privcmd.c

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/*
 * Copyright (c) 2014 Roger Pau Monné <roger.pau@citrix.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
 
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <sys/bus.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/rwlock.h>
#include <sys/selinfo.h>
#include <sys/poll.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/ioccom.h>
#include <sys/rman.h>
#include <sys/tree.h>
#include <sys/module.h>
#include <sys/proc.h>
#include <sys/bitset.h>
 
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
 
#include <machine/md_var.h>
 
#include <xen/xen-os.h>
#include <xen/hypervisor.h>
#include <xen/privcmd.h>
#include <xen/error.h>
 
MALLOC_DEFINE(M_PRIVCMD, "privcmd_dev", "Xen privcmd user-space device");
 
#define MAX_DMOP_BUFFERS 16
 
struct privcmd_map {
        vm_object_t mem;
        vm_size_t size;
        struct resource *pseudo_phys_res;
        int pseudo_phys_res_id;
        vm_paddr_t phys_base_addr;
        boolean_t mapped;
        BITSET_DEFINE_VAR() *err;
};
 
static d_ioctl_t     privcmd_ioctl;
static d_open_t      privcmd_open;
static d_mmap_single_t  privcmd_mmap_single;
 
static struct cdevsw privcmd_devsw = {
        .d_version = D_VERSION,
        .d_ioctl = privcmd_ioctl,
        .d_mmap_single = privcmd_mmap_single,
        .d_open = privcmd_open,
        .d_name = "privcmd",
};
 
static int privcmd_pg_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color);
static void privcmd_pg_dtor(void *handle);
static int privcmd_pg_fault(vm_object_t object, vm_ooffset_t offset,
    int prot, vm_page_t *mres);
 
static struct cdev_pager_ops privcmd_pg_ops = {
        .cdev_pg_fault = privcmd_pg_fault,
        .cdev_pg_ctor = privcmd_pg_ctor,
        .cdev_pg_dtor = privcmd_pg_dtor,
};
 
struct per_user_data {
        domid_t dom;
};
 
static device_t privcmd_dev = NULL;
 
/*------------------------- Privcmd Pager functions --------------------------*/
static int
privcmd_pg_ctor(void *handle, vm_ooffset_t size, vm_prot_t prot,
    vm_ooffset_t foff, struct ucred *cred, u_short *color)
{
 
        return (0);
}
 
static void
privcmd_pg_dtor(void *handle)
{
        struct xen_remove_from_physmap rm = { .domid = DOMID_SELF };
        struct privcmd_map *map = handle;
        int error __diagused;
        vm_size_t i;
        vm_page_t m;
 
        /*
         * Remove the mappings from the used pages. This will remove the
         * underlying p2m bindings in Xen second stage translation.
         */
        if (map->mapped == true) {
                VM_OBJECT_WLOCK(map->mem);
retry:
                for (i = 0; i < map->size; i++) {
                        m = vm_page_lookup(map->mem, i);
                        if (m == NULL)
                                continue;
                        if (vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL) == 0)
                                goto retry;
                        cdev_pager_free_page(map->mem, m);
                }
                VM_OBJECT_WUNLOCK(map->mem);
 
                for (i = 0; i < map->size; i++) {
                        rm.gpfn = atop(map->phys_base_addr) + i;
                        HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &rm);
                }
                free(map->err, M_PRIVCMD);
        }
 
        error = xenmem_free(privcmd_dev, map->pseudo_phys_res_id,
            map->pseudo_phys_res);
        KASSERT(error == 0, ("Unable to release memory resource: %d", error));
 
        free(map, M_PRIVCMD);
}
 
static int
privcmd_pg_fault(vm_object_t object, vm_ooffset_t offset,
    int prot, vm_page_t *mres)
{
        struct privcmd_map *map = object->handle;
        vm_pindex_t pidx;
        vm_page_t page;
 
        if (map->mapped != true)
                return (VM_PAGER_FAIL);
 
        pidx = OFF_TO_IDX(offset);
        if (pidx >= map->size || BIT_ISSET(map->size, pidx, map->err))
                return (VM_PAGER_FAIL);
 
        page = PHYS_TO_VM_PAGE(map->phys_base_addr + offset);
        if (page == NULL)
                return (VM_PAGER_FAIL);
 
        KASSERT((page->flags & PG_FICTITIOUS) != 0,
            ("not fictitious %p", page));
        KASSERT(vm_page_wired(page), ("page %p not wired", page));
        KASSERT(!vm_page_busied(page), ("page %p is busy", page));
 
        vm_page_busy_acquire(page, 0);
        vm_page_valid(page);
 
        if (*mres != NULL)
                vm_page_replace(page, object, pidx, *mres);
        else
                vm_page_insert(page, object, pidx);
        *mres = page;
        return (VM_PAGER_OK);
}
 
/*----------------------- Privcmd char device methods ------------------------*/
static int
privcmd_mmap_single(struct cdev *cdev, vm_ooffset_t *offset, vm_size_t size,
    vm_object_t *object, int nprot)
{
        struct privcmd_map *map;
 
        map = malloc(sizeof(*map), M_PRIVCMD, M_WAITOK | M_ZERO);
 
        map->size = OFF_TO_IDX(size);
        map->pseudo_phys_res_id = 0;
 
        map->pseudo_phys_res = xenmem_alloc(privcmd_dev,
            &map->pseudo_phys_res_id, size);
        if (map->pseudo_phys_res == NULL) {
                free(map, M_PRIVCMD);
                return (ENOMEM);
        }
 
        map->phys_base_addr = rman_get_start(map->pseudo_phys_res);
        map->mem = cdev_pager_allocate(map, OBJT_MGTDEVICE, &privcmd_pg_ops,
            size, nprot, *offset, NULL);
        if (map->mem == NULL) {
                xenmem_free(privcmd_dev, map->pseudo_phys_res_id,
                    map->pseudo_phys_res);
                free(map, M_PRIVCMD);
                return (ENOMEM);
        }
 
        *object = map->mem;
 
        return (0);
}
 
static struct privcmd_map *
setup_virtual_area(struct thread *td, unsigned long addr, unsigned long num)
{
        vm_map_t map;
        vm_map_entry_t entry;
        vm_object_t mem;
        vm_pindex_t pindex;
        vm_prot_t prot;
        boolean_t wired;
        struct privcmd_map *umap;
        int error;
 
        if ((num == 0) || ((addr & PAGE_MASK) != 0))
                return NULL;
 
        map = &td->td_proc->p_vmspace->vm_map;
        error = vm_map_lookup(&map, addr, VM_PROT_NONE, &entry, &mem, &pindex,
            &prot, &wired);
        if (error != KERN_SUCCESS || (entry->start != addr) ||
            (entry->end != addr + (num * PAGE_SIZE)))
                return NULL;
 
        vm_map_lookup_done(map, entry);
        if ((mem->type != OBJT_MGTDEVICE) ||
            (mem->un_pager.devp.ops != &privcmd_pg_ops))
                return NULL;
 
        umap = mem->handle;
        /* Allocate a bitset to store broken page mappings. */
        umap->err = BITSET_ALLOC(num, M_PRIVCMD, M_WAITOK | M_ZERO);
 
        return umap;
}
 
static int
privcmd_ioctl(struct cdev *dev, unsigned long cmd, caddr_t arg,
              int mode, struct thread *td)
{
        int error;
        unsigned int i;
        void *data;
        const struct per_user_data *u;
 
        error = devfs_get_cdevpriv(&data);
        if (error != 0)
                return (EINVAL);
        /*
         * Constify user-data to prevent unintended changes to the restriction
         * limits.
         */
        u = data;
 
        switch (cmd) {
        case IOCTL_PRIVCMD_HYPERCALL: {
                struct ioctl_privcmd_hypercall *hcall;
 
                hcall = (struct ioctl_privcmd_hypercall *)arg;
 
                /* Forbid hypercalls if restricted. */
                if (u->dom != DOMID_INVALID) {
                        error = EPERM;
                        break;
                }
 
#ifdef __amd64__
                /*
                 * The hypervisor page table walker will refuse to access
                 * user-space pages if SMAP is enabled, so temporary disable it
                 * while performing the hypercall.
                 */
                if (cpu_stdext_feature & CPUID_STDEXT_SMAP)
                        stac();
#endif
                error = privcmd_hypercall(hcall->op, hcall->arg[0],
                    hcall->arg[1], hcall->arg[2], hcall->arg[3], hcall->arg[4]);
#ifdef __amd64__
                if (cpu_stdext_feature & CPUID_STDEXT_SMAP)
                        clac();
#endif
                if (error >= 0) {
                        hcall->retval = error;
                        error = 0;
                } else {
                        error = xen_translate_error(error);
                        hcall->retval = 0;
                }
                break;
        }
        case IOCTL_PRIVCMD_MMAPBATCH: {
                struct ioctl_privcmd_mmapbatch *mmap;
                struct xen_add_to_physmap_range add;
                xen_ulong_t *idxs;
                xen_pfn_t *gpfns;
                int *errs;
                unsigned int index;
                struct privcmd_map *umap;
                uint16_t num;
 
                mmap = (struct ioctl_privcmd_mmapbatch *)arg;
 
                if (u->dom != DOMID_INVALID && u->dom != mmap->dom) {
                        error = EPERM;
                        break;
                }
 
                umap = setup_virtual_area(td, mmap->addr, mmap->num);
                if (umap == NULL) {
                        error = EINVAL;
                        break;
                }
 
                add.domid = DOMID_SELF;
                add.space = XENMAPSPACE_gmfn_foreign;
                add.foreign_domid = mmap->dom;
 
                /*
                 * The 'size' field in the xen_add_to_physmap_range only
                 * allows for UINT16_MAX mappings in a single hypercall.
                 */
                num = MIN(mmap->num, UINT16_MAX);
 
                idxs = malloc(sizeof(*idxs) * num, M_PRIVCMD, M_WAITOK);
                gpfns = malloc(sizeof(*gpfns) * num, M_PRIVCMD, M_WAITOK);
                errs = malloc(sizeof(*errs) * num, M_PRIVCMD, M_WAITOK);
 
                set_xen_guest_handle(add.idxs, idxs);
                set_xen_guest_handle(add.gpfns, gpfns);
                set_xen_guest_handle(add.errs, errs);
 
                for (index = 0; index < mmap->num; index += num) {
                        num = MIN(mmap->num - index, UINT16_MAX);
                        add.size = num;
 
                        error = copyin(&mmap->arr[index], idxs,
                            sizeof(idxs[0]) * num);
                        if (error != 0)
                                goto mmap_out;
 
                        for (i = 0; i < num; i++)
                                gpfns[i] = atop(umap->phys_base_addr +
                                    (i + index) * PAGE_SIZE);
 
                        bzero(errs, sizeof(*errs) * num);
 
                        error = HYPERVISOR_memory_op(
                            XENMEM_add_to_physmap_range, &add);
                        if (error != 0) {
                                error = xen_translate_error(error);
                                goto mmap_out;
                        }
 
                        for (i = 0; i < num; i++) {
                                if (errs[i] != 0) {
                                        errs[i] = xen_translate_error(errs[i]);
 
                                        /* Mark the page as invalid. */
                                        BIT_SET(mmap->num, index + i,
                                            umap->err);
                                }
                        }
 
                        error = copyout(errs, &mmap->err[index],
                            sizeof(errs[0]) * num);
                        if (error != 0)
                                goto mmap_out;
                }
 
                umap->mapped = true;
 
mmap_out:
                free(idxs, M_PRIVCMD);
                free(gpfns, M_PRIVCMD);
                free(errs, M_PRIVCMD);
                if (!umap->mapped)
                        free(umap->err, M_PRIVCMD);
 
                break;
        }
        case IOCTL_PRIVCMD_MMAP_RESOURCE: {
                struct ioctl_privcmd_mmapresource *mmap;
                struct xen_mem_acquire_resource adq;
                xen_pfn_t *gpfns;
                struct privcmd_map *umap;
 
                mmap = (struct ioctl_privcmd_mmapresource *)arg;
 
                if (u->dom != DOMID_INVALID && u->dom != mmap->dom) {
                        error = EPERM;
                        break;
                }
 
                bzero(&adq, sizeof(adq));
 
                adq.domid = mmap->dom;
                adq.type = mmap->type;
                adq.id = mmap->id;
 
                /* Shortcut for getting the resource size. */
                if (mmap->addr == 0 && mmap->num == 0) {
                        error = HYPERVISOR_memory_op(XENMEM_acquire_resource,
                            &adq);
                        if (error != 0)
                                error = xen_translate_error(error);
                        else
                                mmap->num = adq.nr_frames;
                        break;
                }
 
                umap = setup_virtual_area(td, mmap->addr, mmap->num);
                if (umap == NULL) {
                        error = EINVAL;
                        break;
                }
 
                adq.nr_frames = mmap->num;
                adq.frame = mmap->idx;
 
                gpfns = malloc(sizeof(*gpfns) * mmap->num, M_PRIVCMD, M_WAITOK);
                for (i = 0; i < mmap->num; i++)
                        gpfns[i] = atop(umap->phys_base_addr) + i;
                set_xen_guest_handle(adq.frame_list, gpfns);
 
                error = HYPERVISOR_memory_op(XENMEM_acquire_resource, &adq);
                if (error != 0)
                        error = xen_translate_error(error);
                else
                        umap->mapped = true;
 
                free(gpfns, M_PRIVCMD);
                if (!umap->mapped)
                        free(umap->err, M_PRIVCMD);
 
                break;
        }
        case IOCTL_PRIVCMD_DM_OP: {
                const struct ioctl_privcmd_dmop *dmop;
                struct privcmd_dmop_buf *bufs;
                struct xen_dm_op_buf *hbufs;
 
                dmop = (struct ioctl_privcmd_dmop *)arg;
 
                if (u->dom != DOMID_INVALID && u->dom != dmop->dom) {
                        error = EPERM;
                        break;
                }
 
                if (dmop->num == 0)
                        break;
 
                if (dmop->num > MAX_DMOP_BUFFERS) {
                        error = E2BIG;
                        break;
                }
 
                bufs = malloc(sizeof(*bufs) * dmop->num, M_PRIVCMD, M_WAITOK);
 
                error = copyin(dmop->ubufs, bufs, sizeof(*bufs) * dmop->num);
                if (error != 0) {
                        free(bufs, M_PRIVCMD);
                        break;
                }
 
                hbufs = malloc(sizeof(*hbufs) * dmop->num, M_PRIVCMD, M_WAITOK);
                for (i = 0; i < dmop->num; i++) {
                        set_xen_guest_handle(hbufs[i].h, bufs[i].uptr);
                        hbufs[i].size = bufs[i].size;
                }
 
#ifdef __amd64__
                if (cpu_stdext_feature & CPUID_STDEXT_SMAP)
                        stac();
#endif
                error = HYPERVISOR_dm_op(dmop->dom, dmop->num, hbufs);
#ifdef __amd64__
                if (cpu_stdext_feature & CPUID_STDEXT_SMAP)
                        clac();
#endif
                if (error != 0)
                        error = xen_translate_error(error);
 
                free(bufs, M_PRIVCMD);
                free(hbufs, M_PRIVCMD);
 
 
                break;
        }
        case IOCTL_PRIVCMD_RESTRICT: {
                struct per_user_data *u;
                domid_t dom;
 
                dom = *(domid_t *)arg;
 
                error = devfs_get_cdevpriv((void **)&u);
                if (error != 0)
                        break;
 
                if (u->dom != DOMID_INVALID && u->dom != dom) {
                        error = -EINVAL;
                        break;
                }
                u->dom = dom;
 
                break;
        }
        default:
                error = ENOSYS;
                break;
        }
 
        return (error);
}
 
static void
user_release(void *arg)
{
 
        free(arg, M_PRIVCMD);
}
 
static int
privcmd_open(struct cdev *dev, int flag, int otyp, struct thread *td)
{
        struct per_user_data *u;
        int error;
 
        u = malloc(sizeof(*u), M_PRIVCMD, M_WAITOK);
        u->dom = DOMID_INVALID;
 
        /* Assign the allocated per_user_data to this open instance. */
        error = devfs_set_cdevpriv(u, user_release);
        if (error != 0) {
                free(u, M_PRIVCMD);
        }
 
        return (error);
}
 
/*------------------ Private Device Attachment Functions  --------------------*/
static void
privcmd_identify(driver_t *driver, device_t parent)
{
 
        KASSERT(xen_domain(),
            ("Trying to attach privcmd device on non Xen domain"));
 
        if (BUS_ADD_CHILD(parent, 0, "privcmd", 0) == NULL)
                panic("unable to attach privcmd user-space device");
}
 
static int
privcmd_probe(device_t dev)
{
 
        privcmd_dev = dev;
        device_set_desc(dev, "Xen privileged interface user-space device");
        return (BUS_PROBE_NOWILDCARD);
}
 
static int
privcmd_attach(device_t dev)
{
 
        make_dev_credf(MAKEDEV_ETERNAL, &privcmd_devsw, 0, NULL, UID_ROOT,
            GID_WHEEL, 0600, "xen/privcmd");
        return (0);
}
 
/*-------------------- Private Device Attachment Data  -----------------------*/
static device_method_t privcmd_methods[] = {
        DEVMETHOD(device_identify,      privcmd_identify),
        DEVMETHOD(device_probe,         privcmd_probe),
        DEVMETHOD(device_attach,        privcmd_attach),
 
        DEVMETHOD_END
};
 
static driver_t privcmd_driver = {
        "privcmd",
        privcmd_methods,
        0,
};
 
devclass_t privcmd_devclass;
 
DRIVER_MODULE(privcmd, xenpv, privcmd_driver, privcmd_devclass, 0, 0);
MODULE_DEPEND(privcmd, xenpv, 1, 1, 1);