1 /* SPDX-License-Identifier: GPL-2.0 */
11  *         Netlink Messages and Attributes Interface (As Seen On TV)
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  *   +----------------------+- - -+--------------------------------+
29  *   |     Family Header    | Pad |           Attributes           |
30  *   +----------------------+- - -+--------------------------------+
31  *   nlmsg_attrdata(nlh, hdrlen)---^
59  *   nlmsg_attrdata(nlh, hdrlen)	head of attributes data
60  *   nlmsg_attrlen(nlh, hdrlen)		length of attributes data
65  *   nlmsg_parse()			parse attributes of a message
69  *   nlmsg_for_each_attr()		loop over all attributes
74  * ------------------------------------------------------------------------
75  *                          Attributes Interface
76  * ------------------------------------------------------------------------
79  *    <------- nla_total_size(payload) ------->
80  *    <---- nla_attr_size(payload) ----->
81  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
83  *   +----------+- - -+- - - - - - - - - +- - -+-------- - -
84  *                     <- nla_len(nla) ->      ^
85  *   nla_data(nla)----^                        |
86  *   nla_next(nla)-----------------------------'
116  * Nested Attributes Construction:
117  *   nla_nest_start(skb, type)		start a nested attribute
118  *   nla_nest_end(skb, nla)		finalize a nested attribute
119  *   nla_nest_cancel(skb, nla)		cancel nested attribute construction
151  *   nla_validate()			validate a stream of attributes
152  *   nla_validate_nested()		validate a stream of nested attributes
153  *   nla_find()				find attribute in stream of attributes
154  *   nla_find_nested()			find attribute in nested attributes
156  *   nla_parse_nested()			parse nested attributes
157  *   nla_for_each_attr()		loop over all attributes
158  *   nla_for_each_nested()		loop over the nested attributes
189 #define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
211  * struct nla_policy - attribute validation policy
214  *	type-specific validation (e.g. range, function call), see
229  *                         nested header (or empty); len field is used if
231  *                         number in the nested policy.
245  *    NLA_BITFIELD32       This is a 32-bit bitmap/bitselector attribute and
250  *    NLA_NESTED           `nested_policy' to a nested policy to validate, must
254  *                         parse, the nested sub-policies.
255  *    NLA_NESTED_ARRAY     `nested_policy' points to a nested policy to validate,
259  *                         NLA_NESTED has the nested attributes directly inside
260  *                         while an array has the nested attributes at another
279  *                         of s16 - do that using the NLA_POLICY_FULL_RANGE()
304  *    All other            Unused - but note that it's a union
308  *    All other            Unused - but note that it's a union
342 		 * validation is enforced for all attributes. For existing ones
343 		 * it should be set at least when new attributes are added to
372 	_NLA_POLICY_NESTED(ARRAY_SIZE(policy) - 1, policy)
374 	_NLA_POLICY_NESTED_ARRAY(ARRAY_SIZE(policy) - 1, policy)
458  * struct nl_info - netlink source information
463  * @skip_notify_kernel: Skip selected in-kernel notifications
474  * enum netlink_validation - netlink message/attribute validation levels
475  * @NL_VALIDATE_LIBERAL: Old-style "be liberal" validation, not caring about
476  *	extra data at the end of the message, attributes being longer than
477  *	they should be, or unknown attributes being present.
479  * @NL_VALIDATE_MAXTYPE: Reject attributes > max type; Together with _TRAILING
481  * @NL_VALIDATE_UNSPEC: Reject attributes with NLA_UNSPEC in the policy.
550  * nlmsg_msg_size - length of netlink message not including padding
559  * nlmsg_total_size - length of netlink message including padding
568  * nlmsg_padlen - length of padding at the message's tail
573 	return nlmsg_total_size(payload) - nlmsg_msg_size(payload);  in nlmsg_padlen()
577  * nlmsg_data - head of message payload
586  * nlmsg_len - length of message payload
591 	return nlh->nlmsg_len - NLMSG_HDRLEN;  in nlmsg_len()
595  * nlmsg_attrdata - head of attributes data
607  * nlmsg_attrlen - length of attributes data
613 	return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);  in nlmsg_attrlen()
617  * nlmsg_ok - check if the netlink message fits into the remaining bytes
624 		nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&  in nlmsg_ok()
625 		nlh->nlmsg_len <= remaining);  in nlmsg_ok()
629  * nlmsg_next - next netlink message in message stream
639 	int totlen = NLMSG_ALIGN(nlh->nlmsg_len);  in nlmsg_next()
641 	*remaining -= totlen;  in nlmsg_next()
647  * nla_parse - Parse a stream of attributes into a tb buffer
655  * Parses a stream of attributes and stores a pointer to each attribute in
656  * the tb array accessible via the attribute type. Attributes with a type
657  * exceeding maxtype will be rejected, policy must be specified, attributes
672  * nla_parse_deprecated - Parse a stream of attributes into a tb buffer
680  * Parses a stream of attributes and stores a pointer to each attribute in
681  * the tb array accessible via the attribute type. Attributes with a type
682  * exceeding maxtype will be ignored and attributes from the policy are not
683  * always strictly validated (only for new attributes).
697  * nla_parse_deprecated_strict - Parse a stream of attributes into a tb buffer
705  * Parses a stream of attributes and stores a pointer to each attribute in
706  * the tb array accessible via the attribute type. Attributes with a type
708  * policy is not completely strictly validated (only for new attributes).
723  * __nlmsg_parse - parse attributes of a netlink message
740 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) {  in __nlmsg_parse()
742 		return -EINVAL;  in __nlmsg_parse()
751  * nlmsg_parse - parse attributes of a netlink message
771  * nlmsg_parse_deprecated - parse attributes of a netlink message
791  * nlmsg_parse_deprecated_strict - parse attributes of a netlink message
812  * nlmsg_find_attr - find a specific attribute in a netlink message
827  * nla_validate_deprecated - Validate a stream of attributes
834  * Validates all attributes in the specified attribute stream against the
850  * nla_validate - Validate a stream of attributes
857  * Validates all attributes in the specified attribute stream against the
872  * nlmsg_validate_deprecated - validate a netlink message including attributes
884 	if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))  in nlmsg_validate_deprecated()
885 		return -EINVAL;  in nlmsg_validate_deprecated()
895  * nlmsg_report - need to report back to application?
902 	return nlh ? !!(nlh->nlmsg_flags & NLM_F_ECHO) : 0;  in nlmsg_report()
906  * nlmsg_seq - return the seq number of netlink message
913 	return nlh ? nlh->nlmsg_seq : 0;  in nlmsg_seq()
917  * nlmsg_for_each_attr - iterate over a stream of attributes
928  * nlmsg_put - Add a new netlink message to an skb
949  * nlmsg_append - Add more data to a nlmsg in a skb
954  * with multiple fixed-format headers (which is rare).
963 	if (NLMSG_ALIGN(size) - size)  in nlmsg_append()
965 		       NLMSG_ALIGN(size) - size);  in nlmsg_append()
970  * nlmsg_put_answer - Add a new callback based netlink message to an skb
985 	return nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,  in nlmsg_put_answer()
990  * nlmsg_new - Allocate a new netlink message
1003  * nlmsg_end - Finalize a netlink message
1008  * attributes. Only necessary if attributes have been added to
1013 	nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;  in nlmsg_end()
1017  * nlmsg_get_pos - return current position in netlink message
1028  * nlmsg_trim - Trim message to a mark
1037 		WARN_ON((unsigned char *) mark < skb->data);  in nlmsg_trim()
1038 		skb_trim(skb, (unsigned char *) mark - skb->data);  in nlmsg_trim()
1043  * nlmsg_cancel - Cancel construction of a netlink message
1048  * attributes from the socket buffer again.
1056  * nlmsg_free - free a netlink message
1065  * nlmsg_multicast - multicast a netlink message
1087  * nlmsg_unicast - unicast a netlink message
1104  * nlmsg_for_each_msg - iterate over a stream of messages
1116  * nl_dump_check_consistent - check if sequence is consistent and advertise if not
1123  * The correct way to use it is to set cb->seq to the generation counter when
1134 	if (cb->prev_seq && cb->seq != cb->prev_seq)  in nl_dump_check_consistent()
1135 		nlh->nlmsg_flags |= NLM_F_DUMP_INTR;  in nl_dump_check_consistent()
1136 	cb->prev_seq = cb->seq;  in nl_dump_check_consistent()
1140  * Netlink Attributes
1144  * nla_attr_size - length of attribute not including padding
1153  * nla_total_size - total length of attribute including padding
1162  * nla_padlen - length of padding at the tail of attribute
1167 	return nla_total_size(payload) - nla_attr_size(payload);  in nla_padlen()
1171  * nla_type - attribute type
1176 	return nla->nla_type & NLA_TYPE_MASK;  in nla_type()
1180  * nla_data - head of payload
1189  * nla_len - length of payload
1194 	return nla->nla_len - NLA_HDRLEN;  in nla_len()
1198  * nla_ok - check if the netlink attribute fits into the remaining bytes
1205 	       nla->nla_len >= sizeof(*nla) &&  in nla_ok()
1206 	       nla->nla_len <= remaining;  in nla_ok()
1210  * nla_next - next netlink attribute in attribute stream
1219 	unsigned int totlen = NLA_ALIGN(nla->nla_len);  in nla_next()
1221 	*remaining -= totlen;  in nla_next()
1226  * nla_find_nested - find attribute in a set of nested attributes
1227  * @nla: attribute containing the nested attributes
1239  * nla_parse_nested - parse nested attributes
1242  * @nla: attribute containing the nested attributes
1253 	if (!(nla->nla_type & NLA_F_NESTED)) {  in nla_parse_nested()
1255 		return -EINVAL;  in nla_parse_nested()
1263  * nla_parse_nested_deprecated - parse nested attributes
1266  * @nla: attribute containing the nested attributes
1282  * nla_put_u8 - Add a u8 netlink attribute to a socket buffer
1289 	/* temporary variables to work around GCC PR81715 with asan-stack=1 */  in nla_put_u8()
1296  * nla_put_u16 - Add a u16 netlink attribute to a socket buffer
1309  * nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
1322  * nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
1335  * nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
1348  * nla_put_u32 - Add a u32 netlink attribute to a socket buffer
1361  * nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
1374  * nla_put_net32 - Add 32-bit network byte order netlink attribute to a socket buffer
1387  * nla_put_le32 - Add a __le32 netlink attribute to a socket buffer
1400  * nla_put_u64_64bit - Add a u64 netlink attribute to a skb and align it
1415  * nla_put_be64 - Add a __be64 netlink attribute to a socket buffer and align it
1430  * nla_put_net64 - Add 64-bit network byte order nlattr to a skb and align it
1446  * nla_put_le64 - Add a __le64 netlink attribute to a socket buffer and align it
1461  * nla_put_s8 - Add a s8 netlink attribute to a socket buffer
1474  * nla_put_s16 - Add a s16 netlink attribute to a socket buffer
1487  * nla_put_s32 - Add a s32 netlink attribute to a socket buffer
1500  * nla_put_s64 - Add a s64 netlink attribute to a socket buffer and align it
1515  * nla_put_string - Add a string netlink attribute to a socket buffer
1527  * nla_put_flag - Add a flag netlink attribute to a socket buffer
1537  * nla_put_msecs - Add a msecs netlink attribute to a skb and align it
1552  * nla_put_in_addr - Add an IPv4 address netlink attribute to a socket
1567  * nla_put_in6_addr - Add an IPv6 address netlink attribute to a socket
1580  * nla_put_bitfield32 - Add a bitfield32 netlink attribute to a socket buffer
1595  * nla_get_u32 - return payload of u32 attribute
1604  * nla_get_be32 - return payload of __be32 attribute
1613  * nla_get_le32 - return payload of __le32 attribute
1622  * nla_get_u16 - return payload of u16 attribute
1631  * nla_get_be16 - return payload of __be16 attribute
1640  * nla_get_le16 - return payload of __le16 attribute
1649  * nla_get_u8 - return payload of u8 attribute
1658  * nla_get_u64 - return payload of u64 attribute
1671  * nla_get_be64 - return payload of __be64 attribute
1684  * nla_get_le64 - return payload of __le64 attribute
1693  * nla_get_s32 - return payload of s32 attribute
1702  * nla_get_s16 - return payload of s16 attribute
1711  * nla_get_s8 - return payload of s8 attribute
1720  * nla_get_s64 - return payload of s64 attribute
1733  * nla_get_flag - return payload of flag attribute
1742  * nla_get_msecs - return payload of msecs attribute
1755  * nla_get_in_addr - return payload of IPv4 address attribute
1764  * nla_get_in6_addr - return payload of IPv6 address attribute
1776  * nla_get_bitfield32 - return payload of 32 bitfield attribute
1788  * nla_memdup - duplicate attribute memory (kmemdup)
1798  * nla_nest_start_noflag - Start a new level of nested attributes
1799  * @skb: socket buffer to add attributes to
1803  * marked their nest attributes with NLA_F_NESTED flag. New APIs should use
1820  * nla_nest_start - Start a new level of nested attributes, with NLA_F_NESTED
1821  * @skb: socket buffer to add attributes to
1835  * nla_nest_end - Finalize nesting of attributes
1836  * @skb: socket buffer the attributes are stored in
1840  * appeneded attributes.
1846 	start->nla_len = skb_tail_pointer(skb) - (unsigned char *)start;  in nla_nest_end()
1847 	return skb->len;  in nla_nest_end()
1851  * nla_nest_cancel - Cancel nesting of attributes
1855  * Removes the container attribute and including all nested
1856  * attributes. Returns -EMSGSIZE
1864  * __nla_validate_nested - Validate a stream of nested attributes
1871  * Validates all attributes in the nested attribute stream against the
1872  * specified policy. Attributes with a type exceeding maxtype will be
1905  * nla_need_padding_for_64bit - test 64-bit alignment of the next attribute
1909  * a 64-bit aligned area.
1915 	 * if the skb->data _is_ aligned.  A NOP attribute, plus  in nla_need_padding_for_64bit()
1917 	 * 8-byte aligned.  in nla_need_padding_for_64bit()
1926  * nla_align_64bit - 64-bit align the nla_data() of next attribute
1931  * the next attribute we emit have a 64-bit aligned nla_data() area.
1941 		return -EMSGSIZE;  in nla_align_64bit()
1947  * nla_total_size_64bit - total length of attribute including padding
1960  * nla_for_each_attr - iterate over a stream of attributes
1972  * nla_for_each_nested - iterate over nested attributes
1974  * @nla: attribute containing the nested attributes
1981  * nla_is_last - Test if attribute is last in stream
1987 	return nla->nla_len == rem;  in nla_is_last()