cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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x25_subr.c (9423B)


      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *	X.25 Packet Layer release 002
      4 *
      5 *	This is ALPHA test software. This code may break your machine,
      6 *	randomly fail to work with new releases, misbehave and/or generally
      7 *	screw up. It might even work.
      8 *
      9 *	This code REQUIRES 2.1.15 or higher
     10 *
     11 *	History
     12 *	X.25 001	Jonathan Naylor	  Started coding.
     13 *	X.25 002	Jonathan Naylor	  Centralised disconnection processing.
     14 *	mar/20/00	Daniela Squassoni Disabling/enabling of facilities
     15 *					  negotiation.
     16 *	jun/24/01	Arnaldo C. Melo	  use skb_queue_purge, cleanups
     17 *	apr/04/15	Shaun Pereira		Fast select with no
     18 *						restriction on response.
     19 */
     20
     21#define pr_fmt(fmt) "X25: " fmt
     22
     23#include <linux/slab.h>
     24#include <linux/kernel.h>
     25#include <linux/string.h>
     26#include <linux/skbuff.h>
     27#include <net/sock.h>
     28#include <net/tcp_states.h>
     29#include <net/x25.h>
     30
     31/*
     32 *	This routine purges all of the queues of frames.
     33 */
     34void x25_clear_queues(struct sock *sk)
     35{
     36	struct x25_sock *x25 = x25_sk(sk);
     37
     38	skb_queue_purge(&sk->sk_write_queue);
     39	skb_queue_purge(&x25->ack_queue);
     40	skb_queue_purge(&x25->interrupt_in_queue);
     41	skb_queue_purge(&x25->interrupt_out_queue);
     42	skb_queue_purge(&x25->fragment_queue);
     43}
     44
     45
     46/*
     47 * This routine purges the input queue of those frames that have been
     48 * acknowledged. This replaces the boxes labelled "V(a) <- N(r)" on the
     49 * SDL diagram.
     50*/
     51void x25_frames_acked(struct sock *sk, unsigned short nr)
     52{
     53	struct sk_buff *skb;
     54	struct x25_sock *x25 = x25_sk(sk);
     55	int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
     56
     57	/*
     58	 * Remove all the ack-ed frames from the ack queue.
     59	 */
     60	if (x25->va != nr)
     61		while (skb_peek(&x25->ack_queue) && x25->va != nr) {
     62			skb = skb_dequeue(&x25->ack_queue);
     63			kfree_skb(skb);
     64			x25->va = (x25->va + 1) % modulus;
     65		}
     66}
     67
     68void x25_requeue_frames(struct sock *sk)
     69{
     70	struct sk_buff *skb, *skb_prev = NULL;
     71
     72	/*
     73	 * Requeue all the un-ack-ed frames on the output queue to be picked
     74	 * up by x25_kick. This arrangement handles the possibility of an empty
     75	 * output queue.
     76	 */
     77	while ((skb = skb_dequeue(&x25_sk(sk)->ack_queue)) != NULL) {
     78		if (!skb_prev)
     79			skb_queue_head(&sk->sk_write_queue, skb);
     80		else
     81			skb_append(skb_prev, skb, &sk->sk_write_queue);
     82		skb_prev = skb;
     83	}
     84}
     85
     86/*
     87 *	Validate that the value of nr is between va and vs. Return true or
     88 *	false for testing.
     89 */
     90int x25_validate_nr(struct sock *sk, unsigned short nr)
     91{
     92	struct x25_sock *x25 = x25_sk(sk);
     93	unsigned short vc = x25->va;
     94	int modulus = x25->neighbour->extended ? X25_EMODULUS : X25_SMODULUS;
     95
     96	while (vc != x25->vs) {
     97		if (nr == vc)
     98			return 1;
     99		vc = (vc + 1) % modulus;
    100	}
    101
    102	return nr == x25->vs ? 1 : 0;
    103}
    104
    105/*
    106 *  This routine is called when the packet layer internally generates a
    107 *  control frame.
    108 */
    109void x25_write_internal(struct sock *sk, int frametype)
    110{
    111	struct x25_sock *x25 = x25_sk(sk);
    112	struct sk_buff *skb;
    113	unsigned char  *dptr;
    114	unsigned char  facilities[X25_MAX_FAC_LEN];
    115	unsigned char  addresses[1 + X25_ADDR_LEN];
    116	unsigned char  lci1, lci2;
    117	/*
    118	 *	Default safe frame size.
    119	 */
    120	int len = X25_MAX_L2_LEN + X25_EXT_MIN_LEN;
    121
    122	/*
    123	 *	Adjust frame size.
    124	 */
    125	switch (frametype) {
    126	case X25_CALL_REQUEST:
    127		len += 1 + X25_ADDR_LEN + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
    128		break;
    129	case X25_CALL_ACCEPTED: /* fast sel with no restr on resp */
    130		if (x25->facilities.reverse & 0x80) {
    131			len += 1 + X25_MAX_FAC_LEN + X25_MAX_CUD_LEN;
    132		} else {
    133			len += 1 + X25_MAX_FAC_LEN;
    134		}
    135		break;
    136	case X25_CLEAR_REQUEST:
    137	case X25_RESET_REQUEST:
    138		len += 2;
    139		break;
    140	case X25_RR:
    141	case X25_RNR:
    142	case X25_REJ:
    143	case X25_CLEAR_CONFIRMATION:
    144	case X25_INTERRUPT_CONFIRMATION:
    145	case X25_RESET_CONFIRMATION:
    146		break;
    147	default:
    148		pr_err("invalid frame type %02X\n", frametype);
    149		return;
    150	}
    151
    152	if ((skb = alloc_skb(len, GFP_ATOMIC)) == NULL)
    153		return;
    154
    155	/*
    156	 *	Space for Ethernet and 802.2 LLC headers.
    157	 */
    158	skb_reserve(skb, X25_MAX_L2_LEN);
    159
    160	/*
    161	 *	Make space for the GFI and LCI, and fill them in.
    162	 */
    163	dptr = skb_put(skb, 2);
    164
    165	lci1 = (x25->lci >> 8) & 0x0F;
    166	lci2 = (x25->lci >> 0) & 0xFF;
    167
    168	if (x25->neighbour->extended) {
    169		*dptr++ = lci1 | X25_GFI_EXTSEQ;
    170		*dptr++ = lci2;
    171	} else {
    172		*dptr++ = lci1 | X25_GFI_STDSEQ;
    173		*dptr++ = lci2;
    174	}
    175
    176	/*
    177	 *	Now fill in the frame type specific information.
    178	 */
    179	switch (frametype) {
    180
    181		case X25_CALL_REQUEST:
    182			dptr    = skb_put(skb, 1);
    183			*dptr++ = X25_CALL_REQUEST;
    184			len     = x25_addr_aton(addresses, &x25->dest_addr,
    185						&x25->source_addr);
    186			skb_put_data(skb, addresses, len);
    187			len     = x25_create_facilities(facilities,
    188					&x25->facilities,
    189					&x25->dte_facilities,
    190					x25->neighbour->global_facil_mask);
    191			skb_put_data(skb, facilities, len);
    192			skb_put_data(skb, x25->calluserdata.cuddata,
    193				     x25->calluserdata.cudlength);
    194			x25->calluserdata.cudlength = 0;
    195			break;
    196
    197		case X25_CALL_ACCEPTED:
    198			dptr    = skb_put(skb, 2);
    199			*dptr++ = X25_CALL_ACCEPTED;
    200			*dptr++ = 0x00;		/* Address lengths */
    201			len     = x25_create_facilities(facilities,
    202							&x25->facilities,
    203							&x25->dte_facilities,
    204							x25->vc_facil_mask);
    205			skb_put_data(skb, facilities, len);
    206
    207			/* fast select with no restriction on response
    208				allows call user data. Userland must
    209				ensure it is ours and not theirs */
    210			if(x25->facilities.reverse & 0x80) {
    211				skb_put_data(skb,
    212					     x25->calluserdata.cuddata,
    213					     x25->calluserdata.cudlength);
    214			}
    215			x25->calluserdata.cudlength = 0;
    216			break;
    217
    218		case X25_CLEAR_REQUEST:
    219			dptr    = skb_put(skb, 3);
    220			*dptr++ = frametype;
    221			*dptr++ = x25->causediag.cause;
    222			*dptr++ = x25->causediag.diagnostic;
    223			break;
    224
    225		case X25_RESET_REQUEST:
    226			dptr    = skb_put(skb, 3);
    227			*dptr++ = frametype;
    228			*dptr++ = 0x00;		/* XXX */
    229			*dptr++ = 0x00;		/* XXX */
    230			break;
    231
    232		case X25_RR:
    233		case X25_RNR:
    234		case X25_REJ:
    235			if (x25->neighbour->extended) {
    236				dptr     = skb_put(skb, 2);
    237				*dptr++  = frametype;
    238				*dptr++  = (x25->vr << 1) & 0xFE;
    239			} else {
    240				dptr     = skb_put(skb, 1);
    241				*dptr    = frametype;
    242				*dptr++ |= (x25->vr << 5) & 0xE0;
    243			}
    244			break;
    245
    246		case X25_CLEAR_CONFIRMATION:
    247		case X25_INTERRUPT_CONFIRMATION:
    248		case X25_RESET_CONFIRMATION:
    249			dptr  = skb_put(skb, 1);
    250			*dptr = frametype;
    251			break;
    252	}
    253
    254	x25_transmit_link(skb, x25->neighbour);
    255}
    256
    257/*
    258 *	Unpick the contents of the passed X.25 Packet Layer frame.
    259 */
    260int x25_decode(struct sock *sk, struct sk_buff *skb, int *ns, int *nr, int *q,
    261	       int *d, int *m)
    262{
    263	struct x25_sock *x25 = x25_sk(sk);
    264	unsigned char *frame;
    265
    266	if (!pskb_may_pull(skb, X25_STD_MIN_LEN))
    267		return X25_ILLEGAL;
    268	frame = skb->data;
    269
    270	*ns = *nr = *q = *d = *m = 0;
    271
    272	switch (frame[2]) {
    273	case X25_CALL_REQUEST:
    274	case X25_CALL_ACCEPTED:
    275	case X25_CLEAR_REQUEST:
    276	case X25_CLEAR_CONFIRMATION:
    277	case X25_INTERRUPT:
    278	case X25_INTERRUPT_CONFIRMATION:
    279	case X25_RESET_REQUEST:
    280	case X25_RESET_CONFIRMATION:
    281	case X25_RESTART_REQUEST:
    282	case X25_RESTART_CONFIRMATION:
    283	case X25_REGISTRATION_REQUEST:
    284	case X25_REGISTRATION_CONFIRMATION:
    285	case X25_DIAGNOSTIC:
    286		return frame[2];
    287	}
    288
    289	if (x25->neighbour->extended) {
    290		if (frame[2] == X25_RR  ||
    291		    frame[2] == X25_RNR ||
    292		    frame[2] == X25_REJ) {
    293			if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
    294				return X25_ILLEGAL;
    295			frame = skb->data;
    296
    297			*nr = (frame[3] >> 1) & 0x7F;
    298			return frame[2];
    299		}
    300	} else {
    301		if ((frame[2] & 0x1F) == X25_RR  ||
    302		    (frame[2] & 0x1F) == X25_RNR ||
    303		    (frame[2] & 0x1F) == X25_REJ) {
    304			*nr = (frame[2] >> 5) & 0x07;
    305			return frame[2] & 0x1F;
    306		}
    307	}
    308
    309	if (x25->neighbour->extended) {
    310		if ((frame[2] & 0x01) == X25_DATA) {
    311			if (!pskb_may_pull(skb, X25_EXT_MIN_LEN))
    312				return X25_ILLEGAL;
    313			frame = skb->data;
    314
    315			*q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
    316			*d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
    317			*m  = (frame[3] & X25_EXT_M_BIT) == X25_EXT_M_BIT;
    318			*nr = (frame[3] >> 1) & 0x7F;
    319			*ns = (frame[2] >> 1) & 0x7F;
    320			return X25_DATA;
    321		}
    322	} else {
    323		if ((frame[2] & 0x01) == X25_DATA) {
    324			*q  = (frame[0] & X25_Q_BIT) == X25_Q_BIT;
    325			*d  = (frame[0] & X25_D_BIT) == X25_D_BIT;
    326			*m  = (frame[2] & X25_STD_M_BIT) == X25_STD_M_BIT;
    327			*nr = (frame[2] >> 5) & 0x07;
    328			*ns = (frame[2] >> 1) & 0x07;
    329			return X25_DATA;
    330		}
    331	}
    332
    333	pr_debug("invalid PLP frame %3ph\n", frame);
    334
    335	return X25_ILLEGAL;
    336}
    337
    338void x25_disconnect(struct sock *sk, int reason, unsigned char cause,
    339		    unsigned char diagnostic)
    340{
    341	struct x25_sock *x25 = x25_sk(sk);
    342
    343	x25_clear_queues(sk);
    344	x25_stop_timer(sk);
    345
    346	x25->lci   = 0;
    347	x25->state = X25_STATE_0;
    348
    349	x25->causediag.cause      = cause;
    350	x25->causediag.diagnostic = diagnostic;
    351
    352	sk->sk_state     = TCP_CLOSE;
    353	sk->sk_err       = reason;
    354	sk->sk_shutdown |= SEND_SHUTDOWN;
    355
    356	if (!sock_flag(sk, SOCK_DEAD)) {
    357		sk->sk_state_change(sk);
    358		sock_set_flag(sk, SOCK_DEAD);
    359	}
    360	if (x25->neighbour) {
    361		read_lock_bh(&x25_list_lock);
    362		x25_neigh_put(x25->neighbour);
    363		x25->neighbour = NULL;
    364		read_unlock_bh(&x25_list_lock);
    365	}
    366}
    367
    368/*
    369 * Clear an own-rx-busy condition and tell the peer about this, provided
    370 * that there is a significant amount of free receive buffer space available.
    371 */
    372void x25_check_rbuf(struct sock *sk)
    373{
    374	struct x25_sock *x25 = x25_sk(sk);
    375
    376	if (atomic_read(&sk->sk_rmem_alloc) < (sk->sk_rcvbuf >> 1) &&
    377	    (x25->condition & X25_COND_OWN_RX_BUSY)) {
    378		x25->condition &= ~X25_COND_OWN_RX_BUSY;
    379		x25->condition &= ~X25_COND_ACK_PENDING;
    380		x25->vl         = x25->vr;
    381		x25_write_internal(sk, X25_RR);
    382		x25_stop_timer(sk);
    383	}
    384}