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linux/include/net/llc_pdu.h
Daniel Borkmann 7e0309631e net: llc: fix order of evaluation in llc_conn_ac_inc_vr_by_1 
Function llc_conn_ac_inc_vr_by_1() evaluates via macro
PDU_GET_NEXT_Vr() into ...

  llc_sk(sk)->vR = ++llc_sk(sk)->vR & 0xffffffffffffff7f

... but the order in which the side effects take place is
undefined because there is no intervening sequence point.

As llc_sk(sk)->vR is written in llc_sk(sk)->vR (assignment
left-hand side) and written in ++llc_sk(sk)->vR & 0xffffffffffffff7f
this might possibly yield undefined behavior.

The final value of llc_sk(sk)->vR is ambiguous, because,
depending on the order of expression evaluation, the
increment may occur before, after, or interleaved with
the assignment. In C, evaluating such an expression yields
undefined behavior.

Since we're doing the increment via PDU_GET_NEXT_Vr() macro
and the only place it is being used is from
llc_conn_ac_inc_vr_by_1(), in order to increment vR by 1
with a follow-up optimized modulo, rewrite the expression
into ((vR + 1) & CONST) in order to fix this.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-01-01 22:22:43 -05:00

430 lines
14 KiB
C
Raw Blame History

#ifndef LLC_PDU_H
#define LLC_PDU_H
/*
* 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 <linux/if_ether.h>
/* Lengths of frame formats */
#define LLC_PDU_LEN_I 4 /* header and 2 control bytes */
#define LLC_PDU_LEN_S 4
#define LLC_PDU_LEN_U 3 /* header and 1 control byte */
/* Known SAP addresses */
#define LLC_GLOBAL_SAP 0xFF
#define LLC_NULL_SAP 0x00 /* not network-layer visible */
#define LLC_MGMT_INDIV 0x02 /* station LLC mgmt indiv addr */
#define LLC_MGMT_GRP 0x03 /* station LLC mgmt group addr */
#define LLC_RDE_SAP 0xA6 /* route ... */
/* SAP field bit masks */
#define LLC_ISO_RESERVED_SAP 0x02
#define LLC_SAP_GROUP_DSAP 0x01
#define LLC_SAP_RESP_SSAP 0x01
/* Group/individual DSAP indicator is DSAP field */
#define LLC_PDU_GROUP_DSAP_MASK 0x01
#define LLC_PDU_IS_GROUP_DSAP(pdu) \
((pdu->dsap & LLC_PDU_GROUP_DSAP_MASK) ? 0 : 1)
#define LLC_PDU_IS_INDIV_DSAP(pdu) \
(!(pdu->dsap & LLC_PDU_GROUP_DSAP_MASK) ? 0 : 1)
/* Command/response PDU indicator in SSAP field */
#define LLC_PDU_CMD_RSP_MASK 0x01
#define LLC_PDU_CMD 0
#define LLC_PDU_RSP 1
#define LLC_PDU_IS_CMD(pdu) ((pdu->ssap & LLC_PDU_RSP) ? 0 : 1)
#define LLC_PDU_IS_RSP(pdu) ((pdu->ssap & LLC_PDU_RSP) ? 1 : 0)
/* Get PDU type from 2 lowest-order bits of control field first byte */
#define LLC_PDU_TYPE_I_MASK 0x01 /* 16-bit control field */
#define LLC_PDU_TYPE_S_MASK 0x03
#define LLC_PDU_TYPE_U_MASK 0x03 /* 8-bit control field */
#define LLC_PDU_TYPE_MASK 0x03
#define LLC_PDU_TYPE_I 0 /* first bit */
#define LLC_PDU_TYPE_S 1 /* first two bits */
#define LLC_PDU_TYPE_U 3 /* first two bits */
#define LLC_PDU_TYPE_IS_I(pdu) \
((!(pdu->ctrl_1 & LLC_PDU_TYPE_I_MASK)) ? 1 : 0)
#define LLC_PDU_TYPE_IS_U(pdu) \
(((pdu->ctrl_1 & LLC_PDU_TYPE_U_MASK) == LLC_PDU_TYPE_U) ? 1 : 0)
#define LLC_PDU_TYPE_IS_S(pdu) \
(((pdu->ctrl_1 & LLC_PDU_TYPE_S_MASK) == LLC_PDU_TYPE_S) ? 1 : 0)
/* U-format PDU control field masks */
#define LLC_U_PF_BIT_MASK 0x10 /* P/F bit mask */
#define LLC_U_PF_IS_1(pdu) ((pdu->ctrl_1 & LLC_U_PF_BIT_MASK) ? 1 : 0)
#define LLC_U_PF_IS_0(pdu) ((!(pdu->ctrl_1 & LLC_U_PF_BIT_MASK)) ? 1 : 0)
#define LLC_U_PDU_CMD_MASK 0xEC /* cmd/rsp mask */
#define LLC_U_PDU_CMD(pdu) (pdu->ctrl_1 & LLC_U_PDU_CMD_MASK)
#define LLC_U_PDU_RSP(pdu) (pdu->ctrl_1 & LLC_U_PDU_CMD_MASK)
#define LLC_1_PDU_CMD_UI 0x00 /* Type 1 cmds/rsps */
#define LLC_1_PDU_CMD_XID 0xAC
#define LLC_1_PDU_CMD_TEST 0xE0
#define LLC_2_PDU_CMD_SABME 0x6C /* Type 2 cmds/rsps */
#define LLC_2_PDU_CMD_DISC 0x40
#define LLC_2_PDU_RSP_UA 0x60
#define LLC_2_PDU_RSP_DM 0x0C
#define LLC_2_PDU_RSP_FRMR 0x84
/* Type 1 operations */
/* XID information field bit masks */
/* LLC format identifier (byte 1) */
#define LLC_XID_FMT_ID 0x81 /* first byte must be this */
/* LLC types/classes identifier (byte 2) */
#define LLC_XID_CLASS_ZEROS_MASK 0xE0 /* these must be zeros */
#define LLC_XID_CLASS_MASK 0x1F /* AND with byte to get below */
#define LLC_XID_NULL_CLASS_1 0x01 /* if NULL LSAP...use these */
#define LLC_XID_NULL_CLASS_2 0x03
#define LLC_XID_NULL_CLASS_3 0x05
#define LLC_XID_NULL_CLASS_4 0x07
#define LLC_XID_NNULL_TYPE_1 0x01 /* if non-NULL LSAP...use these */
#define LLC_XID_NNULL_TYPE_2 0x02
#define LLC_XID_NNULL_TYPE_3 0x04
#define LLC_XID_NNULL_TYPE_1_2 0x03
#define LLC_XID_NNULL_TYPE_1_3 0x05
#define LLC_XID_NNULL_TYPE_2_3 0x06
#define LLC_XID_NNULL_ALL 0x07
/* Sender Receive Window (byte 3) */
#define LLC_XID_RW_MASK 0xFE /* AND with value to get below */
#define LLC_XID_MIN_RW 0x02 /* lowest-order bit always zero */
/* Type 2 operations */
#define LLC_2_SEQ_NBR_MODULO ((u8) 128)
/* I-PDU masks ('ctrl' is I-PDU control word) */
#define LLC_I_GET_NS(pdu) (u8)((pdu->ctrl_1 & 0xFE) >> 1)
#define LLC_I_GET_NR(pdu) (u8)((pdu->ctrl_2 & 0xFE) >> 1)
#define LLC_I_PF_BIT_MASK 0x01
#define LLC_I_PF_IS_0(pdu) ((!(pdu->ctrl_2 & LLC_I_PF_BIT_MASK)) ? 1 : 0)
#define LLC_I_PF_IS_1(pdu) ((pdu->ctrl_2 & LLC_I_PF_BIT_MASK) ? 1 : 0)
/* S-PDU supervisory commands and responses */
#define LLC_S_PDU_CMD_MASK 0x0C
#define LLC_S_PDU_CMD(pdu) (pdu->ctrl_1 & LLC_S_PDU_CMD_MASK)
#define LLC_S_PDU_RSP(pdu) (pdu->ctrl_1 & LLC_S_PDU_CMD_MASK)
#define LLC_2_PDU_CMD_RR 0x00 /* rx ready cmd */
#define LLC_2_PDU_RSP_RR 0x00 /* rx ready rsp */
#define LLC_2_PDU_CMD_REJ 0x08 /* reject PDU cmd */
#define LLC_2_PDU_RSP_REJ 0x08 /* reject PDU rsp */
#define LLC_2_PDU_CMD_RNR 0x04 /* rx not ready cmd */
#define LLC_2_PDU_RSP_RNR 0x04 /* rx not ready rsp */
#define LLC_S_PF_BIT_MASK 0x01
#define LLC_S_PF_IS_0(pdu) ((!(pdu->ctrl_2 & LLC_S_PF_BIT_MASK)) ? 1 : 0)
#define LLC_S_PF_IS_1(pdu) ((pdu->ctrl_2 & LLC_S_PF_BIT_MASK) ? 1 : 0)
#define PDU_SUPV_GET_Nr(pdu) ((pdu->ctrl_2 & 0xFE) >> 1)
#define PDU_GET_NEXT_Vr(sn) (((sn) + 1) & ~LLC_2_SEQ_NBR_MODULO)
/* FRMR information field macros */
#define FRMR_INFO_LENGTH 5 /* 5 bytes of information */
/*
* info is pointer to FRMR info field structure; 'rej_ctrl' is byte pointer
* (if U-PDU) or word pointer to rejected PDU control field
*/
#define FRMR_INFO_SET_REJ_CNTRL(info,rej_ctrl) \
info->rej_pdu_ctrl = ((*((u8 *) rej_ctrl) & \
LLC_PDU_TYPE_U) != LLC_PDU_TYPE_U ? \
(u16)*((u16 *) rej_ctrl) : \
(((u16) *((u8 *) rej_ctrl)) & 0x00FF))
/*
* Info is pointer to FRMR info field structure; 'vs' is a byte containing
* send state variable value in low-order 7 bits (insure the lowest-order
* bit remains zero (0))
*/
#define FRMR_INFO_SET_Vs(info,vs) (info->curr_ssv = (((u8) vs) << 1))
#define FRMR_INFO_SET_Vr(info,vr) (info->curr_rsv = (((u8) vr) << 1))
/*
* Info is pointer to FRMR info field structure; 'cr' is a byte containing
* the C/R bit value in the low-order bit
*/
#define FRMR_INFO_SET_C_R_BIT(info, cr) (info->curr_rsv |= (((u8) cr) & 0x01))
/*
* In the remaining five macros, 'info' is pointer to FRMR info field
* structure; 'ind' is a byte containing the bit value to set in the
* lowest-order bit)
*/
#define FRMR_INFO_SET_INVALID_PDU_CTRL_IND(info, ind) \
(info->ind_bits = ((info->ind_bits & 0xFE) | (((u8) ind) & 0x01)))
#define FRMR_INFO_SET_INVALID_PDU_INFO_IND(info, ind) \
(info->ind_bits = ( (info->ind_bits & 0xFD) | (((u8) ind) & 0x02)))
#define FRMR_INFO_SET_PDU_INFO_2LONG_IND(info, ind) \
(info->ind_bits = ( (info->ind_bits & 0xFB) | (((u8) ind) & 0x04)))
#define FRMR_INFO_SET_PDU_INVALID_Nr_IND(info, ind) \
(info->ind_bits = ( (info->ind_bits & 0xF7) | (((u8) ind) & 0x08)))
#define FRMR_INFO_SET_PDU_INVALID_Ns_IND(info, ind) \
(info->ind_bits = ( (info->ind_bits & 0xEF) | (((u8) ind) & 0x10)))
/* Sequence-numbered PDU format (4 bytes in length) */
struct llc_pdu_sn {
u8 dsap;
u8 ssap;
u8 ctrl_1;
u8 ctrl_2;
} __packed;
static inline struct llc_pdu_sn *llc_pdu_sn_hdr(struct sk_buff *skb)
{
return (struct llc_pdu_sn *)skb_network_header(skb);
}
/* Un-numbered PDU format (3 bytes in length) */
struct llc_pdu_un {
u8 dsap;
u8 ssap;
u8 ctrl_1;
} __packed;
static inline struct llc_pdu_un *llc_pdu_un_hdr(struct sk_buff *skb)
{
return (struct llc_pdu_un *)skb_network_header(skb);
}
/**
* llc_pdu_header_init - initializes pdu header
* @skb: input skb that header must be set into it.
* @type: type of PDU (U, I or S).
* @ssap: source sap.
* @dsap: destination sap.
* @cr: command/response bit (0 or 1).
*
* This function sets DSAP, SSAP and command/Response bit in LLC header.
*/
static inline void llc_pdu_header_init(struct sk_buff *skb, u8 type,
u8 ssap, u8 dsap, u8 cr)
{
const int hlen = type == LLC_PDU_TYPE_U ? 3 : 4;
struct llc_pdu_un *pdu;
skb_push(skb, hlen);
skb_reset_network_header(skb);
pdu = llc_pdu_un_hdr(skb);
pdu->dsap = dsap;
pdu->ssap = ssap;
pdu->ssap |= cr;
}
/**
* llc_pdu_decode_sa - extracs source address (MAC) of input frame
* @skb: input skb that source address must be extracted from it.
* @sa: pointer to source address (6 byte array).
*
* This function extracts source address(MAC) of input frame.
*/
static inline void llc_pdu_decode_sa(struct sk_buff *skb, u8 *sa)
{
if (skb->protocol == htons(ETH_P_802_2))
memcpy(sa, eth_hdr(skb)->h_source, ETH_ALEN);
}
/**
* llc_pdu_decode_da - extracts dest address of input frame
* @skb: input skb that destination address must be extracted from it
* @sa: pointer to destination address (6 byte array).
*
* This function extracts destination address(MAC) of input frame.
*/
static inline void llc_pdu_decode_da(struct sk_buff *skb, u8 *da)
{
if (skb->protocol == htons(ETH_P_802_2))
memcpy(da, eth_hdr(skb)->h_dest, ETH_ALEN);
}
/**
* llc_pdu_decode_ssap - extracts source SAP of input frame
* @skb: input skb that source SAP must be extracted from it.
* @ssap: source SAP (output argument).
*
* This function extracts source SAP of input frame. Right bit of SSAP is
* command/response bit.
*/
static inline void llc_pdu_decode_ssap(struct sk_buff *skb, u8 *ssap)
{
*ssap = llc_pdu_un_hdr(skb)->ssap & 0xFE;
}
/**
* llc_pdu_decode_dsap - extracts dest SAP of input frame
* @skb: input skb that destination SAP must be extracted from it.
* @dsap: destination SAP (output argument).
*
* This function extracts destination SAP of input frame. right bit of
* DSAP designates individual/group SAP.
*/
static inline void llc_pdu_decode_dsap(struct sk_buff *skb, u8 *dsap)
{
*dsap = llc_pdu_un_hdr(skb)->dsap & 0xFE;
}
/**
* llc_pdu_init_as_ui_cmd - sets LLC header as UI PDU
* @skb: input skb that header must be set into it.
*
* This function sets third byte of LLC header as a UI PDU.
*/
static inline void llc_pdu_init_as_ui_cmd(struct sk_buff *skb)
{
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
pdu->ctrl_1 = LLC_PDU_TYPE_U;
pdu->ctrl_1 |= LLC_1_PDU_CMD_UI;
}
/**
* llc_pdu_init_as_test_cmd - sets PDU as TEST
* @skb - Address of the skb to build
*
* Sets a PDU as TEST
*/
static inline void llc_pdu_init_as_test_cmd(struct sk_buff *skb)
{
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
pdu->ctrl_1 = LLC_PDU_TYPE_U;
pdu->ctrl_1 |= LLC_1_PDU_CMD_TEST;
pdu->ctrl_1 |= LLC_U_PF_BIT_MASK;
}
/**
* llc_pdu_init_as_test_rsp - build TEST response PDU
* @skb: Address of the skb to build
* @ev_skb: The received TEST command PDU frame
*
* Builds a pdu frame as a TEST response.
*/
static inline void llc_pdu_init_as_test_rsp(struct sk_buff *skb,
struct sk_buff *ev_skb)
{
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
pdu->ctrl_1 = LLC_PDU_TYPE_U;
pdu->ctrl_1 |= LLC_1_PDU_CMD_TEST;
pdu->ctrl_1 |= LLC_U_PF_BIT_MASK;
if (ev_skb->protocol == htons(ETH_P_802_2)) {
struct llc_pdu_un *ev_pdu = llc_pdu_un_hdr(ev_skb);
int dsize;
dsize = ntohs(eth_hdr(ev_skb)->h_proto) - 3;
memcpy(((u8 *)pdu) + 3, ((u8 *)ev_pdu) + 3, dsize);
skb_put(skb, dsize);
}
}
/* LLC Type 1 XID command/response information fields format */
struct llc_xid_info {
u8 fmt_id; /* always 0x81 for LLC */
u8 type; /* different if NULL/non-NULL LSAP */
u8 rw; /* sender receive window */
} __packed;
/**
* llc_pdu_init_as_xid_cmd - sets bytes 3, 4 & 5 of LLC header as XID
* @skb: input skb that header must be set into it.
*
* This function sets third,fourth,fifth and sixth bytes of LLC header as
* a XID PDU.
*/
static inline void llc_pdu_init_as_xid_cmd(struct sk_buff *skb,
u8 svcs_supported, u8 rx_window)
{
struct llc_xid_info *xid_info;
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
pdu->ctrl_1 = LLC_PDU_TYPE_U;
pdu->ctrl_1 |= LLC_1_PDU_CMD_XID;
pdu->ctrl_1 |= LLC_U_PF_BIT_MASK;
xid_info = (struct llc_xid_info *)(((u8 *)&pdu->ctrl_1) + 1);
xid_info->fmt_id = LLC_XID_FMT_ID; /* 0x81 */
xid_info->type = svcs_supported;
xid_info->rw = rx_window << 1; /* size of receive window */
skb_put(skb, sizeof(struct llc_xid_info));
}
/**
* llc_pdu_init_as_xid_rsp - builds XID response PDU
* @skb: Address of the skb to build
* @svcs_supported: The class of the LLC (I or II)
* @rx_window: The size of the receive window of the LLC
*
* Builds a pdu frame as an XID response.
*/
static inline void llc_pdu_init_as_xid_rsp(struct sk_buff *skb,
u8 svcs_supported, u8 rx_window)
{
struct llc_xid_info *xid_info;
struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
pdu->ctrl_1 = LLC_PDU_TYPE_U;
pdu->ctrl_1 |= LLC_1_PDU_CMD_XID;
pdu->ctrl_1 |= LLC_U_PF_BIT_MASK;
xid_info = (struct llc_xid_info *)(((u8 *)&pdu->ctrl_1) + 1);
xid_info->fmt_id = LLC_XID_FMT_ID;
xid_info->type = svcs_supported;
xid_info->rw = rx_window << 1;
skb_put(skb, sizeof(struct llc_xid_info));
}
/* LLC Type 2 FRMR response information field format */
struct llc_frmr_info {
u16 rej_pdu_ctrl; /* bits 1-8 if U-PDU */
u8 curr_ssv; /* current send state variable val */
u8 curr_rsv; /* current receive state variable */
u8 ind_bits; /* indicator bits set with macro */
} __packed;
void llc_pdu_set_cmd_rsp(struct sk_buff *skb, u8 type);
void llc_pdu_set_pf_bit(struct sk_buff *skb, u8 bit_value);
void llc_pdu_decode_pf_bit(struct sk_buff *skb, u8 *pf_bit);
void llc_pdu_init_as_disc_cmd(struct sk_buff *skb, u8 p_bit);
void llc_pdu_init_as_i_cmd(struct sk_buff *skb, u8 p_bit, u8 ns, u8 nr);
void llc_pdu_init_as_rej_cmd(struct sk_buff *skb, u8 p_bit, u8 nr);
void llc_pdu_init_as_rnr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr);
void llc_pdu_init_as_rr_cmd(struct sk_buff *skb, u8 p_bit, u8 nr);
void llc_pdu_init_as_sabme_cmd(struct sk_buff *skb, u8 p_bit);
void llc_pdu_init_as_dm_rsp(struct sk_buff *skb, u8 f_bit);
void llc_pdu_init_as_frmr_rsp(struct sk_buff *skb, struct llc_pdu_sn *prev_pdu,
u8 f_bit, u8 vs, u8 vr, u8 vzyxw);
void llc_pdu_init_as_rr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr);
void llc_pdu_init_as_rej_rsp(struct sk_buff *skb, u8 f_bit, u8 nr);
void llc_pdu_init_as_rnr_rsp(struct sk_buff *skb, u8 f_bit, u8 nr);
void llc_pdu_init_as_ua_rsp(struct sk_buff *skb, u8 f_bit);
#endif /* LLC_PDU_H */
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