fs/sockfs/sockparams.c

	sockparams.c revision 51899d8c0e357e637cdb75d1083ee3d64615b130
/*
 * 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/types.h>
#include <sys/t_lock.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysmacros.h>
#include <sys/cmn_err.h>
#include <sys/list.h>

#include <sys/stropts.h>
#include <sys/socket.h>
#include <sys/socketvar.h>

#include <fs/sockfs/sockcommon.h>
#include <fs/sockfs/socktpi.h>

/*
 * Socket Parameters
 *
 * Socket parameter (struct sockparams) entries represent the socket types
 * available on the system.
 *
 * Flags (sp_flags):
 *
 * SOCKPARAMS_EPHEMERAL: A temporary sockparams entry that will be deleted
 * as soon as its' ref count drops to zero. In addition, ephemeral entries will
 * never be hooked onto the global sockparams list. Ephemeral entries are
 * created when application requests to create a socket using an application
 * supplied device path, or when a socket is falling back to TPI.
 *
 * Lock order:
 *   The lock order is splist_lock -> sp_lock.
 *   The lock order is sp_ephem_lock -> sp_lock.
 */
extern int  kobj_path_exists(char *, int);
extern void nl7c_init(void);
extern int  sockfs_defer_nl7c_init;

static int  sockparams_sdev_init(struct sockparams *, char *, int);
static void     sockparams_sdev_fini(struct sockparams *);

/*
 * Global sockparams list (populated via soconfig(1M)).
 */
static list_t sphead;
static krwlock_t splist_lock;

/*
 * List of ephemeral sockparams.
 */
static list_t sp_ephem_list;
static krwlock_t sp_ephem_lock;

/* Global kstats for sockparams */
typedef struct sockparams_g_stats {
    kstat_named_t spgs_ephem_nalloc;
    kstat_named_t spgs_ephem_nreuse;
} sockparams_g_stats_t;

static sockparams_g_stats_t sp_g_stats;
static kstat_t *sp_g_kstat;


void
sockparams_init(void)
{
    list_create(&sphead, sizeof (struct sockparams),
        offsetof(struct sockparams, sp_node));
    list_create(&sp_ephem_list, sizeof (struct sockparams),
        offsetof(struct sockparams, sp_node));

    rw_init(&splist_lock, NULL, RW_DEFAULT, NULL);
    rw_init(&sp_ephem_lock, NULL, RW_DEFAULT, NULL);

    kstat_named_init(&sp_g_stats.spgs_ephem_nalloc, "ephemeral_nalloc",
        KSTAT_DATA_UINT64);
    kstat_named_init(&sp_g_stats.spgs_ephem_nreuse, "ephemeral_nreuse",
        KSTAT_DATA_UINT64);

    sp_g_kstat = kstat_create("sockfs", 0, "sockparams", "misc",
        KSTAT_TYPE_NAMED, sizeof (sp_g_stats) / sizeof (kstat_named_t),
        KSTAT_FLAG_VIRTUAL);
    if (sp_g_kstat == NULL)
        return;

    sp_g_kstat->ks_data = &sp_g_stats;

    kstat_install(sp_g_kstat);
}

static int
sockparams_kstat_update(kstat_t *ksp, int rw)
{
    struct sockparams *sp = ksp->ks_private;
    sockparams_stats_t *sps = ksp->ks_data;

    if (rw == KSTAT_WRITE)
        return (EACCES);

    sps->sps_nactive.value.ui64 = sp->sp_refcnt;

    return (0);
}

/*
 * Setup kstats for the given sockparams entry.
 */
static void
sockparams_kstat_init(struct sockparams *sp)
{
    char name[KSTAT_STRLEN];

    (void) snprintf(name, KSTAT_STRLEN, "socket_%d_%d_%d", sp->sp_family,
        sp->sp_type, sp->sp_protocol);

    sp->sp_kstat = kstat_create("sockfs", 0, name, "misc", KSTAT_TYPE_NAMED,
        sizeof (sockparams_stats_t) / sizeof (kstat_named_t),
        KSTAT_FLAG_VIRTUAL);

    if (sp->sp_kstat == NULL)
        return;

    sp->sp_kstat->ks_data = &sp->sp_stats;
    sp->sp_kstat->ks_update = sockparams_kstat_update;
    sp->sp_kstat->ks_private = sp;
    kstat_install(sp->sp_kstat);
}

static void
sockparams_kstat_fini(struct sockparams *sp)
{
    if (sp->sp_kstat != NULL) {
        kstat_delete(sp->sp_kstat);
        sp->sp_kstat = NULL;
    }
}

/*
 * sockparams_create(int family, int type, int protocol, char *modname,
 *     char *devpath, int devpathlen, int flags, int kmflags, int *errorp)
 *
 * Create a new sockparams entry.
 *
 * Arguments:
 *   family, type, protocol: specifies the socket type
 *   modname: Name of the module associated with the socket type. The
 *            module can be NULL if a device path is given, in which
 *            case the TPI module is used.
 *   devpath: Path to the STREAMS device. May be NULL for non-STREAMS
 *            based transports, or those transports that do not provide
 *            the capability to fallback to STREAMS.
 *   devpathlen: Length of the devpath string. The argument can be 0,
 *            indicating that devpath was allocated statically, and should
 *            not be freed when the sockparams entry is destroyed.
 *
 *   flags  : SOCKPARAMS_EPHEMERAL is the only flag that is allowed.
 *   kmflags: KM_{NO,}SLEEP
 *   errorp : Value-return argument, set when an error occurs.
 *
 * Returns:
 *   On success a new sockparams entry is returned, and *errorp is set
 *   to 0. On failure NULL is returned and *errorp is set to indicate the
 *   type of error that occured.
 *
 * Notes:
 *   devpath and modname are freed upon failure.
 */
struct sockparams *
sockparams_create(int family, int type, int protocol, char *modname,
    char *devpath, int devpathlen, int flags, int kmflags, int *errorp)
{
    struct sockparams *sp = NULL;
    size_t size;

    ASSERT((flags & ~SOCKPARAMS_EPHEMERAL) == 0);
    if (flags & ~SOCKPARAMS_EPHEMERAL) {
        *errorp = EINVAL;
        goto error;
    }

    /* either a module or device must be given */
    if (modname == NULL && devpath == NULL) {
        *errorp = EINVAL;
        goto error;
    }

    sp = kmem_zalloc(sizeof (*sp), kmflags);
    if (sp == NULL) {
        *errorp = ENOMEM;
        goto error;
    }
    sp->sp_family = family;
    sp->sp_type = type;
    sp->sp_protocol = protocol;
    sp->sp_refcnt = 0;
    sp->sp_flags = flags;

    kstat_named_init(&sp->sp_stats.sps_nfallback, "nfallback",
        KSTAT_DATA_UINT64);
    kstat_named_init(&sp->sp_stats.sps_nactive, "nactive",
        KSTAT_DATA_UINT64);
    kstat_named_init(&sp->sp_stats.sps_ncreate, "ncreate",
        KSTAT_DATA_UINT64);

    /*
     * Track how many ephemeral entries we have created.
     */
    if (sp->sp_flags & SOCKPARAMS_EPHEMERAL)
        sp_g_stats.spgs_ephem_nalloc.value.ui64++;

    if (modname != NULL) {
        sp->sp_smod_name = modname;
    } else {
        size = strlen(SOTPI_SMOD_NAME) + 1;
        modname = kmem_zalloc(size, kmflags);
        if (modname == NULL) {
            *errorp = ENOMEM;
            goto error;
        }
        sp->sp_smod_name = modname;
        (void) sprintf(sp->sp_smod_name, "%s", SOTPI_SMOD_NAME);
    }

    if (devpath != NULL) {
        /* Set up the device entry. */
        *errorp = sockparams_sdev_init(sp, devpath, devpathlen);
        if (*errorp != 0)
            goto error;
    }

    mutex_init(&sp->sp_lock, NULL, MUTEX_DEFAULT, NULL);
    *errorp = 0;
    return (sp);
error:
    ASSERT(*errorp != 0);
    if (modname != NULL)
        kmem_free(modname, strlen(modname) + 1);
    if (devpathlen != 0)
        kmem_free(devpath, devpathlen);
    if (sp != NULL)
        kmem_free(sp, sizeof (*sp));
    return (NULL);
}

/*
 * Initialize the STREAMS device aspect of the sockparams entry.
 */
static int
sockparams_sdev_init(struct sockparams *sp, char *devpath, int devpathlen)
{
    vnode_t *vp = NULL;
    int error;

    ASSERT(devpath != NULL);

    if ((error = sogetvp(devpath, &vp, UIO_SYSSPACE)) != 0) {
        dprint(0, ("sockparams_sdev_init: vp %s failed with %d\n",
            devpath, error));
        return (error);
    }

    ASSERT(vp != NULL);
    sp->sp_sdev_info.sd_vnode = vp;
    sp->sp_sdev_info.sd_devpath = devpath;
    sp->sp_sdev_info.sd_devpathlen = devpathlen;

    return (0);
}

/*
 * sockparams_destroy(struct sockparams *sp)
 *
 * Releases all the resources associated with the sockparams entry,
 * and frees the sockparams entry.
 *
 * Arguments:
 *   sp: the sockparams entry to destroy.
 *
 * Returns:
 *   Nothing.
 *
 * Locking:
 *   The sp_lock of the entry can not be held.
 */
void
sockparams_destroy(struct sockparams *sp)
{
    ASSERT(sp->sp_refcnt == 0);
    ASSERT(!list_link_active(&sp->sp_node));

    sockparams_sdev_fini(sp);

    if (sp->sp_smod_info != NULL)
        SMOD_DEC_REF(sp, sp->sp_smod_info);
    kmem_free(sp->sp_smod_name, strlen(sp->sp_smod_name) + 1);
    sp->sp_smod_name = NULL;
    sp->sp_smod_info = NULL;
    mutex_destroy(&sp->sp_lock);
    sockparams_kstat_fini(sp);

    kmem_free(sp, sizeof (*sp));
}

/*
 * Clean up the STREAMS device part of the sockparams entry.
 */
static void
sockparams_sdev_fini(struct sockparams *sp)
{
    sdev_info_t sd;

    /*
     * if the entry does not have a STREAMS device, then there
     * is nothing to do.
     */
    if (!SOCKPARAMS_HAS_DEVICE(sp))
        return;

    sd = sp->sp_sdev_info;
    if (sd.sd_vnode != NULL)
        VN_RELE(sd.sd_vnode);
    if (sd.sd_devpathlen != 0)
        kmem_free(sd.sd_devpath, sd.sd_devpathlen);

    sp->sp_sdev_info.sd_vnode = NULL;
    sp->sp_sdev_info.sd_devpath = NULL;
}

/*
 * Look for a matching sockparams entry on the given list.
 * The caller must hold the associated list lock.
 */
static struct sockparams *
sockparams_find(list_t *list, int family, int type, int protocol,
    boolean_t by_devpath, const char *name)
{
    struct sockparams *sp;

    for (sp = list_head(list); sp != NULL; sp = list_next(list, sp)) {
        if (sp->sp_family == family && sp->sp_type == type) {
            if (sp->sp_protocol == protocol) {
                if (name == NULL)
                    break;
                else if (by_devpath &&
                    sp->sp_sdev_info.sd_devpath != NULL &&
                    strcmp(sp->sp_sdev_info.sd_devpath,
                    name) == 0)
                    break;
                else if (strcmp(sp->sp_smod_name, name) == 0)
                    break;
            }
        }
    }
    return (sp);
}

/*
 * sockparams_hold_ephemeral()
 *
 * Returns an ephemeral sockparams entry of the requested family, type and
 * protocol. The entry is returned held, and the caller is responsible for
 * dropping the reference using SOCKPARAMS_DEC_REF() once done.
 *
 * All ephemeral entries are on list (sp_ephem_list). If there is an
 * entry on the list that match the search criteria, then a reference is
 * placed on that entry. Otherwise, a new entry is created and inserted
 * in the list. The entry is removed from the list when the last reference
 * is dropped.
 *
 * The tpi flag is used to determine whether name refers to a device or
 * module name.
 */
static struct sockparams *
sockparams_hold_ephemeral(int family, int type, int protocol,
    const char *name, boolean_t by_devpath, int kmflag, int *errorp)
{
    struct sockparams *sp = NULL;
    *errorp = 0;

    /*
     * First look for an existing entry
     */
    rw_enter(&sp_ephem_lock, RW_READER);
    sp = sockparams_find(&sp_ephem_list, family, type, protocol,
        by_devpath, name);
    if (sp != NULL) {
        SOCKPARAMS_INC_REF(sp);
        rw_exit(&sp_ephem_lock);
        sp_g_stats.spgs_ephem_nreuse.value.ui64++;

        return (sp);
    } else {
        struct sockparams *newsp = NULL;
        char *namebuf = NULL;
        int namelen = 0;

        rw_exit(&sp_ephem_lock);

        namelen = strlen(name) + 1;
        namebuf = kmem_alloc(namelen, kmflag);
        if (namebuf == NULL) {
            *errorp = ENOMEM;
            return (NULL);
        }

        (void *)strncpy(namebuf, name, namelen);
        if (by_devpath) {
            newsp = sockparams_create(family, type,
                protocol, NULL, namebuf, namelen,
                SOCKPARAMS_EPHEMERAL, kmflag, errorp);
        } else {
            newsp = sockparams_create(family, type,
                protocol, namebuf, NULL, 0,
                SOCKPARAMS_EPHEMERAL, kmflag, errorp);
        }

        if (newsp == NULL) {
            ASSERT(*errorp != 0);
            return (NULL);
        }

        /*
         * Time to load the socket module.
         */
        ASSERT(newsp->sp_smod_info == NULL);
        newsp->sp_smod_info =
            smod_lookup_byname(newsp->sp_smod_name);
        if (newsp->sp_smod_info == NULL) {
            /* Failed to load */
            sockparams_destroy(newsp);
            *errorp = ENXIO;
            return (NULL);
        }

        /*
         * The sockparams entry was created, now try to add it
         * to the list. We need to hold the lock as a WRITER.
         */
        rw_enter(&sp_ephem_lock, RW_WRITER);
        sp = sockparams_find(&sp_ephem_list, family, type, protocol,
            by_devpath, name);
        if (sp != NULL) {
            /*
             * Someone has requested a matching entry, so just
             * place a hold on it and release the entry we alloc'ed.
             */
            SOCKPARAMS_INC_REF(sp);
            rw_exit(&sp_ephem_lock);

            sockparams_destroy(newsp);
        } else {
            SOCKPARAMS_INC_REF(newsp);
            list_insert_tail(&sp_ephem_list, newsp);
            rw_exit(&sp_ephem_lock);

            sp = newsp;
        }
        ASSERT(*errorp == 0);

        return (sp);
    }
}

struct sockparams *
sockparams_hold_ephemeral_bydev(int family, int type, int protocol,
    const char *dev, int kmflag, int *errorp)
{
    return (sockparams_hold_ephemeral(family, type, protocol, dev, B_TRUE,
        kmflag, errorp));
}

struct sockparams *
sockparams_hold_ephemeral_bymod(int family, int type, int protocol,
    const char *mod, int kmflag, int *errorp)
{
    return (sockparams_hold_ephemeral(family, type, protocol, mod, B_FALSE,
        kmflag, errorp));
}

/*
 * Called when the last socket using the ephemeral entry is dropping
 * its' reference. To maintain lock order we must drop the sockparams
 * lock before calling this function. As a result, a new reference
 * might be placed on the entry, in which case there is nothing to
 * do. However, if ref count goes to zero, we delete the entry.
 */
void
sockparams_ephemeral_drop_last_ref(struct sockparams *sp)
{
    ASSERT(sp->sp_flags & SOCKPARAMS_EPHEMERAL);
    ASSERT(MUTEX_NOT_HELD(&sp->sp_lock));

    rw_enter(&sp_ephem_lock, RW_WRITER);
    mutex_enter(&sp->sp_lock);

    if (--sp->sp_refcnt == 0) {
        list_remove(&sp_ephem_list, sp);
        mutex_exit(&sp->sp_lock);
        rw_exit(&sp_ephem_lock);

        sockparams_destroy(sp);
    } else {
        mutex_exit(&sp->sp_lock);
        rw_exit(&sp_ephem_lock);
    }
}

/*
 * sockparams_add(struct sockparams *sp)
 *
 * Tries to add the given sockparams entry to the global list.
 *
 * Arguments:
 *   sp: the sockparms entry to add
 *
 * Returns:
 *   On success 0, but if an entry already exists, then EEXIST
 *   is returned.
 *
 * Locking:
 *   The caller can not be holding splist_lock.
 */
static int
sockparams_add(struct sockparams *sp)
{
    ASSERT(!(sp->sp_flags & SOCKPARAMS_EPHEMERAL));

    rw_enter(&splist_lock, RW_WRITER);
    if (sockparams_find(&sphead, sp->sp_family, sp->sp_type,
        sp->sp_protocol, B_TRUE, NULL) != 0) {
        rw_exit(&splist_lock);
        return (EEXIST);
    } else {
        list_insert_tail(&sphead, sp);
        rw_exit(&splist_lock);
        return (0);
    }
}

/*
 * sockparams_delete(int family, int type, int protocol)
 *
 * Marks the sockparams entry for a specific family, type and protocol
 * for deletion. The entry is removed from the list and destroyed
 * if no one is holding a reference to it.
 *
 * Arguments:
 *   family, type, protocol: the socket type that should be removed.
 *
 * Returns:
 *   On success 0, otherwise ENXIO.
 *
 * Locking:
 *   Caller can not be holding splist_lock or the sp_lock of
 *   any sockparams entry.
 */
static int
sockparams_delete(int family, int type, int protocol)
{
    struct sockparams *sp;

    rw_enter(&splist_lock, RW_WRITER);
    sp = sockparams_find(&sphead, family, type, protocol, B_TRUE, NULL);

    if (sp != NULL) {
        /*
         * If no one is holding a reference to the entry, then
         * we go ahead and remove it from the list and then
         * destroy it.
         */
        mutex_enter(&sp->sp_lock);
        if (sp->sp_refcnt != 0) {
            mutex_exit(&sp->sp_lock);
            rw_exit(&splist_lock);
            return (EBUSY);
        }
        mutex_exit(&sp->sp_lock);
        /* Delete the sockparams entry. */
        list_remove(&sphead, sp);
        rw_exit(&splist_lock);

        sockparams_destroy(sp);
        return (0);
    } else {
        rw_exit(&splist_lock);
        return (ENXIO);
    }
}

/*
 * soconfig(int family, int type, int protocol,
 *     char *devpath, int devpathlen, char *module)
 *
 * Add or delete an entry to the sockparams table.
 * When devpath and module both are NULL, it will delete an entry.
 *
 * Arguments:
 *   family, type, protocol: the tuple in question
 *   devpath: STREAMS device path. Can be NULL for module based sockets.
 *   module : Name of the socket module. Can be NULL for STREAMS
 *            based sockets.
 *   devpathlen: length of the devpath string, or 0 if devpath
 *            was statically allocated.
 *
 * Note:
 *   This routine assumes that the caller has kmem_alloced
 *   devpath (if devpathlen > 0) and module for this routine to
 *   consume.
 */
int
soconfig(int family, int type, int protocol,
    char *devpath, int devpathlen, char *module)
{
    struct sockparams *sp;
    int error = 0;

    dprint(0, ("soconfig(%d,%d,%d,%s,%d,%s)\n",
        family, type, protocol, devpath, devpathlen,
        module == NULL ? "NULL" : module));

    if (sockfs_defer_nl7c_init) {
        nl7c_init();
        sockfs_defer_nl7c_init = 0;
    }

    if (devpath == NULL && module == NULL) {
        /*
         * Delete existing entry,
         * both socket module and STEAMS device.
         */
        ASSERT(module == NULL);
        error = sockparams_delete(family, type, protocol);
    } else {
        /*
         * Adding an entry
         * sockparams_create frees mod name and devpath upon failure.
         */
        sp = sockparams_create(family, type, protocol, module,
            devpath, devpathlen, 0, KM_SLEEP, &error);

        if (sp != NULL) {
            /*
             * The sockparams entry becomes globally visible once
             * we call sockparams_add(). So we add a reference so
             * we do not have to worry about the entry being
             * immediately deleted.
             */
            SOCKPARAMS_INC_REF(sp);
            error = sockparams_add(sp);
            if (error != 0) {
                SOCKPARAMS_DEC_REF(sp);
                sockparams_destroy(sp);
            } else {
                /*
                 * Unique sockparams entry, so init the kstats.
                 */
                sockparams_kstat_init(sp);
                SOCKPARAMS_DEC_REF(sp);
            }
        }
    }

    return (error);
}

/*
 * solookup(int family, int type, int protocol, struct sockparams **spp)
 *
 * Lookup an entry in the sockparams list based on the triple. The returned
 * entry either exactly match the given tuple, or it is the 'default' entry
 * for the given <family, type>. A default entry is on with a protocol
 * value of zero.
 *
 * Arguments:
 *   family, type, protocol: tuple to search for
 *   spp: Value-return argument
 *
 * Returns:
 *   If an entry is found, 0 is returned and *spp is set to point to the
 *   entry. In case an entry is not found, *spp is set to NULL, and an
 *   error code is returned. The errors are (in decreasing precedence):
 *  EAFNOSUPPORT - address family not in list
 *  EPROTONOSUPPORT - address family supported but not protocol.
 *  EPROTOTYPE - address family and protocol supported but not socket type.
 *
 * TODO: should use ddi_modopen()/ddi_modclose()
 */
int
solookup(int family, int type, int protocol, struct sockparams **spp)
{
    struct sockparams *sp = NULL;
    int error = 0;

    *spp = NULL;
    rw_enter(&splist_lock, RW_READER);

    /*
     * Search the sockparams list for an appropiate entry.
     * Hopefully we find an entry that match the exact family,
     * type and protocol specified by the user, in which case
     * we return that entry. However, we also keep track of
     * the default entry for a specific family and type, the
     * entry of which would have a protocol value of 0.
     */
    sp = sockparams_find(&sphead, family, type, protocol, B_TRUE, NULL);

    if (sp == NULL) {
        int found = 0;

        /* Determine correct error code */
        for (sp = list_head(&sphead); sp != NULL;
            sp = list_next(&sphead, sp)) {
            if (sp->sp_family == family && found < 1)
                found = 1;
            if (sp->sp_family == family &&
                sp->sp_protocol == protocol && found < 2)
                found = 2;
        }
        rw_exit(&splist_lock);
        switch (found) {
        case 0:
            error = EAFNOSUPPORT;
            break;
        case 1:
            error = EPROTONOSUPPORT;
            break;
        case 2:
            error = EPROTOTYPE;
            break;
        }
        return (error);
    }

    /*
     * An entry was found.
     *
     * We put a hold on the entry early on, so if the
     * sockmod is not loaded, and we have to exit
     * splist_lock to call modload(), we know that the
     * sockparams entry wont go away. That way we don't
     * have to look up the entry once we come back from
     * modload().
     */
    SOCKPARAMS_INC_REF(sp);
    rw_exit(&splist_lock);

    if (sp->sp_smod_info == NULL) {
        sp->sp_smod_info = smod_lookup_byname(sp->sp_smod_name);
        if (sp->sp_smod_info == NULL) {
            /*
             * We put a hold on the sockparams entry
             * earlier, hoping everything would work out.
             * That obviously did not happen, so release
             * the hold here.
             */
            SOCKPARAMS_DEC_REF(sp);
            /*
             * We should probably mark the sockparams as
             * "bad", and redo the lookup skipping the
             * "bad" entries. I.e., sp->sp_mod_state |= BAD,
             * return (solookup(...))
             */
            return (ENXIO);
        }
    }

    /*
     * Alright, we have a valid sockparams entry.
     */
    *spp = sp;
    return (0);
}