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
  12 struct net;
  13
  14 void do_trace_netlink_extack(const char *msg);
  15
  16 static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
  17 {
  18         return (struct nlmsghdr *)skb->data;
  19 }
  20
  21 enum netlink_skb_flags {
  22         NETLINK_SKB_DST         = 0x8,  /* Dst set in sendto or sendmsg */
  23 };
  24
  25 struct 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
  39 void netlink_table_grab(void);
  40 void 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 */
  46 struct 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
  56 struct sock *__netlink_kernel_create(struct net *net, int unit,
  57                                             struct module *module,
  58                                             struct netlink_kernel_cfg *cfg);
  59 static inline struct sock *
  60 netlink_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  */
  77 struct 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
 129 static 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
 138 static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack,
 139                                             u32 cookie)
 140 {
 141         if (!extack)
 142                 return;
 143         memcpy(extack->cookie, &cookie, sizeof(cookie));
 144         extack->cookie_len = sizeof(cookie);
 145 }
 146
 147 void netlink_kernel_release(struct sock *sk);
 148 int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
 149 int netlink_change_ngroups(struct sock *sk, unsigned int groups);
 150 void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
 151 void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
 152                  const struct netlink_ext_ack *extack);
 153 int netlink_has_listeners(struct sock *sk, unsigned int group);
 154 bool netlink_strict_get_check(struct sk_buff *skb);
 155
 156 int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
 157 int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
 158                       __u32 group, gfp_t allocation);
 159 int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
 160                                __u32 portid, __u32 group, gfp_t allocation,
 161                                int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
 162                                void *filter_data);
 163 int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
 164 int netlink_register_notifier(struct notifier_block *nb);
 165 int netlink_unregister_notifier(struct notifier_block *nb);
 166
 167 /* finegrained unicast helpers: */
 168 struct sock *netlink_getsockbyfilp(struct file *filp);
 169 int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
 170                       long *timeo, struct sock *ssk);
 171 void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
 172 int netlink_sendskb(struct sock *sk, struct sk_buff *skb);
 173
 174 static inline struct sk_buff *
 175 netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
 176 {
 177         struct sk_buff *nskb;
 178
 179         nskb = skb_clone(skb, gfp_mask);
 180         if (!nskb)
 181                 return NULL;
 182
 183         /* This is a large skb, set destructor callback to release head */
 184         if (is_vmalloc_addr(skb->head))
 185                 nskb->destructor = skb->destructor;
 186
 187         return nskb;
 188 }
 189
 190 /*
 191  *      skb should fit one page. This choice is good for headerless malloc.
 192  *      But we should limit to 8K so that userspace does not have to
 193  *      use enormous buffer sizes on recvmsg() calls just to avoid
 194  *      MSG_TRUNC when PAGE_SIZE is very large.
 195  */
 196 #if PAGE_SIZE < 8192UL
 197 #define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
 198 #else
 199 #define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
 200 #endif
 201
 202 #define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)
 203
 204
 205 struct netlink_callback {
 206         struct sk_buff          *skb;
 207         const struct nlmsghdr   *nlh;
 208         int                     (*dump)(struct sk_buff * skb,
 209                                         struct netlink_callback *cb);
 210         int                     (*done)(struct netlink_callback *cb);
 211         void                    *data;
 212         /* the module that dump function belong to */
 213         struct module           *module;
 214         struct netlink_ext_ack  *extack;
 215         u16                     family;
 216         u16                     answer_flags;
 217         u32                     min_dump_alloc;
 218         unsigned int            prev_seq, seq;
 219         bool                    strict_check;
 220         union {
 221                 u8              ctx[48];
 222
 223                 /* args is deprecated. Cast a struct over ctx instead
 224                  * for proper type safety.
 225                  */
 226                 long            args[6];
 227         };
 228 };
 229
 230 struct netlink_notify {
 231         struct net *net;
 232         u32 portid;
 233         int protocol;
 234 };
 235
 236 struct nlmsghdr *
 237 __nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);
 238
 239 struct netlink_dump_control {
 240         int (*start)(struct netlink_callback *);
 241         int (*dump)(struct sk_buff *skb, struct netlink_callback *);
 242         int (*done)(struct netlink_callback *);
 243         void *data;
 244         struct module *module;
 245         u32 min_dump_alloc;
 246 };
 247
 248 int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 249                                 const struct nlmsghdr *nlh,
 250                                 struct netlink_dump_control *control);
 251 static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
 252                                      const struct nlmsghdr *nlh,
 253                                      struct netlink_dump_control *control)
 254 {
 255         if (!control->module)
 256                 control->module = THIS_MODULE;
 257
 258         return __netlink_dump_start(ssk, skb, nlh, control);
 259 }
 260
 261 struct netlink_tap {
 262         struct net_device *dev;
 263         struct module *module;
 264         struct list_head list;
 265 };
 266
 267 int netlink_add_tap(struct netlink_tap *nt);
 268 int netlink_remove_tap(struct netlink_tap *nt);
 269
 270 bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
 271                           struct user_namespace *ns, int cap);
 272 bool netlink_ns_capable(const struct sk_buff *skb,
 273                         struct user_namespace *ns, int cap);
 274 bool netlink_capable(const struct sk_buff *skb, int cap);
 275 bool netlink_net_capable(const struct sk_buff *skb, int cap);
 276
 277 #endif  /* __LINUX_NETLINK_H */