[qemu.git] / ui / vnc-auth-sasl.c

/*
 * QEMU VNC display driver: SASL auth protocol
 *
 * Copyright (C) 2009 Red Hat, Inc
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "vnc.h"

/* Max amount of data we send/recv for SASL steps to prevent DOS */
#define SASL_DATA_MAX_LEN (1024 * 1024)


void vnc_sasl_client_cleanup(VncState *vs)
{
    if (vs->sasl.conn) {
        vs->sasl.runSSF = false;
        vs->sasl.wantSSF = false;
        vs->sasl.waitWriteSSF = 0;
        vs->sasl.encodedLength = vs->sasl.encodedOffset = 0;
        vs->sasl.encoded = NULL;
        g_free(vs->sasl.username);
        g_free(vs->sasl.mechlist);
        vs->sasl.username = vs->sasl.mechlist = NULL;
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
    }
}


long vnc_client_write_sasl(VncState *vs)
{
    long ret;

    VNC_DEBUG("Write SASL: Pending output %p size %zd offset %zd "
              "Encoded: %p size %d offset %d\n",
              vs->output.buffer, vs->output.capacity, vs->output.offset,
              vs->sasl.encoded, vs->sasl.encodedLength, vs->sasl.encodedOffset);

    if (!vs->sasl.encoded) {
        int err;
        err = sasl_encode(vs->sasl.conn,
                          (char *)vs->output.buffer,
                          vs->output.offset,
                          (const char **)&vs->sasl.encoded,
                          &vs->sasl.encodedLength);
        if (err != SASL_OK)
            return vnc_client_io_error(vs, -1, EIO);

        vs->sasl.encodedOffset = 0;
    }

    ret = vnc_client_write_buf(vs,
                               vs->sasl.encoded + vs->sasl.encodedOffset,
                               vs->sasl.encodedLength - vs->sasl.encodedOffset);
    if (!ret)
        return 0;

    vs->sasl.encodedOffset += ret;
    if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
        vs->output.offset = 0;
        vs->sasl.encoded = NULL;
        vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
    }

    /* Can't merge this block with one above, because
     * someone might have written more unencrypted
     * data in vs->output while we were processing
     * SASL encoded output
     */
    if (vs->output.offset == 0) {
        qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
    }

    return ret;
}


long vnc_client_read_sasl(VncState *vs)
{
    long ret;
    uint8_t encoded[4096];
    const char *decoded;
    unsigned int decodedLen;
    int err;

    ret = vnc_client_read_buf(vs, encoded, sizeof(encoded));
    if (!ret)
        return 0;

    err = sasl_decode(vs->sasl.conn,
                      (char *)encoded, ret,
                      &decoded, &decodedLen);

    if (err != SASL_OK)
        return vnc_client_io_error(vs, -1, -EIO);
    VNC_DEBUG("Read SASL Encoded %p size %ld Decoded %p size %d\n",
              encoded, ret, decoded, decodedLen);
    buffer_reserve(&vs->input, decodedLen);
    buffer_append(&vs->input, decoded, decodedLen);
    return decodedLen;
}


static int vnc_auth_sasl_check_access(VncState *vs)
{
    const void *val;
    int err;
    int allow;

    err = sasl_getprop(vs->sasl.conn, SASL_USERNAME, &val);
    if (err != SASL_OK) {
        VNC_DEBUG("cannot query SASL username on connection %d (%s), denying access\n",
                  err, sasl_errstring(err, NULL, NULL));
        return -1;
    }
    if (val == NULL) {
        VNC_DEBUG("no client username was found, denying access\n");
        return -1;
    }
    VNC_DEBUG("SASL client username %s\n", (const char *)val);

    vs->sasl.username = g_strdup((const char*)val);

    if (vs->vd->sasl.acl == NULL) {
        VNC_DEBUG("no ACL activated, allowing access\n");
        return 0;
    }

    allow = qemu_acl_party_is_allowed(vs->vd->sasl.acl, vs->sasl.username);

    VNC_DEBUG("SASL client %s %s by ACL\n", vs->sasl.username,
              allow ? "allowed" : "denied");
    return allow ? 0 : -1;
}

static int vnc_auth_sasl_check_ssf(VncState *vs)
{
    const void *val;
    int err, ssf;

    if (!vs->sasl.wantSSF)
        return 1;

    err = sasl_getprop(vs->sasl.conn, SASL_SSF, &val);
    if (err != SASL_OK)
        return 0;

    ssf = *(const int *)val;
    VNC_DEBUG("negotiated an SSF of %d\n", ssf);
    if (ssf < 56)
        return 0; /* 56 is good for Kerberos */

    /* Only setup for read initially, because we're about to send an RPC
     * reply which must be in plain text. When the next incoming RPC
     * arrives, we'll switch on writes too
     *
     * cf qemudClientReadSASL  in qemud.c
     */
    vs->sasl.runSSF = 1;

    /* We have a SSF that's good enough */
    return 1;
}

/*
 * Step Msg
 *
 * Input from client:
 *
 * u32 clientin-length
 * u8-array clientin-string
 *
 * Output to client:
 *
 * u32 serverout-length
 * u8-array serverout-strin
 * u8 continue
 */

static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len);

static int protocol_client_auth_sasl_step(VncState *vs, uint8_t *data, size_t len)
{
    uint32_t datalen = len;
    const char *serverout;
    unsigned int serveroutlen;
    int err;
    char *clientdata = NULL;

    /* NB, distinction of NULL vs "" is *critical* in SASL */
    if (datalen) {
        clientdata = (char*)data;
        clientdata[datalen-1] = '\0'; /* Wire includes '\0', but make sure */
        datalen--; /* Don't count NULL byte when passing to _start() */
    }

    VNC_DEBUG("Step using SASL Data %p (%d bytes)\n",
              clientdata, datalen);
    err = sasl_server_step(vs->sasl.conn,
                           clientdata,
                           datalen,
                           &serverout,
                           &serveroutlen);
    if (err != SASL_OK &&
        err != SASL_CONTINUE) {
        VNC_DEBUG("sasl step failed %d (%s)\n",
                  err, sasl_errdetail(vs->sasl.conn));
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }

    if (serveroutlen > SASL_DATA_MAX_LEN) {
        VNC_DEBUG("sasl step reply data too long %d\n",
                  serveroutlen);
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }

    VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
              serveroutlen, serverout ? 0 : 1);

    if (serveroutlen) {
        vnc_write_u32(vs, serveroutlen + 1);
        vnc_write(vs, serverout, serveroutlen + 1);
    } else {
        vnc_write_u32(vs, 0);
    }

    /* Whether auth is complete */
    vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);

    if (err == SASL_CONTINUE) {
        VNC_DEBUG("%s", "Authentication must continue\n");
        /* Wait for step length */
        vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
    } else {
        if (!vnc_auth_sasl_check_ssf(vs)) {
            VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
            goto authreject;
        }

        /* Check username whitelist ACL */
        if (vnc_auth_sasl_check_access(vs) < 0) {
            VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
            goto authreject;
        }

        VNC_DEBUG("Authentication successful %d\n", vs->csock);
        vnc_write_u32(vs, 0); /* Accept auth */
        /*
         * Delay writing in SSF encoded mode until pending output
         * buffer is written
         */
        if (vs->sasl.runSSF)
            vs->sasl.waitWriteSSF = vs->output.offset;
        start_client_init(vs);
    }

    return 0;

 authreject:
    vnc_write_u32(vs, 1); /* Reject auth */
    vnc_write_u32(vs, sizeof("Authentication failed"));
    vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
    vnc_flush(vs);
    vnc_client_error(vs);
    return -1;

 authabort:
    vnc_client_error(vs);
    return -1;
}

static int protocol_client_auth_sasl_step_len(VncState *vs, uint8_t *data, size_t len)
{
    uint32_t steplen = read_u32(data, 0);
    VNC_DEBUG("Got client step len %d\n", steplen);
    if (steplen > SASL_DATA_MAX_LEN) {
        VNC_DEBUG("Too much SASL data %d\n", steplen);
        vnc_client_error(vs);
        return -1;
    }

    if (steplen == 0)
        return protocol_client_auth_sasl_step(vs, NULL, 0);
    else
        vnc_read_when(vs, protocol_client_auth_sasl_step, steplen);
    return 0;
}

/*
 * Start Msg
 *
 * Input from client:
 *
 * u32 clientin-length
 * u8-array clientin-string
 *
 * Output to client:
 *
 * u32 serverout-length
 * u8-array serverout-strin
 * u8 continue
 */

#define SASL_DATA_MAX_LEN (1024 * 1024)

static int protocol_client_auth_sasl_start(VncState *vs, uint8_t *data, size_t len)
{
    uint32_t datalen = len;
    const char *serverout;
    unsigned int serveroutlen;
    int err;
    char *clientdata = NULL;

    /* NB, distinction of NULL vs "" is *critical* in SASL */
    if (datalen) {
        clientdata = (char*)data;
        clientdata[datalen-1] = '\0'; /* Should be on wire, but make sure */
        datalen--; /* Don't count NULL byte when passing to _start() */
    }

    VNC_DEBUG("Start SASL auth with mechanism %s. Data %p (%d bytes)\n",
              vs->sasl.mechlist, clientdata, datalen);
    err = sasl_server_start(vs->sasl.conn,
                            vs->sasl.mechlist,
                            clientdata,
                            datalen,
                            &serverout,
                            &serveroutlen);
    if (err != SASL_OK &&
        err != SASL_CONTINUE) {
        VNC_DEBUG("sasl start failed %d (%s)\n",
                  err, sasl_errdetail(vs->sasl.conn));
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }
    if (serveroutlen > SASL_DATA_MAX_LEN) {
        VNC_DEBUG("sasl start reply data too long %d\n",
                  serveroutlen);
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }

    VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
              serveroutlen, serverout ? 0 : 1);

    if (serveroutlen) {
        vnc_write_u32(vs, serveroutlen + 1);
        vnc_write(vs, serverout, serveroutlen + 1);
    } else {
        vnc_write_u32(vs, 0);
    }

    /* Whether auth is complete */
    vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);

    if (err == SASL_CONTINUE) {
        VNC_DEBUG("%s", "Authentication must continue\n");
        /* Wait for step length */
        vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
    } else {
        if (!vnc_auth_sasl_check_ssf(vs)) {
            VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
            goto authreject;
        }

        /* Check username whitelist ACL */
        if (vnc_auth_sasl_check_access(vs) < 0) {
            VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
            goto authreject;
        }

        VNC_DEBUG("Authentication successful %d\n", vs->csock);
        vnc_write_u32(vs, 0); /* Accept auth */
        start_client_init(vs);
    }

    return 0;

 authreject:
    vnc_write_u32(vs, 1); /* Reject auth */
    vnc_write_u32(vs, sizeof("Authentication failed"));
    vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
    vnc_flush(vs);
    vnc_client_error(vs);
    return -1;

 authabort:
    vnc_client_error(vs);
    return -1;
}

static int protocol_client_auth_sasl_start_len(VncState *vs, uint8_t *data, size_t len)
{
    uint32_t startlen = read_u32(data, 0);
    VNC_DEBUG("Got client start len %d\n", startlen);
    if (startlen > SASL_DATA_MAX_LEN) {
        VNC_DEBUG("Too much SASL data %d\n", startlen);
        vnc_client_error(vs);
        return -1;
    }

    if (startlen == 0)
        return protocol_client_auth_sasl_start(vs, NULL, 0);

    vnc_read_when(vs, protocol_client_auth_sasl_start, startlen);
    return 0;
}

static int protocol_client_auth_sasl_mechname(VncState *vs, uint8_t *data, size_t len)
{
    char *mechname = g_strndup((const char *) data, len);
    VNC_DEBUG("Got client mechname '%s' check against '%s'\n",
              mechname, vs->sasl.mechlist);

    if (strncmp(vs->sasl.mechlist, mechname, len) == 0) {
        if (vs->sasl.mechlist[len] != '\0' &&
            vs->sasl.mechlist[len] != ',') {
            VNC_DEBUG("One %d", vs->sasl.mechlist[len]);
            goto fail;
        }
    } else {
        char *offset = strstr(vs->sasl.mechlist, mechname);
        VNC_DEBUG("Two %p\n", offset);
        if (!offset) {
            goto fail;
        }
        VNC_DEBUG("Two '%s'\n", offset);
        if (offset[-1] != ',' ||
            (offset[len] != '\0'&&
             offset[len] != ',')) {
            goto fail;
        }
    }

    g_free(vs->sasl.mechlist);
    vs->sasl.mechlist = mechname;

    VNC_DEBUG("Validated mechname '%s'\n", mechname);
    vnc_read_when(vs, protocol_client_auth_sasl_start_len, 4);
    return 0;

 fail:
    vnc_client_error(vs);
    g_free(mechname);
    return -1;
}

static int protocol_client_auth_sasl_mechname_len(VncState *vs, uint8_t *data, size_t len)
{
    uint32_t mechlen = read_u32(data, 0);
    VNC_DEBUG("Got client mechname len %d\n", mechlen);
    if (mechlen > 100) {
        VNC_DEBUG("Too long SASL mechname data %d\n", mechlen);
        vnc_client_error(vs);
        return -1;
    }
    if (mechlen < 1) {
        VNC_DEBUG("Too short SASL mechname %d\n", mechlen);
        vnc_client_error(vs);
        return -1;
    }
    vnc_read_when(vs, protocol_client_auth_sasl_mechname,mechlen);
    return 0;
}

void start_auth_sasl(VncState *vs)
{
    const char *mechlist = NULL;
    sasl_security_properties_t secprops;
    int err;
    char *localAddr, *remoteAddr;
    int mechlistlen;

    VNC_DEBUG("Initialize SASL auth %d\n", vs->csock);

    /* Get local & remote client addresses in form  IPADDR;PORT */
    if (!(localAddr = vnc_socket_local_addr("%s;%s", vs->csock)))
        goto authabort;

    if (!(remoteAddr = vnc_socket_remote_addr("%s;%s", vs->csock))) {
        g_free(localAddr);
        goto authabort;
    }

    err = sasl_server_new("vnc",
                          NULL, /* FQDN - just delegates to gethostname */
                          NULL, /* User realm */
                          localAddr,
                          remoteAddr,
                          NULL, /* Callbacks, not needed */
                          SASL_SUCCESS_DATA,
                          &vs->sasl.conn);
    g_free(localAddr);
    g_free(remoteAddr);
    localAddr = remoteAddr = NULL;

    if (err != SASL_OK) {
        VNC_DEBUG("sasl context setup failed %d (%s)",
                  err, sasl_errstring(err, NULL, NULL));
        vs->sasl.conn = NULL;
        goto authabort;
    }

#ifdef CONFIG_VNC_TLS
    /* Inform SASL that we've got an external SSF layer from TLS/x509 */
    if (vs->auth == VNC_AUTH_VENCRYPT &&
        vs->subauth == VNC_AUTH_VENCRYPT_X509SASL) {
        gnutls_cipher_algorithm_t cipher;
        sasl_ssf_t ssf;

        cipher = gnutls_cipher_get(vs->tls.session);
        if (!(ssf = (sasl_ssf_t)gnutls_cipher_get_key_size(cipher))) {
            VNC_DEBUG("%s", "cannot TLS get cipher size\n");
            sasl_dispose(&vs->sasl.conn);
            vs->sasl.conn = NULL;
            goto authabort;
        }
        ssf *= 8; /* tls key size is bytes, sasl wants bits */

        err = sasl_setprop(vs->sasl.conn, SASL_SSF_EXTERNAL, &ssf);
        if (err != SASL_OK) {
            VNC_DEBUG("cannot set SASL external SSF %d (%s)\n",
                      err, sasl_errstring(err, NULL, NULL));
            sasl_dispose(&vs->sasl.conn);
            vs->sasl.conn = NULL;
            goto authabort;
        }
    } else
#endif /* CONFIG_VNC_TLS */
        vs->sasl.wantSSF = 1;

    memset (&secprops, 0, sizeof secprops);
    /* Inform SASL that we've got an external SSF layer from TLS */
    if (strncmp(vs->vd->display, "unix:", 5) == 0
#ifdef CONFIG_VNC_TLS
        /* Disable SSF, if using TLS+x509+SASL only. TLS without x509
           is not sufficiently strong */
        || (vs->auth == VNC_AUTH_VENCRYPT &&
            vs->subauth == VNC_AUTH_VENCRYPT_X509SASL)
#endif /* CONFIG_VNC_TLS */
        ) {
        /* If we've got TLS or UNIX domain sock, we don't care about SSF */
        secprops.min_ssf = 0;
        secprops.max_ssf = 0;
        secprops.maxbufsize = 8192;
        secprops.security_flags = 0;
    } else {
        /* Plain TCP, better get an SSF layer */
        secprops.min_ssf = 56; /* Good enough to require kerberos */
        secprops.max_ssf = 100000; /* Arbitrary big number */
        secprops.maxbufsize = 8192;
        /* Forbid any anonymous or trivially crackable auth */
        secprops.security_flags =
            SASL_SEC_NOANONYMOUS | SASL_SEC_NOPLAINTEXT;
    }

    err = sasl_setprop(vs->sasl.conn, SASL_SEC_PROPS, &secprops);
    if (err != SASL_OK) {
        VNC_DEBUG("cannot set SASL security props %d (%s)\n",
                  err, sasl_errstring(err, NULL, NULL));
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }

    err = sasl_listmech(vs->sasl.conn,
                        NULL, /* Don't need to set user */
                        "", /* Prefix */
                        ",", /* Separator */
                        "", /* Suffix */
                        &mechlist,
                        NULL,
                        NULL);
    if (err != SASL_OK) {
        VNC_DEBUG("cannot list SASL mechanisms %d (%s)\n",
                  err, sasl_errdetail(vs->sasl.conn));
        sasl_dispose(&vs->sasl.conn);
        vs->sasl.conn = NULL;
        goto authabort;
    }
    VNC_DEBUG("Available mechanisms for client: '%s'\n", mechlist);

    vs->sasl.mechlist = g_strdup(mechlist);
    mechlistlen = strlen(mechlist);
    vnc_write_u32(vs, mechlistlen);
    vnc_write(vs, mechlist, mechlistlen);
    vnc_flush(vs);

    VNC_DEBUG("Wait for client mechname length\n");
    vnc_read_when(vs, protocol_client_auth_sasl_mechname_len, 4);

    return;

 authabort:
    vnc_client_error(vs);
}
Commit	Line	Data
2f9606b3 AL	1	/*
	2	* QEMU VNC display driver: SASL auth protocol
	3	*
	4	* Copyright (C) 2009 Red Hat, Inc
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a copy
	7	* of this software and associated documentation files (the "Software"), to deal
	8	* in the Software without restriction, including without limitation the rights
	9	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	10	* copies of the Software, and to permit persons to whom the Software is
	11	* furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice shall be included in
	14	* all copies or substantial portions of the Software.
	15	*
	16	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	17	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	18	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	19	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	20	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	21	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	22	* THE SOFTWARE.
	23	*/
	24
	25	#include "vnc.h"
	26
	27	/* Max amount of data we send/recv for SASL steps to prevent DOS */
	28	#define SASL_DATA_MAX_LEN (1024 * 1024)
	29
	30
	31	void vnc_sasl_client_cleanup(VncState *vs)
	32	{
	33	if (vs->sasl.conn) {
ee032ca1 SW	34	vs->sasl.runSSF = false;
	35	vs->sasl.wantSSF = false;
	36	vs->sasl.waitWriteSSF = 0;
28a76be8 AL	37	vs->sasl.encodedLength = vs->sasl.encodedOffset = 0;
28a76be8 AL	38	vs->sasl.encoded = NULL;
ae878b17	39	g_free(vs->sasl.username);
302d9d6f	40	g_free(vs->sasl.mechlist);
28a76be8 AL	41	vs->sasl.username = vs->sasl.mechlist = NULL;
	42	sasl_dispose(&vs->sasl.conn);
	43	vs->sasl.conn = NULL;
2f9606b3 AL	44	}
	45	}
	46
	47
	48	long vnc_client_write_sasl(VncState *vs)
	49	{
	50	long ret;
	51
bc47d201 CC	52	VNC_DEBUG("Write SASL: Pending output %p size %zd offset %zd "
bc47d201 CC	53	"Encoded: %p size %d offset %d\n",
28a76be8 AL	54	vs->output.buffer, vs->output.capacity, vs->output.offset,
28a76be8 AL	55	vs->sasl.encoded, vs->sasl.encodedLength, vs->sasl.encodedOffset);
2f9606b3 AL	56
2f9606b3 AL	57	if (!vs->sasl.encoded) {
28a76be8 AL	58	int err;
	59	err = sasl_encode(vs->sasl.conn,
	60	(char *)vs->output.buffer,
	61	vs->output.offset,
	62	(const char **)&vs->sasl.encoded,
	63	&vs->sasl.encodedLength);
	64	if (err != SASL_OK)
	65	return vnc_client_io_error(vs, -1, EIO);
	66
	67	vs->sasl.encodedOffset = 0;
2f9606b3 AL	68	}
	69
	70	ret = vnc_client_write_buf(vs,
28a76be8 AL	71	vs->sasl.encoded + vs->sasl.encodedOffset,
28a76be8 AL	72	vs->sasl.encodedLength - vs->sasl.encodedOffset);
2f9606b3	73	if (!ret)
28a76be8	74	return 0;
2f9606b3 AL	75
	76	vs->sasl.encodedOffset += ret;
	77	if (vs->sasl.encodedOffset == vs->sasl.encodedLength) {
28a76be8 AL	78	vs->output.offset = 0;
	79	vs->sasl.encoded = NULL;
	80	vs->sasl.encodedOffset = vs->sasl.encodedLength = 0;
2f9606b3 AL	81	}
	82
	83	/* Can't merge this block with one above, because
	84	* someone might have written more unencrypted
	85	* data in vs->output while we were processing
	86	* SASL encoded output
	87	*/
	88	if (vs->output.offset == 0) {
28a76be8	89	qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, NULL, vs);
2f9606b3 AL	90	}
	91
	92	return ret;
	93	}
	94
	95
	96	long vnc_client_read_sasl(VncState *vs)
	97	{
	98	long ret;
	99	uint8_t encoded[4096];
	100	const char *decoded;
	101	unsigned int decodedLen;
	102	int err;
	103
	104	ret = vnc_client_read_buf(vs, encoded, sizeof(encoded));
	105	if (!ret)
28a76be8	106	return 0;
2f9606b3 AL	107
2f9606b3 AL	108	err = sasl_decode(vs->sasl.conn,
28a76be8 AL	109	(char *)encoded, ret,
28a76be8 AL	110	&decoded, &decodedLen);
2f9606b3 AL	111
2f9606b3 AL	112	if (err != SASL_OK)
28a76be8	113	return vnc_client_io_error(vs, -1, -EIO);
2f9606b3	114	VNC_DEBUG("Read SASL Encoded %p size %ld Decoded %p size %d\n",
28a76be8	115	encoded, ret, decoded, decodedLen);
2f9606b3 AL	116	buffer_reserve(&vs->input, decodedLen);
	117	buffer_append(&vs->input, decoded, decodedLen);
	118	return decodedLen;
	119	}
	120
	121
	122	static int vnc_auth_sasl_check_access(VncState *vs)
	123	{
	124	const void *val;
	125	int err;
76655d6d	126	int allow;
2f9606b3 AL	127
	128	err = sasl_getprop(vs->sasl.conn, SASL_USERNAME, &val);
	129	if (err != SASL_OK) {
28a76be8 AL	130	VNC_DEBUG("cannot query SASL username on connection %d (%s), denying access\n",
	131	err, sasl_errstring(err, NULL, NULL));
	132	return -1;
2f9606b3 AL	133	}
2f9606b3 AL	134	if (val == NULL) {
28a76be8 AL	135	VNC_DEBUG("no client username was found, denying access\n");
28a76be8 AL	136	return -1;
2f9606b3 AL	137	}
	138	VNC_DEBUG("SASL client username %s\n", (const char *)val);
	139
7267c094	140	vs->sasl.username = g_strdup((const char*)val);
2f9606b3	141
76655d6d	142	if (vs->vd->sasl.acl == NULL) {
28a76be8 AL	143	VNC_DEBUG("no ACL activated, allowing access\n");
28a76be8 AL	144	return 0;
76655d6d AL	145	}
	146
	147	allow = qemu_acl_party_is_allowed(vs->vd->sasl.acl, vs->sasl.username);
	148
	149	VNC_DEBUG("SASL client %s %s by ACL\n", vs->sasl.username,
28a76be8	150	allow ? "allowed" : "denied");
76655d6d	151	return allow ? 0 : -1;
2f9606b3 AL	152	}
	153
	154	static int vnc_auth_sasl_check_ssf(VncState *vs)
	155	{
	156	const void *val;
	157	int err, ssf;
	158
	159	if (!vs->sasl.wantSSF)
28a76be8	160	return 1;
2f9606b3 AL	161
	162	err = sasl_getprop(vs->sasl.conn, SASL_SSF, &val);
	163	if (err != SASL_OK)
28a76be8	164	return 0;
2f9606b3 AL	165
	166	ssf = (const int )val;
	167	VNC_DEBUG("negotiated an SSF of %d\n", ssf);
	168	if (ssf < 56)
28a76be8	169	return 0; /* 56 is good for Kerberos */
2f9606b3 AL	170
	171	/* Only setup for read initially, because we're about to send an RPC
	172	* reply which must be in plain text. When the next incoming RPC
	173	* arrives, we'll switch on writes too
	174	*
	175	* cf qemudClientReadSASL in qemud.c
	176	*/
	177	vs->sasl.runSSF = 1;
	178
	179	/* We have a SSF that's good enough */
	180	return 1;
	181	}
	182
	183	/*
	184	* Step Msg
	185	*
	186	* Input from client:
	187	*
	188	* u32 clientin-length
	189	* u8-array clientin-string
	190	*
	191	* Output to client:
	192	*
	193	* u32 serverout-length
	194	* u8-array serverout-strin
	195	* u8 continue
	196	*/
	197
	198	static int protocol_client_auth_sasl_step_len(VncState vs, uint8_t data, size_t len);
	199
	200	static int protocol_client_auth_sasl_step(VncState vs, uint8_t data, size_t len)
	201	{
	202	uint32_t datalen = len;
	203	const char *serverout;
	204	unsigned int serveroutlen;
	205	int err;
	206	char *clientdata = NULL;
	207
	208	/* NB, distinction of NULL vs "" is critical in SASL */
	209	if (datalen) {
28a76be8 AL	210	clientdata = (char*)data;
	211	clientdata[datalen-1] = '\0'; /* Wire includes '\0', but make sure */
	212	datalen--; /* Don't count NULL byte when passing to _start() */
2f9606b3 AL	213	}
	214
	215	VNC_DEBUG("Step using SASL Data %p (%d bytes)\n",
28a76be8	216	clientdata, datalen);
2f9606b3	217	err = sasl_server_step(vs->sasl.conn,
28a76be8 AL	218	clientdata,
	219	datalen,
	220	&serverout,
	221	&serveroutlen);
2f9606b3	222	if (err != SASL_OK &&
28a76be8 AL	223	err != SASL_CONTINUE) {
	224	VNC_DEBUG("sasl step failed %d (%s)\n",
	225	err, sasl_errdetail(vs->sasl.conn));
	226	sasl_dispose(&vs->sasl.conn);
	227	vs->sasl.conn = NULL;
	228	goto authabort;
2f9606b3 AL	229	}
	230
	231	if (serveroutlen > SASL_DATA_MAX_LEN) {
28a76be8 AL	232	VNC_DEBUG("sasl step reply data too long %d\n",
	233	serveroutlen);
	234	sasl_dispose(&vs->sasl.conn);
	235	vs->sasl.conn = NULL;
	236	goto authabort;
2f9606b3 AL	237	}
	238
	239	VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
28a76be8	240	serveroutlen, serverout ? 0 : 1);
2f9606b3 AL	241
2f9606b3 AL	242	if (serveroutlen) {
28a76be8 AL	243	vnc_write_u32(vs, serveroutlen + 1);
28a76be8 AL	244	vnc_write(vs, serverout, serveroutlen + 1);
2f9606b3	245	} else {
28a76be8	246	vnc_write_u32(vs, 0);
2f9606b3 AL	247	}
	248
	249	/* Whether auth is complete */
	250	vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
	251
	252	if (err == SASL_CONTINUE) {
28a76be8 AL	253	VNC_DEBUG("%s", "Authentication must continue\n");
	254	/* Wait for step length */
	255	vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
2f9606b3	256	} else {
28a76be8 AL	257	if (!vnc_auth_sasl_check_ssf(vs)) {
	258	VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
	259	goto authreject;
	260	}
	261
	262	/* Check username whitelist ACL */
	263	if (vnc_auth_sasl_check_access(vs) < 0) {
	264	VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
	265	goto authreject;
	266	}
	267
	268	VNC_DEBUG("Authentication successful %d\n", vs->csock);
	269	vnc_write_u32(vs, 0); /* Accept auth */
	270	/*
	271	* Delay writing in SSF encoded mode until pending output
	272	* buffer is written
	273	*/
	274	if (vs->sasl.runSSF)
	275	vs->sasl.waitWriteSSF = vs->output.offset;
	276	start_client_init(vs);
2f9606b3 AL	277	}
	278
	279	return 0;
	280
	281	authreject:
	282	vnc_write_u32(vs, 1); /* Reject auth */
	283	vnc_write_u32(vs, sizeof("Authentication failed"));
	284	vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
	285	vnc_flush(vs);
	286	vnc_client_error(vs);
	287	return -1;
	288
	289	authabort:
	290	vnc_client_error(vs);
	291	return -1;
	292	}
	293
	294	static int protocol_client_auth_sasl_step_len(VncState vs, uint8_t data, size_t len)
	295	{
	296	uint32_t steplen = read_u32(data, 0);
	297	VNC_DEBUG("Got client step len %d\n", steplen);
	298	if (steplen > SASL_DATA_MAX_LEN) {
28a76be8 AL	299	VNC_DEBUG("Too much SASL data %d\n", steplen);
	300	vnc_client_error(vs);
	301	return -1;
2f9606b3 AL	302	}
	303
	304	if (steplen == 0)
28a76be8	305	return protocol_client_auth_sasl_step(vs, NULL, 0);
2f9606b3	306	else
28a76be8	307	vnc_read_when(vs, protocol_client_auth_sasl_step, steplen);
2f9606b3 AL	308	return 0;
	309	}
	310
	311	/*
	312	* Start Msg
	313	*
	314	* Input from client:
	315	*
	316	* u32 clientin-length
	317	* u8-array clientin-string
	318	*
	319	* Output to client:
	320	*
	321	* u32 serverout-length
	322	* u8-array serverout-strin
	323	* u8 continue
	324	*/
	325
	326	#define SASL_DATA_MAX_LEN (1024 * 1024)
	327
	328	static int protocol_client_auth_sasl_start(VncState vs, uint8_t data, size_t len)
	329	{
	330	uint32_t datalen = len;
	331	const char *serverout;
	332	unsigned int serveroutlen;
	333	int err;
	334	char *clientdata = NULL;
	335
	336	/* NB, distinction of NULL vs "" is critical in SASL */
	337	if (datalen) {
28a76be8 AL	338	clientdata = (char*)data;
	339	clientdata[datalen-1] = '\0'; /* Should be on wire, but make sure */
	340	datalen--; /* Don't count NULL byte when passing to _start() */
2f9606b3 AL	341	}
	342
	343	VNC_DEBUG("Start SASL auth with mechanism %s. Data %p (%d bytes)\n",
28a76be8	344	vs->sasl.mechlist, clientdata, datalen);
2f9606b3	345	err = sasl_server_start(vs->sasl.conn,
28a76be8 AL	346	vs->sasl.mechlist,
	347	clientdata,
	348	datalen,
	349	&serverout,
	350	&serveroutlen);
2f9606b3	351	if (err != SASL_OK &&
28a76be8 AL	352	err != SASL_CONTINUE) {
	353	VNC_DEBUG("sasl start failed %d (%s)\n",
	354	err, sasl_errdetail(vs->sasl.conn));
	355	sasl_dispose(&vs->sasl.conn);
	356	vs->sasl.conn = NULL;
	357	goto authabort;
2f9606b3 AL	358	}
2f9606b3 AL	359	if (serveroutlen > SASL_DATA_MAX_LEN) {
28a76be8 AL	360	VNC_DEBUG("sasl start reply data too long %d\n",
	361	serveroutlen);
	362	sasl_dispose(&vs->sasl.conn);
	363	vs->sasl.conn = NULL;
	364	goto authabort;
2f9606b3 AL	365	}
	366
	367	VNC_DEBUG("SASL return data %d bytes, nil; %d\n",
28a76be8	368	serveroutlen, serverout ? 0 : 1);
2f9606b3 AL	369
2f9606b3 AL	370	if (serveroutlen) {
28a76be8 AL	371	vnc_write_u32(vs, serveroutlen + 1);
28a76be8 AL	372	vnc_write(vs, serverout, serveroutlen + 1);
2f9606b3	373	} else {
28a76be8	374	vnc_write_u32(vs, 0);
2f9606b3 AL	375	}
	376
	377	/* Whether auth is complete */
	378	vnc_write_u8(vs, err == SASL_CONTINUE ? 0 : 1);
	379
	380	if (err == SASL_CONTINUE) {
28a76be8 AL	381	VNC_DEBUG("%s", "Authentication must continue\n");
	382	/* Wait for step length */
	383	vnc_read_when(vs, protocol_client_auth_sasl_step_len, 4);
2f9606b3	384	} else {
28a76be8 AL	385	if (!vnc_auth_sasl_check_ssf(vs)) {
	386	VNC_DEBUG("Authentication rejected for weak SSF %d\n", vs->csock);
	387	goto authreject;
	388	}
	389
	390	/* Check username whitelist ACL */
	391	if (vnc_auth_sasl_check_access(vs) < 0) {
	392	VNC_DEBUG("Authentication rejected for ACL %d\n", vs->csock);
	393	goto authreject;
	394	}
	395
	396	VNC_DEBUG("Authentication successful %d\n", vs->csock);
	397	vnc_write_u32(vs, 0); /* Accept auth */
	398	start_client_init(vs);
2f9606b3 AL	399	}
	400
	401	return 0;
	402
	403	authreject:
	404	vnc_write_u32(vs, 1); /* Reject auth */
	405	vnc_write_u32(vs, sizeof("Authentication failed"));
	406	vnc_write(vs, "Authentication failed", sizeof("Authentication failed"));
	407	vnc_flush(vs);
	408	vnc_client_error(vs);
	409	return -1;
	410
	411	authabort:
	412	vnc_client_error(vs);
	413	return -1;
	414	}
	415
	416	static int protocol_client_auth_sasl_start_len(VncState vs, uint8_t data, size_t len)
	417	{
	418	uint32_t startlen = read_u32(data, 0);
	419	VNC_DEBUG("Got client start len %d\n", startlen);
	420	if (startlen > SASL_DATA_MAX_LEN) {
28a76be8 AL	421	VNC_DEBUG("Too much SASL data %d\n", startlen);
	422	vnc_client_error(vs);
	423	return -1;
2f9606b3 AL	424	}
	425
	426	if (startlen == 0)
28a76be8	427	return protocol_client_auth_sasl_start(vs, NULL, 0);
2f9606b3 AL	428
	429	vnc_read_when(vs, protocol_client_auth_sasl_start, startlen);
	430	return 0;
	431	}
	432
	433	static int protocol_client_auth_sasl_mechname(VncState vs, uint8_t data, size_t len)
	434	{
5847d9e1	435	char mechname = g_strndup((const char ) data, len);
2f9606b3	436	VNC_DEBUG("Got client mechname '%s' check against '%s'\n",
28a76be8	437	mechname, vs->sasl.mechlist);
2f9606b3 AL	438
2f9606b3 AL	439	if (strncmp(vs->sasl.mechlist, mechname, len) == 0) {
28a76be8 AL	440	if (vs->sasl.mechlist[len] != '\0' &&
	441	vs->sasl.mechlist[len] != ',') {
	442	VNC_DEBUG("One %d", vs->sasl.mechlist[len]);
8ce7d352	443	goto fail;
28a76be8	444	}
2f9606b3	445	} else {
28a76be8 AL	446	char *offset = strstr(vs->sasl.mechlist, mechname);
	447	VNC_DEBUG("Two %p\n", offset);
	448	if (!offset) {
8ce7d352	449	goto fail;
28a76be8 AL	450	}
	451	VNC_DEBUG("Two '%s'\n", offset);
	452	if (offset[-1] != ',' \|\|
	453	(offset[len] != '\0'&&
	454	offset[len] != ',')) {
8ce7d352	455	goto fail;
28a76be8	456	}
2f9606b3 AL	457	}
2f9606b3 AL	458
302d9d6f	459	g_free(vs->sasl.mechlist);
2f9606b3 AL	460	vs->sasl.mechlist = mechname;
	461
	462	VNC_DEBUG("Validated mechname '%s'\n", mechname);
	463	vnc_read_when(vs, protocol_client_auth_sasl_start_len, 4);
	464	return 0;
8ce7d352 BS	465
	466	fail:
	467	vnc_client_error(vs);
302d9d6f	468	g_free(mechname);
8ce7d352	469	return -1;
2f9606b3 AL	470	}
	471
	472	static int protocol_client_auth_sasl_mechname_len(VncState vs, uint8_t data, size_t len)
	473	{
	474	uint32_t mechlen = read_u32(data, 0);
	475	VNC_DEBUG("Got client mechname len %d\n", mechlen);
	476	if (mechlen > 100) {
28a76be8 AL	477	VNC_DEBUG("Too long SASL mechname data %d\n", mechlen);
	478	vnc_client_error(vs);
	479	return -1;
2f9606b3 AL	480	}
2f9606b3 AL	481	if (mechlen < 1) {
28a76be8 AL	482	VNC_DEBUG("Too short SASL mechname %d\n", mechlen);
	483	vnc_client_error(vs);
	484	return -1;
2f9606b3 AL	485	}
	486	vnc_read_when(vs, protocol_client_auth_sasl_mechname,mechlen);
	487	return 0;
	488	}
	489
2f9606b3 AL	490	void start_auth_sasl(VncState *vs)
	491	{
	492	const char *mechlist = NULL;
	493	sasl_security_properties_t secprops;
	494	int err;
	495	char localAddr, remoteAddr;
	496	int mechlistlen;
	497
	498	VNC_DEBUG("Initialize SASL auth %d\n", vs->csock);
	499
	500	/* Get local & remote client addresses in form IPADDR;PORT */
	501	if (!(localAddr = vnc_socket_local_addr("%s;%s", vs->csock)))
28a76be8	502	goto authabort;
2f9606b3 AL	503
2f9606b3 AL	504	if (!(remoteAddr = vnc_socket_remote_addr("%s;%s", vs->csock))) {
ae878b17	505	g_free(localAddr);
28a76be8	506	goto authabort;
2f9606b3 AL	507	}
	508
	509	err = sasl_server_new("vnc",
28a76be8 AL	510	NULL, /* FQDN - just delegates to gethostname */
	511	NULL, /* User realm */
	512	localAddr,
	513	remoteAddr,
	514	NULL, /* Callbacks, not needed */
	515	SASL_SUCCESS_DATA,
	516	&vs->sasl.conn);
ae878b17 SW	517	g_free(localAddr);
ae878b17 SW	518	g_free(remoteAddr);
2f9606b3 AL	519	localAddr = remoteAddr = NULL;
	520
	521	if (err != SASL_OK) {
28a76be8 AL	522	VNC_DEBUG("sasl context setup failed %d (%s)",
	523	err, sasl_errstring(err, NULL, NULL));
	524	vs->sasl.conn = NULL;
	525	goto authabort;
2f9606b3 AL	526	}
	527
	528	#ifdef CONFIG_VNC_TLS
	529	/* Inform SASL that we've got an external SSF layer from TLS/x509 */
7e7e2ebc DB	530	if (vs->auth == VNC_AUTH_VENCRYPT &&
7e7e2ebc DB	531	vs->subauth == VNC_AUTH_VENCRYPT_X509SASL) {
28a76be8 AL	532	gnutls_cipher_algorithm_t cipher;
	533	sasl_ssf_t ssf;
	534
	535	cipher = gnutls_cipher_get(vs->tls.session);
	536	if (!(ssf = (sasl_ssf_t)gnutls_cipher_get_key_size(cipher))) {
	537	VNC_DEBUG("%s", "cannot TLS get cipher size\n");
	538	sasl_dispose(&vs->sasl.conn);
	539	vs->sasl.conn = NULL;
	540	goto authabort;
	541	}
	542	ssf = 8; / tls key size is bytes, sasl wants bits */
	543
	544	err = sasl_setprop(vs->sasl.conn, SASL_SSF_EXTERNAL, &ssf);
	545	if (err != SASL_OK) {
	546	VNC_DEBUG("cannot set SASL external SSF %d (%s)\n",
	547	err, sasl_errstring(err, NULL, NULL));
	548	sasl_dispose(&vs->sasl.conn);
	549	vs->sasl.conn = NULL;
	550	goto authabort;
	551	}
2f9606b3 AL	552	} else
2f9606b3 AL	553	#endif /* CONFIG_VNC_TLS */
28a76be8	554	vs->sasl.wantSSF = 1;
2f9606b3 AL	555
	556	memset (&secprops, 0, sizeof secprops);
	557	/* Inform SASL that we've got an external SSF layer from TLS */
	558	if (strncmp(vs->vd->display, "unix:", 5) == 0
	559	#ifdef CONFIG_VNC_TLS
28a76be8 AL	560	/* Disable SSF, if using TLS+x509+SASL only. TLS without x509
28a76be8 AL	561	is not sufficiently strong */
7e7e2ebc DB	562	\|\| (vs->auth == VNC_AUTH_VENCRYPT &&
7e7e2ebc DB	563	vs->subauth == VNC_AUTH_VENCRYPT_X509SASL)
2f9606b3	564	#endif /* CONFIG_VNC_TLS */
28a76be8 AL	565	) {
	566	/* If we've got TLS or UNIX domain sock, we don't care about SSF */
	567	secprops.min_ssf = 0;
	568	secprops.max_ssf = 0;
	569	secprops.maxbufsize = 8192;
	570	secprops.security_flags = 0;
2f9606b3	571	} else {
28a76be8 AL	572	/* Plain TCP, better get an SSF layer */
	573	secprops.min_ssf = 56; /* Good enough to require kerberos */
	574	secprops.max_ssf = 100000; /* Arbitrary big number */
	575	secprops.maxbufsize = 8192;
	576	/* Forbid any anonymous or trivially crackable auth */
	577	secprops.security_flags =
	578	SASL_SEC_NOANONYMOUS \| SASL_SEC_NOPLAINTEXT;
2f9606b3 AL	579	}
	580
	581	err = sasl_setprop(vs->sasl.conn, SASL_SEC_PROPS, &secprops);
	582	if (err != SASL_OK) {
28a76be8 AL	583	VNC_DEBUG("cannot set SASL security props %d (%s)\n",
	584	err, sasl_errstring(err, NULL, NULL));
	585	sasl_dispose(&vs->sasl.conn);
	586	vs->sasl.conn = NULL;
	587	goto authabort;
2f9606b3 AL	588	}
	589
	590	err = sasl_listmech(vs->sasl.conn,
28a76be8 AL	591	NULL, /* Don't need to set user */
	592	"", /* Prefix */
	593	",", /* Separator */
	594	"", /* Suffix */
	595	&mechlist,
	596	NULL,
	597	NULL);
2f9606b3	598	if (err != SASL_OK) {
28a76be8 AL	599	VNC_DEBUG("cannot list SASL mechanisms %d (%s)\n",
	600	err, sasl_errdetail(vs->sasl.conn));
	601	sasl_dispose(&vs->sasl.conn);
	602	vs->sasl.conn = NULL;
	603	goto authabort;
2f9606b3 AL	604	}
	605	VNC_DEBUG("Available mechanisms for client: '%s'\n", mechlist);
	606
302d9d6f	607	vs->sasl.mechlist = g_strdup(mechlist);
2f9606b3 AL	608	mechlistlen = strlen(mechlist);
	609	vnc_write_u32(vs, mechlistlen);
	610	vnc_write(vs, mechlist, mechlistlen);
	611	vnc_flush(vs);
	612
	613	VNC_DEBUG("Wait for client mechname length\n");
	614	vnc_read_when(vs, protocol_client_auth_sasl_mechname_len, 4);
	615
	616	return;
	617
	618	authabort:
	619	vnc_client_error(vs);
2f9606b3 AL	620	}
	621
	622