linux/include/net/dn_fib.h
Gustavo A. R. Silva a79b41ec98 net: dn_fib: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-29 21:52:20 -08:00

168 lines
4.0 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NET_DN_FIB_H
#define _NET_DN_FIB_H
#include <linux/netlink.h>
#include <linux/refcount.h>
extern const struct nla_policy rtm_dn_policy[];
struct dn_fib_res {
struct fib_rule *r;
struct dn_fib_info *fi;
unsigned char prefixlen;
unsigned char nh_sel;
unsigned char type;
unsigned char scope;
};
struct dn_fib_nh {
struct net_device *nh_dev;
unsigned int nh_flags;
unsigned char nh_scope;
int nh_weight;
int nh_power;
int nh_oif;
__le16 nh_gw;
};
struct dn_fib_info {
struct dn_fib_info *fib_next;
struct dn_fib_info *fib_prev;
int fib_treeref;
refcount_t fib_clntref;
int fib_dead;
unsigned int fib_flags;
int fib_protocol;
__le16 fib_prefsrc;
__u32 fib_priority;
__u32 fib_metrics[RTAX_MAX];
int fib_nhs;
int fib_power;
struct dn_fib_nh fib_nh[0];
#define dn_fib_dev fib_nh[0].nh_dev
};
#define DN_FIB_RES_RESET(res) ((res).nh_sel = 0)
#define DN_FIB_RES_NH(res) ((res).fi->fib_nh[(res).nh_sel])
#define DN_FIB_RES_PREFSRC(res) ((res).fi->fib_prefsrc ? : __dn_fib_res_prefsrc(&res))
#define DN_FIB_RES_GW(res) (DN_FIB_RES_NH(res).nh_gw)
#define DN_FIB_RES_DEV(res) (DN_FIB_RES_NH(res).nh_dev)
#define DN_FIB_RES_OIF(res) (DN_FIB_RES_NH(res).nh_oif)
typedef struct {
__le16 datum;
} dn_fib_key_t;
typedef struct {
__le16 datum;
} dn_fib_hash_t;
typedef struct {
__u16 datum;
} dn_fib_idx_t;
struct dn_fib_node {
struct dn_fib_node *fn_next;
struct dn_fib_info *fn_info;
#define DN_FIB_INFO(f) ((f)->fn_info)
dn_fib_key_t fn_key;
u8 fn_type;
u8 fn_scope;
u8 fn_state;
};
struct dn_fib_table {
struct hlist_node hlist;
u32 n;
int (*insert)(struct dn_fib_table *t, struct rtmsg *r,
struct nlattr *attrs[], struct nlmsghdr *n,
struct netlink_skb_parms *req);
int (*delete)(struct dn_fib_table *t, struct rtmsg *r,
struct nlattr *attrs[], struct nlmsghdr *n,
struct netlink_skb_parms *req);
int (*lookup)(struct dn_fib_table *t, const struct flowidn *fld,
struct dn_fib_res *res);
int (*flush)(struct dn_fib_table *t);
int (*dump)(struct dn_fib_table *t, struct sk_buff *skb, struct netlink_callback *cb);
unsigned char data[];
};
#ifdef CONFIG_DECNET_ROUTER
/*
* dn_fib.c
*/
void dn_fib_init(void);
void dn_fib_cleanup(void);
int dn_fib_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r,
struct nlattr *attrs[],
const struct nlmsghdr *nlh, int *errp);
int dn_fib_semantic_match(int type, struct dn_fib_info *fi,
const struct flowidn *fld, struct dn_fib_res *res);
void dn_fib_release_info(struct dn_fib_info *fi);
void dn_fib_flush(void);
void dn_fib_select_multipath(const struct flowidn *fld, struct dn_fib_res *res);
/*
* dn_tables.c
*/
struct dn_fib_table *dn_fib_get_table(u32 n, int creat);
struct dn_fib_table *dn_fib_empty_table(void);
void dn_fib_table_init(void);
void dn_fib_table_cleanup(void);
/*
* dn_rules.c
*/
void dn_fib_rules_init(void);
void dn_fib_rules_cleanup(void);
unsigned int dnet_addr_type(__le16 addr);
int dn_fib_lookup(struct flowidn *fld, struct dn_fib_res *res);
int dn_fib_dump(struct sk_buff *skb, struct netlink_callback *cb);
void dn_fib_free_info(struct dn_fib_info *fi);
static inline void dn_fib_info_put(struct dn_fib_info *fi)
{
if (refcount_dec_and_test(&fi->fib_clntref))
dn_fib_free_info(fi);
}
static inline void dn_fib_res_put(struct dn_fib_res *res)
{
if (res->fi)
dn_fib_info_put(res->fi);
if (res->r)
fib_rule_put(res->r);
}
#else /* Endnode */
#define dn_fib_init() do { } while(0)
#define dn_fib_cleanup() do { } while(0)
#define dn_fib_lookup(fl, res) (-ESRCH)
#define dn_fib_info_put(fi) do { } while(0)
#define dn_fib_select_multipath(fl, res) do { } while(0)
#define dn_fib_rules_policy(saddr,res,flags) (0)
#define dn_fib_res_put(res) do { } while(0)
#endif /* CONFIG_DECNET_ROUTER */
static inline __le16 dnet_make_mask(int n)
{
if (n)
return cpu_to_le16(~((1 << (16 - n)) - 1));
return cpu_to_le16(0);
}
#endif /* _NET_DN_FIB_H */