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-rw-r--r--net/x25/x25_facilities.c350
1 files changed, 350 insertions, 0 deletions
diff --git a/net/x25/x25_facilities.c b/net/x25/x25_facilities.c
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index 000000000..8e1a49b0c
--- /dev/null
+++ b/net/x25/x25_facilities.c
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * X.25 Packet Layer release 002
+ *
+ * This is ALPHA test software. This code may break your machine,
+ * randomly fail to work with new releases, misbehave and/or generally
+ * screw up. It might even work.
+ *
+ * This code REQUIRES 2.1.15 or higher
+ *
+ * History
+ * X.25 001 Split from x25_subr.c
+ * mar/20/00 Daniela Squassoni Disabling/enabling of facilities
+ * negotiation.
+ * apr/14/05 Shaun Pereira - Allow fast select with no restriction
+ * on response.
+ */
+
+#define pr_fmt(fmt) "X25: " fmt
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/x25.h>
+
+/**
+ * x25_parse_facilities - Parse facilities from skb into the facilities structs
+ *
+ * @skb: sk_buff to parse
+ * @facilities: Regular facilities, updated as facilities are found
+ * @dte_facs: ITU DTE facilities, updated as DTE facilities are found
+ * @vc_fac_mask: mask is updated with all facilities found
+ *
+ * Return codes:
+ * -1 - Parsing error, caller should drop call and clean up
+ * 0 - Parse OK, this skb has no facilities
+ * >0 - Parse OK, returns the length of the facilities header
+ *
+ */
+int x25_parse_facilities(struct sk_buff *skb, struct x25_facilities *facilities,
+ struct x25_dte_facilities *dte_facs, unsigned long *vc_fac_mask)
+{
+ unsigned char *p;
+ unsigned int len;
+
+ *vc_fac_mask = 0;
+
+ /*
+ * The kernel knows which facilities were set on an incoming call but
+ * currently this information is not available to userspace. Here we
+ * give userspace who read incoming call facilities 0 length to indicate
+ * it wasn't set.
+ */
+ dte_facs->calling_len = 0;
+ dte_facs->called_len = 0;
+ memset(dte_facs->called_ae, '\0', sizeof(dte_facs->called_ae));
+ memset(dte_facs->calling_ae, '\0', sizeof(dte_facs->calling_ae));
+
+ if (!pskb_may_pull(skb, 1))
+ return 0;
+
+ len = skb->data[0];
+
+ if (!pskb_may_pull(skb, 1 + len))
+ return -1;
+
+ p = skb->data + 1;
+
+ while (len > 0) {
+ switch (*p & X25_FAC_CLASS_MASK) {
+ case X25_FAC_CLASS_A:
+ if (len < 2)
+ return -1;
+ switch (*p) {
+ case X25_FAC_REVERSE:
+ if((p[1] & 0x81) == 0x81) {
+ facilities->reverse = p[1] & 0x81;
+ *vc_fac_mask |= X25_MASK_REVERSE;
+ break;
+ }
+
+ if((p[1] & 0x01) == 0x01) {
+ facilities->reverse = p[1] & 0x01;
+ *vc_fac_mask |= X25_MASK_REVERSE;
+ break;
+ }
+
+ if((p[1] & 0x80) == 0x80) {
+ facilities->reverse = p[1] & 0x80;
+ *vc_fac_mask |= X25_MASK_REVERSE;
+ break;
+ }
+
+ if(p[1] == 0x00) {
+ facilities->reverse
+ = X25_DEFAULT_REVERSE;
+ *vc_fac_mask |= X25_MASK_REVERSE;
+ break;
+ }
+ fallthrough;
+ case X25_FAC_THROUGHPUT:
+ facilities->throughput = p[1];
+ *vc_fac_mask |= X25_MASK_THROUGHPUT;
+ break;
+ case X25_MARKER:
+ break;
+ default:
+ pr_debug("unknown facility "
+ "%02X, value %02X\n",
+ p[0], p[1]);
+ break;
+ }
+ p += 2;
+ len -= 2;
+ break;
+ case X25_FAC_CLASS_B:
+ if (len < 3)
+ return -1;
+ switch (*p) {
+ case X25_FAC_PACKET_SIZE:
+ facilities->pacsize_in = p[1];
+ facilities->pacsize_out = p[2];
+ *vc_fac_mask |= X25_MASK_PACKET_SIZE;
+ break;
+ case X25_FAC_WINDOW_SIZE:
+ facilities->winsize_in = p[1];
+ facilities->winsize_out = p[2];
+ *vc_fac_mask |= X25_MASK_WINDOW_SIZE;
+ break;
+ default:
+ pr_debug("unknown facility "
+ "%02X, values %02X, %02X\n",
+ p[0], p[1], p[2]);
+ break;
+ }
+ p += 3;
+ len -= 3;
+ break;
+ case X25_FAC_CLASS_C:
+ if (len < 4)
+ return -1;
+ pr_debug("unknown facility %02X, "
+ "values %02X, %02X, %02X\n",
+ p[0], p[1], p[2], p[3]);
+ p += 4;
+ len -= 4;
+ break;
+ case X25_FAC_CLASS_D:
+ if (len < p[1] + 2)
+ return -1;
+ switch (*p) {
+ case X25_FAC_CALLING_AE:
+ if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
+ return -1;
+ if (p[2] > X25_MAX_AE_LEN)
+ return -1;
+ dte_facs->calling_len = p[2];
+ memcpy(dte_facs->calling_ae, &p[3], p[1] - 1);
+ *vc_fac_mask |= X25_MASK_CALLING_AE;
+ break;
+ case X25_FAC_CALLED_AE:
+ if (p[1] > X25_MAX_DTE_FACIL_LEN || p[1] <= 1)
+ return -1;
+ if (p[2] > X25_MAX_AE_LEN)
+ return -1;
+ dte_facs->called_len = p[2];
+ memcpy(dte_facs->called_ae, &p[3], p[1] - 1);
+ *vc_fac_mask |= X25_MASK_CALLED_AE;
+ break;
+ default:
+ pr_debug("unknown facility %02X,"
+ "length %d\n", p[0], p[1]);
+ break;
+ }
+ len -= p[1] + 2;
+ p += p[1] + 2;
+ break;
+ }
+ }
+
+ return p - skb->data;
+}
+
+/*
+ * Create a set of facilities.
+ */
+int x25_create_facilities(unsigned char *buffer,
+ struct x25_facilities *facilities,
+ struct x25_dte_facilities *dte_facs, unsigned long facil_mask)
+{
+ unsigned char *p = buffer + 1;
+ int len;
+
+ if (!facil_mask) {
+ /*
+ * Length of the facilities field in call_req or
+ * call_accept packets
+ */
+ buffer[0] = 0;
+ len = 1; /* 1 byte for the length field */
+ return len;
+ }
+
+ if (facilities->reverse && (facil_mask & X25_MASK_REVERSE)) {
+ *p++ = X25_FAC_REVERSE;
+ *p++ = facilities->reverse;
+ }
+
+ if (facilities->throughput && (facil_mask & X25_MASK_THROUGHPUT)) {
+ *p++ = X25_FAC_THROUGHPUT;
+ *p++ = facilities->throughput;
+ }
+
+ if ((facilities->pacsize_in || facilities->pacsize_out) &&
+ (facil_mask & X25_MASK_PACKET_SIZE)) {
+ *p++ = X25_FAC_PACKET_SIZE;
+ *p++ = facilities->pacsize_in ? : facilities->pacsize_out;
+ *p++ = facilities->pacsize_out ? : facilities->pacsize_in;
+ }
+
+ if ((facilities->winsize_in || facilities->winsize_out) &&
+ (facil_mask & X25_MASK_WINDOW_SIZE)) {
+ *p++ = X25_FAC_WINDOW_SIZE;
+ *p++ = facilities->winsize_in ? : facilities->winsize_out;
+ *p++ = facilities->winsize_out ? : facilities->winsize_in;
+ }
+
+ if (facil_mask & (X25_MASK_CALLING_AE|X25_MASK_CALLED_AE)) {
+ *p++ = X25_MARKER;
+ *p++ = X25_DTE_SERVICES;
+ }
+
+ if (dte_facs->calling_len && (facil_mask & X25_MASK_CALLING_AE)) {
+ unsigned int bytecount = (dte_facs->calling_len + 1) >> 1;
+ *p++ = X25_FAC_CALLING_AE;
+ *p++ = 1 + bytecount;
+ *p++ = dte_facs->calling_len;
+ memcpy(p, dte_facs->calling_ae, bytecount);
+ p += bytecount;
+ }
+
+ if (dte_facs->called_len && (facil_mask & X25_MASK_CALLED_AE)) {
+ unsigned int bytecount = (dte_facs->called_len % 2) ?
+ dte_facs->called_len / 2 + 1 :
+ dte_facs->called_len / 2;
+ *p++ = X25_FAC_CALLED_AE;
+ *p++ = 1 + bytecount;
+ *p++ = dte_facs->called_len;
+ memcpy(p, dte_facs->called_ae, bytecount);
+ p+=bytecount;
+ }
+
+ len = p - buffer;
+ buffer[0] = len - 1;
+
+ return len;
+}
+
+/*
+ * Try to reach a compromise on a set of facilities.
+ *
+ * The only real problem is with reverse charging.
+ */
+int x25_negotiate_facilities(struct sk_buff *skb, struct sock *sk,
+ struct x25_facilities *new, struct x25_dte_facilities *dte)
+{
+ struct x25_sock *x25 = x25_sk(sk);
+ struct x25_facilities *ours = &x25->facilities;
+ struct x25_facilities theirs;
+ int len;
+
+ memset(&theirs, 0, sizeof(theirs));
+ memcpy(new, ours, sizeof(*new));
+ memset(dte, 0, sizeof(*dte));
+
+ len = x25_parse_facilities(skb, &theirs, dte, &x25->vc_facil_mask);
+ if (len < 0)
+ return len;
+
+ /*
+ * They want reverse charging, we won't accept it.
+ */
+ if ((theirs.reverse & 0x01 ) && (ours->reverse & 0x01)) {
+ SOCK_DEBUG(sk, "X.25: rejecting reverse charging request\n");
+ return -1;
+ }
+
+ new->reverse = theirs.reverse;
+
+ if (theirs.throughput) {
+ int theirs_in = theirs.throughput & 0x0f;
+ int theirs_out = theirs.throughput & 0xf0;
+ int ours_in = ours->throughput & 0x0f;
+ int ours_out = ours->throughput & 0xf0;
+ if (!ours_in || theirs_in < ours_in) {
+ SOCK_DEBUG(sk, "X.25: inbound throughput negotiated\n");
+ new->throughput = (new->throughput & 0xf0) | theirs_in;
+ }
+ if (!ours_out || theirs_out < ours_out) {
+ SOCK_DEBUG(sk,
+ "X.25: outbound throughput negotiated\n");
+ new->throughput = (new->throughput & 0x0f) | theirs_out;
+ }
+ }
+
+ if (theirs.pacsize_in && theirs.pacsize_out) {
+ if (theirs.pacsize_in < ours->pacsize_in) {
+ SOCK_DEBUG(sk, "X.25: packet size inwards negotiated down\n");
+ new->pacsize_in = theirs.pacsize_in;
+ }
+ if (theirs.pacsize_out < ours->pacsize_out) {
+ SOCK_DEBUG(sk, "X.25: packet size outwards negotiated down\n");
+ new->pacsize_out = theirs.pacsize_out;
+ }
+ }
+
+ if (theirs.winsize_in && theirs.winsize_out) {
+ if (theirs.winsize_in < ours->winsize_in) {
+ SOCK_DEBUG(sk, "X.25: window size inwards negotiated down\n");
+ new->winsize_in = theirs.winsize_in;
+ }
+ if (theirs.winsize_out < ours->winsize_out) {
+ SOCK_DEBUG(sk, "X.25: window size outwards negotiated down\n");
+ new->winsize_out = theirs.winsize_out;
+ }
+ }
+
+ return len;
+}
+
+/*
+ * Limit values of certain facilities according to the capability of the
+ * currently attached x25 link.
+ */
+void x25_limit_facilities(struct x25_facilities *facilities,
+ struct x25_neigh *nb)
+{
+
+ if (!nb->extended) {
+ if (facilities->winsize_in > 7) {
+ pr_debug("incoming winsize limited to 7\n");
+ facilities->winsize_in = 7;
+ }
+ if (facilities->winsize_out > 7) {
+ facilities->winsize_out = 7;
+ pr_debug("outgoing winsize limited to 7\n");
+ }
+ }
+}
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