
498  *	This can safely be set by the kernel when the given policy has no
501  * @NL_VALIDATE_STRICT_ATTRS: strict attribute policy parsing (e.g.
503  * @NL_VALIDATE_NESTED: Check that NLA_F_NESTED is set for NLA_NESTED(_ARRAY)
566  * nlmsg_msg_size - length of netlink message not including padding
575  * nlmsg_total_size - length of netlink message including padding
584  * nlmsg_padlen - length of padding at the message's tail
589 	return nlmsg_total_size(payload) - nlmsg_msg_size(payload);  in nlmsg_padlen()
593  * nlmsg_data - head of message payload
602  * nlmsg_len - length of message payload
607 	return nlh->nlmsg_len - NLMSG_HDRLEN;  in nlmsg_len()
611  * nlmsg_attrdata - head of attributes data
623  * nlmsg_attrlen - length of attributes data
629 	return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);  in nlmsg_attrlen()
633  * nlmsg_ok - check if the netlink message fits into the remaining bytes
640 		nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&  in nlmsg_ok()
641 		nlh->nlmsg_len <= remaining);  in nlmsg_ok()
645  * nlmsg_next - next netlink message in message stream
655 	int totlen = NLMSG_ALIGN(nlh->nlmsg_len);  in nlmsg_next()
657 	*remaining -= totlen;  in nlmsg_next()
663  * nla_parse - Parse a stream of attributes into a tb buffer
665  * @maxtype: maximum attribute type to be expected
666  * @head: head of attribute stream
667  * @len: length of attribute stream
671  * Parses a stream of attributes and stores a pointer to each attribute in
672  * the tb array accessible via the attribute type. Attributes with a type
688  * nla_parse_deprecated - Parse a stream of attributes into a tb buffer
690  * @maxtype: maximum attribute type to be expected
691  * @head: head of attribute stream
692  * @len: length of attribute stream
696  * Parses a stream of attributes and stores a pointer to each attribute in
697  * the tb array accessible via the attribute type. Attributes with a type
713  * nla_parse_deprecated_strict - Parse a stream of attributes into a tb buffer
715  * @maxtype: maximum attribute type to be expected
716  * @head: head of attribute stream
717  * @len: length of attribute stream
721  * Parses a stream of attributes and stores a pointer to each attribute in
722  * the tb array accessible via the attribute type. Attributes with a type
739  * __nlmsg_parse - parse attributes of a netlink message
743  * @maxtype: maximum attribute type to be expected
756 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) {  in __nlmsg_parse()
758 		return -EINVAL;  in __nlmsg_parse()
767  * nlmsg_parse - parse attributes of a netlink message
771  * @maxtype: maximum attribute type to be expected
787  * nlmsg_parse_deprecated - parse attributes of a netlink message
791  * @maxtype: maximum attribute type to be expected
807  * nlmsg_parse_deprecated_strict - parse attributes of a netlink message
811  * @maxtype: maximum attribute type to be expected
828  * nlmsg_find_attr - find a specific attribute in a netlink message
831  * @attrtype: type of attribute to look for
833  * Returns the first attribute which matches the specified type.
843  * nla_validate_deprecated - Validate a stream of attributes
844  * @head: head of attribute stream
845  * @len: length of attribute stream
846  * @maxtype: maximum attribute type to be expected
850  * Validates all attributes in the specified attribute stream against the
866  * nla_validate - Validate a stream of attributes
867  * @head: head of attribute stream
868  * @len: length of attribute stream
869  * @maxtype: maximum attribute type to be expected
873  * Validates all attributes in the specified attribute stream against the
888  * nlmsg_validate_deprecated - validate a netlink message including attributes
891  * @maxtype: maximum attribute type to be expected
900 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))  in nlmsg_validate_deprecated()
901 		return -EINVAL;  in nlmsg_validate_deprecated()
911  * nlmsg_report - need to report back to application?
918 	return nlh ? !!(nlh->nlmsg_flags & NLM_F_ECHO) : 0;  in nlmsg_report()
922  * nlmsg_seq - return the seq number of netlink message
929 	return nlh ? nlh->nlmsg_seq : 0;  in nlmsg_seq()
933  * nlmsg_for_each_attr - iterate over a stream of attributes
934  * @pos: loop counter, set to current attribute
944  * nlmsg_put - Add a new netlink message to an skb
965  * nlmsg_append - Add more data to a nlmsg in a skb
970  * with multiple fixed-format headers (which is rare).
979 	if (NLMSG_ALIGN(size) - size)  in nlmsg_append()
981 		       NLMSG_ALIGN(size) - size);  in nlmsg_append()
986  * nlmsg_put_answer - Add a new callback based netlink message to an skb
1001 	return nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,  in nlmsg_put_answer()
1006  * nlmsg_new - Allocate a new netlink message
1019  * nlmsg_new_large - Allocate a new netlink message with non-contiguous
1023  * The allocated skb is unable to have frag page for shinfo->frags*,
1024  * as the NULL setting for skb->head in netlink_skb_destructor() will
1033  * nlmsg_end - Finalize a netlink message
1043 	nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;  in nlmsg_end()
1047  * nlmsg_get_pos - return current position in netlink message
1058  * nlmsg_trim - Trim message to a mark
1067 		WARN_ON((unsigned char *) mark < skb->data);  in nlmsg_trim()
1068 		skb_trim(skb, (unsigned char *) mark - skb->data);  in nlmsg_trim()
1073  * nlmsg_cancel - Cancel construction of a netlink message
1086  * nlmsg_free - drop a netlink message
1095  * nlmsg_consume - free a netlink message
1104  * nlmsg_multicast_filtered - multicast a netlink message with filter function
1134  * nlmsg_multicast - multicast a netlink message
1149  * nlmsg_unicast - unicast a netlink message
1166  * nlmsg_for_each_msg - iterate over a stream of messages
1167  * @pos: loop counter, set to current message
1178  * nl_dump_check_consistent - check if sequence is consistent and advertise if not
1185  * The correct way to use it is to set cb->seq to the generation counter when
1196 	if (cb->prev_seq && cb->seq != cb->prev_seq)  in nl_dump_check_consistent()
1197 		nlh->nlmsg_flags |= NLM_F_DUMP_INTR;  in nl_dump_check_consistent()
1198 	cb->prev_seq = cb->seq;  in nl_dump_check_consistent()
1206  * nla_attr_size - length of attribute not including padding
1215  * nla_total_size - total length of attribute including padding
1224  * nla_padlen - length of padding at the tail of attribute
1229 	return nla_total_size(payload) - nla_attr_size(payload);  in nla_padlen()
1233  * nla_type - attribute type
1234  * @nla: netlink attribute
1238 	return nla->nla_type & NLA_TYPE_MASK;  in nla_type()
1242  * nla_data - head of payload
1243  * @nla: netlink attribute
1251  * nla_len - length of payload
1252  * @nla: netlink attribute
1256 	return nla->nla_len - NLA_HDRLEN;  in nla_len()
1260  * nla_ok - check if the netlink attribute fits into the remaining bytes
1261  * @nla: netlink attribute
1262  * @remaining: number of bytes remaining in attribute stream
1267 	       nla->nla_len >= sizeof(*nla) &&  in nla_ok()
1268 	       nla->nla_len <= remaining;  in nla_ok()
1272  * nla_next - next netlink attribute in attribute stream
1273  * @nla: netlink attribute
1274  * @remaining: number of bytes remaining in attribute stream
1276  * Returns the next netlink attribute in the attribute stream and
1277  * decrements remaining by the size of the current attribute.
1281 	unsigned int totlen = NLA_ALIGN(nla->nla_len);  in nla_next()
1283 	*remaining -= totlen;  in nla_next()
1288  * nla_find_nested - find attribute in a set of nested attributes
1289  * @nla: attribute containing the nested attributes
1290  * @attrtype: type of attribute to look for
1292  * Returns the first attribute which matches the specified type.
1301  * nla_parse_nested - parse nested attributes
1303  * @maxtype: maximum attribute type to be expected
1304  * @nla: attribute containing the nested attributes
1315 	if (!(nla->nla_type & NLA_F_NESTED)) {  in nla_parse_nested()
1317 		return -EINVAL;  in nla_parse_nested()
1325  * nla_parse_nested_deprecated - parse nested attributes
1327  * @maxtype: maximum attribute type to be expected
1328  * @nla: attribute containing the nested attributes
1344  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
1345  * @skb: socket buffer to add attribute to
1346  * @attrtype: attribute type
1351 	/* temporary variables to work around GCC PR81715 with asan-stack=1 */  in nla_put_u8()
1358  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
1359  * @skb: socket buffer to add attribute to
1360  * @attrtype: attribute type
1371  * nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
1372  * @skb: socket buffer to add attribute to
1373  * @attrtype: attribute type
1384  * nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
1385  * @skb: socket buffer to add attribute to
1386  * @attrtype: attribute type
1397  * nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
1398  * @skb: socket buffer to add attribute to
1399  * @attrtype: attribute type
1410  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
1411  * @skb: socket buffer to add attribute to
1412  * @attrtype: attribute type
1423  * nla_put_uint - Add a variable-size unsigned int to a socket buffer
1424  * @skb: socket buffer to add attribute to
1425  * @attrtype: attribute type
1439  * nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
1440  * @skb: socket buffer to add attribute to
1441  * @attrtype: attribute type
1452  * nla_put_net32 - Add 32-bit network byte order netlink attribute to a socket buffer
1453  * @skb: socket buffer to add attribute to
1454  * @attrtype: attribute type
1465  * nla_put_le32 - Add a __le32 netlink attribute to a socket buffer
1466  * @skb: socket buffer to add attribute to
1467  * @attrtype: attribute type
1478  * nla_put_u64_64bit - Add a u64 netlink attribute to a skb and align it
1479  * @skb: socket buffer to add attribute to
1480  * @attrtype: attribute type
1482  * @padattr: attribute type for the padding
1493  * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer and align it
1494  * @skb: socket buffer to add attribute to
1495  * @attrtype: attribute type
1497  * @padattr: attribute type for the padding
1508  * nla_put_net64 - Add 64-bit network byte order nlattr to a skb and align it
1509  * @skb: socket buffer to add attribute to
1510  * @attrtype: attribute type
1512  * @padattr: attribute type for the padding
1524  * nla_put_le64 - Add a __le64 netlink attribute to a socket buffer and align it
1525  * @skb: socket buffer to add attribute to
1526  * @attrtype: attribute type
1528  * @padattr: attribute type for the padding
1539  * nla_put_s8 - Add a s8 netlink attribute to a socket buffer
1540  * @skb: socket buffer to add attribute to
1541  * @attrtype: attribute type
1552  * nla_put_s16 - Add a s16 netlink attribute to a socket buffer
1553  * @skb: socket buffer to add attribute to
1554  * @attrtype: attribute type
1565  * nla_put_s32 - Add a s32 netlink attribute to a socket buffer
1566  * @skb: socket buffer to add attribute to
1567  * @attrtype: attribute type
1578  * nla_put_s64 - Add a s64 netlink attribute to a socket buffer and align it
1579  * @skb: socket buffer to add attribute to
1580  * @attrtype: attribute type
1582  * @padattr: attribute type for the padding
1593  * nla_put_sint - Add a variable-size signed int to a socket buffer
1594  * @skb: socket buffer to add attribute to
1595  * @attrtype: attribute type
1609  * nla_put_string - Add a string netlink attribute to a socket buffer
1610  * @skb: socket buffer to add attribute to
1611  * @attrtype: attribute type
1621  * nla_put_flag - Add a flag netlink attribute to a socket buffer
1622  * @skb: socket buffer to add attribute to
1623  * @attrtype: attribute type
1631  * nla_put_msecs - Add a msecs netlink attribute to a skb and align it
1632  * @skb: socket buffer to add attribute to
1633  * @attrtype: attribute type
1635  * @padattr: attribute type for the padding
1646  * nla_put_in_addr - Add an IPv4 address netlink attribute to a socket
1648  * @skb: socket buffer to add attribute to
1649  * @attrtype: attribute type
1661  * nla_put_in6_addr - Add an IPv6 address netlink attribute to a socket
1663  * @skb: socket buffer to add attribute to
1664  * @attrtype: attribute type
1674  * nla_put_bitfield32 - Add a bitfield32 netlink attribute to a socket buffer
1675  * @skb: socket buffer to add attribute to
1676  * @attrtype: attribute type
1689  * nla_get_u32 - return payload of u32 attribute
1690  * @nla: u32 netlink attribute
1698  * nla_get_be32 - return payload of __be32 attribute
1699  * @nla: __be32 netlink attribute
1707  * nla_get_le32 - return payload of __le32 attribute
1708  * @nla: __le32 netlink attribute
1716  * nla_get_u16 - return payload of u16 attribute
1717  * @nla: u16 netlink attribute
1725  * nla_get_be16 - return payload of __be16 attribute
1726  * @nla: __be16 netlink attribute
1734  * nla_get_le16 - return payload of __le16 attribute
1735  * @nla: __le16 netlink attribute
1743  * nla_get_u8 - return payload of u8 attribute
1744  * @nla: u8 netlink attribute
1752  * nla_get_u64 - return payload of u64 attribute
1753  * @nla: u64 netlink attribute
1765  * nla_get_uint - return payload of uint attribute
1766  * @nla: uint netlink attribute
1776  * nla_get_be64 - return payload of __be64 attribute
1777  * @nla: __be64 netlink attribute
1789  * nla_get_le64 - return payload of __le64 attribute
1790  * @nla: __le64 netlink attribute
1798  * nla_get_s32 - return payload of s32 attribute
1799  * @nla: s32 netlink attribute
1807  * nla_get_s16 - return payload of s16 attribute
1808  * @nla: s16 netlink attribute
1816  * nla_get_s8 - return payload of s8 attribute
1817  * @nla: s8 netlink attribute
1825  * nla_get_s64 - return payload of s64 attribute
1826  * @nla: s64 netlink attribute
1838  * nla_get_sint - return payload of uint attribute
1839  * @nla: uint netlink attribute
1849  * nla_get_flag - return payload of flag attribute
1850  * @nla: flag netlink attribute
1858  * nla_get_msecs - return payload of msecs attribute
1859  * @nla: msecs netlink attribute
1871  * nla_get_in_addr - return payload of IPv4 address attribute
1872  * @nla: IPv4 address netlink attribute
1880  * nla_get_in6_addr - return payload of IPv6 address attribute
1881  * @nla: IPv6 address netlink attribute
1892  * nla_get_bitfield32 - return payload of 32 bitfield attribute
1893  * @nla: nla_bitfield32 attribute
1904  * nla_memdup - duplicate attribute memory (kmemdup)
1905  * @src: netlink attribute to duplicate from
1915  * nla_nest_start_noflag - Start a new level of nested attributes
1917  * @attrtype: attribute type of container
1923  * Returns the container attribute or NULL on error
1937  * nla_nest_start - Start a new level of nested attributes, with NLA_F_NESTED
1939  * @attrtype: attribute type of container
1941  * Unlike nla_nest_start_noflag(), mark the nest attribute with NLA_F_NESTED
1944  * Returns the container attribute or NULL on error
1952  * nla_nest_end - Finalize nesting of attributes
1954  * @start: container attribute
1956  * Corrects the container attribute header to include the all
1963 	start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;  in nla_nest_end()
1964 	return skb->len;  in nla_nest_end()
1968  * nla_nest_cancel - Cancel nesting of attributes
1970  * @start: container attribute
1972  * Removes the container attribute and including all nested
1973  * attributes. Returns -EMSGSIZE
1981  * __nla_validate_nested - Validate a stream of nested attributes
1982  * @start: container attribute
1983  * @maxtype: maximum attribute type to be expected
1988  * Validates all attributes in the nested attribute stream against the
2022  * nla_need_padding_for_64bit - test 64-bit alignment of the next attribute
2025  * Return true if padding is needed to align the next attribute (nla_data()) to
2026  * a 64-bit aligned area.
2032 	 * if the skb->data _is_ aligned.  A NOP attribute, plus  in nla_need_padding_for_64bit()
2033 	 * nlattr header for next attribute, will make nla_data()  in nla_need_padding_for_64bit()
2034 	 * 8-byte aligned.  in nla_need_padding_for_64bit()
2043  * nla_align_64bit - 64-bit align the nla_data() of next attribute
2045  * @padattr: attribute type for the padding
2047  * Conditionally emit a padding netlink attribute in order to make
2048  * the next attribute we emit have a 64-bit aligned nla_data() area.
2058 		return -EMSGSIZE;  in nla_align_64bit()
2064  * nla_total_size_64bit - total length of attribute including padding
2077  * nla_for_each_attr - iterate over a stream of attributes
2078  * @pos: loop counter, set to current attribute
2079  * @head: head of attribute stream
2080  * @len: length of attribute stream
2089  * nla_for_each_attr_type - iterate over a stream of attributes
2090  * @pos: loop counter, set to current attribute
2091  * @type: required attribute type for @pos
2092  * @head: head of attribute stream
2093  * @len: length of attribute stream
2101  * nla_for_each_nested - iterate over nested attributes
2102  * @pos: loop counter, set to current attribute
2103  * @nla: attribute containing the nested attributes
2110  * nla_for_each_nested_type - iterate over nested attributes
2111  * @pos: loop counter, set to current attribute
2112  * @type: required attribute type for @pos
2113  * @nla: attribute containing the nested attributes
2121  * nla_is_last - Test if attribute is last in stream
2122  * @nla: attribute to test
2127 	return nla->nla_len == rem;  in nla_is_last()