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Diffstat (limited to 'include/net/genetlink.h')
| -rw-r--r-- | include/net/genetlink.h | 588 |
1 files changed, 588 insertions, 0 deletions
diff --git a/include/net/genetlink.h b/include/net/genetlink.h new file mode 100644 index 0000000000..c53244f204 --- /dev/null +++ b/include/net/genetlink.h @@ -0,0 +1,588 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __NET_GENERIC_NETLINK_H +#define __NET_GENERIC_NETLINK_H + +#include <linux/genetlink.h> +#include <net/netlink.h> +#include <net/net_namespace.h> + +#define GENLMSG_DEFAULT_SIZE (NLMSG_DEFAULT_SIZE - GENL_HDRLEN) + +/** + * struct genl_multicast_group - generic netlink multicast group + * @name: name of the multicast group, names are per-family + * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM) + * @cap_sys_admin: whether %CAP_SYS_ADMIN is required for binding + */ +struct genl_multicast_group { + char name[GENL_NAMSIZ]; + u8 flags; + u8 cap_sys_admin:1; +}; + +struct genl_split_ops; +struct genl_info; + +/** + * struct genl_family - generic netlink family + * @hdrsize: length of user specific header in bytes + * @name: name of family + * @version: protocol version + * @maxattr: maximum number of attributes supported + * @policy: netlink policy + * @netnsok: set to true if the family can handle network + * namespaces and should be presented in all of them + * @parallel_ops: operations can be called in parallel and aren't + * synchronized by the core genetlink code + * @pre_doit: called before an operation's doit callback, it may + * do additional, common, filtering and return an error + * @post_doit: called after an operation's doit callback, it may + * undo operations done by pre_doit, for example release locks + * @module: pointer to the owning module (set to THIS_MODULE) + * @mcgrps: multicast groups used by this family + * @n_mcgrps: number of multicast groups + * @resv_start_op: first operation for which reserved fields of the header + * can be validated and policies are required (see below); + * new families should leave this field at zero + * @ops: the operations supported by this family + * @n_ops: number of operations supported by this family + * @small_ops: the small-struct operations supported by this family + * @n_small_ops: number of small-struct operations supported by this family + * @split_ops: the split do/dump form of operation definition + * @n_split_ops: number of entries in @split_ops, not that with split do/dump + * ops the number of entries is not the same as number of commands + * + * Attribute policies (the combination of @policy and @maxattr fields) + * can be attached at the family level or at the operation level. + * If both are present the per-operation policy takes precedence. + * For operations before @resv_start_op lack of policy means that the core + * will perform no attribute parsing or validation. For newer operations + * if policy is not provided core will reject all TLV attributes. + */ +struct genl_family { + unsigned int hdrsize; + char name[GENL_NAMSIZ]; + unsigned int version; + unsigned int maxattr; + u8 netnsok:1; + u8 parallel_ops:1; + u8 n_ops; + u8 n_small_ops; + u8 n_split_ops; + u8 n_mcgrps; + u8 resv_start_op; + const struct nla_policy *policy; + int (*pre_doit)(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info); + void (*post_doit)(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info); + const struct genl_ops * ops; + const struct genl_small_ops *small_ops; + const struct genl_split_ops *split_ops; + const struct genl_multicast_group *mcgrps; + struct module *module; + +/* private: internal use only */ + /* protocol family identifier */ + int id; + /* starting number of multicast group IDs in this family */ + unsigned int mcgrp_offset; +}; + +/** + * struct genl_info - receiving information + * @snd_seq: sending sequence number + * @snd_portid: netlink portid of sender + * @family: generic netlink family + * @nlhdr: netlink message header + * @genlhdr: generic netlink message header + * @attrs: netlink attributes + * @_net: network namespace + * @user_ptr: user pointers + * @extack: extended ACK report struct + */ +struct genl_info { + u32 snd_seq; + u32 snd_portid; + const struct genl_family *family; + const struct nlmsghdr * nlhdr; + struct genlmsghdr * genlhdr; + struct nlattr ** attrs; + possible_net_t _net; + void * user_ptr[2]; + struct netlink_ext_ack *extack; +}; + +static inline struct net *genl_info_net(const struct genl_info *info) +{ + return read_pnet(&info->_net); +} + +static inline void genl_info_net_set(struct genl_info *info, struct net *net) +{ + write_pnet(&info->_net, net); +} + +static inline void *genl_info_userhdr(const struct genl_info *info) +{ + return (u8 *)info->genlhdr + GENL_HDRLEN; +} + +#define GENL_SET_ERR_MSG(info, msg) NL_SET_ERR_MSG((info)->extack, msg) + +#define GENL_SET_ERR_MSG_FMT(info, msg, args...) \ + NL_SET_ERR_MSG_FMT((info)->extack, msg, ##args) + +/* Report that a root attribute is missing */ +#define GENL_REQ_ATTR_CHECK(info, attr) ({ \ + struct genl_info *__info = (info); \ + \ + NL_REQ_ATTR_CHECK(__info->extack, NULL, __info->attrs, (attr)); \ +}) + +enum genl_validate_flags { + GENL_DONT_VALIDATE_STRICT = BIT(0), + GENL_DONT_VALIDATE_DUMP = BIT(1), + GENL_DONT_VALIDATE_DUMP_STRICT = BIT(2), +}; + +/** + * struct genl_small_ops - generic netlink operations (small version) + * @cmd: command identifier + * @internal_flags: flags used by the family + * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM) + * @validate: validation flags from enum genl_validate_flags + * @doit: standard command callback + * @dumpit: callback for dumpers + * + * This is a cut-down version of struct genl_ops for users who don't need + * most of the ancillary infra and want to save space. + */ +struct genl_small_ops { + int (*doit)(struct sk_buff *skb, struct genl_info *info); + int (*dumpit)(struct sk_buff *skb, struct netlink_callback *cb); + u8 cmd; + u8 internal_flags; + u8 flags; + u8 validate; +}; + +/** + * struct genl_ops - generic netlink operations + * @cmd: command identifier + * @internal_flags: flags used by the family + * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM) + * @maxattr: maximum number of attributes supported + * @policy: netlink policy (takes precedence over family policy) + * @validate: validation flags from enum genl_validate_flags + * @doit: standard command callback + * @start: start callback for dumps + * @dumpit: callback for dumpers + * @done: completion callback for dumps + */ +struct genl_ops { + int (*doit)(struct sk_buff *skb, + struct genl_info *info); + int (*start)(struct netlink_callback *cb); + int (*dumpit)(struct sk_buff *skb, + struct netlink_callback *cb); + int (*done)(struct netlink_callback *cb); + const struct nla_policy *policy; + unsigned int maxattr; + u8 cmd; + u8 internal_flags; + u8 flags; + u8 validate; +}; + +/** + * struct genl_split_ops - generic netlink operations (do/dump split version) + * @cmd: command identifier + * @internal_flags: flags used by the family + * @flags: GENL_* flags (%GENL_ADMIN_PERM or %GENL_UNS_ADMIN_PERM) + * @validate: validation flags from enum genl_validate_flags + * @policy: netlink policy (takes precedence over family policy) + * @maxattr: maximum number of attributes supported + * + * Do callbacks: + * @pre_doit: called before an operation's @doit callback, it may + * do additional, common, filtering and return an error + * @doit: standard command callback + * @post_doit: called after an operation's @doit callback, it may + * undo operations done by pre_doit, for example release locks + * + * Dump callbacks: + * @start: start callback for dumps + * @dumpit: callback for dumpers + * @done: completion callback for dumps + * + * Do callbacks can be used if %GENL_CMD_CAP_DO is set in @flags. + * Dump callbacks can be used if %GENL_CMD_CAP_DUMP is set in @flags. + * Exactly one of those flags must be set. + */ +struct genl_split_ops { + union { + struct { + int (*pre_doit)(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info); + int (*doit)(struct sk_buff *skb, + struct genl_info *info); + void (*post_doit)(const struct genl_split_ops *ops, + struct sk_buff *skb, + struct genl_info *info); + }; + struct { + int (*start)(struct netlink_callback *cb); + int (*dumpit)(struct sk_buff *skb, + struct netlink_callback *cb); + int (*done)(struct netlink_callback *cb); + }; + }; + const struct nla_policy *policy; + unsigned int maxattr; + u8 cmd; + u8 internal_flags; + u8 flags; + u8 validate; +}; + +/** + * struct genl_dumpit_info - info that is available during dumpit op call + * @op: generic netlink ops - for internal genl code usage + * @attrs: netlink attributes + * @info: struct genl_info describing the request + */ +struct genl_dumpit_info { + struct genl_split_ops op; + struct genl_info info; +}; + +static inline const struct genl_dumpit_info * +genl_dumpit_info(struct netlink_callback *cb) +{ + return cb->data; +} + +static inline const struct genl_info * +genl_info_dump(struct netlink_callback *cb) +{ + return &genl_dumpit_info(cb)->info; +} + +/** + * genl_info_init_ntf() - initialize genl_info for notifications + * @info: genl_info struct to set up + * @family: pointer to the genetlink family + * @cmd: command to be used in the notification + * + * Initialize a locally declared struct genl_info to pass to various APIs. + * Intended to be used when creating notifications. + */ +static inline void +genl_info_init_ntf(struct genl_info *info, const struct genl_family *family, + u8 cmd) +{ + struct genlmsghdr *hdr = (void *) &info->user_ptr[0]; + + memset(info, 0, sizeof(*info)); + info->family = family; + info->genlhdr = hdr; + hdr->cmd = cmd; +} + +static inline bool genl_info_is_ntf(const struct genl_info *info) +{ + return !info->nlhdr; +} + +int genl_register_family(struct genl_family *family); +int genl_unregister_family(const struct genl_family *family); +void genl_notify(const struct genl_family *family, struct sk_buff *skb, + struct genl_info *info, u32 group, gfp_t flags); + +void *genlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, + const struct genl_family *family, int flags, u8 cmd); + +static inline void * +__genlmsg_iput(struct sk_buff *skb, const struct genl_info *info, int flags) +{ + return genlmsg_put(skb, info->snd_portid, info->snd_seq, info->family, + flags, info->genlhdr->cmd); +} + +/** + * genlmsg_iput - start genetlink message based on genl_info + * @skb: skb in which message header will be placed + * @info: genl_info as provided to do/dump handlers + * + * Convenience wrapper which starts a genetlink message based on + * information in user request. @info should be either the struct passed + * by genetlink core to do/dump handlers (when constructing replies to + * such requests) or a struct initialized by genl_info_init_ntf() + * when constructing notifications. + * + * Returns pointer to new genetlink header. + */ +static inline void * +genlmsg_iput(struct sk_buff *skb, const struct genl_info *info) +{ + return __genlmsg_iput(skb, info, 0); +} + +/** + * genlmsg_nlhdr - Obtain netlink header from user specified header + * @user_hdr: user header as returned from genlmsg_put() + * + * Returns pointer to netlink header. + */ +static inline struct nlmsghdr *genlmsg_nlhdr(void *user_hdr) +{ + return (struct nlmsghdr *)((char *)user_hdr - + GENL_HDRLEN - + NLMSG_HDRLEN); +} + +/** + * genlmsg_parse_deprecated - parse attributes of a genetlink message + * @nlh: netlink message header + * @family: genetlink message family + * @tb: destination array with maxtype+1 elements + * @maxtype: maximum attribute type to be expected + * @policy: validation policy + * @extack: extended ACK report struct + */ +static inline int genlmsg_parse_deprecated(const struct nlmsghdr *nlh, + const struct genl_family *family, + struct nlattr *tb[], int maxtype, + const struct nla_policy *policy, + struct netlink_ext_ack *extack) +{ + return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype, + policy, NL_VALIDATE_LIBERAL, extack); +} + +/** + * genlmsg_parse - parse attributes of a genetlink message + * @nlh: netlink message header + * @family: genetlink message family + * @tb: destination array with maxtype+1 elements + * @maxtype: maximum attribute type to be expected + * @policy: validation policy + * @extack: extended ACK report struct + */ +static inline int genlmsg_parse(const struct nlmsghdr *nlh, + const struct genl_family *family, + struct nlattr *tb[], int maxtype, + const struct nla_policy *policy, + struct netlink_ext_ack *extack) +{ + return __nlmsg_parse(nlh, family->hdrsize + GENL_HDRLEN, tb, maxtype, + policy, NL_VALIDATE_STRICT, extack); +} + +/** + * genl_dump_check_consistent - check if sequence is consistent and advertise if not + * @cb: netlink callback structure that stores the sequence number + * @user_hdr: user header as returned from genlmsg_put() + * + * Cf. nl_dump_check_consistent(), this just provides a wrapper to make it + * simpler to use with generic netlink. + */ +static inline void genl_dump_check_consistent(struct netlink_callback *cb, + void *user_hdr) +{ + nl_dump_check_consistent(cb, genlmsg_nlhdr(user_hdr)); +} + +/** + * genlmsg_put_reply - Add generic netlink header to a reply message + * @skb: socket buffer holding the message + * @info: receiver info + * @family: generic netlink family + * @flags: netlink message flags + * @cmd: generic netlink command + * + * Returns pointer to user specific header + */ +static inline void *genlmsg_put_reply(struct sk_buff *skb, + struct genl_info *info, + const struct genl_family *family, + int flags, u8 cmd) +{ + return genlmsg_put(skb, info->snd_portid, info->snd_seq, family, + flags, cmd); +} + +/** + * genlmsg_end - Finalize a generic netlink message + * @skb: socket buffer the message is stored in + * @hdr: user specific header + */ +static inline void genlmsg_end(struct sk_buff *skb, void *hdr) +{ + nlmsg_end(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); +} + +/** + * genlmsg_cancel - Cancel construction of a generic netlink message + * @skb: socket buffer the message is stored in + * @hdr: generic netlink message header + */ +static inline void genlmsg_cancel(struct sk_buff *skb, void *hdr) +{ + if (hdr) + nlmsg_cancel(skb, hdr - GENL_HDRLEN - NLMSG_HDRLEN); +} + +/** + * genlmsg_multicast_netns - multicast a netlink message to a specific netns + * @family: the generic netlink family + * @net: the net namespace + * @skb: netlink message as socket buffer + * @portid: own netlink portid to avoid sending to yourself + * @group: offset of multicast group in groups array + * @flags: allocation flags + */ +static inline int genlmsg_multicast_netns(const struct genl_family *family, + struct net *net, struct sk_buff *skb, + u32 portid, unsigned int group, gfp_t flags) +{ + if (WARN_ON_ONCE(group >= family->n_mcgrps)) + return -EINVAL; + group = family->mcgrp_offset + group; + return nlmsg_multicast(net->genl_sock, skb, portid, group, flags); +} + +/** + * genlmsg_multicast - multicast a netlink message to the default netns + * @family: the generic netlink family + * @skb: netlink message as socket buffer + * @portid: own netlink portid to avoid sending to yourself + * @group: offset of multicast group in groups array + * @flags: allocation flags + */ +static inline int genlmsg_multicast(const struct genl_family *family, + struct sk_buff *skb, u32 portid, + unsigned int group, gfp_t flags) +{ + return genlmsg_multicast_netns(family, &init_net, skb, + portid, group, flags); +} + +/** + * genlmsg_multicast_allns - multicast a netlink message to all net namespaces + * @family: the generic netlink family + * @skb: netlink message as socket buffer + * @portid: own netlink portid to avoid sending to yourself + * @group: offset of multicast group in groups array + * @flags: allocation flags + * + * This function must hold the RTNL or rcu_read_lock(). + */ +int genlmsg_multicast_allns(const struct genl_family *family, + struct sk_buff *skb, u32 portid, + unsigned int group, gfp_t flags); + +/** + * genlmsg_unicast - unicast a netlink message + * @net: network namespace to look up @portid in + * @skb: netlink message as socket buffer + * @portid: netlink portid of the destination socket + */ +static inline int genlmsg_unicast(struct net *net, struct sk_buff *skb, u32 portid) +{ + return nlmsg_unicast(net->genl_sock, skb, portid); +} + +/** + * genlmsg_reply - reply to a request + * @skb: netlink message to be sent back + * @info: receiver information + */ +static inline int genlmsg_reply(struct sk_buff *skb, struct genl_info *info) +{ + return genlmsg_unicast(genl_info_net(info), skb, info->snd_portid); +} + +/** + * genlmsg_data - head of message payload + * @gnlh: genetlink message header + */ +static inline void *genlmsg_data(const struct genlmsghdr *gnlh) +{ + return ((unsigned char *) gnlh + GENL_HDRLEN); +} + +/** + * genlmsg_len - length of message payload + * @gnlh: genetlink message header + */ +static inline int genlmsg_len(const struct genlmsghdr *gnlh) +{ + struct nlmsghdr *nlh = (struct nlmsghdr *)((unsigned char *)gnlh - + NLMSG_HDRLEN); + return (nlh->nlmsg_len - GENL_HDRLEN - NLMSG_HDRLEN); +} + +/** + * genlmsg_msg_size - length of genetlink message not including padding + * @payload: length of message payload + */ +static inline int genlmsg_msg_size(int payload) +{ + return GENL_HDRLEN + payload; +} + +/** + * genlmsg_total_size - length of genetlink message including padding + * @payload: length of message payload + */ +static inline int genlmsg_total_size(int payload) +{ + return NLMSG_ALIGN(genlmsg_msg_size(payload)); +} + +/** + * genlmsg_new - Allocate a new generic netlink message + * @payload: size of the message payload + * @flags: the type of memory to allocate. + */ +static inline struct sk_buff *genlmsg_new(size_t payload, gfp_t flags) +{ + return nlmsg_new(genlmsg_total_size(payload), flags); +} + +/** + * genl_set_err - report error to genetlink broadcast listeners + * @family: the generic netlink family + * @net: the network namespace to report the error to + * @portid: the PORTID of a process that we want to skip (if any) + * @group: the broadcast group that will notice the error + * (this is the offset of the multicast group in the groups array) + * @code: error code, must be negative (as usual in kernelspace) + * + * This function returns the number of broadcast listeners that have set the + * NETLINK_RECV_NO_ENOBUFS socket option. + */ +static inline int genl_set_err(const struct genl_family *family, + struct net *net, u32 portid, + u32 group, int code) +{ + if (WARN_ON_ONCE(group >= family->n_mcgrps)) + return -EINVAL; + group = family->mcgrp_offset + group; + return netlink_set_err(net->genl_sock, portid, group, code); +} + +static inline int genl_has_listeners(const struct genl_family *family, + struct net *net, unsigned int group) +{ + if (WARN_ON_ONCE(group >= family->n_mcgrps)) + return -EINVAL; + group = family->mcgrp_offset + group; + return netlink_has_listeners(net->genl_sock, group); +} +#endif /* __NET_GENERIC_NETLINK_H */ |