/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_NETLINK_H
#define __LINUX_NETLINK_H


#include <linux/capability.h>
#include <linux/skbuff.h>
#include <linux/export.h>
#include <net/scm.h>
#include <uapi/linux/netlink.h>

struct net;

static inline struct nlmsghdr *nlmsg_hdr(const struct sk_buff *skb)
{
        return (struct nlmsghdr *)skb->data;
}

enum netlink_skb_flags {
        NETLINK_SKB_DST         = 0x8,  /* Dst set in sendto or sendmsg */
};

struct netlink_skb_parms {
        struct scm_creds        creds;          /* Skb credentials      */
        __u32                   portid;
        __u32                   dst_group;
        __u32                   flags;
        struct sock             *sk;
        bool                    nsid_is_set;
        int                     nsid;
};

#define NETLINK_CB(skb)         (*(struct netlink_skb_parms*)&((skb)->cb))
#define NETLINK_CREDS(skb)      (&NETLINK_CB((skb)).creds)


void netlink_table_grab(void);
void netlink_table_ungrab(void);

#define NL_CFG_F_NONROOT_RECV   (1 << 0)
#define NL_CFG_F_NONROOT_SEND   (1 << 1)

/* optional Netlink kernel configuration parameters */
struct netlink_kernel_cfg {
        unsigned int    groups;
        unsigned int    flags;
        void            (*input)(struct sk_buff *skb);
        struct mutex    *cb_mutex;
        int             (*bind)(struct net *net, int group);
        void            (*unbind)(struct net *net, int group);
        bool            (*compare)(struct net *net, struct sock *sk);
};

struct sock *__netlink_kernel_create(struct net *net, int unit,
                                            struct module *module,
                                            struct netlink_kernel_cfg *cfg);
static inline struct sock *
netlink_kernel_create(struct net *net, int unit, struct netlink_kernel_cfg *cfg)
{
        return __netlink_kernel_create(net, unit, THIS_MODULE, cfg);
}

/* this can be increased when necessary - don't expose to userland */
#define NETLINK_MAX_COOKIE_LEN  20

/**
 * struct netlink_ext_ack - netlink extended ACK report struct
 * @_msg: message string to report - don't access directly, use
 *      %NL_SET_ERR_MSG
 * @bad_attr: attribute with error
 * @policy: policy for a bad attribute
 * @cookie: cookie data to return to userspace (for success)
 * @cookie_len: actual cookie data length
 */
struct netlink_ext_ack {
        const char *_msg;
        const struct nlattr *bad_attr;
        const struct nla_policy *policy;
        u8 cookie[NETLINK_MAX_COOKIE_LEN];
        u8 cookie_len;
};

/* Always use this macro, this allows later putting the
 * message into a separate section or such for things
 * like translation or listing all possible messages.
 * Currently string formatting is not supported (due
 * to the lack of an output buffer.)
 */
#define NL_SET_ERR_MSG(extack, msg) do {                \
        static const char __msg[] = msg;                \
        struct netlink_ext_ack *__extack = (extack);    \
                                                        \
        if (__extack)                                   \
                __extack->_msg = __msg;                 \
} while (0)

#define NL_SET_ERR_MSG_MOD(extack, msg)                 \
        NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)

#define NL_SET_BAD_ATTR_POLICY(extack, attr, pol) do {  \
        if ((extack)) {                                 \
                (extack)->bad_attr = (attr);            \
                (extack)->policy = (pol);               \
        }                                               \
} while (0)

#define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL)

#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do {    \
        static const char __msg[] = msg;                        \
        struct netlink_ext_ack *__extack = (extack);            \
                                                                \
        if (__extack) {                                         \
                __extack->_msg = __msg;                         \
                __extack->bad_attr = (attr);                    \
                __extack->policy = (pol);                       \
        }                                                       \
} while (0)

#define NL_SET_ERR_MSG_ATTR(extack, attr, msg)          \
        NL_SET_ERR_MSG_ATTR_POL(extack, attr, NULL, msg)

static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
                                            u64 cookie)
{
        u64 __cookie = cookie;

        if (!extack)
                return;
        memcpy(extack->cookie, &__cookie, sizeof(__cookie));
        extack->cookie_len = sizeof(__cookie);
}

static inline void nl_set_extack_cookie_u32(struct netlink_ext_ack *extack,
                                            u32 cookie)
{
        u32 __cookie = cookie;

        if (!extack)
                return;
        memcpy(extack->cookie, &__cookie, sizeof(__cookie));
        extack->cookie_len = sizeof(__cookie);
}

void netlink_kernel_release(struct sock *sk);
int __netlink_change_ngroups(struct sock *sk, unsigned int groups);
int netlink_change_ngroups(struct sock *sk, unsigned int groups);
void __netlink_clear_multicast_users(struct sock *sk, unsigned int group);
void netlink_ack(struct sk_buff *in_skb, struct nlmsghdr *nlh, int err,
                 const struct netlink_ext_ack *extack);
int netlink_has_listeners(struct sock *sk, unsigned int group);
bool netlink_strict_get_check(struct sk_buff *skb);

int netlink_unicast(struct sock *ssk, struct sk_buff *skb, __u32 portid, int nonblock);
int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, __u32 portid,
                      __u32 group, gfp_t allocation);
int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
                               __u32 portid, __u32 group, gfp_t allocation,
                               int (*filter)(struct sock *dsk, struct sk_buff *skb, void *data),
                               void *filter_data);
int netlink_set_err(struct sock *ssk, __u32 portid, __u32 group, int code);
int netlink_register_notifier(struct notifier_block *nb);
int netlink_unregister_notifier(struct notifier_block *nb);

/* finegrained unicast helpers: */
struct sock *netlink_getsockbyfilp(struct file *filp);
int netlink_attachskb(struct sock *sk, struct sk_buff *skb,
                      long *timeo, struct sock *ssk);
void netlink_detachskb(struct sock *sk, struct sk_buff *skb);
int netlink_sendskb(struct sock *sk, struct sk_buff *skb);

static inline struct sk_buff *
netlink_skb_clone(struct sk_buff *skb, gfp_t gfp_mask)
{
        struct sk_buff *nskb;

        nskb = skb_clone(skb, gfp_mask);
        if (!nskb)
                return NULL;

        /* This is a large skb, set destructor callback to release head */
        if (is_vmalloc_addr(skb->head))
                nskb->destructor = skb->destructor;

        return nskb;
}

/*
 *      skb should fit one page. This choice is good for headerless malloc.
 *      But we should limit to 8K so that userspace does not have to
 *      use enormous buffer sizes on recvmsg() calls just to avoid
 *      MSG_TRUNC when PAGE_SIZE is very large.
 */
#if PAGE_SIZE < 8192UL
#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(PAGE_SIZE)
#else
#define NLMSG_GOODSIZE  SKB_WITH_OVERHEAD(8192UL)
#endif

#define NLMSG_DEFAULT_SIZE (NLMSG_GOODSIZE - NLMSG_HDRLEN)


struct netlink_callback {
        struct sk_buff          *skb;
        const struct nlmsghdr   *nlh;
        int                     (*dump)(struct sk_buff * skb,
                                        struct netlink_callback *cb);
        int                     (*done)(struct netlink_callback *cb);
        void                    *data;
        /* the module that dump function belong to */
        struct module           *module;
        struct netlink_ext_ack  *extack;
        u16                     family;
        u16                     answer_flags;
        u32                     min_dump_alloc;
        unsigned int            prev_seq, seq;
        bool                    strict_check;
        union {
                u8              ctx[48];

                /* args is deprecated. Cast a struct over ctx instead
                 * for proper type safety.
                 */
                long            args[6];
        };
};

struct netlink_notify {
        struct net *net;
        u32 portid;
        int protocol;
};

struct nlmsghdr *
__nlmsg_put(struct sk_buff *skb, u32 portid, u32 seq, int type, int len, int flags);

struct netlink_dump_control {
        int (*start)(struct netlink_callback *);
        int (*dump)(struct sk_buff *skb, struct netlink_callback *);
        int (*done)(struct netlink_callback *);
        void *data;
        struct module *module;
        u32 min_dump_alloc;
};

int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                                const struct nlmsghdr *nlh,
                                struct netlink_dump_control *control);
static inline int netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
                                     const struct nlmsghdr *nlh,
                                     struct netlink_dump_control *control)
{
        if (!control->module)
                control->module = THIS_MODULE;

        return __netlink_dump_start(ssk, skb, nlh, control);
}

struct netlink_tap {
        struct net_device *dev;
        struct module *module;
        struct list_head list;
};

int netlink_add_tap(struct netlink_tap *nt);
int netlink_remove_tap(struct netlink_tap *nt);

bool __netlink_ns_capable(const struct netlink_skb_parms *nsp,
                          struct user_namespace *ns, int cap);
bool netlink_ns_capable(const struct sk_buff *skb,
                        struct user_namespace *ns, int cap);
bool netlink_capable(const struct sk_buff *skb, int cap);
bool netlink_net_capable(const struct sk_buff *skb, int cap);

#endif  /* __LINUX_NETLINK_H */