linux-stable/net/mpls/internal.h
Gustavo A. R. Silva 680a93166e net: mpls: 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>
2020-02-28 12:08:37 -08:00

214 lines
5.8 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef MPLS_INTERNAL_H
#define MPLS_INTERNAL_H
#include <net/mpls.h>
/* put a reasonable limit on the number of labels
* we will accept from userspace
*/
#define MAX_NEW_LABELS 30
struct mpls_entry_decoded {
u32 label;
u8 ttl;
u8 tc;
u8 bos;
};
struct mpls_pcpu_stats {
struct mpls_link_stats stats;
struct u64_stats_sync syncp;
};
struct mpls_dev {
int input_enabled;
struct net_device *dev;
struct mpls_pcpu_stats __percpu *stats;
struct ctl_table_header *sysctl;
struct rcu_head rcu;
};
#if BITS_PER_LONG == 32
#define MPLS_INC_STATS_LEN(mdev, len, pkts_field, bytes_field) \
do { \
__typeof__(*(mdev)->stats) *ptr = \
raw_cpu_ptr((mdev)->stats); \
local_bh_disable(); \
u64_stats_update_begin(&ptr->syncp); \
ptr->stats.pkts_field++; \
ptr->stats.bytes_field += (len); \
u64_stats_update_end(&ptr->syncp); \
local_bh_enable(); \
} while (0)
#define MPLS_INC_STATS(mdev, field) \
do { \
__typeof__(*(mdev)->stats) *ptr = \
raw_cpu_ptr((mdev)->stats); \
local_bh_disable(); \
u64_stats_update_begin(&ptr->syncp); \
ptr->stats.field++; \
u64_stats_update_end(&ptr->syncp); \
local_bh_enable(); \
} while (0)
#else
#define MPLS_INC_STATS_LEN(mdev, len, pkts_field, bytes_field) \
do { \
this_cpu_inc((mdev)->stats->stats.pkts_field); \
this_cpu_add((mdev)->stats->stats.bytes_field, (len)); \
} while (0)
#define MPLS_INC_STATS(mdev, field) \
this_cpu_inc((mdev)->stats->stats.field)
#endif
struct sk_buff;
#define LABEL_NOT_SPECIFIED (1 << 20)
/* This maximum ha length copied from the definition of struct neighbour */
#define VIA_ALEN_ALIGN sizeof(unsigned long)
#define MAX_VIA_ALEN (ALIGN(MAX_ADDR_LEN, VIA_ALEN_ALIGN))
enum mpls_payload_type {
MPT_UNSPEC, /* IPv4 or IPv6 */
MPT_IPV4 = 4,
MPT_IPV6 = 6,
/* Other types not implemented:
* - Pseudo-wire with or without control word (RFC4385)
* - GAL (RFC5586)
*/
};
struct mpls_nh { /* next hop label forwarding entry */
struct net_device __rcu *nh_dev;
/* nh_flags is accessed under RCU in the packet path; it is
* modified handling netdev events with rtnl lock held
*/
unsigned int nh_flags;
u8 nh_labels;
u8 nh_via_alen;
u8 nh_via_table;
u8 nh_reserved1;
u32 nh_label[];
};
/* offset of via from beginning of mpls_nh */
#define MPLS_NH_VIA_OFF(num_labels) \
ALIGN(sizeof(struct mpls_nh) + (num_labels) * sizeof(u32), \
VIA_ALEN_ALIGN)
/* all nexthops within a route have the same size based on the
* max number of labels and max via length across all nexthops
*/
#define MPLS_NH_SIZE(num_labels, max_via_alen) \
(MPLS_NH_VIA_OFF((num_labels)) + \
ALIGN((max_via_alen), VIA_ALEN_ALIGN))
enum mpls_ttl_propagation {
MPLS_TTL_PROP_DEFAULT,
MPLS_TTL_PROP_ENABLED,
MPLS_TTL_PROP_DISABLED,
};
/* The route, nexthops and vias are stored together in the same memory
* block:
*
* +----------------------+
* | mpls_route |
* +----------------------+
* | mpls_nh 0 |
* +----------------------+
* | alignment padding | 4 bytes for odd number of labels
* +----------------------+
* | via[rt_max_alen] 0 |
* +----------------------+
* | alignment padding | via's aligned on sizeof(unsigned long)
* +----------------------+
* | ... |
* +----------------------+
* | mpls_nh n-1 |
* +----------------------+
* | via[rt_max_alen] n-1 |
* +----------------------+
*/
struct mpls_route { /* next hop label forwarding entry */
struct rcu_head rt_rcu;
u8 rt_protocol;
u8 rt_payload_type;
u8 rt_max_alen;
u8 rt_ttl_propagate;
u8 rt_nhn;
/* rt_nhn_alive is accessed under RCU in the packet path; it
* is modified handling netdev events with rtnl lock held
*/
u8 rt_nhn_alive;
u8 rt_nh_size;
u8 rt_via_offset;
u8 rt_reserved1;
struct mpls_nh rt_nh[];
};
#define for_nexthops(rt) { \
int nhsel; struct mpls_nh *nh; u8 *__nh; \
for (nhsel = 0, nh = (rt)->rt_nh, __nh = (u8 *)((rt)->rt_nh); \
nhsel < (rt)->rt_nhn; \
__nh += rt->rt_nh_size, nh = (struct mpls_nh *)__nh, nhsel++)
#define change_nexthops(rt) { \
int nhsel; struct mpls_nh *nh; u8 *__nh; \
for (nhsel = 0, nh = (struct mpls_nh *)((rt)->rt_nh), \
__nh = (u8 *)((rt)->rt_nh); \
nhsel < (rt)->rt_nhn; \
__nh += rt->rt_nh_size, nh = (struct mpls_nh *)__nh, nhsel++)
#define endfor_nexthops(rt) }
static inline struct mpls_shim_hdr mpls_entry_encode(u32 label, unsigned ttl, unsigned tc, bool bos)
{
struct mpls_shim_hdr result;
result.label_stack_entry =
cpu_to_be32((label << MPLS_LS_LABEL_SHIFT) |
(tc << MPLS_LS_TC_SHIFT) |
(bos ? (1 << MPLS_LS_S_SHIFT) : 0) |
(ttl << MPLS_LS_TTL_SHIFT));
return result;
}
static inline struct mpls_entry_decoded mpls_entry_decode(struct mpls_shim_hdr *hdr)
{
struct mpls_entry_decoded result;
unsigned entry = be32_to_cpu(hdr->label_stack_entry);
result.label = (entry & MPLS_LS_LABEL_MASK) >> MPLS_LS_LABEL_SHIFT;
result.ttl = (entry & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT;
result.tc = (entry & MPLS_LS_TC_MASK) >> MPLS_LS_TC_SHIFT;
result.bos = (entry & MPLS_LS_S_MASK) >> MPLS_LS_S_SHIFT;
return result;
}
static inline struct mpls_dev *mpls_dev_get(const struct net_device *dev)
{
return rcu_dereference_rtnl(dev->mpls_ptr);
}
int nla_put_labels(struct sk_buff *skb, int attrtype, u8 labels,
const u32 label[]);
int nla_get_labels(const struct nlattr *nla, u8 max_labels, u8 *labels,
u32 label[], struct netlink_ext_ack *extack);
bool mpls_output_possible(const struct net_device *dev);
unsigned int mpls_dev_mtu(const struct net_device *dev);
bool mpls_pkt_too_big(const struct sk_buff *skb, unsigned int mtu);
void mpls_stats_inc_outucastpkts(struct net_device *dev,
const struct sk_buff *skb);
#endif /* MPLS_INTERNAL_H */