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netlink.h
1566 lines (1414 loc) · 46 KB
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netlink.h
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __NET_NETLINK_H
#define __NET_NETLINK_H
#include <linux/types.h>
#include <linux/netlink.h>
#include <linux/jiffies.h>
#include <linux/in6.h>
/* ========================================================================
* Netlink Messages and Attributes Interface (As Seen On TV)
* ------------------------------------------------------------------------
* Messages Interface
* ------------------------------------------------------------------------
*
* Message Format:
* <--- nlmsg_total_size(payload) --->
* <-- nlmsg_msg_size(payload) ->
* +----------+- - -+-------------+- - -+-------- - -
* | nlmsghdr | Pad | Payload | Pad | nlmsghdr
* +----------+- - -+-------------+- - -+-------- - -
* nlmsg_data(nlh)---^ ^
* nlmsg_next(nlh)-----------------------+
*
* Payload Format:
* <---------------------- nlmsg_len(nlh) --------------------->
* <------ hdrlen ------> <- nlmsg_attrlen(nlh, hdrlen) ->
* +----------------------+- - -+--------------------------------+
* | Family Header | Pad | Attributes |
* +----------------------+- - -+--------------------------------+
* nlmsg_attrdata(nlh, hdrlen)---^
*
* Data Structures:
* struct nlmsghdr netlink message header
*
* Message Construction:
* nlmsg_new() create a new netlink message
* nlmsg_put() add a netlink message to an skb
* nlmsg_put_answer() callback based nlmsg_put()
* nlmsg_end() finalize netlink message
* nlmsg_get_pos() return current position in message
* nlmsg_trim() trim part of message
* nlmsg_cancel() cancel message construction
* nlmsg_free() free a netlink message
*
* Message Sending:
* nlmsg_multicast() multicast message to several groups
* nlmsg_unicast() unicast a message to a single socket
* nlmsg_notify() send notification message
*
* Message Length Calculations:
* nlmsg_msg_size(payload) length of message w/o padding
* nlmsg_total_size(payload) length of message w/ padding
* nlmsg_padlen(payload) length of padding at tail
*
* Message Payload Access:
* nlmsg_data(nlh) head of message payload
* nlmsg_len(nlh) length of message payload
* nlmsg_attrdata(nlh, hdrlen) head of attributes data
* nlmsg_attrlen(nlh, hdrlen) length of attributes data
*
* Message Parsing:
* nlmsg_ok(nlh, remaining) does nlh fit into remaining bytes?
* nlmsg_next(nlh, remaining) get next netlink message
* nlmsg_parse() parse attributes of a message
* nlmsg_find_attr() find an attribute in a message
* nlmsg_for_each_msg() loop over all messages
* nlmsg_validate() validate netlink message incl. attrs
* nlmsg_for_each_attr() loop over all attributes
*
* Misc:
* nlmsg_report() report back to application?
*
* ------------------------------------------------------------------------
* Attributes Interface
* ------------------------------------------------------------------------
*
* Attribute Format:
* <------- nla_total_size(payload) ------->
* <---- nla_attr_size(payload) ----->
* +----------+- - -+- - - - - - - - - +- - -+-------- - -
* | Header | Pad | Payload | Pad | Header
* +----------+- - -+- - - - - - - - - +- - -+-------- - -
* <- nla_len(nla) -> ^
* nla_data(nla)----^ |
* nla_next(nla)-----------------------------'
*
* Data Structures:
* struct nlattr netlink attribute header
*
* Attribute Construction:
* nla_reserve(skb, type, len) reserve room for an attribute
* nla_reserve_nohdr(skb, len) reserve room for an attribute w/o hdr
* nla_put(skb, type, len, data) add attribute to skb
* nla_put_nohdr(skb, len, data) add attribute w/o hdr
* nla_append(skb, len, data) append data to skb
*
* Attribute Construction for Basic Types:
* nla_put_u8(skb, type, value) add u8 attribute to skb
* nla_put_u16(skb, type, value) add u16 attribute to skb
* nla_put_u32(skb, type, value) add u32 attribute to skb
* nla_put_u64_64bit(skb, type,
* value, padattr) add u64 attribute to skb
* nla_put_s8(skb, type, value) add s8 attribute to skb
* nla_put_s16(skb, type, value) add s16 attribute to skb
* nla_put_s32(skb, type, value) add s32 attribute to skb
* nla_put_s64(skb, type, value,
* padattr) add s64 attribute to skb
* nla_put_string(skb, type, str) add string attribute to skb
* nla_put_flag(skb, type) add flag attribute to skb
* nla_put_msecs(skb, type, jiffies,
* padattr) add msecs attribute to skb
* nla_put_in_addr(skb, type, addr) add IPv4 address attribute to skb
* nla_put_in6_addr(skb, type, addr) add IPv6 address attribute to skb
*
* Nested Attributes Construction:
* nla_nest_start(skb, type) start a nested attribute
* nla_nest_end(skb, nla) finalize a nested attribute
* nla_nest_cancel(skb, nla) cancel nested attribute construction
*
* Attribute Length Calculations:
* nla_attr_size(payload) length of attribute w/o padding
* nla_total_size(payload) length of attribute w/ padding
* nla_padlen(payload) length of padding
*
* Attribute Payload Access:
* nla_data(nla) head of attribute payload
* nla_len(nla) length of attribute payload
*
* Attribute Payload Access for Basic Types:
* nla_get_u8(nla) get payload for a u8 attribute
* nla_get_u16(nla) get payload for a u16 attribute
* nla_get_u32(nla) get payload for a u32 attribute
* nla_get_u64(nla) get payload for a u64 attribute
* nla_get_s8(nla) get payload for a s8 attribute
* nla_get_s16(nla) get payload for a s16 attribute
* nla_get_s32(nla) get payload for a s32 attribute
* nla_get_s64(nla) get payload for a s64 attribute
* nla_get_flag(nla) return 1 if flag is true
* nla_get_msecs(nla) get payload for a msecs attribute
*
* Attribute Misc:
* nla_memcpy(dest, nla, count) copy attribute into memory
* nla_memcmp(nla, data, size) compare attribute with memory area
* nla_strlcpy(dst, nla, size) copy attribute to a sized string
* nla_strcmp(nla, str) compare attribute with string
*
* Attribute Parsing:
* nla_ok(nla, remaining) does nla fit into remaining bytes?
* nla_next(nla, remaining) get next netlink attribute
* nla_validate() validate a stream of attributes
* nla_validate_nested() validate a stream of nested attributes
* nla_find() find attribute in stream of attributes
* nla_find_nested() find attribute in nested attributes
* nla_parse() parse and validate stream of attrs
* nla_parse_nested() parse nested attributes
* nla_for_each_attr() loop over all attributes
* nla_for_each_nested() loop over the nested attributes
*=========================================================================
*/
/**
* Standard attribute types to specify validation policy
*/
enum {
NLA_UNSPEC,
NLA_U8,
NLA_U16,
NLA_U32,
NLA_U64,
NLA_STRING,
NLA_FLAG,
NLA_MSECS,
NLA_NESTED,
NLA_NESTED_ARRAY,
NLA_NUL_STRING,
NLA_BINARY,
NLA_S8,
NLA_S16,
NLA_S32,
NLA_S64,
NLA_BITFIELD32,
NLA_REJECT,
NLA_EXACT_LEN,
NLA_EXACT_LEN_WARN,
__NLA_TYPE_MAX,
};
#define NLA_TYPE_MAX (__NLA_TYPE_MAX - 1)
enum nla_policy_validation {
NLA_VALIDATE_NONE,
NLA_VALIDATE_RANGE,
NLA_VALIDATE_MIN,
NLA_VALIDATE_MAX,
NLA_VALIDATE_FUNCTION,
};
/**
* struct nla_policy - attribute validation policy
* @type: Type of attribute or NLA_UNSPEC
* @validation_type: type of attribute validation done in addition to
* type-specific validation (e.g. range, function call), see
* &enum nla_policy_validation
* @len: Type specific length of payload
*
* Policies are defined as arrays of this struct, the array must be
* accessible by attribute type up to the highest identifier to be expected.
*
* Meaning of `len' field:
* NLA_STRING Maximum length of string
* NLA_NUL_STRING Maximum length of string (excluding NUL)
* NLA_FLAG Unused
* NLA_BINARY Maximum length of attribute payload
* NLA_NESTED,
* NLA_NESTED_ARRAY Length verification is done by checking len of
* nested header (or empty); len field is used if
* validation_data is also used, for the max attr
* number in the nested policy.
* NLA_U8, NLA_U16,
* NLA_U32, NLA_U64,
* NLA_S8, NLA_S16,
* NLA_S32, NLA_S64,
* NLA_MSECS Leaving the length field zero will verify the
* given type fits, using it verifies minimum length
* just like "All other"
* NLA_BITFIELD32 Unused
* NLA_REJECT Unused
* NLA_EXACT_LEN Attribute must have exactly this length, otherwise
* it is rejected.
* NLA_EXACT_LEN_WARN Attribute should have exactly this length, a warning
* is logged if it is longer, shorter is rejected.
* All other Minimum length of attribute payload
*
* Meaning of `validation_data' field:
* NLA_BITFIELD32 This is a 32-bit bitmap/bitselector attribute and
* validation data must point to a u32 value of valid
* flags
* NLA_REJECT This attribute is always rejected and validation data
* may point to a string to report as the error instead
* of the generic one in extended ACK.
* NLA_NESTED Points to a nested policy to validate, must also set
* `len' to the max attribute number.
* Note that nla_parse() will validate, but of course not
* parse, the nested sub-policies.
* NLA_NESTED_ARRAY Points to a nested policy to validate, must also set
* `len' to the max attribute number. The difference to
* NLA_NESTED is the structure - NLA_NESTED has the
* nested attributes directly inside, while an array has
* the nested attributes at another level down and the
* attributes directly in the nesting don't matter.
* All other Unused - but note that it's a union
*
* Meaning of `min' and `max' fields, use via NLA_POLICY_MIN, NLA_POLICY_MAX
* and NLA_POLICY_RANGE:
* NLA_U8,
* NLA_U16,
* NLA_U32,
* NLA_U64,
* NLA_S8,
* NLA_S16,
* NLA_S32,
* NLA_S64 These are used depending on the validation_type
* field, if that is min/max/range then the minimum,
* maximum and both are used (respectively) to check
* the value of the integer attribute.
* Note that in the interest of code simplicity and
* struct size both limits are s16, so you cannot
* enforce a range that doesn't fall within the range
* of s16 - do that as usual in the code instead.
* All other Unused - but note that it's a union
*
* Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN:
* NLA_BINARY Validation function called for the attribute,
* not compatible with use of the validation_data
* as in NLA_BITFIELD32, NLA_REJECT, NLA_NESTED and
* NLA_NESTED_ARRAY.
* All other Unused - but note that it's a union
*
* Example:
* static const struct nla_policy my_policy[ATTR_MAX+1] = {
* [ATTR_FOO] = { .type = NLA_U16 },
* [ATTR_BAR] = { .type = NLA_STRING, .len = BARSIZ },
* [ATTR_BAZ] = { .len = sizeof(struct mystruct) },
* [ATTR_GOO] = { .type = NLA_BITFIELD32, .validation_data = &myvalidflags },
* };
*/
struct nla_policy {
u8 type;
u8 validation_type;
u16 len;
union {
const void *validation_data;
struct {
s16 min, max;
};
int (*validate)(const struct nlattr *attr,
struct netlink_ext_ack *extack);
};
};
#define NLA_POLICY_EXACT_LEN(_len) { .type = NLA_EXACT_LEN, .len = _len }
#define NLA_POLICY_EXACT_LEN_WARN(_len) { .type = NLA_EXACT_LEN_WARN, \
.len = _len }
#define NLA_POLICY_ETH_ADDR NLA_POLICY_EXACT_LEN(ETH_ALEN)
#define NLA_POLICY_ETH_ADDR_COMPAT NLA_POLICY_EXACT_LEN_WARN(ETH_ALEN)
#define NLA_POLICY_NESTED(maxattr, policy) \
{ .type = NLA_NESTED, .validation_data = policy, .len = maxattr }
#define NLA_POLICY_NESTED_ARRAY(maxattr, policy) \
{ .type = NLA_NESTED_ARRAY, .validation_data = policy, .len = maxattr }
#define __NLA_ENSURE(condition) BUILD_BUG_ON_ZERO(!(condition))
#define NLA_ENSURE_INT_TYPE(tp) \
(__NLA_ENSURE(tp == NLA_S8 || tp == NLA_U8 || \
tp == NLA_S16 || tp == NLA_U16 || \
tp == NLA_S32 || tp == NLA_U32 || \
tp == NLA_S64 || tp == NLA_U64) + tp)
#define NLA_ENSURE_NO_VALIDATION_PTR(tp) \
(__NLA_ENSURE(tp != NLA_BITFIELD32 && \
tp != NLA_REJECT && \
tp != NLA_NESTED && \
tp != NLA_NESTED_ARRAY) + tp)
#define NLA_POLICY_RANGE(tp, _min, _max) { \
.type = NLA_ENSURE_INT_TYPE(tp), \
.validation_type = NLA_VALIDATE_RANGE, \
.min = _min, \
.max = _max \
}
#define NLA_POLICY_MIN(tp, _min) { \
.type = NLA_ENSURE_INT_TYPE(tp), \
.validation_type = NLA_VALIDATE_MIN, \
.min = _min, \
}
#define NLA_POLICY_MAX(tp, _max) { \
.type = NLA_ENSURE_INT_TYPE(tp), \
.validation_type = NLA_VALIDATE_MAX, \
.max = _max, \
}
#define NLA_POLICY_VALIDATE_FN(tp, fn, ...) { \
.type = NLA_ENSURE_NO_VALIDATION_PTR(tp), \
.validation_type = NLA_VALIDATE_FUNCTION, \
.validate = fn, \
.len = __VA_ARGS__ + 0, \
}
/**
* struct nl_info - netlink source information
* @nlh: Netlink message header of original request
* @portid: Netlink PORTID of requesting application
*/
struct nl_info {
struct nlmsghdr *nlh;
struct net *nl_net;
u32 portid;
bool skip_notify;
};
int netlink_rcv_skb(struct sk_buff *skb,
int (*cb)(struct sk_buff *, struct nlmsghdr *,
struct netlink_ext_ack *));
int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
unsigned int group, int report, gfp_t flags);
int nla_validate(const struct nlattr *head, int len, int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack);
int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
int len, const struct nla_policy *policy,
struct netlink_ext_ack *extack);
int nla_parse_strict(struct nlattr **tb, int maxtype, const struct nlattr *head,
int len, const struct nla_policy *policy,
struct netlink_ext_ack *extack);
int nla_policy_len(const struct nla_policy *, int);
struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype);
size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);
char *nla_strdup(const struct nlattr *nla, gfp_t flags);
int nla_memcpy(void *dest, const struct nlattr *src, int count);
int nla_memcmp(const struct nlattr *nla, const void *data, size_t size);
int nla_strcmp(const struct nlattr *nla, const char *str);
struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
int attrlen, int padattr);
void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen);
struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype,
int attrlen, int padattr);
void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen);
void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,
const void *data);
void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
const void *data, int padattr);
void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data);
int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
const void *data, int padattr);
int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data);
int nla_append(struct sk_buff *skb, int attrlen, const void *data);
/**************************************************************************
* Netlink Messages
**************************************************************************/
/**
* nlmsg_msg_size - length of netlink message not including padding
* @payload: length of message payload
*/
static inline int nlmsg_msg_size(int payload)
{
return NLMSG_HDRLEN + payload;
}
/**
* nlmsg_total_size - length of netlink message including padding
* @payload: length of message payload
*/
static inline int nlmsg_total_size(int payload)
{
return NLMSG_ALIGN(nlmsg_msg_size(payload));
}
/**
* nlmsg_padlen - length of padding at the message's tail
* @payload: length of message payload
*/
static inline int nlmsg_padlen(int payload)
{
return nlmsg_total_size(payload) - nlmsg_msg_size(payload);
}
/**
* nlmsg_data - head of message payload
* @nlh: netlink message header
*/
static inline void *nlmsg_data(const struct nlmsghdr *nlh)
{
return (unsigned char *) nlh + NLMSG_HDRLEN;
}
/**
* nlmsg_len - length of message payload
* @nlh: netlink message header
*/
static inline int nlmsg_len(const struct nlmsghdr *nlh)
{
return nlh->nlmsg_len - NLMSG_HDRLEN;
}
/**
* nlmsg_attrdata - head of attributes data
* @nlh: netlink message header
* @hdrlen: length of family specific header
*/
static inline struct nlattr *nlmsg_attrdata(const struct nlmsghdr *nlh,
int hdrlen)
{
unsigned char *data = nlmsg_data(nlh);
return (struct nlattr *) (data + NLMSG_ALIGN(hdrlen));
}
/**
* nlmsg_attrlen - length of attributes data
* @nlh: netlink message header
* @hdrlen: length of family specific header
*/
static inline int nlmsg_attrlen(const struct nlmsghdr *nlh, int hdrlen)
{
return nlmsg_len(nlh) - NLMSG_ALIGN(hdrlen);
}
/**
* nlmsg_ok - check if the netlink message fits into the remaining bytes
* @nlh: netlink message header
* @remaining: number of bytes remaining in message stream
*/
static inline int nlmsg_ok(const struct nlmsghdr *nlh, int remaining)
{
return (remaining >= (int) sizeof(struct nlmsghdr) &&
nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
nlh->nlmsg_len <= remaining);
}
/**
* nlmsg_next - next netlink message in message stream
* @nlh: netlink message header
* @remaining: number of bytes remaining in message stream
*
* Returns the next netlink message in the message stream and
* decrements remaining by the size of the current message.
*/
static inline struct nlmsghdr *
nlmsg_next(const struct nlmsghdr *nlh, int *remaining)
{
int totlen = NLMSG_ALIGN(nlh->nlmsg_len);
*remaining -= totlen;
return (struct nlmsghdr *) ((unsigned char *) nlh + totlen);
}
/**
* nlmsg_parse - parse attributes of a netlink message
* @nlh: netlink message header
* @hdrlen: length of family specific header
* @tb: destination array with maxtype+1 elements
* @maxtype: maximum attribute type to be expected
* @policy: validation policy
* @extack: extended ACK report struct
*
* See nla_parse()
*/
static inline int nlmsg_parse(const struct nlmsghdr *nlh, int hdrlen,
struct nlattr *tb[], int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) {
NL_SET_ERR_MSG(extack, "Invalid header length");
return -EINVAL;
}
return nla_parse(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
nlmsg_attrlen(nlh, hdrlen), policy, extack);
}
static inline int nlmsg_parse_strict(const struct nlmsghdr *nlh, int hdrlen,
struct nlattr *tb[], int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen)) {
NL_SET_ERR_MSG(extack, "Invalid header length");
return -EINVAL;
}
return nla_parse_strict(tb, maxtype, nlmsg_attrdata(nlh, hdrlen),
nlmsg_attrlen(nlh, hdrlen), policy, extack);
}
/**
* nlmsg_find_attr - find a specific attribute in a netlink message
* @nlh: netlink message header
* @hdrlen: length of familiy specific header
* @attrtype: type of attribute to look for
*
* Returns the first attribute which matches the specified type.
*/
static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
int hdrlen, int attrtype)
{
return nla_find(nlmsg_attrdata(nlh, hdrlen),
nlmsg_attrlen(nlh, hdrlen), attrtype);
}
/**
* nlmsg_validate - validate a netlink message including attributes
* @nlh: netlinket message header
* @hdrlen: length of familiy specific header
* @maxtype: maximum attribute type to be expected
* @policy: validation policy
* @extack: extended ACK report struct
*/
static inline int nlmsg_validate(const struct nlmsghdr *nlh,
int hdrlen, int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
return -EINVAL;
return nla_validate(nlmsg_attrdata(nlh, hdrlen),
nlmsg_attrlen(nlh, hdrlen), maxtype, policy,
extack);
}
/**
* nlmsg_report - need to report back to application?
* @nlh: netlink message header
*
* Returns 1 if a report back to the application is requested.
*/
static inline int nlmsg_report(const struct nlmsghdr *nlh)
{
return !!(nlh->nlmsg_flags & NLM_F_ECHO);
}
/**
* nlmsg_for_each_attr - iterate over a stream of attributes
* @pos: loop counter, set to current attribute
* @nlh: netlink message header
* @hdrlen: length of familiy specific header
* @rem: initialized to len, holds bytes currently remaining in stream
*/
#define nlmsg_for_each_attr(pos, nlh, hdrlen, rem) \
nla_for_each_attr(pos, nlmsg_attrdata(nlh, hdrlen), \
nlmsg_attrlen(nlh, hdrlen), rem)
/**
* nlmsg_put - Add a new netlink message to an skb
* @skb: socket buffer to store message in
* @portid: netlink PORTID of requesting application
* @seq: sequence number of message
* @type: message type
* @payload: length of message payload
* @flags: message flags
*
* Returns NULL if the tailroom of the skb is insufficient to store
* the message header and payload.
*/
static inline struct nlmsghdr *nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq,
int type, int payload, int flags)
{
if (unlikely(skb_tailroom(skb) < nlmsg_total_size(payload)))
return NULL;
return __nlmsg_put(skb, portid, seq, type, payload, flags);
}
/**
* nlmsg_put_answer - Add a new callback based netlink message to an skb
* @skb: socket buffer to store message in
* @cb: netlink callback
* @type: message type
* @payload: length of message payload
* @flags: message flags
*
* Returns NULL if the tailroom of the skb is insufficient to store
* the message header and payload.
*/
static inline struct nlmsghdr *nlmsg_put_answer(struct sk_buff *skb,
struct netlink_callback *cb,
int type, int payload,
int flags)
{
return nlmsg_put(skb, NETLINK_CB(cb->skb).portid, cb->nlh->nlmsg_seq,
type, payload, flags);
}
/**
* nlmsg_new - Allocate a new netlink message
* @payload: size of the message payload
* @flags: the type of memory to allocate.
*
* Use NLMSG_DEFAULT_SIZE if the size of the payload isn't known
* and a good default is needed.
*/
static inline struct sk_buff *nlmsg_new(size_t payload, gfp_t flags)
{
return alloc_skb(nlmsg_total_size(payload), flags);
}
/**
* nlmsg_end - Finalize a netlink message
* @skb: socket buffer the message is stored in
* @nlh: netlink message header
*
* Corrects the netlink message header to include the appeneded
* attributes. Only necessary if attributes have been added to
* the message.
*/
static inline void nlmsg_end(struct sk_buff *skb, struct nlmsghdr *nlh)
{
nlh->nlmsg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
}
/**
* nlmsg_get_pos - return current position in netlink message
* @skb: socket buffer the message is stored in
*
* Returns a pointer to the current tail of the message.
*/
static inline void *nlmsg_get_pos(struct sk_buff *skb)
{
return skb_tail_pointer(skb);
}
/**
* nlmsg_trim - Trim message to a mark
* @skb: socket buffer the message is stored in
* @mark: mark to trim to
*
* Trims the message to the provided mark.
*/
static inline void nlmsg_trim(struct sk_buff *skb, const void *mark)
{
if (mark) {
WARN_ON((unsigned char *) mark < skb->data);
skb_trim(skb, (unsigned char *) mark - skb->data);
}
}
/**
* nlmsg_cancel - Cancel construction of a netlink message
* @skb: socket buffer the message is stored in
* @nlh: netlink message header
*
* Removes the complete netlink message including all
* attributes from the socket buffer again.
*/
static inline void nlmsg_cancel(struct sk_buff *skb, struct nlmsghdr *nlh)
{
nlmsg_trim(skb, nlh);
}
/**
* nlmsg_free - free a netlink message
* @skb: socket buffer of netlink message
*/
static inline void nlmsg_free(struct sk_buff *skb)
{
kfree_skb(skb);
}
/**
* nlmsg_multicast - multicast a netlink message
* @sk: netlink socket to spread messages to
* @skb: netlink message as socket buffer
* @portid: own netlink portid to avoid sending to yourself
* @group: multicast group id
* @flags: allocation flags
*/
static inline int nlmsg_multicast(struct sock *sk, struct sk_buff *skb,
u32 portid, unsigned int group, gfp_t flags)
{
int err;
NETLINK_CB(skb).dst_group = group;
err = netlink_broadcast(sk, skb, portid, group, flags);
if (err > 0)
err = 0;
return err;
}
/**
* nlmsg_unicast - unicast a netlink message
* @sk: netlink socket to spread message to
* @skb: netlink message as socket buffer
* @portid: netlink portid of the destination socket
*/
static inline int nlmsg_unicast(struct sock *sk, struct sk_buff *skb, u32 portid)
{
int err;
err = netlink_unicast(sk, skb, portid, MSG_DONTWAIT);
if (err > 0)
err = 0;
return err;
}
/**
* nlmsg_for_each_msg - iterate over a stream of messages
* @pos: loop counter, set to current message
* @head: head of message stream
* @len: length of message stream
* @rem: initialized to len, holds bytes currently remaining in stream
*/
#define nlmsg_for_each_msg(pos, head, len, rem) \
for (pos = head, rem = len; \
nlmsg_ok(pos, rem); \
pos = nlmsg_next(pos, &(rem)))
/**
* nl_dump_check_consistent - check if sequence is consistent and advertise if not
* @cb: netlink callback structure that stores the sequence number
* @nlh: netlink message header to write the flag to
*
* This function checks if the sequence (generation) number changed during dump
* and if it did, advertises it in the netlink message header.
*
* The correct way to use it is to set cb->seq to the generation counter when
* all locks for dumping have been acquired, and then call this function for
* each message that is generated.
*
* Note that due to initialisation concerns, 0 is an invalid sequence number
* and must not be used by code that uses this functionality.
*/
static inline void
nl_dump_check_consistent(struct netlink_callback *cb,
struct nlmsghdr *nlh)
{
if (cb->prev_seq && cb->seq != cb->prev_seq)
nlh->nlmsg_flags |= NLM_F_DUMP_INTR;
cb->prev_seq = cb->seq;
}
/**************************************************************************
* Netlink Attributes
**************************************************************************/
/**
* nla_attr_size - length of attribute not including padding
* @payload: length of payload
*/
static inline int nla_attr_size(int payload)
{
return NLA_HDRLEN + payload;
}
/**
* nla_total_size - total length of attribute including padding
* @payload: length of payload
*/
static inline int nla_total_size(int payload)
{
return NLA_ALIGN(nla_attr_size(payload));
}
/**
* nla_padlen - length of padding at the tail of attribute
* @payload: length of payload
*/
static inline int nla_padlen(int payload)
{
return nla_total_size(payload) - nla_attr_size(payload);
}
/**
* nla_type - attribute type
* @nla: netlink attribute
*/
static inline int nla_type(const struct nlattr *nla)
{
return nla->nla_type & NLA_TYPE_MASK;
}
/**
* nla_data - head of payload
* @nla: netlink attribute
*/
static inline void *nla_data(const struct nlattr *nla)
{
return (char *) nla + NLA_HDRLEN;
}
/**
* nla_len - length of payload
* @nla: netlink attribute
*/
static inline int nla_len(const struct nlattr *nla)
{
return nla->nla_len - NLA_HDRLEN;
}
/**
* nla_ok - check if the netlink attribute fits into the remaining bytes
* @nla: netlink attribute
* @remaining: number of bytes remaining in attribute stream
*/
static inline int nla_ok(const struct nlattr *nla, int remaining)
{
return remaining >= (int) sizeof(*nla) &&
nla->nla_len >= sizeof(*nla) &&
nla->nla_len <= remaining;
}
/**
* nla_next - next netlink attribute in attribute stream
* @nla: netlink attribute
* @remaining: number of bytes remaining in attribute stream
*
* Returns the next netlink attribute in the attribute stream and
* decrements remaining by the size of the current attribute.
*/
static inline struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
{
unsigned int totlen = NLA_ALIGN(nla->nla_len);
*remaining -= totlen;
return (struct nlattr *) ((char *) nla + totlen);
}
/**
* nla_find_nested - find attribute in a set of nested attributes
* @nla: attribute containing the nested attributes
* @attrtype: type of attribute to look for
*
* Returns the first attribute which matches the specified type.
*/
static inline struct nlattr *
nla_find_nested(const struct nlattr *nla, int attrtype)
{
return nla_find(nla_data(nla), nla_len(nla), attrtype);
}
/**
* nla_parse_nested - parse nested attributes
* @tb: destination array with maxtype+1 elements
* @maxtype: maximum attribute type to be expected
* @nla: attribute containing the nested attributes
* @policy: validation policy
* @extack: extended ACK report struct
*
* See nla_parse()
*/
static inline int nla_parse_nested(struct nlattr *tb[], int maxtype,
const struct nlattr *nla,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
return nla_parse(tb, maxtype, nla_data(nla), nla_len(nla), policy,
extack);
}
/**
* nla_put_u8 - Add a u8 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_u8(struct sk_buff *skb, int attrtype, u8 value)
{
/* temporary variables to work around GCC PR81715 with asan-stack=1 */
u8 tmp = value;
return nla_put(skb, attrtype, sizeof(u8), &tmp);
}
/**
* nla_put_u16 - Add a u16 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_u16(struct sk_buff *skb, int attrtype, u16 value)
{
u16 tmp = value;
return nla_put(skb, attrtype, sizeof(u16), &tmp);
}
/**
* nla_put_be16 - Add a __be16 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_be16(struct sk_buff *skb, int attrtype, __be16 value)
{
__be16 tmp = value;
return nla_put(skb, attrtype, sizeof(__be16), &tmp);
}
/**
* nla_put_net16 - Add 16-bit network byte order netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_net16(struct sk_buff *skb, int attrtype, __be16 value)
{
__be16 tmp = value;
return nla_put_be16(skb, attrtype | NLA_F_NET_BYTEORDER, tmp);
}
/**
* nla_put_le16 - Add a __le16 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_le16(struct sk_buff *skb, int attrtype, __le16 value)
{
__le16 tmp = value;
return nla_put(skb, attrtype, sizeof(__le16), &tmp);
}
/**
* nla_put_u32 - Add a u32 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_u32(struct sk_buff *skb, int attrtype, u32 value)
{
u32 tmp = value;
return nla_put(skb, attrtype, sizeof(u32), &tmp);
}
/**
* nla_put_be32 - Add a __be32 netlink attribute to a socket buffer
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @value: numeric value
*/
static inline int nla_put_be32(struct sk_buff *skb, int attrtype, __be32 value)
{
__be32 tmp = value;