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kernel-fxtec-pro1x/net/llc/llc_sap.c
Salvatore Mesoraca 678f4bda35 net: llc: drop VLA in llc_sap_mcast() 
Avoid a VLA[1] by using a real constant expression instead of a variable.
The compiler should be able to optimize the original code and avoid using
an actual VLA. Anyway this change is useful because it will avoid a false
positive with -Wvla, it might also help the compiler generating better
code.

[1] https://lkml.org/lkml/2018/3/7/621

Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-03-12 11:14:06 -04:00

443 lines
11 KiB
C
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/*
* llc_sap.c - driver routines for SAP component.
*
* Copyright (c) 1997 by Procom Technology, Inc.
* 2001-2003 by Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program can be redistributed or modified under the terms of the
* GNU General Public License as published by the Free Software Foundation.
* This program is distributed without any warranty or implied warranty
* of merchantability or fitness for a particular purpose.
*
* See the GNU General Public License for more details.
*/
#include <net/llc.h>
#include <net/llc_if.h>
#include <net/llc_conn.h>
#include <net/llc_pdu.h>
#include <net/llc_sap.h>
#include <net/llc_s_ac.h>
#include <net/llc_s_ev.h>
#include <net/llc_s_st.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <linux/llc.h>
#include <linux/slab.h>
static int llc_mac_header_len(unsigned short devtype)
{
switch (devtype) {
case ARPHRD_ETHER:
case ARPHRD_LOOPBACK:
return sizeof(struct ethhdr);
}
return 0;
}
/**
* llc_alloc_frame - allocates sk_buff for frame
* @dev: network device this skb will be sent over
* @type: pdu type to allocate
* @data_size: data size to allocate
*
* Allocates an sk_buff for frame and initializes sk_buff fields.
* Returns allocated skb or %NULL when out of memory.
*/
struct sk_buff *llc_alloc_frame(struct sock *sk, struct net_device *dev,
u8 type, u32 data_size)
{
int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
struct sk_buff *skb;
hlen += llc_mac_header_len(dev->type);
skb = alloc_skb(hlen + data_size, GFP_ATOMIC);
if (skb) {
skb_reset_mac_header(skb);
skb_reserve(skb, hlen);
skb_reset_network_header(skb);
skb_reset_transport_header(skb);
skb->protocol = htons(ETH_P_802_2);
skb->dev = dev;
if (sk != NULL)
skb_set_owner_w(skb, sk);
}
return skb;
}
void llc_save_primitive(struct sock *sk, struct sk_buff *skb, u8 prim)
{
struct sockaddr_llc *addr;
/* save primitive for use by the user. */
addr = llc_ui_skb_cb(skb);
memset(addr, 0, sizeof(*addr));
addr->sllc_family = sk->sk_family;
addr->sllc_arphrd = skb->dev->type;
addr->sllc_test = prim == LLC_TEST_PRIM;
addr->sllc_xid = prim == LLC_XID_PRIM;
addr->sllc_ua = prim == LLC_DATAUNIT_PRIM;
llc_pdu_decode_sa(skb, addr->sllc_mac);
llc_pdu_decode_ssap(skb, &addr->sllc_sap);
}
/**
* llc_sap_rtn_pdu - Informs upper layer on rx of an UI, XID or TEST pdu.
* @sap: pointer to SAP
* @skb: received pdu
*/
void llc_sap_rtn_pdu(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
switch (LLC_U_PDU_RSP(pdu)) {
case LLC_1_PDU_CMD_TEST:
ev->prim = LLC_TEST_PRIM; break;
case LLC_1_PDU_CMD_XID:
ev->prim = LLC_XID_PRIM; break;
case LLC_1_PDU_CMD_UI:
ev->prim = LLC_DATAUNIT_PRIM; break;
}
ev->ind_cfm_flag = LLC_IND;
}
/**
* llc_find_sap_trans - finds transition for event
* @sap: pointer to SAP
* @skb: happened event
*
* This function finds transition that matches with happened event.
* Returns the pointer to found transition on success or %NULL for
* failure.
*/
static struct llc_sap_state_trans *llc_find_sap_trans(struct llc_sap *sap,
struct sk_buff *skb)
{
int i = 0;
struct llc_sap_state_trans *rc = NULL;
struct llc_sap_state_trans **next_trans;
struct llc_sap_state *curr_state = &llc_sap_state_table[sap->state - 1];
/*
* Search thru events for this state until list exhausted or until
* its obvious the event is not valid for the current state
*/
for (next_trans = curr_state->transitions; next_trans[i]->ev; i++)
if (!next_trans[i]->ev(sap, skb)) {
rc = next_trans[i]; /* got event match; return it */
break;
}
return rc;
}
/**
* llc_exec_sap_trans_actions - execute actions related to event
* @sap: pointer to SAP
* @trans: pointer to transition that it's actions must be performed
* @skb: happened event.
*
* This function executes actions that is related to happened event.
* Returns 0 for success and 1 for failure of at least one action.
*/
static int llc_exec_sap_trans_actions(struct llc_sap *sap,
struct llc_sap_state_trans *trans,
struct sk_buff *skb)
{
int rc = 0;
const llc_sap_action_t *next_action = trans->ev_actions;
for (; next_action && *next_action; next_action++)
if ((*next_action)(sap, skb))
rc = 1;
return rc;
}
/**
* llc_sap_next_state - finds transition, execs actions & change SAP state
* @sap: pointer to SAP
* @skb: happened event
*
* This function finds transition that matches with happened event, then
* executes related actions and finally changes state of SAP. It returns
* 0 on success and 1 for failure.
*/
static int llc_sap_next_state(struct llc_sap *sap, struct sk_buff *skb)
{
int rc = 1;
struct llc_sap_state_trans *trans;
if (sap->state > LLC_NR_SAP_STATES)
goto out;
trans = llc_find_sap_trans(sap, skb);
if (!trans)
goto out;
/*
* Got the state to which we next transition; perform the actions
* associated with this transition before actually transitioning to the
* next state
*/
rc = llc_exec_sap_trans_actions(sap, trans, skb);
if (rc)
goto out;
/*
* Transition SAP to next state if all actions execute successfully
*/
sap->state = trans->next_state;
out:
return rc;
}
/**
* llc_sap_state_process - sends event to SAP state machine
* @sap: sap to use
* @skb: pointer to occurred event
*
* After executing actions of the event, upper layer will be indicated
* if needed(on receiving an UI frame). sk can be null for the
* datalink_proto case.
*/
static void llc_sap_state_process(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
/*
* We have to hold the skb, because llc_sap_next_state
* will kfree it in the sending path and we need to
* look at the skb->cb, where we encode llc_sap_state_ev.
*/
skb_get(skb);
ev->ind_cfm_flag = 0;
llc_sap_next_state(sap, skb);
if (ev->ind_cfm_flag == LLC_IND) {
if (skb->sk->sk_state == TCP_LISTEN)
kfree_skb(skb);
else {
llc_save_primitive(skb->sk, skb, ev->prim);
/* queue skb to the user. */
if (sock_queue_rcv_skb(skb->sk, skb))
kfree_skb(skb);
}
}
kfree_skb(skb);
}
/**
* llc_build_and_send_test_pkt - TEST interface for upper layers.
* @sap: sap to use
* @skb: packet to send
* @dmac: destination mac address
* @dsap: destination sap
*
* This function is called when upper layer wants to send a TEST pdu.
* Returns 0 for success, 1 otherwise.
*/
void llc_build_and_send_test_pkt(struct llc_sap *sap,
struct sk_buff *skb, u8 *dmac, u8 dsap)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
ev->saddr.lsap = sap->laddr.lsap;
ev->daddr.lsap = dsap;
memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
ev->type = LLC_SAP_EV_TYPE_PRIM;
ev->prim = LLC_TEST_PRIM;
ev->prim_type = LLC_PRIM_TYPE_REQ;
llc_sap_state_process(sap, skb);
}
/**
* llc_build_and_send_xid_pkt - XID interface for upper layers
* @sap: sap to use
* @skb: packet to send
* @dmac: destination mac address
* @dsap: destination sap
*
* This function is called when upper layer wants to send a XID pdu.
* Returns 0 for success, 1 otherwise.
*/
void llc_build_and_send_xid_pkt(struct llc_sap *sap, struct sk_buff *skb,
u8 *dmac, u8 dsap)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
ev->saddr.lsap = sap->laddr.lsap;
ev->daddr.lsap = dsap;
memcpy(ev->saddr.mac, skb->dev->dev_addr, IFHWADDRLEN);
memcpy(ev->daddr.mac, dmac, IFHWADDRLEN);
ev->type = LLC_SAP_EV_TYPE_PRIM;
ev->prim = LLC_XID_PRIM;
ev->prim_type = LLC_PRIM_TYPE_REQ;
llc_sap_state_process(sap, skb);
}
/**
* llc_sap_rcv - sends received pdus to the sap state machine
* @sap: current sap component structure.
* @skb: received frame.
*
* Sends received pdus to the sap state machine.
*/
static void llc_sap_rcv(struct llc_sap *sap, struct sk_buff *skb,
struct sock *sk)
{
struct llc_sap_state_ev *ev = llc_sap_ev(skb);
ev->type = LLC_SAP_EV_TYPE_PDU;
ev->reason = 0;
skb_orphan(skb);
sock_hold(sk);
skb->sk = sk;
skb->destructor = sock_efree;
llc_sap_state_process(sap, skb);
}
static inline bool llc_dgram_match(const struct llc_sap *sap,
const struct llc_addr *laddr,
const struct sock *sk)
{
struct llc_sock *llc = llc_sk(sk);
return sk->sk_type == SOCK_DGRAM &&
llc->laddr.lsap == laddr->lsap &&
ether_addr_equal(llc->laddr.mac, laddr->mac);
}
/**
* llc_lookup_dgram - Finds dgram socket for the local sap/mac
* @sap: SAP
* @laddr: address of local LLC (MAC + SAP)
*
* Search socket list of the SAP and finds connection using the local
* mac, and local sap. Returns pointer for socket found, %NULL otherwise.
*/
static struct sock *llc_lookup_dgram(struct llc_sap *sap,
const struct llc_addr *laddr)
{
struct sock *rc;
struct hlist_nulls_node *node;
int slot = llc_sk_laddr_hashfn(sap, laddr);
struct hlist_nulls_head *laddr_hb = &sap->sk_laddr_hash[slot];
rcu_read_lock_bh();
again:
sk_nulls_for_each_rcu(rc, node, laddr_hb) {
if (llc_dgram_match(sap, laddr, rc)) {
/* Extra checks required by SLAB_TYPESAFE_BY_RCU */
if (unlikely(!refcount_inc_not_zero(&rc->sk_refcnt)))
goto again;
if (unlikely(llc_sk(rc)->sap != sap ||
!llc_dgram_match(sap, laddr, rc))) {
sock_put(rc);
continue;
}
goto found;
}
}
rc = NULL;
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (unlikely(get_nulls_value(node) != slot))
goto again;
found:
rcu_read_unlock_bh();
return rc;
}
static inline bool llc_mcast_match(const struct llc_sap *sap,
const struct llc_addr *laddr,
const struct sk_buff *skb,
const struct sock *sk)
{
struct llc_sock *llc = llc_sk(sk);
return sk->sk_type == SOCK_DGRAM &&
llc->laddr.lsap == laddr->lsap &&
llc->dev == skb->dev;
}
static void llc_do_mcast(struct llc_sap *sap, struct sk_buff *skb,
struct sock **stack, int count)
{
struct sk_buff *skb1;
int i;
for (i = 0; i < count; i++) {
skb1 = skb_clone(skb, GFP_ATOMIC);
if (!skb1) {
sock_put(stack[i]);
continue;
}
llc_sap_rcv(sap, skb1, stack[i]);
sock_put(stack[i]);
}
}
/**
* llc_sap_mcast - Deliver multicast PDU's to all matching datagram sockets.
* @sap: SAP
* @laddr: address of local LLC (MAC + SAP)
*
* Search socket list of the SAP and finds connections with same sap.
* Deliver clone to each.
*/
static void llc_sap_mcast(struct llc_sap *sap,
const struct llc_addr *laddr,
struct sk_buff *skb)
{
int i = 0;
struct sock *sk;
struct sock *stack[256 / sizeof(struct sock *)];
struct llc_sock *llc;
struct hlist_head *dev_hb = llc_sk_dev_hash(sap, skb->dev->ifindex);
spin_lock_bh(&sap->sk_lock);
hlist_for_each_entry(llc, dev_hb, dev_hash_node) {
sk = &llc->sk;
if (!llc_mcast_match(sap, laddr, skb, sk))
continue;
sock_hold(sk);
if (i < ARRAY_SIZE(stack))
stack[i++] = sk;
else {
llc_do_mcast(sap, skb, stack, i);
i = 0;
}
}
spin_unlock_bh(&sap->sk_lock);
llc_do_mcast(sap, skb, stack, i);
}
void llc_sap_handler(struct llc_sap *sap, struct sk_buff *skb)
{
struct llc_addr laddr;
llc_pdu_decode_da(skb, laddr.mac);
llc_pdu_decode_dsap(skb, &laddr.lsap);
if (is_multicast_ether_addr(laddr.mac)) {
llc_sap_mcast(sap, &laddr, skb);
kfree_skb(skb);
} else {
struct sock *sk = llc_lookup_dgram(sap, &laddr);
if (sk) {
llc_sap_rcv(sap, skb, sk);
sock_put(sk);
} else
kfree_skb(skb);
}
}
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