xnu-7195.101.1.tar.gz

[apple/xnu.git] / bsd / kern / imageboot.c

/*
 * Copyright (c) 2006-2020 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/proc_internal.h>
#include <sys/systm.h>
#include <sys/systm.h>
#include <sys/mount_internal.h>
#include <sys/fsctl.h>
#include <sys/filedesc.h>
#include <sys/vnode_internal.h>
#include <sys/imageboot.h>
#include <kern/assert.h>

#include <sys/namei.h>
#include <sys/fcntl.h>
#include <sys/vnode.h>
#include <sys/sysproto.h>
#include <sys/csr.h>
#include <miscfs/devfs/devfsdefs.h>
#include <libkern/crypto/sha2.h>
#include <libkern/crypto/rsa.h>
#include <libkern/OSKextLibPrivate.h>
#include <sys/ubc_internal.h>

#if CONFIG_IMAGEBOOT_IMG4
#include <libkern/img4/interface.h>
#include <img4/firmware.h>
#endif

#include <kern/kalloc.h>

#include <pexpert/pexpert.h>
#include <kern/chunklist.h>

extern struct filedesc filedesc0;

extern int (*mountroot)(void);
extern char rootdevice[DEVMAXNAMESIZE];

#if CONFIG_LOCKERBOOT
typedef struct _locker_mount_args {
        char lmnt_path[PATH_MAX];
        uint16_t lmnt_preferred_hash;
} locker_mount_args_t;
#endif

#define DEBUG_IMAGEBOOT 0

#if DEBUG_IMAGEBOOT
#define DBG_TRACE(...) printf("imageboot: " __VA_ARGS__)
#else
#define DBG_TRACE(...) do {} while(0)
#endif

#define AUTHDBG(fmt, args...) do { printf("%s: " fmt "\n", __func__, ##args); } while (0)
#define AUTHPRNT(fmt, args...) do { printf("%s: " fmt "\n", __func__, ##args); } while (0)
#define kheap_free_safe(h, x, l) do { if ((x)) { kheap_free(h, x, l); (x) = NULL; } } while (0)

extern int di_root_image_ext(const char *path, char *devname, size_t devsz, dev_t *dev_p, bool removable);
extern int di_root_image(const char *path, char *devname, size_t devsz, dev_t *dev_p);
extern int di_root_ramfile_buf(void *buf, size_t bufsz, char *devname, size_t devsz, dev_t *dev_p);

static boolean_t imageboot_setup_new(imageboot_type_t type);

void *ubc_getobject_from_filename(const char *filename, struct vnode **vpp, off_t *file_size);

extern lck_rw_t rootvnode_rw_lock;

#define kIBFilePrefix "file://"

__private_extern__ int
imageboot_format_is_valid(const char *root_path)
{
        return strncmp(root_path, kIBFilePrefix,
                   strlen(kIBFilePrefix)) == 0;
}

static void
vnode_get_and_drop_always(vnode_t vp)
{
        vnode_getalways(vp);
        vnode_rele(vp);
        vnode_put(vp);
}

__private_extern__ bool
imageboot_desired(void)
{
        bool do_imageboot = false;

        char *root_path = NULL;
        root_path = zalloc(ZV_NAMEI);
        /*
         * Check for first layer DMG rooting.
         *
         * Note that here we are principally concerned with whether or not we
         * SHOULD try to imageboot, not whether or not we are going to be able to.
         *
         * If NONE of the boot-args are present, then assume that image-rooting
         * is not requested.
         *
         * [!! Note parens guard the entire logically OR'd set of statements, below. It validates
         * that NONE of the below-mentioned boot-args is present...!!]
         */
        if (!(PE_parse_boot_argn("rp0", root_path, MAXPATHLEN) ||
#if CONFIG_IMAGEBOOT_IMG4
            PE_parse_boot_argn("arp0", root_path, MAXPATHLEN) ||
#endif
            PE_parse_boot_argn("rp", root_path, MAXPATHLEN) ||
            PE_parse_boot_argn(IMAGEBOOT_ROOT_ARG, root_path, MAXPATHLEN) ||
            PE_parse_boot_argn(IMAGEBOOT_AUTHROOT_ARG, root_path, MAXPATHLEN))) {
                /* explicitly set to false */
                do_imageboot = false;
        } else {
                /* now sanity check the file-path format */
                if (imageboot_format_is_valid(root_path)) {
                        DBG_TRACE("%s: Found %s\n", __FUNCTION__, root_path);
                        /* root_path looks good and we have one of the aforementioned bootargs */
                        do_imageboot = true;
                } else {
                        /* explicitly set to false */
                        do_imageboot = false;
                }
        }

        zfree(ZV_NAMEI, root_path);
        return do_imageboot;
}

__private_extern__ imageboot_type_t
imageboot_needed(void)
{
        imageboot_type_t result = IMAGEBOOT_NONE;
        char *root_path = NULL;

        DBG_TRACE("%s: checking for presence of root path\n", __FUNCTION__);

        if (!imageboot_desired()) {
                goto out;
        }

        root_path = zalloc(ZV_NAMEI);
        result = IMAGEBOOT_DMG;

        /* Check for second layer */
        if (!(PE_parse_boot_argn("rp1", root_path, MAXPATHLEN) ||
            PE_parse_boot_argn(IMAGEBOOT_CONTAINER_ARG, root_path, MAXPATHLEN))) {
                goto out;
        }

        /* Sanity-check second layer */
        if (imageboot_format_is_valid(root_path)) {
                DBG_TRACE("%s: Found %s\n", __FUNCTION__, root_path);
        } else {
                panic("%s: Invalid URL scheme for %s\n",
                    __FUNCTION__, root_path);
        }

out:
        if (root_path != NULL) {
                zfree(ZV_NAMEI, root_path);
        }
        return result;
}

extern bool IOBaseSystemARVRootHashAvailable(void);


/*
 * Mounts new filesystem based on image path, and pivots it to the root.
 * The image to be mounted is located at image_path.
 * It will be mounted at mount_path.
 * The vfs_switch_root operation will be performed.
 * After the pivot, the outgoing root filesystem (the filesystem at root when
 * this function begins) will be at outgoing_root_path.  If `skip_signature_check` is true,
 * then ignore the chunklisted or authAPFS checks on this image
 */
__private_extern__ int
imageboot_pivot_image(const char *image_path, imageboot_type_t type, const char *mount_path,
    const char *outgoing_root_path, const bool rooted_dmg, const bool skip_signature_check)
{
        int error;
        boolean_t authenticated_dmg_chunklist = false;
        vnode_t mount_vp = NULLVP;
        errno_t rootauth;


        if (type != IMAGEBOOT_DMG) {
                panic("not supported");
        }

        /*
         * Check that the image file actually exists.
         * We also need to find the mount it's on, to mark it as backing the
         * root.
         */
        vnode_t imagevp = NULLVP;
        error = vnode_lookup(image_path, 0, &imagevp, vfs_context_kernel());
        if (error) {
                printf("%s: image file not found or couldn't be read: %d\n", __FUNCTION__, error);
                /*
                 * bail out here to short-circuit out of panic logic below.
                 * Failure to find the pivot-image should not be a fatal condition (ENOENT)
                 * since it may result in natural consequences (ergo, cannot unlock filevault prompt).
                 */
                return error;
        }

        /*
         * load the disk image and obtain its device.
         * di_root_image's name and the names of its arguments suggest it has
         * to be mounted at the root, but that's not actually needed.
         * We just need to obtain the device info.
         */

        dev_t dev;
        char devname[DEVMAXNAMESIZE];

        error = di_root_image_ext(image_path, devname, DEVMAXNAMESIZE, &dev, true);
        if (error) {
                panic("%s: di_root_image failed: %d\n", __FUNCTION__, error);
        }

        printf("%s: attached disk image %s as %s\n", __FUNCTION__, image_path, devname);


#if CONFIG_IMAGEBOOT_CHUNKLIST
        if ((rooted_dmg == false) && !IOBaseSystemARVRootHashAvailable()) {
                error = authenticate_root_with_chunklist(image_path, NULL);
                if (error == 0) {
                        printf("authenticated root-dmg via chunklist...\n");
                        authenticated_dmg_chunklist = true;
                } else {
                        /* root hash was not available, and image is NOT chunklisted? */
                        printf("failed to chunklist-authenticate root-dmg @ %s\n", image_path);
                }
        }
#endif

        char fulldevname[DEVMAXNAMESIZE + 5]; // "/dev/"
        strlcpy(fulldevname, "/dev/", sizeof(fulldevname));
        strlcat(fulldevname, devname, sizeof(fulldevname));

        /*
         * mount expects another layer of indirection (because it expects to
         * be getting a user_addr_t of a char *.
         * Make a pointer-to-pointer on our stack. It won't use this
         * address after it returns so this should be safe.
         */
        char *fulldevnamep = &(fulldevname[0]);
        char **fulldevnamepp = &fulldevnamep;

#define PIVOTMNT "/System/Volumes/BaseSystem"


        /* Attempt to mount as HFS; if it fails, then try as APFS */
        printf("%s: attempting to mount as hfs...\n", __FUNCTION__);
        error = kernel_mount("hfs", NULLVP, NULLVP, PIVOTMNT, fulldevnamepp, 0, (MNT_RDONLY | MNT_DONTBROWSE), (KERNEL_MOUNT_NOAUTH | KERNEL_MOUNT_BASESYSTEMROOT), vfs_context_kernel());
        if (error) {
                printf("mount failed: %d\n", error);
                printf("%s: attempting to mount as apfs...\n", __FUNCTION__);
                error = kernel_mount("apfs", NULLVP, NULLVP, PIVOTMNT, fulldevnamepp, 0, (MNT_RDONLY | MNT_DONTBROWSE), (KERNEL_MOUNT_NOAUTH | KERNEL_MOUNT_BASESYSTEMROOT), vfs_context_kernel());
        }

        /* If we didn't mount as either HFS or APFS, then bail out */
        if (error) {
                /*
                 * Note that for this particular failure case (failure to mount), the disk image
                 * being attached may have failed to quiesce within the alloted time out (20-30 sec).
                 * For example, it may be still probing, or APFS container enumeration may have not
                 * completed. If so, then we may have fallen into this particular error case. However,
                 * failure to complete matching should be an exceptional case as 30 sec. is quite a
                 * long time to wait for matching to complete (which would have occurred in
                 * di_root_image_ext).
                 */
#if defined(__arm64__) && XNU_TARGET_OS_OSX
                panic("%s: failed to mount pivot image(%d)!", __FUNCTION__, error);
#endif
                printf("%s: failed to mount pivot image(%d) !", __FUNCTION__, error);
                goto done;
        }

        /* otherwise, if the mount succeeded, then assert that the DMG is authenticated (either chunklist or authapfs) */
        error = vnode_lookup(PIVOTMNT, 0, &mount_vp, vfs_context_kernel());
        if (error) {
#if defined(__arm64__) && XNU_TARGET_OS_OSX
                panic("%s: failed to lookup pivot root (%d) !", __FUNCTION__, error);
#endif
                printf("%s: failed to lookup pivot root (%d)!", __FUNCTION__, error);
                goto done;
        }

        /* the 0x1 implies base system */
        rootauth = VNOP_IOCTL(mount_vp, FSIOC_KERNEL_ROOTAUTH, (caddr_t)0x1, 0, vfs_context_kernel());
        if (rootauth) {
                printf("BS-DMG failed to authenticate intra-FS \n");
                /*
                 * If we are using a custom rooted DMG, or if we have already authenticated
                 * the DMG via chunklist, then it is permissible to use.
                 * Or, if CSR_ALLOW_ANY_RECOVERY_OS is set on Development or Debug build variant.
                 */
                if (rooted_dmg || authenticated_dmg_chunklist || skip_signature_check) {
                        rootauth = 0;
                }
                error = rootauth;
        }
        vnode_put(mount_vp);
        mount_vp = NULLVP;

        if (error) {
                /*
                 * Failure here exclusively means that the mount failed to authenticate.
                 * This means that the disk image either was not sealed (authapfs), or it was
                 * not hosted on a chunklisted DMG.  Both scenarios may be fatal depending
                 * on the platform.
                 */
#if defined(__arm64__) && XNU_TARGET_OS_OSX
                panic("%s: could not authenticate the pivot image: %d. giving up.\n", __FUNCTION__, error);
#endif
                printf("%s: could not authenticate the pivot image: %d. giving up.\n", __FUNCTION__, error);
                goto done;
        }

        if (rootvnode) {
                mount_t root_mp = vnode_mount(rootvnode);
                if (root_mp && (root_mp->mnt_kern_flag & MNTK_SSD)) {
                        rootvp_is_ssd = true;
                }
        }
        /*
         * pivot the incoming and outgoing filesystems
         */
        error = vfs_switch_root(mount_path, outgoing_root_path, 0);
        if (error) {
                panic("%s: vfs_switch_root failed: %d\n", __FUNCTION__, error);
        }

        /*
         * Mark the filesystem containing the image as backing root, so it
         * won't be unmountable.
         *
         * vfs_switch_root() clears this flag, so we have to set it after
         * the pivot call.
         * If the system later pivots out of the image, vfs_switch_root
         * will clear it again, so the backing filesystem can be unmounted.
         */
        mount_t imagemp = imagevp->v_mount;
        lck_rw_lock_exclusive(&imagemp->mnt_rwlock);
        imagemp->mnt_kern_flag |= MNTK_BACKS_ROOT;
        lck_rw_done(&imagemp->mnt_rwlock);

        error = 0;

        /*
         * Note that we do NOT change kern.bootuuid here -
         * imageboot_mount_image() does, but imageboot_pivot_image() doesn't.
         * imageboot_mount_image() is used when the root volume uuid was
         * "always supposed to be" the one inside the dmg. imageboot_pivot_
         * image() is used when the true root volume just needs to be
         * obscured for a moment by the dmg.
         */

done:
        if (imagevp != NULLVP) {
                vnode_put(imagevp);
        }
        return error;
}

/* kern_sysctl.c */
extern uuid_string_t fake_bootuuid;

static void
set_fake_bootuuid(mount_t mp)
{
        struct vfs_attr va;
        VFSATTR_INIT(&va);
        VFSATTR_WANTED(&va, f_uuid);

        if (vfs_getattr(mp, &va, vfs_context_current()) != 0) {
                return;
        }

        if (!VFSATTR_IS_SUPPORTED(&va, f_uuid)) {
                return;
        }

        uuid_unparse(va.f_uuid, fake_bootuuid);
}

/*
 * Swaps in new root filesystem based on image path.
 * Current root filesystem is removed from mount list and
 * tagged MNTK_BACKS_ROOT, MNT_ROOTFS is cleared on it, and
 * "rootvnode" is reset.  Root vnode of currentroot filesystem
 * is returned with usecount (no iocount).
 * kern.bootuuid is arranged to return the UUID of the mounted image. (If
 * we did nothing here, it would be the UUID of the image source volume.)
 */
__private_extern__ int
imageboot_mount_image(const char *root_path, int height, imageboot_type_t type)
{
        dev_t           dev;
        int             error;
        /*
         * Need to stash this here since we may do a kernel_mount() on /, which will
         * automatically update the rootvnode global. Note that vfs_mountroot() does
         * not update that global, which is a bit weird.
         */
        vnode_t         old_rootvnode = rootvnode;
        vnode_t         newdp;
        mount_t         new_rootfs;
        boolean_t update_rootvnode = FALSE;

        if (type == IMAGEBOOT_DMG) {
                error = di_root_image(root_path, rootdevice, DEVMAXNAMESIZE, &dev);
                if (error) {
                        panic("%s: di_root_image failed: %d\n", __FUNCTION__, error);
                }

                rootdev = dev;
                mountroot = NULL;
                printf("%s: root device 0x%x\n", __FUNCTION__, rootdev);
                error = vfs_mountroot();
                if (error != 0) {
                        panic("vfs_mountroot() failed.\n");
                }

                update_rootvnode = TRUE;
        }
#if CONFIG_LOCKERBOOT
        else if (type == IMAGEBOOT_LOCKER) {
                locker_mount_args_t *mntargs = kheap_alloc(KHEAP_TEMP,
                    sizeof(*mntargs), Z_WAITOK);
                if (!mntargs) {
                        panic("could not alloc mount args");
                }

                strlcpy(mntargs->lmnt_path, root_path, sizeof(mntargs->lmnt_path));
                mntargs->lmnt_preferred_hash = 0;

                DBG_TRACE("%s: mounting locker: %s\n", __FUNCTION__, root_path);
                error = kernel_mount(LOCKERFS_NAME, NULLVP, NULLVP, "/",
                    mntargs, sizeof(*mntargs), 0, 0, vfs_context_kernel());
                if (error) {
                        panic("failed to mount locker: %d", error);
                }
                kheap_free(KHEAP_TEMP, mntargs, sizeof(*mntargs));

                /* Clear the old mount association. */
                old_rootvnode->v_mountedhere = NULL;
                rootvnode->v_mount->mnt_vnodecovered = NULL;
        }
#endif
        else {
                panic("invalid imageboot type: %d", type);
        }

        /*
         * Get the vnode for '/'.
         * Set fdp->fd_fd.fd_cdir to reference it.
         */
        if (VFS_ROOT(TAILQ_LAST(&mountlist, mntlist), &newdp, vfs_context_kernel())) {
                panic("%s: cannot find root vnode", __FUNCTION__);
        }
        DBG_TRACE("%s: old root fsname: %s\n", __FUNCTION__, old_rootvnode->v_mount->mnt_vtable->vfc_name);

        if (old_rootvnode != NULL) {
                /* remember the old rootvnode, but remove it from mountlist */
                mount_t old_rootfs = old_rootvnode->v_mount;

                mount_list_remove(old_rootfs);
                mount_lock(old_rootfs);
                old_rootfs->mnt_kern_flag |= MNTK_BACKS_ROOT;
                old_rootfs->mnt_flag &= ~MNT_ROOTFS;
                mount_unlock(old_rootfs);
        }

        vnode_ref(newdp);
        vnode_put(newdp);

        lck_rw_lock_exclusive(&rootvnode_rw_lock);
        /* switch to the new rootvnode */
        if (update_rootvnode) {
                rootvnode = newdp;
                set_fake_bootuuid(rootvnode->v_mount);
        }

        new_rootfs = rootvnode->v_mount;
        mount_lock(new_rootfs);
        new_rootfs->mnt_flag |= MNT_ROOTFS;
        mount_unlock(new_rootfs);

        filedesc0.fd_cdir = newdp;
        lck_rw_unlock_exclusive(&rootvnode_rw_lock);

        DBG_TRACE("%s: root switched\n", __FUNCTION__);

        if (old_rootvnode != NULL) {
#ifdef CONFIG_IMGSRC_ACCESS
                if (height >= 0 && PE_imgsrc_mount_supported()) {
                        imgsrc_rootvnodes[height] = old_rootvnode;
                } else {
                        vnode_get_and_drop_always(old_rootvnode);
                }
#else
#pragma unused(height)
                vnode_get_and_drop_always(old_rootvnode);
#endif /* CONFIG_IMGSRC_ACCESS */
        }
        return 0;
}

/*
 * Return a memory object for given file path.
 * Also returns a vnode reference for the given file path.
 */
void *
ubc_getobject_from_filename(const char *filename, struct vnode **vpp, off_t *file_size)
{
        int err = 0;
        struct nameidata ndp = {};
        struct vnode *vp = NULL;
        off_t fsize = 0;
        vfs_context_t ctx = vfs_context_kernel();
        void *control = NULL;

        NDINIT(&ndp, LOOKUP, OP_OPEN, LOCKLEAF, UIO_SYSSPACE, CAST_USER_ADDR_T(filename), ctx);
        if ((err = namei(&ndp)) != 0) {
                goto errorout;
        }
        nameidone(&ndp);
        vp = ndp.ni_vp;

        if ((err = vnode_size(vp, &fsize, ctx)) != 0) {
                goto errorout;
        }

        if (fsize < 0) {
                goto errorout;
        }

        control = ubc_getobject(vp, UBC_FLAGS_NONE);
        if (control == NULL) {
                goto errorout;
        }

        *file_size = fsize;
        *vpp = vp;
        vp = NULL;

errorout:
        if (vp) {
                vnode_put(vp);
        }
        return control;
}

int
imageboot_read_file_from_offset(kalloc_heap_t kheap, const char *path, off_t offset, void **bufp, size_t *bufszp)
{
        int err = 0;
        struct nameidata ndp = {};
        struct vnode *vp = NULL;
        off_t fsize = 0;
        int resid = 0;
        char *buf = NULL;
        bool doclose = false;

        vfs_context_t ctx = vfs_context_kernel();
        proc_t p = vfs_context_proc(ctx);
        kauth_cred_t kerncred = vfs_context_ucred(ctx);

        NDINIT(&ndp, LOOKUP, OP_OPEN, LOCKLEAF, UIO_SYSSPACE, CAST_USER_ADDR_T(path), ctx);
        if ((err = namei(&ndp)) != 0) {
                AUTHPRNT("namei failed (%s) - %d", path, err);
                goto out;
        }
        nameidone(&ndp);
        vp = ndp.ni_vp;

        if ((err = vnode_size(vp, &fsize, ctx)) != 0) {
                AUTHPRNT("failed to get vnode size of %s - %d", path, err);
                goto out;
        }
        if (fsize < 0) {
                panic("negative file size");
        }

        if ((err = VNOP_OPEN(vp, FREAD, ctx)) != 0) {
                AUTHPRNT("failed to open %s - %d", path, err);
                goto out;
        }
        doclose = true;

        /* if bufsz is non-zero, cap the read at bufsz bytes */
        if (*bufszp && *bufszp < (size_t)fsize) {
                fsize = *bufszp;
        }

        fsize = (off_t)MIN((size_t)fsize, INT_MAX);

        buf = kheap_alloc(kheap, (size_t)fsize, Z_WAITOK);
        if (buf == NULL) {
                err = ENOMEM;
                goto out;
        }

        if ((err = vn_rdwr(UIO_READ, vp, (caddr_t)buf, (int)fsize, offset, UIO_SYSSPACE, IO_NODELOCKED, kerncred, &resid, p)) != 0) {
                AUTHPRNT("Cannot read %d bytes at offset %d from %s - %d", (int)fsize, (int)offset, path, err);
                goto out;
        }

        if (resid) {
                /* didnt get everything we wanted */
                AUTHPRNT("Short read of %d bytes at offset %d from %s - %d", (int)fsize, (int)offset, path, resid);
                err = EINVAL;
                goto out;
        }

out:
        if (doclose) {
                VNOP_CLOSE(vp, FREAD, ctx);
        }
        if (vp) {
                vnode_put(vp);
                vp = NULL;
        }

        if (err) {
                kheap_free_safe(kheap, buf, (size_t)fsize);
        } else {
                *bufp = buf;
                *bufszp = (size_t)fsize;
        }

        return err;
}

int
imageboot_read_file(kalloc_heap_t kheap, const char *path, void **bufp, size_t *bufszp)
{
        return imageboot_read_file_from_offset(kheap, path, 0, bufp, bufszp);
}

#if CONFIG_IMAGEBOOT_IMG4 || CONFIG_IMAGEBOOT_CHUNKLIST
vnode_t
imgboot_get_image_file(const char *path, off_t *fsize, int *errp)
{
        struct nameidata ndp = {};
        vnode_t vp = NULL;
        vfs_context_t ctx = vfs_context_kernel();
        int err;

        NDINIT(&ndp, LOOKUP, OP_OPEN, LOCKLEAF, UIO_SYSSPACE, CAST_USER_ADDR_T(path), ctx);
        if ((err = namei(&ndp)) != 0) {
                AUTHPRNT("Cannot find %s - error %d", path, err);
        } else {
                nameidone(&ndp);
                vp = ndp.ni_vp;

                if (vp->v_type != VREG) {
                        err = EINVAL;
                        AUTHPRNT("%s it not a regular file", path);
                } else if (fsize) {
                        if ((err = vnode_size(vp, fsize, ctx)) != 0) {
                                AUTHPRNT("Cannot get file size of %s - error %d", path, err);
                        }
                }
        }

        if (err) {
                if (vp) {
                        vnode_put(vp);
                }
                *errp = err;
                vp = NULL;
        }
        return vp;
}
#endif /* CONFIG_IMAGEBOOT_CHUNKLIST || CONFIG_IMAGEBOOT_CHUNKLIST */

#if CONFIG_IMAGEBOOT_IMG4

#define APTICKET_NAME "apticket.der"

static char *
imgboot_get_apticket_path(const char *rootpath, size_t *sz)
{
        size_t plen = strlen(rootpath) + sizeof(APTICKET_NAME) + 1;
        char *path = kheap_alloc(KHEAP_TEMP, plen, Z_WAITOK);

        if (path) {
                char *slash;

                strlcpy(path, rootpath, plen);
                slash = strrchr(path, '/');
                if (slash == NULL) {
                        slash = path;
                } else {
                        slash++;
                }
                strlcpy(slash, APTICKET_NAME, sizeof(APTICKET_NAME) + 1);
        }

        *sz = plen;
        return path;
}

static int
authenticate_root_with_img4(const char *rootpath)
{
        errno_t rv;
        vnode_t vp;
        size_t ticket_pathsz = 0;
        char *ticket_path;
        img4_buff_t tck = IMG4_BUFF_INIT;
        img4_firmware_execution_context_t exec = {
                .i4fex_version = IMG4_FIRMWARE_EXECUTION_CONTEXT_STRUCT_VERSION,
                .i4fex_execute = NULL,
                .i4fex_context = NULL,
        };
        img4_firmware_t fw = NULL;
        img4_firmware_flags_t fw_flags = IMG4_FIRMWARE_FLAG_BARE |
            IMG4_FIRMWARE_FLAG_SUBSEQUENT_STAGE;

        DBG_TRACE("Check %s\n", rootpath);

        if (img4if == NULL) {
                AUTHPRNT("AppleImage4 is not ready");
                return EAGAIN;
        }

        ticket_path = imgboot_get_apticket_path(rootpath, &ticket_pathsz);
        if (ticket_path == NULL) {
                AUTHPRNT("Cannot construct ticket path - out of memory");
                return ENOMEM;
        }

        rv = imageboot_read_file(KHEAP_TEMP, ticket_path, (void **)&tck.i4b_bytes, &tck.i4b_len);
        if (rv) {
                AUTHPRNT("Cannot get a ticket from %s - %d\n", ticket_path, rv);
                goto out_with_ticket_path;
        }

        DBG_TRACE("Got %lu bytes of manifest from %s\n", tck.i4b_len, ticket_path);

        vp = imgboot_get_image_file(rootpath, NULL, &rv);
        if (vp == NULL) {
                /* Error message had been printed already */
                rv = EIO;
                goto out_with_ticket_bytes;
        }

        fw = img4_firmware_new_from_vnode_4xnu(IMG4_RUNTIME_DEFAULT, &exec, 'rosi',
            vp, fw_flags);
        if (!fw) {
                AUTHPRNT("Could not allocate new firmware");
                rv = ENOMEM;
                goto out_with_ticket_bytes;
        }

        img4_firmware_attach_manifest(fw, &tck);
        rv = img4_firmware_evaluate(fw, img4_chip_select_personalized_ap(), NULL);

out_with_ticket_bytes:
        kheap_free_safe(KHEAP_TEMP, tck.i4b_bytes, tck.i4b_len);
out_with_ticket_path:
        kheap_free_safe(KHEAP_TEMP, ticket_path, ticket_pathsz);

        img4_firmware_destroy(&fw);
        return rv;
}
#endif /* CONFIG_IMAGEBOOT_IMG4 */


/*
 * Attach the image at 'path' as a ramdisk and mount it as our new rootfs.
 * All existing mounts are first umounted.
 */
static int
imageboot_mount_ramdisk(const char *path)
{
        int err = 0;
        size_t bufsz = 0;
        void *buf = NULL;
        dev_t dev;
        vnode_t newdp;
        vnode_t tvp;
        mount_t new_rootfs;

        /* Read our target image from disk */
        err = imageboot_read_file(KHEAP_DATA_BUFFERS, path, &buf, &bufsz);
        if (err) {
                printf("%s: failed: imageboot_read_file() = %d\n", __func__, err);
                goto out;
        }
        DBG_TRACE("%s: read '%s' sz = %lu\n", __func__, path, bufsz);

#if CONFIG_IMGSRC_ACCESS
        /* Re-add all root mounts to the mount list in the correct order... */
        mount_list_remove(rootvnode->v_mount);
        for (int i = 0; i < MAX_IMAGEBOOT_NESTING; i++) {
                struct vnode *vn = imgsrc_rootvnodes[i];
                if (vn) {
                        vnode_getalways(vn);
                        imgsrc_rootvnodes[i] = NULLVP;

                        mount_t mnt = vn->v_mount;
                        mount_lock(mnt);
                        mnt->mnt_flag |= MNT_ROOTFS;
                        mount_list_add(mnt);
                        mount_unlock(mnt);

                        vnode_rele(vn);
                        vnode_put(vn);
                }
        }
        mount_list_add(rootvnode->v_mount);
#endif

        /* ... and unmount everything */
        vfs_unmountall(FALSE);

        lck_rw_lock_exclusive(&rootvnode_rw_lock);
        filedesc0.fd_cdir = NULL;
        tvp = rootvnode;
        rootvnode = NULL;
        rootvp = NULLVP;
        rootdev = NODEV;
        lck_rw_unlock_exclusive(&rootvnode_rw_lock);
        vnode_get_and_drop_always(tvp);

        /* Attach the ramfs image ... */
        err = di_root_ramfile_buf(buf, bufsz, rootdevice, DEVMAXNAMESIZE, &dev);
        if (err) {
                printf("%s: failed: di_root_ramfile_buf() = %d\n", __func__, err);
                goto out;
        }

        /* ... and mount it */
        rootdev = dev;
        mountroot = NULL;
        err = vfs_mountroot();
        if (err) {
                printf("%s: failed: vfs_mountroot() = %d\n", __func__, err);
                goto out;
        }

        /* Switch to new root vnode */
        if (VFS_ROOT(TAILQ_LAST(&mountlist, mntlist), &newdp, vfs_context_kernel())) {
                panic("%s: cannot find root vnode", __func__);
        }
        vnode_ref(newdp);

        lck_rw_lock_exclusive(&rootvnode_rw_lock);
        rootvnode = newdp;
        rootvnode->v_flag |= VROOT;
        new_rootfs = rootvnode->v_mount;
        mount_lock(new_rootfs);
        new_rootfs->mnt_flag |= MNT_ROOTFS;
        mount_unlock(new_rootfs);

        set_fake_bootuuid(new_rootfs);

        filedesc0.fd_cdir = newdp;
        lck_rw_unlock_exclusive(&rootvnode_rw_lock);

        vnode_put(newdp);

        DBG_TRACE("%s: root switched\n", __func__);

out:
        if (err) {
                kheap_free_safe(KHEAP_DATA_BUFFERS, buf, bufsz);
        }
        return err;
}

/*
 * If the path is in <file://> URL format then we allocate memory and decode it,
 * otherwise return the same pointer.
 *
 * Caller is expected to check if the pointers are different.
 */
static char *
url_to_path(char *url_path, size_t *sz)
{
        char *path = url_path;
        size_t len = strlen(kIBFilePrefix);

        if (strncmp(kIBFilePrefix, url_path, len) == 0) {
                /* its a URL - remove the file:// prefix and percent-decode */
                url_path += len;

                len = strlen(url_path);
                if (len) {
                        /* Make a copy of the path to URL-decode */
                        path = kheap_alloc(KHEAP_TEMP, len + 1, Z_WAITOK);
                        if (path == NULL) {
                                panic("imageboot path allocation failed - cannot allocate %d bytes\n", (int)len);
                        }

                        strlcpy(path, url_path, len + 1);
                        *sz = len + 1;
                        url_decode(path);
                } else {
                        panic("Bogus imageboot path URL - missing path\n");
                }

                DBG_TRACE("%s: root image URL <%s> becomes %s\n", __func__, url_path, path);
        }

        return path;
}

static boolean_t
imageboot_setup_new(imageboot_type_t type)
{
        int error;
        char *root_path = NULL;
        int height = 0;
        boolean_t done = FALSE;
        boolean_t auth_root = TRUE;
        boolean_t ramdisk_root = FALSE;

        root_path = zalloc(ZV_NAMEI);
        assert(root_path != NULL);

#if CONFIG_LOCKERBOOT
        if (type == IMAGEBOOT_LOCKER) {
                if (!PE_parse_boot_argn(IMAGEBOOT_LOCKER_ARG, root_path, MAXPATHLEN)) {
                        panic("locker boot with no locker given");
                }

                DBG_TRACE("%s: root fsname: %s\n", __FUNCTION__, rootvnode->v_mount->mnt_vtable->vfc_name);

                /*
                 * The locker path is a path, not a URL, so just pass it directly to
                 * imageboot_mount_image().
                 */
                error = imageboot_mount_image(root_path, 0, type);
                if (error) {
                        panic("failed to mount system locker: %d", error);
                }

                done = TRUE;
                goto out;
        }
#endif /* CONFIG_LOCKERBOOT */

        unsigned imgboot_arg;
        if (PE_parse_boot_argn("-rootdmg-ramdisk", &imgboot_arg, sizeof(imgboot_arg))) {
                ramdisk_root = TRUE;
        }

        if (PE_parse_boot_argn(IMAGEBOOT_CONTAINER_ARG, root_path, MAXPATHLEN) == TRUE) {
                printf("%s: container image url is %s\n", __FUNCTION__, root_path);
                error = imageboot_mount_image(root_path, height, type);
                if (error != 0) {
                        panic("Failed to mount container image.");
                }

                height++;
        }

        if (PE_parse_boot_argn(IMAGEBOOT_AUTHROOT_ARG, root_path, MAXPATHLEN) == FALSE &&
            PE_parse_boot_argn(IMAGEBOOT_ROOT_ARG, root_path, MAXPATHLEN) == FALSE) {
                if (height > 0) {
                        panic("%s specified without %s or %s?\n", IMAGEBOOT_CONTAINER_ARG, IMAGEBOOT_AUTHROOT_ARG, IMAGEBOOT_ROOT_ARG);
                }
                goto out;
        }

        printf("%s: root image URL is '%s'\n", __func__, root_path);

        /* Make a copy of the path to URL-decode */
        size_t pathsz;
        char *path = url_to_path(root_path, &pathsz);
        assert(path);

#if CONFIG_IMAGEBOOT_CHUNKLIST
        if (auth_root) {
                /*
                 * This updates auth_root to reflect whether chunklist was
                 * actually enforced. In effect, this clears auth_root if
                 * CSR_ALLOW_ANY_RECOVERY_OS allowed an invalid image.
                 */
                AUTHDBG("authenticating root image at %s", path);
                error = authenticate_root_with_chunklist(path, &auth_root);
                if (error) {
                        panic("root image authentication failed (err = %d)\n", error);
                }
                AUTHDBG("successfully authenticated %s", path);
        }
#endif

        if (ramdisk_root) {
                error = imageboot_mount_ramdisk(path);
        } else {
                error = imageboot_mount_image(root_path, height, type);
        }

        if (path != root_path) {
                kheap_free_safe(KHEAP_TEMP, path, pathsz);
        }

        if (error) {
                panic("Failed to mount root image (err=%d, auth=%d, ramdisk=%d)\n",
                    error, auth_root, ramdisk_root);
        }

#if CONFIG_IMAGEBOOT_CHUNKLIST
        if (auth_root) {
                /* check that the image version matches the running kernel */
                AUTHDBG("checking root image version");
                error = authenticate_root_version_check();
                if (error) {
                        panic("root image version check failed");
                } else {
                        AUTHDBG("root image version matches kernel");
                }
        }
#endif

        done = TRUE;

out:
        zfree(ZV_NAMEI, root_path);
        return done;
}

__private_extern__ void
imageboot_setup(imageboot_type_t type)
{
        int         error = 0;
        char *root_path = NULL;

        DBG_TRACE("%s: entry\n", __FUNCTION__);

        if (rootvnode == NULL) {
                panic("imageboot_setup: rootvnode is NULL.");
        }

        /*
         * New boot-arg scheme:
         *      root-dmg : the dmg that will be the root filesystem, authenticated by default.
         *      auth-root-dmg : same as root-dmg.
         *      container-dmg : an optional dmg that contains the root-dmg.
         *  locker : the locker that will be the root filesystem -- mutually
         *           exclusive with any other boot-arg.
         */
        if (imageboot_setup_new(type)) {
                return;
        }

        root_path = zalloc(ZV_NAMEI);
        assert(root_path != NULL);

        /*
         * Look for outermost disk image to root from.  If we're doing a nested boot,
         * there's some sense in which the outer image never needs to be the root filesystem,
         * but it does need very similar treatment: it must not be unmounted, needs a fake
         * device vnode created for it, and should not show up in getfsstat() until exposed
         * with MNT_IMGSRC. We just make it the temporary root.
         */
#if CONFIG_IMAGEBOOT_IMG4
        if (PE_parse_boot_argn("arp0", root_path, MAXPATHLEN)) {
                size_t pathsz;
                char *path = url_to_path(root_path, &pathsz);

                assert(path);

                if (authenticate_root_with_img4(path)) {
                        panic("Root image %s does not match the manifest\n", root_path);
                }
                if (path != root_path) {
                        kheap_free_safe(KHEAP_TEMP, path, pathsz);
                }
        } else
#endif /* CONFIG_IMAGEBOOT_IMG4 */
        if ((PE_parse_boot_argn("rp", root_path, MAXPATHLEN) == FALSE) &&
            (PE_parse_boot_argn("rp0", root_path, MAXPATHLEN) == FALSE)) {
                panic("%s: no valid path to image.\n", __FUNCTION__);
        }

        DBG_TRACE("%s: root image url is %s\n", __FUNCTION__, root_path);

        error = imageboot_mount_image(root_path, 0, type);
        if (error) {
                panic("Failed on first stage of imageboot.");
        }

        /*
         * See if we are rooting from a nested image
         */
        if (PE_parse_boot_argn("rp1", root_path, MAXPATHLEN) == FALSE) {
                goto done;
        }

        printf("%s: second level root image url is %s\n", __FUNCTION__, root_path);

        /*
         * If we fail to set up second image, it's not a given that we
         * can safely root off the first.
         */
        error = imageboot_mount_image(root_path, 1, type);
        if (error) {
                panic("Failed on second stage of imageboot.");
        }

done:
        zfree(ZV_NAMEI, root_path);

        DBG_TRACE("%s: exit\n", __FUNCTION__);

        return;
}