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/* 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;
void do_trace_netlink_extack(const char *msg);
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);
void (*release) (struct sock *sk, unsigned long *groups);
};
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
#define NETLINK_MAX_FMTMSG_LEN 80
/**
* 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
* @miss_type: attribute type which was missing
* @miss_nest: nest missing an attribute (%NULL if missing top level attr)
* @cookie: cookie data to return to userspace (for success)
* @cookie_len: actual cookie data length
* @_msg_buf: output buffer for formatted message strings - don't access
* directly, use %NL_SET_ERR_MSG_FMT
*/
struct netlink_ext_ack {
const char *_msg;
const struct nlattr *bad_attr;
const struct nla_policy *policy;
const struct nlattr *miss_nest;
u16 miss_type;
u8 cookie[NETLINK_MAX_COOKIE_LEN];
u8 cookie_len;
char _msg_buf[NETLINK_MAX_FMTMSG_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.
* If string formatting is needed use NL_SET_ERR_MSG_FMT.
*/
#define NL_SET_ERR_MSG(extack, msg) do { \
static const char __msg[] = msg; \
struct netlink_ext_ack *__extack = (extack); \
\
do_trace_netlink_extack(__msg); \
\
if (__extack) \
__extack->_msg = __msg; \
} while (0)
/* We splice fmt with %s at each end even in the snprintf so that both calls
* can use the same string constant, avoiding its duplication in .ro
*/
#define NL_SET_ERR_MSG_FMT(extack, fmt, args...) do { \
struct netlink_ext_ack *__extack = (extack); \
\
if (!__extack) \
break; \
if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
"%s" fmt "%s", "", ##args, "") >= \
NETLINK_MAX_FMTMSG_LEN) \
net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
##args, "\n"); \
\
do_trace_netlink_extack(__extack->_msg_buf); \
\
__extack->_msg = __extack->_msg_buf; \
} while (0)
#define NL_SET_ERR_MSG_MOD(extack, msg) \
NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg)
#define NL_SET_ERR_MSG_FMT_MOD(extack, fmt, args...) \
NL_SET_ERR_MSG_FMT((extack), KBUILD_MODNAME ": " fmt, ##args)
#define NL_SET_ERR_MSG_WEAK(extack, msg) do { \
if ((extack) && !(extack)->_msg) \
NL_SET_ERR_MSG((extack), msg); \
} while (0)
#define NL_SET_ERR_MSG_WEAK_MOD(extack, msg) do { \
if ((extack) && !(extack)->_msg) \
NL_SET_ERR_MSG_MOD((extack), msg); \
} while (0)
#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); \
\
do_trace_netlink_extack(__msg); \
\
if (__extack) { \
__extack->_msg = __msg; \
__extack->bad_attr = (attr); \
__extack->policy = (pol); \
} \
} while (0)
#define NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, pol, fmt, args...) do { \
struct netlink_ext_ack *__extack = (extack); \
\
if (!__extack) \
break; \
\
if (snprintf(__extack->_msg_buf, NETLINK_MAX_FMTMSG_LEN, \
"%s" fmt "%s", "", ##args, "") >= \
NETLINK_MAX_FMTMSG_LEN) \
net_warn_ratelimited("%s" fmt "%s", "truncated extack: ", \
##args, "\n"); \
\
do_trace_netlink_extack(__extack->_msg_buf); \
\
__extack->_msg = __extack->_msg_buf; \
__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)
#define NL_SET_ERR_MSG_ATTR_FMT(extack, attr, msg, args...) \
NL_SET_ERR_MSG_ATTR_POL_FMT(extack, attr, NULL, msg, ##args)
#define NL_SET_ERR_ATTR_MISS(extack, nest, type) do { \
struct netlink_ext_ack *__extack = (extack); \
\
if (__extack) { \
__extack->miss_nest = (nest); \
__extack->miss_type = (type); \
} \
} while (0)
#define NL_REQ_ATTR_CHECK(extack, nest, tb, type) ({ \
struct nlattr **__tb = (tb); \
u32 __attr = (type); \
int __retval; \
\
__retval = !__tb[__attr]; \
if (__retval) \
NL_SET_ERR_ATTR_MISS((extack), (nest), __attr); \
__retval; \
})
static inline void nl_set_extack_cookie_u64(struct netlink_ext_ack *extack,
u64 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);
typedef int (*netlink_filter_fn)(struct sock *dsk, struct sk_buff *skb, void *data);
int netlink_broadcast_filtered(struct sock *ssk, struct sk_buff *skb,
__u32 portid, __u32 group, gfp_t allocation,
netlink_filter_fn filter,
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];
};
};
#define NL_ASSERT_DUMP_CTX_FITS(type_name) \
BUILD_BUG_ON(sizeof(type_name) > \
sizeof_field(struct netlink_callback, ctx))
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 *);
struct netlink_ext_ack *extack;
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);
struct sk_buff *netlink_alloc_large_skb(unsigned int size, int broadcast);
#endif /* __LINUX_NETLINK_H */
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