Import sources from 2011-03-30 iso image

1 files changed, 376 insertions, 0 deletions

diff --git a/sys/src/cmd/ssh/cmsg.c b/sys/src/cmd/ssh/cmsg.c
new file mode 100755
index 000000000..f72f2f33b
--- /dev/null
+++ b/sys/src/cmd/ssh/cmsg.c
@@ -0,0 +1,376 @@
+#include "ssh.h"
+
+static void
+recv_ssh_smsg_public_key(Conn *c)
+{
+	Msg *m;
+
+	m = recvmsg(c, SSH_SMSG_PUBLIC_KEY);
+	memmove(c->cookie, getbytes(m, COOKIELEN), COOKIELEN);
+	c->serverkey = getRSApub(m);
+	c->hostkey = getRSApub(m);
+	c->flags = getlong(m);
+	c->ciphermask = getlong(m);
+	c->authmask = getlong(m);
+	free(m);
+}
+
+static void
+send_ssh_cmsg_session_key(Conn *c)
+{
+	int i, n, buflen, serverkeylen, hostkeylen;
+	mpint *b;
+	uchar *buf;
+	Msg *m;
+	RSApub *ksmall, *kbig;
+
+	m = allocmsg(c, SSH_CMSG_SESSION_KEY, 2048);
+	putbyte(m, c->cipher->id);
+	putbytes(m, c->cookie, COOKIELEN);
+
+	serverkeylen = mpsignif(c->serverkey->n);
+	hostkeylen = mpsignif(c->hostkey->n);
+	ksmall = kbig = nil;
+	if(serverkeylen+128 <= hostkeylen){
+		ksmall = c->serverkey;
+		kbig = c->hostkey;
+	}else if(hostkeylen+128 <= serverkeylen){
+		ksmall = c->hostkey;
+		kbig = c->serverkey;
+	}else
+		error("server session and host keys do not differ by at least 128 bits");
+	
+	buflen = (mpsignif(kbig->n)+7)/8;
+	buf = emalloc(buflen);
+
+	debug(DBG_CRYPTO, "session key is %.*H\n", SESSKEYLEN, c->sesskey);
+	memmove(buf, c->sesskey, SESSKEYLEN);
+	for(i = 0; i < SESSIDLEN; i++)
+		buf[i] ^= c->sessid[i];
+	debug(DBG_CRYPTO, "munged session key is %.*H\n", SESSKEYLEN, buf);
+
+	b = rsaencryptbuf(ksmall, buf, SESSKEYLEN);
+	n = (mpsignif(ksmall->n)+7) / 8;
+	mptoberjust(b, buf, n);
+	mpfree(b);
+	debug(DBG_CRYPTO, "encrypted with ksmall is %.*H\n", n, buf);
+
+	b = rsaencryptbuf(kbig, buf, n);
+	putmpint(m, b);
+	debug(DBG_CRYPTO, "encrypted with kbig is %B\n", b);
+	mpfree(b);
+
+	memset(buf, 0, buflen);
+	free(buf);
+
+	putlong(m, c->flags);
+	sendmsg(m);
+}
+
+static int
+authuser(Conn *c)
+{
+	int i;
+	Msg *m;
+
+	m = allocmsg(c, SSH_CMSG_USER, 4+strlen(c->user));
+	putstring(m, c->user);
+	sendmsg(m);
+
+	m = recvmsg(c, -1);
+	switch(m->type){
+	case SSH_SMSG_SUCCESS:
+		free(m);
+		return 0;
+	case SSH_SMSG_FAILURE:
+		free(m);
+		break;
+	default:
+		badmsg(m, 0);
+	}
+
+	for(i=0; i<c->nokauth; i++){
+		debug(DBG_AUTH, "authmask %#lux, consider %s (%#x)\n",
+			c->authmask, c->okauth[i]->name, 1<<c->okauth[i]->id);
+		if(c->authmask & (1<<c->okauth[i]->id))
+			if((*c->okauth[i]->fn)(c) == 0)
+				return 0;
+	}
+
+	debug(DBG_AUTH, "no auth methods worked; (authmask=%#lux)\n", c->authmask);
+	return -1;
+}
+
+static char
+ask(Conn *c, char *answers, char *question)
+{
+	int fd;
+	char buf[256];
+
+	if(!c->interactive)
+		return answers[0];
+
+	if((fd = open("/dev/cons", ORDWR)) < 0)
+		return answers[0];
+
+	fprint(fd, "%s", question);
+	if(read(fd, buf, 256) <= 0 || buf[0]=='\n'){
+		close(fd);
+		return answers[0];
+	}
+	close(fd);
+	return buf[0];
+}
+static void
+checkkey(Conn *c)
+{
+	char *home, *keyfile;
+
+	debug(DBG_CRYPTO, "checking key %B %B\n", c->hostkey->n, c->hostkey->ek);
+	switch(findkey("/sys/lib/ssh/keyring", c->aliases, c->hostkey)){
+	default:
+		abort();
+	case KeyOk:
+		return;
+	case KeyWrong:
+		fprint(2, "server presented public key different than expected\n");
+		fprint(2, "(expected key in /sys/lib/ssh/keyring).  will not continue.\n");
+		error("bad server key");
+
+	case NoKey:
+	case NoKeyFile:
+		break;
+	}
+
+	home = getenv("home");
+	if(home == nil){
+		fprint(2, "server %s not on keyring; will not continue.\n", c->host);
+		error("bad server key");
+	}
+	
+	keyfile = smprint("%s/lib/keyring", home);
+	if(keyfile == nil)
+		error("out of memory");
+
+	switch(findkey(keyfile, c->aliases, c->hostkey)){
+	default:
+		abort();
+	case KeyOk:
+		return;
+	case KeyWrong:
+		fprint(2, "server %s presented public key different than expected\n", c->host);
+		fprint(2, "(expected key in %s).  will not continue.\n", keyfile);
+		fprint(2, "this could be a man-in-the-middle attack.\n");
+		switch(ask(c, "eri", "replace key in keyfile (r), continue without replacing key (c), or exit (e) [e]")){
+		case 'e':
+			error("bad key");
+		case 'r':
+			if(replacekey(keyfile, c->aliases, c->hostkey) < 0)
+				error("replacekey: %r");
+			break;
+		case 'c':
+			break;
+		}
+		return;
+	case NoKey:
+	case NoKeyFile:
+		fprint(2, "server %s not on keyring.\n", c->host);
+		switch(ask(c, "eac", "add key to keyfile (a), continue without adding key (c), or exit (e) [e]")){
+		case 'e':
+			error("bad key");
+		case 'a':
+			if(appendkey(keyfile, c->aliases, c->hostkey) < 0)
+				error("appendkey: %r");
+			break;
+		case 'c':
+			break;
+		}
+		return;
+	}
+}
+
+void
+sshclienthandshake(Conn *c)
+{
+	char buf[128], *p;
+	int i;
+	Msg *m;
+
+	/* receive id string */
+	if(readstrnl(c->fd[0], buf, sizeof buf) < 0)
+		error("reading server version: %r");
+
+	/* id string is "SSH-m.n-comment".  We need m=1, n>=5. */
+	if(strncmp(buf, "SSH-", 4) != 0
+	|| strtol(buf+4, &p, 10) != 1
+	|| *p != '.'
+	|| strtol(p+1, &p, 10) < 5
+	|| *p != '-')
+		error("protocol mismatch; got %s, need SSH-1.x for x>=5", buf);
+
+	/* send id string */
+	fprint(c->fd[1], "SSH-1.5-Plan 9\n");
+
+	recv_ssh_smsg_public_key(c);
+	checkkey(c);
+
+	for(i=0; i<SESSKEYLEN; i++)
+		c->sesskey[i] = fastrand();
+	c->cipher = nil;
+	for(i=0; i<c->nokcipher; i++)
+		if((1<<c->okcipher[i]->id) & c->ciphermask){
+			c->cipher = c->okcipher[i];
+			break;
+		}
+	if(c->cipher == nil)
+		error("can't agree on ciphers: remote side supports %#lux", c->ciphermask);
+
+	calcsessid(c);
+
+	send_ssh_cmsg_session_key(c);
+
+	c->cstate = (*c->cipher->init)(c, 0);		/* turns on encryption */
+	m = recvmsg(c, SSH_SMSG_SUCCESS);
+	free(m);
+	
+	if(authuser(c) < 0)
+		error("client authentication failed");
+}
+
+static int
+intgetenv(char *name, int def)
+{
+	char *s;
+	int n, val;
+
+	val = def;
+	if((s = getenv(name))!=nil){
+		if((n=atoi(s)) > 0)
+			val = n;
+		free(s);
+	}
+	return val;
+}
+
+/*
+ * assumes that if you care, you're running under vt
+ * and therefore these are set.
+ */
+int
+readgeom(int *nrow, int *ncol, int *width, int *height)
+{
+	static int fd = -1;
+	char buf[64];
+
+	if(fd < 0 && (fd = open("/dev/wctl", OREAD)) < 0)
+		return -1;
+	/* wait for event, but don't care what it says */
+	if(read(fd, buf, sizeof buf) < 0)
+		return -1;
+	*nrow = intgetenv("LINES", 24);
+	*ncol = intgetenv("COLS", 80);
+	*width = intgetenv("XPIXELS", 640);
+	*height = intgetenv("YPIXELS", 480);
+	return 0;
+}
+
+void
+sendwindowsize(Conn *c, int nrow, int ncol, int width, int height)
+{
+	Msg *m;
+
+	m = allocmsg(c, SSH_CMSG_WINDOW_SIZE, 4*4);
+	putlong(m, nrow);
+	putlong(m, ncol);
+	putlong(m, width);
+	putlong(m, height);
+	sendmsg(m);
+}
+
+/*
+ * In each option line, the first byte is the option number
+ * and the second is either a boolean bit or actually an
+ * ASCII code.
+ */
+static uchar ptyopt[] =
+{
+	0x01, 0x7F,	/* interrupt = DEL */
+	0x02, 0x11,	/* quit = ^Q */
+	0x03, 0x08,	/* backspace = ^H */
+	0x04, 0x15,	/* line kill = ^U */
+	0x05, 0x04,	/* EOF = ^D */
+	0x20, 0x00,	/* don't strip high bit */
+	0x48, 0x01,	/* give us CRs */
+
+	0x00,		/* end options */
+};
+
+static uchar rawptyopt[] = 
+{
+	30,	0,		/* ignpar */
+	31,	0,		/* parmrk */
+	32,	0,		/* inpck */
+	33,	0,		/* istrip */
+	34,	0,		/* inlcr */
+	35,	0,		/* igncr */
+	36,	0,		/* icnrl */
+	37,	0,		/* iuclc */
+	38,	0,		/* ixon */
+	39,	1,		/* ixany */
+	40,	0,		/* ixoff */
+	41,	0,		/* imaxbel */
+
+	50,	0,		/* isig: intr, quit, susp processing */
+	51,	0,		/* icanon: erase and kill processing */
+	52,	0,		/* xcase */
+
+	53,	0,		/* echo */
+
+	57,	0,		/* noflsh */
+	58,	0,		/* tostop */
+	59,	0,		/* iexten: impl defined control chars */
+
+	70,	0,		/* opost */
+
+	0x00,
+};
+
+void
+requestpty(Conn *c)
+{
+	char *term;
+	int nrow, ncol, width, height;
+	Msg *m;
+
+	m = allocmsg(c, SSH_CMSG_REQUEST_PTY, 1024);
+	if((term = getenv("TERM")) == nil)
+		term = "9term";
+	putstring(m, term);
+
+	readgeom(&nrow, &ncol, &width, &height);
+	putlong(m, nrow);	/* characters */
+	putlong(m, ncol);
+	putlong(m, width);	/* pixels */
+	putlong(m, height);
+
+	if(rawhack)
+		putbytes(m, rawptyopt, sizeof rawptyopt);
+	else
+		putbytes(m, ptyopt, sizeof ptyopt);
+
+	sendmsg(m);
+
+	m = recvmsg(c, 0);
+	switch(m->type){
+	case SSH_SMSG_SUCCESS:
+		debug(DBG_IO, "PTY allocated\n");
+		break;
+	case SSH_SMSG_FAILURE:
+		debug(DBG_IO, "PTY allocation failed\n");
+		break;
+	default:
+		badmsg(m, 0);
+	}
+	free(m);
+}
+