/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <sys/stat.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/time.h>
#include <sys/varargs.h>
#include <sys/conf.h>
#include <sys/modctl.h>
#include <sys/vnode.h>
#include <fs/fs_subr.h>
#include <sys/types.h>
#include <sys/file.h>
#include <sys/disp.h>
#include <sys/vscan.h>
#include <sys/policy.h>
#include <sys/sdt.h>


/* seconds to wait for daemon to reconnect before disabling */
#define VS_DAEMON_WAIT_SEC      60

/* length of minor node name - vscan%d */
#define VS_NODENAME_LEN         16

/* global variables - tunable via /etc/system */
uint32_t vs_reconnect_timeout = VS_DAEMON_WAIT_SEC;
extern uint32_t vs_nodes_max;   /* max in-progress scan requests */

/*
 * vscan_drv_state
 *
 * Operations on instance 0 represent vscand initiated state
 * transition events:
 * open(0) - vscand connect
 * close(0) - vscan disconnect
 * enable(0) - vscand enable (ready to hand requests)
 * disable(0) - vscand disable (shutting down)
 *
 *   +------------------------+
 *   | VS_DRV_UNCONFIG        |
 *   +------------------------+
 *      |           ^
 *      | attach    | detach
 *      v           |
 *   +------------------------+
 *   | VS_DRV_IDLE            |<------|
 *   +------------------------+       |
 *      |           ^                 |
 *      | open(0)   | close(0)        |
 *      v           |                 |
 *   +------------------------+       |
 *   | VS_DRV_CONNECTED       |<-|    |
 *   +------------------------+  |    |
 *      |           ^            |    |
 *      | enable(0) | disable(0) |    |
 *      v           |            |    |
 *   +------------------------+  |    |
 *   | VS_DRV_ENABLED         |  |    |
 *   +------------------------+  |    |
 *      |                        |    |
 *      | close(0)            open(0) |
 *      v                        |    |
 *   +------------------------+  |    | timeout
 *   | VS_DRV_DELAYED_DISABLE | --    |
 *   +------------------------+ ------|
 *
 */
typedef enum {
        VS_DRV_UNCONFIG,
        VS_DRV_IDLE,
        VS_DRV_CONNECTED,
        VS_DRV_ENABLED,
        VS_DRV_DELAYED_DISABLE
} vscan_drv_state_t;
static vscan_drv_state_t vscan_drv_state = VS_DRV_UNCONFIG;


/*
 * vscan_drv_inst_state
 *
 * Instance 0 controls the state of the driver: vscan_drv_state.
 * vscan_drv_inst_state[0] should NOT be used.
 *
 * vscan_drv_inst_state[n] represents the state of driver
 * instance n, used by vscand to access file data for the
 * scan request with index n in vscan_svc_reqs.
 * Minor nodes are created as required then all are destroyed
 * during driver detach.
 *
 *   +------------------------+
 *   | VS_DRV_INST_UNCONFIG   |
 *   +------------------------+
 *      |                 ^
 *      | create_node(n)  | detach
 *      v                 |
 *   +------------------------+
 *   | VS_DRV_INST_INIT       |<-|
 *   +------------------------+  |
 *      |                        |
 *      | open(n)                |
 *      v                        |
 *   +------------------------+  |
 *   | VS_DRV_INST_OPEN       |--|
 *   +------------------------+  |
 *      |                        |
 *      | read(n)                |
 *      v                        | close(n)
 *   +------------------------+  |
 *   | VS_DRV_INST_READING    |--|
 *   +------------------------+
 */
typedef enum {
        VS_DRV_INST_UNCONFIG = 0, /* minor node not created */
        VS_DRV_INST_INIT,
        VS_DRV_INST_OPEN,
        VS_DRV_INST_READING
} vscan_drv_inst_state_t;

static vscan_drv_inst_state_t *vscan_drv_inst_state;
static int vscan_drv_inst_state_sz;

static dev_info_t *vscan_drv_dip;
static kmutex_t vscan_drv_mutex;
static kcondvar_t vscan_drv_cv; /* wait for daemon reconnect */

/*
 * DDI entry points.
 */
static int vscan_drv_attach(dev_info_t *, ddi_attach_cmd_t);
static int vscan_drv_detach(dev_info_t *, ddi_detach_cmd_t);
static int vscan_drv_getinfo(dev_info_t *, ddi_info_cmd_t, void *, void **);
static int vscan_drv_open(dev_t *, int, int, cred_t *);
static int vscan_drv_close(dev_t, int, int, cred_t *);
static int vscan_drv_read(dev_t, struct uio *, cred_t *);
static int vscan_drv_ioctl(dev_t, int, intptr_t, int, cred_t *, int *);

static boolean_t vscan_drv_in_use(void);
static void vscan_drv_delayed_disable(void);


/*
 * module linkage info for the kernel
 */
static struct cb_ops cbops = {
        vscan_drv_open,         /* cb_open */
        vscan_drv_close,        /* cb_close */
        nodev,                  /* cb_strategy */
        nodev,                  /* cb_print */
        nodev,                  /* cb_dump */
        vscan_drv_read,         /* cb_read */
        nodev,                  /* cb_write */
        vscan_drv_ioctl,        /* cb_ioctl */
        nodev,                  /* cb_devmap */
        nodev,                  /* cb_mmap */
        nodev,                  /* cb_segmap */
        nochpoll,               /* cb_chpoll */
        ddi_prop_op,            /* cb_prop_op */
        NULL,                   /* cb_streamtab */
        D_MP,                   /* cb_flag */
        CB_REV,                 /* cb_rev */
        nodev,                  /* cb_aread */
        nodev,                  /* cb_awrite */
};

static struct dev_ops devops = {
        DEVO_REV,               /* devo_rev */
        0,                      /* devo_refcnt */
        vscan_drv_getinfo,      /* devo_getinfo */
        nulldev,                /* devo_identify */
        nulldev,                /* devo_probe */
        vscan_drv_attach,       /* devo_attach */
        vscan_drv_detach,       /* devo_detach */
        nodev,                  /* devo_reset */
        &cbops,                 /* devo_cb_ops */
        NULL,                   /* devo_bus_ops */
        NULL,                   /* devo_power */
        ddi_quiesce_not_needed,         /* devo_quiesce */
};

static struct modldrv modldrv = {
        &mod_driverops,         /* drv_modops */
        "virus scanning",       /* drv_linkinfo */
        &devops,
};

static struct modlinkage modlinkage = {

        MODREV_1,       /* revision of the module, must be: MODREV_1    */
        &modldrv,       /* ptr to linkage structures                    */
        NULL,
};


/*
 * _init
 */
int
_init(void)
{
        int rc;

        vscan_drv_inst_state_sz =
            sizeof (vscan_drv_inst_state_t) * (vs_nodes_max + 1);

        if (vscan_door_init() != 0)
                return (DDI_FAILURE);

        if (vscan_svc_init() != 0) {
                vscan_door_fini();
                return (DDI_FAILURE);
        }

        mutex_init(&vscan_drv_mutex, NULL, MUTEX_DRIVER, NULL);
        vscan_drv_inst_state = kmem_zalloc(vscan_drv_inst_state_sz, KM_SLEEP);

        cv_init(&vscan_drv_cv, NULL, CV_DEFAULT, NULL);

        if ((rc  = mod_install(&modlinkage)) != 0) {
                vscan_door_fini();
                vscan_svc_fini();
                kmem_free(vscan_drv_inst_state, vscan_drv_inst_state_sz);
                cv_destroy(&vscan_drv_cv);
                mutex_destroy(&vscan_drv_mutex);
        }

        return (rc);
}


/*
 * _info
 */
int
_info(struct modinfo *modinfop)
{
        return (mod_info(&modlinkage, modinfop));
}


/*
 * _fini
 */
int
_fini(void)
{
        int rc;

        if (vscan_drv_in_use())
                return (EBUSY);

        if ((rc = mod_remove(&modlinkage)) == 0) {
                vscan_door_fini();
                vscan_svc_fini();
                kmem_free(vscan_drv_inst_state, vscan_drv_inst_state_sz);
                cv_destroy(&vscan_drv_cv);
                mutex_destroy(&vscan_drv_mutex);
        }

        return (rc);
}


/*
 * DDI entry points.
 */

/*
 * vscan_drv_getinfo
 */
/* ARGSUSED */
static int
vscan_drv_getinfo(dev_info_t *dip, ddi_info_cmd_t cmd, void *arg, void **result)
{
        ulong_t inst = getminor((dev_t)arg);

        switch (cmd) {
        case DDI_INFO_DEVT2DEVINFO:
                *result = vscan_drv_dip;
                return (DDI_SUCCESS);
        case DDI_INFO_DEVT2INSTANCE:
                *result = (void *)inst;
                return (DDI_SUCCESS);
        }
        return (DDI_FAILURE);
}


/*
 * vscan_drv_attach
 */
static int
vscan_drv_attach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
        if (cmd != DDI_ATTACH)
                return (DDI_FAILURE);

        if (ddi_get_instance(dip) != 0)
                return (DDI_FAILURE);

        vscan_drv_dip = dip;

        /* create minor node 0 for daemon-driver synchronization */
        if (vscan_drv_create_node(0) == B_FALSE)
                return (DDI_FAILURE);

        vscan_drv_state = VS_DRV_IDLE;
        return (DDI_SUCCESS);
}


/*
 * vscan_drv_detach
 */
static int
vscan_drv_detach(dev_info_t *dip, ddi_detach_cmd_t cmd)
{
        int i;

        if (cmd != DDI_DETACH)
                return (DDI_FAILURE);

        if (ddi_get_instance(dip) != 0)
                return (DDI_FAILURE);

        if (vscan_drv_in_use())
                return (DDI_FAILURE);

        /* remove all minor nodes */
        vscan_drv_dip = NULL;
        ddi_remove_minor_node(dip, NULL);
        for (i = 0; i <= vs_nodes_max; i++)
                vscan_drv_inst_state[i] = VS_DRV_INST_UNCONFIG;

        vscan_drv_state = VS_DRV_UNCONFIG;
        return (DDI_SUCCESS);
}


/*
 * vscan_drv_in_use
 *
 * If the driver state is not IDLE or UNCONFIG then the
 * driver is in use. Otherwise, check the service interface
 * (vscan_svc) to see if it is still in use - for example
 * there there may be requests still in progress.
 */
static boolean_t
vscan_drv_in_use()
{
        boolean_t in_use = B_FALSE;

        mutex_enter(&vscan_drv_mutex);
        if ((vscan_drv_state != VS_DRV_IDLE) &&
            (vscan_drv_state != VS_DRV_UNCONFIG)) {
                in_use = B_TRUE;
        }
        mutex_exit(&vscan_drv_mutex);

        if (in_use)
                return (B_TRUE);
        else
                return (vscan_svc_in_use());
}


/*
 * vscan_drv_open
 *
 * If inst == 0, this is vscand initializing.
 * If the driver is in DELAYED_DISABLE, ie vscand previously
 * disconnected without a clean shutdown and the driver is
 * waiting for a period to allow vscand to reconnect, signal
 * vscan_drv_cv to cancel the delayed disable.
 *
 * If inst != 0, open the file associated with inst.
 */
/* ARGSUSED */
static int
vscan_drv_open(dev_t *devp, int flag, int otyp, cred_t *credp)
{
        int rc;
        int inst = getminor(*devp);

        if ((inst < 0) || (inst > vs_nodes_max))
                return (EINVAL);

        /* check if caller has privilege for virus scanning */
        if ((rc = secpolicy_vscan(credp)) != 0) {
                DTRACE_PROBE1(vscan__priv, int, rc);
                return (EPERM);
        }

        mutex_enter(&vscan_drv_mutex);
        if (inst == 0) {
                switch (vscan_drv_state) {
                case VS_DRV_IDLE:
                        vscan_drv_state = VS_DRV_CONNECTED;
                        break;
                case VS_DRV_DELAYED_DISABLE:
                        cv_signal(&vscan_drv_cv);
                        vscan_drv_state = VS_DRV_CONNECTED;
                        break;
                default:
                        DTRACE_PROBE1(vscan__drv__state__violation,
                            int, vscan_drv_state);
                        mutex_exit(&vscan_drv_mutex);
                        return (EINVAL);
                }
        } else {
                if ((vscan_drv_state != VS_DRV_ENABLED) ||
                    (vscan_drv_inst_state[inst] != VS_DRV_INST_INIT)) {
                        mutex_exit(&vscan_drv_mutex);
                        return (EINVAL);
                }
                vscan_drv_inst_state[inst] = VS_DRV_INST_OPEN;
        }
        mutex_exit(&vscan_drv_mutex);

        return (0);
}


/*
 * vscan_drv_close
 *
 * If inst == 0, this is vscand detaching.
 * If the driver is in ENABLED state vscand has terminated without
 * a clean shutdown (nod DISABLE received). Enter DELAYED_DISABLE
 * state and initiate a delayed disable to allow vscand time to
 * reconnect.
 *
 * If inst != 0, close the file associated with inst
 */
/* ARGSUSED */
static int
vscan_drv_close(dev_t dev, int flag, int otyp, cred_t *credp)
{
        int i, inst = getminor(dev);

        if ((inst < 0) || (inst > vs_nodes_max))
                return (EINVAL);

        mutex_enter(&vscan_drv_mutex);
        if (inst != 0) {
                vscan_drv_inst_state[inst] = VS_DRV_INST_INIT;
                mutex_exit(&vscan_drv_mutex);
                return (0);
        }

        /* instance 0 - daemon disconnect */
        if ((vscan_drv_state != VS_DRV_CONNECTED) &&
            (vscan_drv_state != VS_DRV_ENABLED)) {
                DTRACE_PROBE1(vscan__drv__state__violation,
                    int, vscan_drv_state);
                mutex_exit(&vscan_drv_mutex);
                return (EINVAL);
        }

        for (i = 1; i <= vs_nodes_max; i++) {
                if (vscan_drv_inst_state[i] != VS_DRV_INST_UNCONFIG)
                        vscan_drv_inst_state[i] = VS_DRV_INST_INIT;
        }

        if (vscan_drv_state == VS_DRV_CONNECTED) {
                vscan_drv_state = VS_DRV_IDLE;
        } else { /* VS_DRV_ENABLED */
                cmn_err(CE_WARN, "Detected vscand exit without clean shutdown");
                if (thread_create(NULL, 0, vscan_drv_delayed_disable,
                    0, 0, &p0, TS_RUN, minclsyspri) == NULL) {
                        vscan_svc_disable();
                        vscan_drv_state = VS_DRV_IDLE;
                } else {
                        vscan_drv_state = VS_DRV_DELAYED_DISABLE;
                }
        }
        mutex_exit(&vscan_drv_mutex);

        vscan_svc_scan_abort();
        vscan_door_close();
        return (0);
}


/*
 * vscan_drv_delayed_disable
 *
 * Invoked from vscan_drv_close if the daemon disconnects
 * without first sending disable (e.g. daemon crashed).
 * Delays for vs_reconnect_timeout before disabling, to allow
 * the daemon to reconnect. During this time, scan requests
 * will be processed locally (see vscan_svc.c)
 */
static void
vscan_drv_delayed_disable(void)
{
        mutex_enter(&vscan_drv_mutex);
        (void) cv_reltimedwait(&vscan_drv_cv, &vscan_drv_mutex,
            SEC_TO_TICK(vs_reconnect_timeout), TR_CLOCK_TICK);

        if (vscan_drv_state == VS_DRV_DELAYED_DISABLE) {
                vscan_svc_disable();
                vscan_drv_state = VS_DRV_IDLE;
        } else {
                DTRACE_PROBE(vscan__reconnect);
        }
        mutex_exit(&vscan_drv_mutex);
}


/*
 * vscan_drv_read
 */
/* ARGSUSED */
static int
vscan_drv_read(dev_t dev, struct uio *uiop, cred_t *credp)
{
        int rc;
        int inst = getminor(dev);
        vnode_t *vp;

        if ((inst <= 0) || (inst > vs_nodes_max))
                return (EINVAL);

        mutex_enter(&vscan_drv_mutex);
        if ((vscan_drv_state != VS_DRV_ENABLED) ||
            (vscan_drv_inst_state[inst] != VS_DRV_INST_OPEN)) {
                mutex_exit(&vscan_drv_mutex);
                return (EINVAL);
        }
        vscan_drv_inst_state[inst] = VS_DRV_INST_READING;
        mutex_exit(&vscan_drv_mutex);

        if ((vp = vscan_svc_get_vnode(inst)) == NULL)
                return (EINVAL);

        (void) VOP_RWLOCK(vp, V_WRITELOCK_FALSE, NULL);
        rc = VOP_READ(vp, uiop, 0, kcred, NULL);
        VOP_RWUNLOCK(vp, V_WRITELOCK_FALSE, NULL);

        mutex_enter(&vscan_drv_mutex);
        if (vscan_drv_inst_state[inst] == VS_DRV_INST_READING)
                vscan_drv_inst_state[inst] = VS_DRV_INST_OPEN;
        mutex_exit(&vscan_drv_mutex);

        return (rc);
}


/*
 * vscan_drv_ioctl
 *
 * Process ioctls from vscand:
 * VS_IOCTL_ENABLE - vscand is ready to handle scan requests,
 *    enable VFS interface.
 * VS_IOCTL_DISABLE - vscand is shutting down, disable VFS interface
 * VS_IOCTL_RESULT - scan response data
 * VS_IOCTL_CONFIG - configuration data from vscand
 * VS_IOCTL_MAX_REQ - provide the max request idx to vscand,
 *    to allow vscand to set appropriate resource allocation limits
 */
/* ARGSUSED */
static int
vscan_drv_ioctl(dev_t dev, int cmd, intptr_t arg, int mode,
        cred_t *credp, int *rvalp)
{
        int inst = getminor(dev);
        vs_config_t conf;
        vs_scan_rsp_t rsp;

        if (inst != 0)
                return (EINVAL);

        switch (cmd) {
        case VS_IOCTL_ENABLE:
                mutex_enter(&vscan_drv_mutex);
                if (vscan_drv_state != VS_DRV_CONNECTED) {
                        DTRACE_PROBE1(vscan__drv__state__violation,
                            int, vscan_drv_state);
                        mutex_exit(&vscan_drv_mutex);
                        return (EINVAL);
                }
                if ((vscan_door_open((int)arg) != 0) ||
                    (vscan_svc_enable() != 0)) {
                        mutex_exit(&vscan_drv_mutex);
                        return (EINVAL);
                }
                vscan_drv_state = VS_DRV_ENABLED;
                mutex_exit(&vscan_drv_mutex);
                break;

        case VS_IOCTL_DISABLE:
                mutex_enter(&vscan_drv_mutex);
                if (vscan_drv_state != VS_DRV_ENABLED) {
                        DTRACE_PROBE1(vscan__drv__state__violation,
                            int, vscan_drv_state);
                        mutex_exit(&vscan_drv_mutex);
                        return (EINVAL);
                }
                vscan_svc_disable();
                vscan_drv_state = VS_DRV_CONNECTED;
                mutex_exit(&vscan_drv_mutex);
                break;

        case VS_IOCTL_RESULT:
                if (ddi_copyin((void *)arg, &rsp,
                    sizeof (vs_scan_rsp_t), 0) == -1)
                        return (EFAULT);
                else
                        vscan_svc_scan_result(&rsp);
                break;

        case VS_IOCTL_CONFIG:
                if (ddi_copyin((void *)arg, &conf,
                    sizeof (vs_config_t), 0) == -1)
                        return (EFAULT);
                if (vscan_svc_configure(&conf) == -1)
                        return (EINVAL);
                break;

        case VS_IOCTL_MAX_REQ:
                if (ddi_copyout(&vs_nodes_max, (void *)arg,
                    sizeof (uint32_t), 0) == -1)
                        return (EFAULT);
                break;

        default:
                return (ENOTTY);
        }

        return (0);
}


/*
 * vscan_drv_create_node
 *
 * Create minor node with which vscan daemon will communicate
 * to access a file. Invoked from vscan_svc before scan request
 * sent up to daemon.
 * Minor node 0 is reserved for daemon-driver synchronization
 * and is created during attach.
 * All minor nodes are removed during detach.
 */
boolean_t
vscan_drv_create_node(int idx)
{
        char name[VS_NODENAME_LEN];
        boolean_t rc = B_TRUE;

        mutex_enter(&vscan_drv_mutex);

        if (vscan_drv_inst_state[idx] == VS_DRV_INST_UNCONFIG) {
                (void) snprintf(name, VS_NODENAME_LEN, "vscan%d", idx);
                if (ddi_create_minor_node(vscan_drv_dip, name,
                    S_IFCHR, idx, DDI_PSEUDO, 0) == DDI_SUCCESS) {
                        vscan_drv_inst_state[idx] = VS_DRV_INST_INIT;
                } else {
                        rc = B_FALSE;
                }
                DTRACE_PROBE2(vscan__minor__node, int, idx, int, rc);
        }

        mutex_exit(&vscan_drv_mutex);

        return (rc);
}