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kernel/include/linux/dccp.h
Gustavo A. R. Silva 8402a31dd8 net: dccp: 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

326 lines
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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_DCCP_H
#define _LINUX_DCCP_H
#include <linux/in.h>
#include <linux/interrupt.h>
#include <linux/ktime.h>
#include <linux/list.h>
#include <linux/uio.h>
#include <linux/workqueue.h>
#include <net/inet_connection_sock.h>
#include <net/inet_sock.h>
#include <net/inet_timewait_sock.h>
#include <net/tcp_states.h>
#include <uapi/linux/dccp.h>
enum dccp_state {
DCCP_OPEN = TCP_ESTABLISHED,
DCCP_REQUESTING = TCP_SYN_SENT,
DCCP_LISTEN = TCP_LISTEN,
DCCP_RESPOND = TCP_SYN_RECV,
/*
* States involved in closing a DCCP connection:
* 1) ACTIVE_CLOSEREQ is entered by a server sending a CloseReq.
*
* 2) CLOSING can have three different meanings (RFC 4340, 8.3):
* a. Client has performed active-close, has sent a Close to the server
* from state OPEN or PARTOPEN, and is waiting for the final Reset
* (in this case, SOCK_DONE == 1).
* b. Client is asked to perform passive-close, by receiving a CloseReq
* in (PART)OPEN state. It sends a Close and waits for final Reset
* (in this case, SOCK_DONE == 0).
* c. Server performs an active-close as in (a), keeps TIMEWAIT state.
*
* 3) The following intermediate states are employed to give passively
* closing nodes a chance to process their unread data:
* - PASSIVE_CLOSE (from OPEN => CLOSED) and
* - PASSIVE_CLOSEREQ (from (PART)OPEN to CLOSING; case (b) above).
*/
DCCP_ACTIVE_CLOSEREQ = TCP_FIN_WAIT1,
DCCP_PASSIVE_CLOSE = TCP_CLOSE_WAIT, /* any node receiving a Close */
DCCP_CLOSING = TCP_CLOSING,
DCCP_TIME_WAIT = TCP_TIME_WAIT,
DCCP_CLOSED = TCP_CLOSE,
DCCP_NEW_SYN_RECV = TCP_NEW_SYN_RECV,
DCCP_PARTOPEN = TCP_MAX_STATES,
DCCP_PASSIVE_CLOSEREQ, /* clients receiving CloseReq */
DCCP_MAX_STATES
};
enum {
DCCPF_OPEN = TCPF_ESTABLISHED,
DCCPF_REQUESTING = TCPF_SYN_SENT,
DCCPF_LISTEN = TCPF_LISTEN,
DCCPF_RESPOND = TCPF_SYN_RECV,
DCCPF_ACTIVE_CLOSEREQ = TCPF_FIN_WAIT1,
DCCPF_CLOSING = TCPF_CLOSING,
DCCPF_TIME_WAIT = TCPF_TIME_WAIT,
DCCPF_CLOSED = TCPF_CLOSE,
DCCPF_NEW_SYN_RECV = TCPF_NEW_SYN_RECV,
DCCPF_PARTOPEN = (1 << DCCP_PARTOPEN),
};
static inline struct dccp_hdr *dccp_hdr(const struct sk_buff *skb)
{
return (struct dccp_hdr *)skb_transport_header(skb);
}
static inline struct dccp_hdr *dccp_zeroed_hdr(struct sk_buff *skb, int headlen)
{
skb_push(skb, headlen);
skb_reset_transport_header(skb);
return memset(skb_transport_header(skb), 0, headlen);
}
static inline struct dccp_hdr_ext *dccp_hdrx(const struct dccp_hdr *dh)
{
return (struct dccp_hdr_ext *)((unsigned char *)dh + sizeof(*dh));
}
static inline unsigned int __dccp_basic_hdr_len(const struct dccp_hdr *dh)
{
return sizeof(*dh) + (dh->dccph_x ? sizeof(struct dccp_hdr_ext) : 0);
}
static inline unsigned int dccp_basic_hdr_len(const struct sk_buff *skb)
{
const struct dccp_hdr *dh = dccp_hdr(skb);
return __dccp_basic_hdr_len(dh);
}
static inline __u64 dccp_hdr_seq(const struct dccp_hdr *dh)
{
__u64 seq_nr = ntohs(dh->dccph_seq);
if (dh->dccph_x != 0)
seq_nr = (seq_nr << 32) + ntohl(dccp_hdrx(dh)->dccph_seq_low);
else
seq_nr += (u32)dh->dccph_seq2 << 16;
return seq_nr;
}
static inline struct dccp_hdr_request *dccp_hdr_request(struct sk_buff *skb)
{
return (struct dccp_hdr_request *)(skb_transport_header(skb) +
dccp_basic_hdr_len(skb));
}
static inline struct dccp_hdr_ack_bits *dccp_hdr_ack_bits(const struct sk_buff *skb)
{
return (struct dccp_hdr_ack_bits *)(skb_transport_header(skb) +
dccp_basic_hdr_len(skb));
}
static inline u64 dccp_hdr_ack_seq(const struct sk_buff *skb)
{
const struct dccp_hdr_ack_bits *dhack = dccp_hdr_ack_bits(skb);
return ((u64)ntohs(dhack->dccph_ack_nr_high) << 32) + ntohl(dhack->dccph_ack_nr_low);
}
static inline struct dccp_hdr_response *dccp_hdr_response(struct sk_buff *skb)
{
return (struct dccp_hdr_response *)(skb_transport_header(skb) +
dccp_basic_hdr_len(skb));
}
static inline struct dccp_hdr_reset *dccp_hdr_reset(struct sk_buff *skb)
{
return (struct dccp_hdr_reset *)(skb_transport_header(skb) +
dccp_basic_hdr_len(skb));
}
static inline unsigned int __dccp_hdr_len(const struct dccp_hdr *dh)
{
return __dccp_basic_hdr_len(dh) +
dccp_packet_hdr_len(dh->dccph_type);
}
static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
{
return __dccp_hdr_len(dccp_hdr(skb));
}
/**
* struct dccp_request_sock - represent DCCP-specific connection request
* @dreq_inet_rsk: structure inherited from
* @dreq_iss: initial sequence number, sent on the first Response (RFC 4340, 7.1)
* @dreq_gss: greatest sequence number sent (for retransmitted Responses)
* @dreq_isr: initial sequence number received in the first Request
* @dreq_gsr: greatest sequence number received (for retransmitted Request(s))
* @dreq_service: service code present on the Request (there is just one)
* @dreq_featneg: feature negotiation options for this connection
* The following two fields are analogous to the ones in dccp_sock:
* @dreq_timestamp_echo: last received timestamp to echo (13.1)
* @dreq_timestamp_echo: the time of receiving the last @dreq_timestamp_echo
*/
struct dccp_request_sock {
struct inet_request_sock dreq_inet_rsk;
__u64 dreq_iss;
__u64 dreq_gss;
__u64 dreq_isr;
__u64 dreq_gsr;
__be32 dreq_service;
spinlock_t dreq_lock;
struct list_head dreq_featneg;
__u32 dreq_timestamp_echo;
__u32 dreq_timestamp_time;
};
static inline struct dccp_request_sock *dccp_rsk(const struct request_sock *req)
{
return (struct dccp_request_sock *)req;
}
extern struct inet_timewait_death_row dccp_death_row;
extern int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
struct sk_buff *skb);
struct dccp_options_received {
u64 dccpor_ndp:48;
u32 dccpor_timestamp;
u32 dccpor_timestamp_echo;
u32 dccpor_elapsed_time;
};
struct ccid;
enum dccp_role {
DCCP_ROLE_UNDEFINED,
DCCP_ROLE_LISTEN,
DCCP_ROLE_CLIENT,
DCCP_ROLE_SERVER,
};
struct dccp_service_list {
__u32 dccpsl_nr;
__be32 dccpsl_list[];
};
#define DCCP_SERVICE_INVALID_VALUE htonl((__u32)-1)
#define DCCP_SERVICE_CODE_IS_ABSENT 0
static inline bool dccp_list_has_service(const struct dccp_service_list *sl,
const __be32 service)
{
if (likely(sl != NULL)) {
u32 i = sl->dccpsl_nr;
while (i--)
if (sl->dccpsl_list[i] == service)
return true;
}
return false;
}
struct dccp_ackvec;
/**
* struct dccp_sock - DCCP socket state
*
* @dccps_swl - sequence number window low
* @dccps_swh - sequence number window high
* @dccps_awl - acknowledgement number window low
* @dccps_awh - acknowledgement number window high
* @dccps_iss - initial sequence number sent
* @dccps_isr - initial sequence number received
* @dccps_osr - first OPEN sequence number received
* @dccps_gss - greatest sequence number sent
* @dccps_gsr - greatest valid sequence number received
* @dccps_gar - greatest valid ack number received on a non-Sync; initialized to %dccps_iss
* @dccps_service - first (passive sock) or unique (active sock) service code
* @dccps_service_list - second .. last service code on passive socket
* @dccps_timestamp_echo - latest timestamp received on a TIMESTAMP option
* @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo
* @dccps_l_ack_ratio - feature-local Ack Ratio
* @dccps_r_ack_ratio - feature-remote Ack Ratio
* @dccps_l_seq_win - local Sequence Window (influences ack number validity)
* @dccps_r_seq_win - remote Sequence Window (influences seq number validity)
* @dccps_pcslen - sender partial checksum coverage (via sockopt)
* @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
* @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
* @dccps_ndp_count - number of Non Data Packets since last data packet
* @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
* @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
* @dccps_featneg - tracks feature-negotiation state (mostly during handshake)
* @dccps_hc_rx_ackvec - rx half connection ack vector
* @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
* @dccps_hc_tx_ccid - CCID used for the sender (or sending half-connection)
* @dccps_options_received - parsed set of retrieved options
* @dccps_qpolicy - TX dequeueing policy, one of %dccp_packet_dequeueing_policy
* @dccps_tx_qlen - maximum length of the TX queue
* @dccps_role - role of this sock, one of %dccp_role
* @dccps_hc_rx_insert_options - receiver wants to add options when acking
* @dccps_hc_tx_insert_options - sender wants to add options when sending
* @dccps_server_timewait - server holds timewait state on close (RFC 4340, 8.3)
* @dccps_sync_scheduled - flag which signals "send out-of-band message soon"
* @dccps_xmitlet - tasklet scheduled by the TX CCID to dequeue data packets
* @dccps_xmit_timer - used by the TX CCID to delay sending (rate-based pacing)
* @dccps_syn_rtt - RTT sample from Request/Response exchange (in usecs)
*/
struct dccp_sock {
/* inet_connection_sock has to be the first member of dccp_sock */
struct inet_connection_sock dccps_inet_connection;
#define dccps_syn_rtt dccps_inet_connection.icsk_ack.lrcvtime
__u64 dccps_swl;
__u64 dccps_swh;
__u64 dccps_awl;
__u64 dccps_awh;
__u64 dccps_iss;
__u64 dccps_isr;
__u64 dccps_osr;
__u64 dccps_gss;
__u64 dccps_gsr;
__u64 dccps_gar;
__be32 dccps_service;
__u32 dccps_mss_cache;
struct dccp_service_list *dccps_service_list;
__u32 dccps_timestamp_echo;
__u32 dccps_timestamp_time;
__u16 dccps_l_ack_ratio;
__u16 dccps_r_ack_ratio;
__u64 dccps_l_seq_win:48;
__u64 dccps_r_seq_win:48;
__u8 dccps_pcslen:4;
__u8 dccps_pcrlen:4;
__u8 dccps_send_ndp_count:1;
__u64 dccps_ndp_count:48;
unsigned long dccps_rate_last;
struct list_head dccps_featneg;
struct dccp_ackvec *dccps_hc_rx_ackvec;
struct ccid *dccps_hc_rx_ccid;
struct ccid *dccps_hc_tx_ccid;
struct dccp_options_received dccps_options_received;
__u8 dccps_qpolicy;
__u32 dccps_tx_qlen;
enum dccp_role dccps_role:2;
__u8 dccps_hc_rx_insert_options:1;
__u8 dccps_hc_tx_insert_options:1;
__u8 dccps_server_timewait:1;
__u8 dccps_sync_scheduled:1;
struct tasklet_struct dccps_xmitlet;
struct timer_list dccps_xmit_timer;
};
static inline struct dccp_sock *dccp_sk(const struct sock *sk)
{
return (struct dccp_sock *)sk;
}
static inline const char *dccp_role(const struct sock *sk)
{
switch (dccp_sk(sk)->dccps_role) {
case DCCP_ROLE_UNDEFINED: return "undefined";
case DCCP_ROLE_LISTEN: return "listen";
case DCCP_ROLE_SERVER: return "server";
case DCCP_ROLE_CLIENT: return "client";
}
return NULL;
}
extern void dccp_syn_ack_timeout(const struct request_sock *req);
#endif /* _LINUX_DCCP_H */
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