io/vscan/vscan_drv.c

/*
 * 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);
}