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1/* SPDX-License-Identifier: GPL-2.0 */2#ifndef __LINUX_NETLINK_H3#define __LINUX_NETLINK_H4 5 6#include <linux/capability.h>7#include <linux/skbuff.h>8#include <linux/export.h>9#include <net/scm.h>10#include <uapi/linux/netlink.h>11 12struct net;13 14void do_trace_netlink_extack(const char *msg);15 16static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)17{18 return (struct nlmsghdr *)skb->data;19}20 21enum netlink_skb_flags {22 NETLINK_SKB_DST = 0x8, /* Dst set in sendto or sendmsg */23};24 25struct netlink_skb_parms {26 struct scm_creds creds; /* Skb credentials */27 __u32 portid;28 __u32 dst_group;29 __u32 flags;30 struct sock *sk;31 bool nsid_is_set;32 int nsid;33};34 35#define NETLINK_CB(skb) (*(struct netlink_skb_parms*)&((skb)->cb))36#define NETLINK_CREDS(skb) (&NETLINK_CB((skb)).creds)37 38 39void netlink_table_grab(void);40void netlink_table_ungrab(void);41 42#define NL_CFG_F_NONROOT_RECV (1 << 0)43#define NL_CFG_F_NONROOT_SEND (1 << 1)44 45/* optional Netlink kernel configuration parameters */46struct netlink_kernel_cfg {47 unsigned int groups;48 unsigned int flags;49 void (*input)(struct sk_buff *skb);50 int (*bind)(struct net *net, int group);51 void (*unbind)(struct net *net, int group);52 void (*release) (struct sock *sk, unsigned long *groups);53};54 55struct sock *__netlink_kernel_create(struct net *net, int unit,56 struct module *module,57 struct netlink_kernel_cfg *cfg);58static inline struct sock *59netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)60{61 return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);62}63 64/* this can be increased when necessary - don't expose to userland */65#define NETLINK_MAX_COOKIE_LEN 2066#define NETLINK_MAX_FMTMSG_LEN 8067 68/**69 * struct netlink_ext_ack - netlink extended ACK report struct70 * @_msg: message string to report - don't access directly, use71 * %NL_SET_ERR_MSG72 * @bad_attr: attribute with error73 * @policy: policy for a bad attribute74 * @miss_type: attribute type which was missing75 * @miss_nest: nest missing an attribute (%NULL if missing top level attr)76 * @cookie: cookie data to return to userspace (for success)77 * @cookie_len: actual cookie data length78 * @_msg_buf: output buffer for formatted message strings - don't access79 * directly, use %NL_SET_ERR_MSG_FMT80 */81struct netlink_ext_ack {82 const char *_msg;83 const struct nlattr *bad_attr;84 const struct nla_policy *policy;85 const struct nlattr *miss_nest;86 u16 miss_type;87 u8 cookie[NETLINK_MAX_COOKIE_LEN];88 u8 cookie_len;89 char _msg_buf[NETLINK_MAX_FMTMSG_LEN];90};91 92/* Always use this macro, this allows later putting the93 * message into a separate section or such for things94 * like translation or listing all possible messages.95 * If string formatting is needed use NL_SET_ERR_MSG_FMT.96 */97#define NL_SET_ERR_MSG(extack, msg) do { \98 static const char __msg[] = msg; \99 struct netlink_ext_ack *__extack = (extack); \100 \101 do_trace_netlink_extack(__msg); \102 \103 if (__extack) \104 __extack->_msg = __msg; \105} while (0)106 107/* We splice fmt with %s at each end even in the snprintf so that both calls108 * can use the same string constant, avoiding its duplication in .ro109 */110#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \111 struct netlink_ext_ack *__extack = (extack); \112 \113 if (!__extack) \114 break; \115 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \116 "%s" fmt "%s", "", ##args, "") >= \117 NETLINK_MAX_FMTMSG_LEN) \118 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \119 ##args, "\n"); \120 \121 do_trace_netlink_extack(__extack->_msg_buf); \122 \123 __extack->_msg = __extack->_msg_buf; \124} while (0)125 126#define NL_SET_ERR_MSG_MOD(extack, msg) \127 NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)128 129#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \130 NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)131 132#define NL_SET_ERR_MSG_WEAK(extack, msg) do { \133 if ((extack) && !(extack)->_msg) \134 NL_SET_ERR_MSG((extack), msg); \135} while (0)136 137#define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do { \138 if ((extack) && !(extack)->_msg) \139 NL_SET_ERR_MSG_MOD((extack), msg); \140} while (0)141 142#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do { \143 if ((extack)) { \144 (extack)->bad_attr = (attr); \145 (extack)->policy = (pol); \146 } \147} while (0)148 149#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)150 151#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \152 static const char __msg[] = msg; \153 struct netlink_ext_ack *__extack = (extack); \154 \155 do_trace_netlink_extack(__msg); \156 \157 if (__extack) { \158 __extack->_msg = __msg; \159 __extack->bad_attr = (attr); \160 __extack->policy = (pol); \161 } \162} while (0)163 164#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do { \165 struct netlink_ext_ack *__extack = (extack); \166 \167 if (!__extack) \168 break; \169 \170 if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \171 "%s" fmt "%s", "", ##args, "") >= \172 NETLINK_MAX_FMTMSG_LEN) \173 net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \174 ##args, "\n"); \175 \176 do_trace_netlink_extack(__extack->_msg_buf); \177 \178 __extack->_msg = __extack->_msg_buf; \179 __extack->bad_attr = (attr); \180 __extack->policy = (pol); \181} while (0)182 183#define NL_SET_ERR_MSG_ATTR(extack, attr, msg) \184 NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)185 186#define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \187 NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args)188 189#define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \190 struct netlink_ext_ack *__extack = (extack); \191 \192 if (__extack) { \193 __extack->miss_nest = (nest); \194 __extack->miss_type = (type); \195 } \196} while (0)197 198#define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \199 struct nlattr **__tb = (tb); \200 u32 __attr = (type); \201 int __retval; \202 \203 __retval = !__tb[__attr]; \204 if (__retval) \205 NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \206 __retval; \207})208 209static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,210 u64 cookie)211{212 if (!extack)213 return;214 memcpy(extack->cookie, &cookie, sizeof(cookie));215 extack->cookie_len = sizeof(cookie);216}217 218void netlink_kernel_release(struct sock *sk);219int __netlink_change_ngroups(struct sock *sk, unsigned int groups);220int netlink_change_ngroups(struct sock *sk, unsigned int groups);221void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);222void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,223 const struct netlink_ext_ack *extack);224int netlink_has_listeners(struct sock *sk, unsigned int group);225bool netlink_strict_get_check(struct sk_buff *skb);226 227int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);228int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,229 __u32 group, gfp_t allocation);230 231typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);232 233int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,234 __u32 portid, __u32 group, gfp_t allocation,235 netlink_filter_fn filter,236 void *filter_data);237int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);238int netlink_register_notifier(struct notifier_block *nb);239int netlink_unregister_notifier(struct notifier_block *nb);240 241/* finegrained unicast helpers: */242struct sock *netlink_getsockbyfilp(struct file *filp);243int netlink_attachskb(struct sock *sk, struct sk_buff *skb,244 long *timeo, struct sock *ssk);245void netlink_detachskb(struct sock *sk, struct sk_buff *skb);246int netlink_sendskb(struct sock *sk, struct sk_buff *skb);247 248static inline struct sk_buff *249netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)250{251 struct sk_buff *nskb;252 253 nskb = skb_clone(skb, gfp_mask);254 if (!nskb)255 return NULL;256 257 /* This is a large skb, set destructor callback to release head */258 if (is_vmalloc_addr(skb->head))259 nskb->destructor = skb->destructor;260 261 return nskb;262}263 264/*265 * skb should fit one page. This choice is good for headerless malloc.266 * But we should limit to 8K so that userspace does not have to267 * use enormous buffer sizes on recvmsg() calls just to avoid268 * MSG_TRUNC when PAGE_SIZE is very large.269 */270#if PAGE_SIZE < 8192UL271#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(PAGE_SIZE)272#else273#define NLMSG_GOODSIZE SKB_WITH_OVERHEAD(8192UL)274#endif275 276#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)277 278 279struct netlink_callback {280 struct sk_buff *skb;281 const struct nlmsghdr *nlh;282 int (*dump)(struct sk_buff * skb,283 struct netlink_callback *cb);284 int (*done)(struct netlink_callback *cb);285 void *data;286 /* the module that dump function belong to */287 struct module *module;288 struct netlink_ext_ack *extack;289 u16 family;290 u16 answer_flags;291 u32 min_dump_alloc;292 unsigned int prev_seq, seq;293 int flags;294 bool strict_check;295 union {296 u8 ctx[48];297 298 /* args is deprecated. Cast a struct over ctx instead299 * for proper type safety.300 */301 long args[6];302 };303};304 305#define NL_ASSERT_DUMP_CTX_FITS(type_name) \306 BUILD_BUG_ON(sizeof(type_name) > \307 sizeof_field(struct netlink_callback, ctx))308 309struct netlink_notify {310 struct net *net;311 u32 portid;312 int protocol;313};314 315struct nlmsghdr *316__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);317 318struct netlink_dump_control {319 int (*start)(struct netlink_callback *);320 int (*dump)(struct sk_buff *skb, struct netlink_callback *);321 int (*done)(struct netlink_callback *);322 struct netlink_ext_ack *extack;323 void *data;324 struct module *module;325 u32 min_dump_alloc;326 int flags;327};328 329int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,330 const struct nlmsghdr *nlh,331 struct netlink_dump_control *control);332static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,333 const struct nlmsghdr *nlh,334 struct netlink_dump_control *control)335{336 if (!control->module)337 control->module = THIS_MODULE;338 339 return __netlink_dump_start(ssk, skb, nlh, control);340}341 342struct netlink_tap {343 struct net_device *dev;344 struct module *module;345 struct list_head list;346};347 348int netlink_add_tap(struct netlink_tap *nt);349int netlink_remove_tap(struct netlink_tap *nt);350 351bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,352 struct user_namespace *ns, int cap);353bool netlink_ns_capable(const struct sk_buff *skb,354 struct user_namespace *ns, int cap);355bool netlink_capable(const struct sk_buff *skb, int cap);356bool netlink_net_capable(const struct sk_buff *skb, int cap);357struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);358 359#endif /* __LINUX_NETLINK_H */360