LXR linux/include/linux/netlink.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __LINUX_NETLINK_H
   3#define __LINUX_NETLINK_H
   4
   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        struct mutex    *cb_mutex;
  51        int             (*bind)(struct net *net, int group);
  52        void            (*unbind)(struct net *net, int group);
  53        bool            (*compare)(struct net *net, struct sock *sk);
  54};
  55
  56struct sock *__netlink_kernel_create(struct net *net, int unit,
  57                                            struct module *module,
  58                                            struct netlink_kernel_cfg *cfg);
  59static inline struct sock *
  60netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
  61{
  62        return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
  63}
  64
  65/* this can be increased when necessary - don't expose to userland */
  66#define NETLINK_MAX_COOKIE_LEN  20
  67
  68/**
  69 * struct netlink_ext_ack - netlink extended ACK report struct
  70 * @_msg: message string to report - don't access directly, use
  71 *      %NL_SET_ERR_MSG
  72 * @bad_attr: attribute with error
  73 * @policy: policy for a bad attribute
  74 * @cookie: cookie data to return to userspace (for success)
  75 * @cookie_len: actual cookie data length
  76 */
  77struct netlink_ext_ack {
  78        const char *_msg;
  79        const struct nlattr *bad_attr;
  80        const struct nla_policy *policy;
  81        u8 cookie[NETLINK_MAX_COOKIE_LEN];
  82        u8 cookie_len;
  83};
  84
  85/* Always use this macro, this allows later putting the
  86 * message into a separate section or such for things
  87 * like translation or listing all possible messages.
  88 * Currently string formatting is not supported (due
  89 * to the lack of an output buffer.)
  90 */
  91#define NL_SET_ERR_MSG(extack, msg) do {                \
  92        static const char __msg[] = msg;                \
  93        struct netlink_ext_ack *__extack = (extack);    \
  94                                                        \
  95        do_trace_netlink_extack(__msg);                 \
  96                                                        \
  97        if (__extack)                                   \
  98                __extack->_msg = __msg;                 \
  99} while (0)
 100
 101#define NL_SET_ERR_MSG_MOD(extack, msg)                 \
 102        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
 103
 104#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {  \
 105        if ((extack)) {                                 \
 106                (extack)->bad_attr = (attr);            \
 107                (extack)->policy = (pol);               \
 108        }                                               \
 109} while (0)
 110
 111#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)
 112
 113#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do {    \
 114        static const char __msg[] = msg;                        \
 115        struct netlink_ext_ack *__extack = (extack);            \
 116                                                                \
 117        do_trace_netlink_extack(__msg);                         \
 118                                                                \
 119        if (__extack) {                                         \
 120                __extack->_msg = __msg;                         \
 121                __extack->bad_attr = (attr);                    \
 122                __extack->policy = (pol);                       \
 123        }                                                       \
 124} while (0)
 125
 126#define NL_SET_ERR_MSG_ATTR(extack, attr, msg)          \
 127        NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)
 128
 129static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
 130                                            u64 cookie)
 131{
 132        if (!extack)
 133                return;
 134        memcpy(extack->cookie, &cookie, sizeof(cookie));
 135        extack->cookie_len = sizeof(cookie);
 136}
 137
 138void netlink_kernel_release(struct sock *sk);
 139int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 140int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 141void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
 142void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 143                 const struct netlink_ext_ack *extack);
 144int netlink_has_listeners(struct sock *sk, unsigned int group);
 145bool netlink_strict_get_check(struct sk_buff *skb);
 146
 147int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
 148int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
 149                      __u32 group, gfp_t allocation);
 150int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
 151int netlink_register_notifier(struct notifier_block *nb);
 152int netlink_unregister_notifier(struct notifier_block *nb);
 153
 154/* finegrained unicast helpers: */
 155struct sock *netlink_getsockbyfilp(struct file *filp);
 156int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 157                      long *timeo, struct sock *ssk);
 158void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 159int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 160
 161static inline struct sk_buff *
 162netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 163{
 164        struct sk_buff *nskb;
 165
 166        nskb = skb_clone(skb, gfp_mask);
 167        if (!nskb)
 168                return NULL;
 169
 170        /* This is a large skb, set destructor callback to release head */
 171        if (is_vmalloc_addr(skb->head))
 172                nskb->destructor = skb->destructor;
 173
 174        return nskb;
 175}
 176
 177/*
 178 *      skb should fit one page. This choice is good for headerless malloc.
 179 *      But we should limit to 8K so that userspace does not have to
 180 *      use enormous buffer sizes on recvmsg() calls just to avoid
 181 *      MSG_TRUNC when PAGE_SIZE is very large.
 182 */
 183#if PAGE_SIZE < 8192UL
 184#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
 185#else
 186#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
 187#endif
 188
 189#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
 190
 191
 192struct netlink_callback {
 193        struct sk_buff          *skb;
 194        const struct nlmsghdr   *nlh;
 195        int                     (*dump)(struct sk_buff * skb,
 196                                        struct netlink_callback *cb);
 197        int                     (*done)(struct netlink_callback *cb);
 198        void                    *data;
 199        /* the module that dump function belong to */
 200        struct module           *module;
 201        struct netlink_ext_ack  *extack;
 202        u16                     family;
 203        u16                     answer_flags;
 204        u32                     min_dump_alloc;
 205        unsigned int            prev_seq, seq;
 206        bool                    strict_check;
 207        union {
 208                u8              ctx[48];
 209
 210                /* args is deprecated. Cast a struct over ctx instead
 211                 * for proper type safety.
 212                 */
 213                long            args[6];
 214        };
 215};
 216
 217struct netlink_notify {
 218        struct net *net;
 219        u32 portid;
 220        int protocol;
 221};
 222
 223struct nlmsghdr *
 224__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 225
 226struct netlink_dump_control {
 227        int (*start)(struct netlink_callback *);
 228        int (*dump)(struct sk_buff *skb, struct netlink_callback *);
 229        int (*done)(struct netlink_callback *);
 230        void *data;
 231        struct module *module;
 232        u32 min_dump_alloc;
 233};
 234
 235int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 236                                const struct nlmsghdr *nlh,
 237                                struct netlink_dump_control *control);
 238static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 239                                     const struct nlmsghdr *nlh,
 240                                     struct netlink_dump_control *control)
 241{
 242        if (!control->module)
 243                control->module = THIS_MODULE;
 244
 245        return __netlink_dump_start(ssk, skb, nlh, control);
 246}
 247
 248struct netlink_tap {
 249        struct net_device *dev;
 250        struct module *module;
 251        struct list_head list;
 252};
 253
 254int netlink_add_tap(struct netlink_tap *nt);
 255int netlink_remove_tap(struct netlink_tap *nt);
 256
 257bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 258                          struct user_namespace *ns, int cap);
 259bool netlink_ns_capable(const struct sk_buff *skb,
 260                        struct user_namespace *ns, int cap);
 261bool netlink_capable(const struct sk_buff *skb, int cap);
 262bool netlink_net_capable(const struct sk_buff *skb, int cap);
 263
 264#endif  /* __LINUX_NETLINK_H */
 265