drm/panthor: Don't add write fences to the shared BOs

[drm/drm-misc.git] / arch / x86 / kernel / cpu / sgx / ioctl.c

// SPDX-License-Identifier: GPL-2.0
/*  Copyright(c) 2016-20 Intel Corporation. */

#include <asm/mman.h>
#include <asm/sgx.h>
#include <linux/mman.h>
#include <linux/delay.h>
#include <linux/file.h>
#include <linux/hashtable.h>
#include <linux/highmem.h>
#include <linux/ratelimit.h>
#include <linux/sched/signal.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/suspend.h>
#include "driver.h"
#include "encl.h"
#include "encls.h"

struct sgx_va_page *sgx_encl_grow(struct sgx_encl *encl, bool reclaim)
{
        struct sgx_va_page *va_page = NULL;
        void *err;

        BUILD_BUG_ON(SGX_VA_SLOT_COUNT !=
                (SGX_ENCL_PAGE_VA_OFFSET_MASK >> 3) + 1);

        if (!(encl->page_cnt % SGX_VA_SLOT_COUNT)) {
                va_page = kzalloc(sizeof(*va_page), GFP_KERNEL);
                if (!va_page)
                        return ERR_PTR(-ENOMEM);

                va_page->epc_page = sgx_alloc_va_page(reclaim);
                if (IS_ERR(va_page->epc_page)) {
                        err = ERR_CAST(va_page->epc_page);
                        kfree(va_page);
                        return err;
                }

                WARN_ON_ONCE(encl->page_cnt % SGX_VA_SLOT_COUNT);
        }
        encl->page_cnt++;
        return va_page;
}

void sgx_encl_shrink(struct sgx_encl *encl, struct sgx_va_page *va_page)
{
        encl->page_cnt--;

        if (va_page) {
                sgx_encl_free_epc_page(va_page->epc_page);
                list_del(&va_page->list);
                kfree(va_page);
        }
}

static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs)
{
        struct sgx_epc_page *secs_epc;
        struct sgx_va_page *va_page;
        struct sgx_pageinfo pginfo;
        struct sgx_secinfo secinfo;
        unsigned long encl_size;
        struct file *backing;
        long ret;

        va_page = sgx_encl_grow(encl, true);
        if (IS_ERR(va_page))
                return PTR_ERR(va_page);
        else if (va_page)
                list_add(&va_page->list, &encl->va_pages);
        /* else the tail page of the VA page list had free slots. */

        /* The extra page goes to SECS. */
        encl_size = secs->size + PAGE_SIZE;

        backing = shmem_file_setup("SGX backing", encl_size + (encl_size >> 5),
                                   VM_NORESERVE);
        if (IS_ERR(backing)) {
                ret = PTR_ERR(backing);
                goto err_out_shrink;
        }

        encl->backing = backing;

        secs_epc = sgx_alloc_epc_page(&encl->secs, true);
        if (IS_ERR(secs_epc)) {
                ret = PTR_ERR(secs_epc);
                goto err_out_backing;
        }

        encl->secs.epc_page = secs_epc;

        pginfo.addr = 0;
        pginfo.contents = (unsigned long)secs;
        pginfo.metadata = (unsigned long)&secinfo;
        pginfo.secs = 0;
        memset(&secinfo, 0, sizeof(secinfo));

        ret = __ecreate((void *)&pginfo, sgx_get_epc_virt_addr(secs_epc));
        if (ret) {
                ret = -EIO;
                goto err_out;
        }

        if (secs->attributes & SGX_ATTR_DEBUG)
                set_bit(SGX_ENCL_DEBUG, &encl->flags);

        encl->secs.encl = encl;
        encl->secs.type = SGX_PAGE_TYPE_SECS;
        encl->base = secs->base;
        encl->size = secs->size;
        encl->attributes = secs->attributes;
        encl->attributes_mask = SGX_ATTR_UNPRIV_MASK;

        /* Set only after completion, as encl->lock has not been taken. */
        set_bit(SGX_ENCL_CREATED, &encl->flags);

        return 0;

err_out:
        sgx_encl_free_epc_page(encl->secs.epc_page);
        encl->secs.epc_page = NULL;

err_out_backing:
        fput(encl->backing);
        encl->backing = NULL;

err_out_shrink:
        sgx_encl_shrink(encl, va_page);

        return ret;
}

/**
 * sgx_ioc_enclave_create() - handler for %SGX_IOC_ENCLAVE_CREATE
 * @encl:       An enclave pointer.
 * @arg:        The ioctl argument.
 *
 * Allocate kernel data structures for the enclave and invoke ECREATE.
 *
 * Return:
 * - 0:         Success.
 * - -EIO:      ECREATE failed.
 * - -errno:    POSIX error.
 */
static long sgx_ioc_enclave_create(struct sgx_encl *encl, void __user *arg)
{
        struct sgx_enclave_create create_arg;
        void *secs;
        int ret;

        if (test_bit(SGX_ENCL_CREATED, &encl->flags))
                return -EINVAL;

        if (copy_from_user(&create_arg, arg, sizeof(create_arg)))
                return -EFAULT;

        secs = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!secs)
                return -ENOMEM;

        if (copy_from_user(secs, (void __user *)create_arg.src, PAGE_SIZE))
                ret = -EFAULT;
        else
                ret = sgx_encl_create(encl, secs);

        kfree(secs);
        return ret;
}

static int sgx_validate_secinfo(struct sgx_secinfo *secinfo)
{
        u64 perm = secinfo->flags & SGX_SECINFO_PERMISSION_MASK;
        u64 pt   = secinfo->flags & SGX_SECINFO_PAGE_TYPE_MASK;

        if (pt != SGX_SECINFO_REG && pt != SGX_SECINFO_TCS)
                return -EINVAL;

        if ((perm & SGX_SECINFO_W) && !(perm & SGX_SECINFO_R))
                return -EINVAL;

        /*
         * CPU will silently overwrite the permissions as zero, which means
         * that we need to validate it ourselves.
         */
        if (pt == SGX_SECINFO_TCS && perm)
                return -EINVAL;

        if (secinfo->flags & SGX_SECINFO_RESERVED_MASK)
                return -EINVAL;

        if (memchr_inv(secinfo->reserved, 0, sizeof(secinfo->reserved)))
                return -EINVAL;

        return 0;
}

static int __sgx_encl_add_page(struct sgx_encl *encl,
                               struct sgx_encl_page *encl_page,
                               struct sgx_epc_page *epc_page,
                               struct sgx_secinfo *secinfo, unsigned long src)
{
        struct sgx_pageinfo pginfo;
        struct vm_area_struct *vma;
        struct page *src_page;
        int ret;

        /* Deny noexec. */
        vma = find_vma(current->mm, src);
        if (!vma)
                return -EFAULT;

        if (!(vma->vm_flags & VM_MAYEXEC))
                return -EACCES;

        ret = get_user_pages(src, 1, 0, &src_page);
        if (ret < 1)
                return -EFAULT;

        pginfo.secs = (unsigned long)sgx_get_epc_virt_addr(encl->secs.epc_page);
        pginfo.addr = encl_page->desc & PAGE_MASK;
        pginfo.metadata = (unsigned long)secinfo;
        pginfo.contents = (unsigned long)kmap_local_page(src_page);

        ret = __eadd(&pginfo, sgx_get_epc_virt_addr(epc_page));

        kunmap_local((void *)pginfo.contents);
        put_page(src_page);

        return ret ? -EIO : 0;
}

/*
 * If the caller requires measurement of the page as a proof for the content,
 * use EEXTEND to add a measurement for 256 bytes of the page. Repeat this
 * operation until the entire page is measured."
 */
static int __sgx_encl_extend(struct sgx_encl *encl,
                             struct sgx_epc_page *epc_page)
{
        unsigned long offset;
        int ret;

        for (offset = 0; offset < PAGE_SIZE; offset += SGX_EEXTEND_BLOCK_SIZE) {
                ret = __eextend(sgx_get_epc_virt_addr(encl->secs.epc_page),
                                sgx_get_epc_virt_addr(epc_page) + offset);
                if (ret) {
                        if (encls_failed(ret))
                                ENCLS_WARN(ret, "EEXTEND");

                        return -EIO;
                }
        }

        return 0;
}

static int sgx_encl_add_page(struct sgx_encl *encl, unsigned long src,
                             unsigned long offset, struct sgx_secinfo *secinfo,
                             unsigned long flags)
{
        struct sgx_encl_page *encl_page;
        struct sgx_epc_page *epc_page;
        struct sgx_va_page *va_page;
        int ret;

        encl_page = sgx_encl_page_alloc(encl, offset, secinfo->flags);
        if (IS_ERR(encl_page))
                return PTR_ERR(encl_page);

        epc_page = sgx_alloc_epc_page(encl_page, true);
        if (IS_ERR(epc_page)) {
                kfree(encl_page);
                return PTR_ERR(epc_page);
        }

        va_page = sgx_encl_grow(encl, true);
        if (IS_ERR(va_page)) {
                ret = PTR_ERR(va_page);
                goto err_out_free;
        }

        mmap_read_lock(current->mm);
        mutex_lock(&encl->lock);

        /*
         * Adding to encl->va_pages must be done under encl->lock.  Ditto for
         * deleting (via sgx_encl_shrink()) in the error path.
         */
        if (va_page)
                list_add(&va_page->list, &encl->va_pages);

        /*
         * Insert prior to EADD in case of OOM.  EADD modifies MRENCLAVE, i.e.
         * can't be gracefully unwound, while failure on EADD/EXTEND is limited
         * to userspace errors (or kernel/hardware bugs).
         */
        ret = xa_insert(&encl->page_array, PFN_DOWN(encl_page->desc),
                        encl_page, GFP_KERNEL);
        if (ret)
                goto err_out_unlock;

        ret = __sgx_encl_add_page(encl, encl_page, epc_page, secinfo,
                                  src);
        if (ret)
                goto err_out;

        /*
         * Complete the "add" before doing the "extend" so that the "add"
         * isn't in a half-baked state in the extremely unlikely scenario
         * the enclave will be destroyed in response to EEXTEND failure.
         */
        encl_page->encl = encl;
        encl_page->epc_page = epc_page;
        encl_page->type = (secinfo->flags & SGX_SECINFO_PAGE_TYPE_MASK) >> 8;
        encl->secs_child_cnt++;

        if (flags & SGX_PAGE_MEASURE) {
                ret = __sgx_encl_extend(encl, epc_page);
                if (ret)
                        goto err_out;
        }

        sgx_mark_page_reclaimable(encl_page->epc_page);
        mutex_unlock(&encl->lock);
        mmap_read_unlock(current->mm);
        return ret;

err_out:
        xa_erase(&encl->page_array, PFN_DOWN(encl_page->desc));

err_out_unlock:
        sgx_encl_shrink(encl, va_page);
        mutex_unlock(&encl->lock);
        mmap_read_unlock(current->mm);

err_out_free:
        sgx_encl_free_epc_page(epc_page);
        kfree(encl_page);

        return ret;
}

/*
 * Ensure user provided offset and length values are valid for
 * an enclave.
 */
static int sgx_validate_offset_length(struct sgx_encl *encl,
                                      unsigned long offset,
                                      unsigned long length)
{
        if (!IS_ALIGNED(offset, PAGE_SIZE))
                return -EINVAL;

        if (!length || !IS_ALIGNED(length, PAGE_SIZE))
                return -EINVAL;

        if (offset + length < offset)
                return -EINVAL;

        if (offset + length - PAGE_SIZE >= encl->size)
                return -EINVAL;

        return 0;
}

/**
 * sgx_ioc_enclave_add_pages() - The handler for %SGX_IOC_ENCLAVE_ADD_PAGES
 * @encl:       an enclave pointer
 * @arg:        a user pointer to a struct sgx_enclave_add_pages instance
 *
 * Add one or more pages to an uninitialized enclave, and optionally extend the
 * measurement with the contents of the page. The SECINFO and measurement mask
 * are applied to all pages.
 *
 * A SECINFO for a TCS is required to always contain zero permissions because
 * CPU silently zeros them. Allowing anything else would cause a mismatch in
 * the measurement.
 *
 * mmap()'s protection bits are capped by the page permissions. For each page
 * address, the maximum protection bits are computed with the following
 * heuristics:
 *
 * 1. A regular page: PROT_R, PROT_W and PROT_X match the SECINFO permissions.
 * 2. A TCS page: PROT_R | PROT_W.
 *
 * mmap() is not allowed to surpass the minimum of the maximum protection bits
 * within the given address range.
 *
 * The function deinitializes kernel data structures for enclave and returns
 * -EIO in any of the following conditions:
 *
 * - Enclave Page Cache (EPC), the physical memory holding enclaves, has
 *   been invalidated. This will cause EADD and EEXTEND to fail.
 * - If the source address is corrupted somehow when executing EADD.
 *
 * Return:
 * - 0:         Success.
 * - -EACCES:   The source page is located in a noexec partition.
 * - -ENOMEM:   Out of EPC pages.
 * - -EINTR:    The call was interrupted before data was processed.
 * - -EIO:      Either EADD or EEXTEND failed because invalid source address
 *              or power cycle.
 * - -errno:    POSIX error.
 */
static long sgx_ioc_enclave_add_pages(struct sgx_encl *encl, void __user *arg)
{
        struct sgx_enclave_add_pages add_arg;
        struct sgx_secinfo secinfo;
        unsigned long c;
        int ret;

        if (!test_bit(SGX_ENCL_CREATED, &encl->flags) ||
            test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
                return -EINVAL;

        if (copy_from_user(&add_arg, arg, sizeof(add_arg)))
                return -EFAULT;

        if (!IS_ALIGNED(add_arg.src, PAGE_SIZE))
                return -EINVAL;

        if (sgx_validate_offset_length(encl, add_arg.offset, add_arg.length))
                return -EINVAL;

        if (copy_from_user(&secinfo, (void __user *)add_arg.secinfo,
                           sizeof(secinfo)))
                return -EFAULT;

        if (sgx_validate_secinfo(&secinfo))
                return -EINVAL;

        for (c = 0 ; c < add_arg.length; c += PAGE_SIZE) {
                if (signal_pending(current)) {
                        if (!c)
                                ret = -ERESTARTSYS;

                        break;
                }

                if (need_resched())
                        cond_resched();

                ret = sgx_encl_add_page(encl, add_arg.src + c, add_arg.offset + c,
                                        &secinfo, add_arg.flags);
                if (ret)
                        break;
        }

        add_arg.count = c;

        if (copy_to_user(arg, &add_arg, sizeof(add_arg)))
                return -EFAULT;

        return ret;
}

static int __sgx_get_key_hash(struct crypto_shash *tfm, const void *modulus,
                              void *hash)
{
        SHASH_DESC_ON_STACK(shash, tfm);

        shash->tfm = tfm;

        return crypto_shash_digest(shash, modulus, SGX_MODULUS_SIZE, hash);
}

static int sgx_get_key_hash(const void *modulus, void *hash)
{
        struct crypto_shash *tfm;
        int ret;

        tfm = crypto_alloc_shash("sha256", 0, CRYPTO_ALG_ASYNC);
        if (IS_ERR(tfm))
                return PTR_ERR(tfm);

        ret = __sgx_get_key_hash(tfm, modulus, hash);

        crypto_free_shash(tfm);
        return ret;
}

static int sgx_encl_init(struct sgx_encl *encl, struct sgx_sigstruct *sigstruct,
                         void *token)
{
        u64 mrsigner[4];
        int i, j;
        void *addr;
        int ret;

        /*
         * Deny initializing enclaves with attributes (namely provisioning)
         * that have not been explicitly allowed.
         */
        if (encl->attributes & ~encl->attributes_mask)
                return -EACCES;

        /*
         * Attributes should not be enforced *only* against what's available on
         * platform (done in sgx_encl_create) but checked and enforced against
         * the mask for enforcement in sigstruct. For example an enclave could
         * opt to sign with AVX bit in xfrm, but still be loadable on a platform
         * without it if the sigstruct->body.attributes_mask does not turn that
         * bit on.
         */
        if (sigstruct->body.attributes & sigstruct->body.attributes_mask &
            sgx_attributes_reserved_mask)
                return -EINVAL;

        if (sigstruct->body.miscselect & sigstruct->body.misc_mask &
            sgx_misc_reserved_mask)
                return -EINVAL;

        if (sigstruct->body.xfrm & sigstruct->body.xfrm_mask &
            sgx_xfrm_reserved_mask)
                return -EINVAL;

        ret = sgx_get_key_hash(sigstruct->modulus, mrsigner);
        if (ret)
                return ret;

        mutex_lock(&encl->lock);

        /*
         * ENCLS[EINIT] is interruptible because it has such a high latency,
         * e.g. 50k+ cycles on success. If an IRQ/NMI/SMI becomes pending,
         * EINIT may fail with SGX_UNMASKED_EVENT so that the event can be
         * serviced.
         */
        for (i = 0; i < SGX_EINIT_SLEEP_COUNT; i++) {
                for (j = 0; j < SGX_EINIT_SPIN_COUNT; j++) {
                        addr = sgx_get_epc_virt_addr(encl->secs.epc_page);

                        preempt_disable();

                        sgx_update_lepubkeyhash(mrsigner);

                        ret = __einit(sigstruct, token, addr);

                        preempt_enable();

                        if (ret == SGX_UNMASKED_EVENT)
                                continue;
                        else
                                break;
                }

                if (ret != SGX_UNMASKED_EVENT)
                        break;

                msleep_interruptible(SGX_EINIT_SLEEP_TIME);

                if (signal_pending(current)) {
                        ret = -ERESTARTSYS;
                        goto err_out;
                }
        }

        if (encls_faulted(ret)) {
                if (encls_failed(ret))
                        ENCLS_WARN(ret, "EINIT");

                ret = -EIO;
        } else if (ret) {
                pr_debug("EINIT returned %d\n", ret);
                ret = -EPERM;
        } else {
                set_bit(SGX_ENCL_INITIALIZED, &encl->flags);
        }

err_out:
        mutex_unlock(&encl->lock);
        return ret;
}

/**
 * sgx_ioc_enclave_init() - handler for %SGX_IOC_ENCLAVE_INIT
 * @encl:       an enclave pointer
 * @arg:        userspace pointer to a struct sgx_enclave_init instance
 *
 * Flush any outstanding enqueued EADD operations and perform EINIT.  The
 * Launch Enclave Public Key Hash MSRs are rewritten as necessary to match
 * the enclave's MRSIGNER, which is calculated from the provided sigstruct.
 *
 * Return:
 * - 0:         Success.
 * - -EPERM:    Invalid SIGSTRUCT.
 * - -EIO:      EINIT failed because of a power cycle.
 * - -errno:    POSIX error.
 */
static long sgx_ioc_enclave_init(struct sgx_encl *encl, void __user *arg)
{
        struct sgx_sigstruct *sigstruct;
        struct sgx_enclave_init init_arg;
        void *token;
        int ret;

        if (!test_bit(SGX_ENCL_CREATED, &encl->flags) ||
            test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
                return -EINVAL;

        if (copy_from_user(&init_arg, arg, sizeof(init_arg)))
                return -EFAULT;

        /*
         * 'sigstruct' must be on a page boundary and 'token' on a 512 byte
         * boundary.  kmalloc() will give this alignment when allocating
         * PAGE_SIZE bytes.
         */
        sigstruct = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!sigstruct)
                return -ENOMEM;

        token = (void *)((unsigned long)sigstruct + PAGE_SIZE / 2);
        memset(token, 0, SGX_LAUNCH_TOKEN_SIZE);

        if (copy_from_user(sigstruct, (void __user *)init_arg.sigstruct,
                           sizeof(*sigstruct))) {
                ret = -EFAULT;
                goto out;
        }

        /*
         * A legacy field used with Intel signed enclaves. These used to mean
         * regular and architectural enclaves. The CPU only accepts these values
         * but they do not have any other meaning.
         *
         * Thus, reject any other values.
         */
        if (sigstruct->header.vendor != 0x0000 &&
            sigstruct->header.vendor != 0x8086) {
                ret = -EINVAL;
                goto out;
        }

        ret = sgx_encl_init(encl, sigstruct, token);

out:
        kfree(sigstruct);
        return ret;
}

/**
 * sgx_ioc_enclave_provision() - handler for %SGX_IOC_ENCLAVE_PROVISION
 * @encl:       an enclave pointer
 * @arg:        userspace pointer to a struct sgx_enclave_provision instance
 *
 * Allow ATTRIBUTE.PROVISION_KEY for an enclave by providing a file handle to
 * /dev/sgx_provision.
 *
 * Return:
 * - 0:         Success.
 * - -errno:    Otherwise.
 */
static long sgx_ioc_enclave_provision(struct sgx_encl *encl, void __user *arg)
{
        struct sgx_enclave_provision params;

        if (copy_from_user(&params, arg, sizeof(params)))
                return -EFAULT;

        return sgx_set_attribute(&encl->attributes_mask, params.fd);
}

/*
 * Ensure enclave is ready for SGX2 functions. Readiness is checked
 * by ensuring the hardware supports SGX2 and the enclave is initialized
 * and thus able to handle requests to modify pages within it.
 */
static int sgx_ioc_sgx2_ready(struct sgx_encl *encl)
{
        if (!(cpu_feature_enabled(X86_FEATURE_SGX2)))
                return -ENODEV;

        if (!test_bit(SGX_ENCL_INITIALIZED, &encl->flags))
                return -EINVAL;

        return 0;
}

/*
 * Some SGX functions require that no cached linear-to-physical address
 * mappings are present before they can succeed. Collaborate with
 * hardware via ENCLS[ETRACK] to ensure that all cached
 * linear-to-physical address mappings belonging to all threads of
 * the enclave are cleared. See sgx_encl_cpumask() for details.
 *
 * Must be called with enclave's mutex held from the time the
 * SGX function requiring that no cached linear-to-physical mappings
 * are present is executed until this ETRACK flow is complete.
 */
static int sgx_enclave_etrack(struct sgx_encl *encl)
{
        void *epc_virt;
        int ret;

        epc_virt = sgx_get_epc_virt_addr(encl->secs.epc_page);
        ret = __etrack(epc_virt);
        if (ret) {
                /*
                 * ETRACK only fails when there is an OS issue. For
                 * example, two consecutive ETRACK was sent without
                 * completed IPI between.
                 */
                pr_err_once("ETRACK returned %d (0x%x)", ret, ret);
                /*
                 * Send IPIs to kick CPUs out of the enclave and
                 * try ETRACK again.
                 */
                on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1);
                ret = __etrack(epc_virt);
                if (ret) {
                        pr_err_once("ETRACK repeat returned %d (0x%x)",
                                    ret, ret);
                        return -EFAULT;
                }
        }
        on_each_cpu_mask(sgx_encl_cpumask(encl), sgx_ipi_cb, NULL, 1);

        return 0;
}

/**
 * sgx_enclave_restrict_permissions() - Restrict EPCM permissions
 * @encl:       Enclave to which the pages belong.
 * @modp:       Checked parameters from user on which pages need modifying and
 *              their new permissions.
 *
 * Return:
 * - 0:         Success.
 * - -errno:    Otherwise.
 */
static long
sgx_enclave_restrict_permissions(struct sgx_encl *encl,
                                 struct sgx_enclave_restrict_permissions *modp)
{
        struct sgx_encl_page *entry;
        struct sgx_secinfo secinfo;
        unsigned long addr;
        unsigned long c;
        void *epc_virt;
        int ret;

        memset(&secinfo, 0, sizeof(secinfo));
        secinfo.flags = modp->permissions & SGX_SECINFO_PERMISSION_MASK;

        for (c = 0 ; c < modp->length; c += PAGE_SIZE) {
                addr = encl->base + modp->offset + c;

                sgx_reclaim_direct();

                mutex_lock(&encl->lock);

                entry = sgx_encl_load_page(encl, addr);
                if (IS_ERR(entry)) {
                        ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT;
                        goto out_unlock;
                }

                /*
                 * Changing EPCM permissions is only supported on regular
                 * SGX pages. Attempting this change on other pages will
                 * result in #PF.
                 */
                if (entry->type != SGX_PAGE_TYPE_REG) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                /*
                 * Apart from ensuring that read-access remains, do not verify
                 * the permission bits requested. Kernel has no control over
                 * how EPCM permissions can be relaxed from within the enclave.
                 * ENCLS[EMODPR] can only remove existing EPCM permissions,
                 * attempting to set new permissions will be ignored by the
                 * hardware.
                 */

                /* Change EPCM permissions. */
                epc_virt = sgx_get_epc_virt_addr(entry->epc_page);
                ret = __emodpr(&secinfo, epc_virt);
                if (encls_faulted(ret)) {
                        /*
                         * All possible faults should be avoidable:
                         * parameters have been checked, will only change
                         * permissions of a regular page, and no concurrent
                         * SGX1/SGX2 ENCLS instructions since these
                         * are protected with mutex.
                         */
                        pr_err_once("EMODPR encountered exception %d\n",
                                    ENCLS_TRAPNR(ret));
                        ret = -EFAULT;
                        goto out_unlock;
                }
                if (encls_failed(ret)) {
                        modp->result = ret;
                        ret = -EFAULT;
                        goto out_unlock;
                }

                ret = sgx_enclave_etrack(encl);
                if (ret) {
                        ret = -EFAULT;
                        goto out_unlock;
                }

                mutex_unlock(&encl->lock);
        }

        ret = 0;
        goto out;

out_unlock:
        mutex_unlock(&encl->lock);
out:
        modp->count = c;

        return ret;
}

/**
 * sgx_ioc_enclave_restrict_permissions() - handler for
 *                                        %SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS
 * @encl:       an enclave pointer
 * @arg:        userspace pointer to a &struct sgx_enclave_restrict_permissions
 *              instance
 *
 * SGX2 distinguishes between relaxing and restricting the enclave page
 * permissions maintained by the hardware (EPCM permissions) of pages
 * belonging to an initialized enclave (after SGX_IOC_ENCLAVE_INIT).
 *
 * EPCM permissions cannot be restricted from within the enclave, the enclave
 * requires the kernel to run the privileged level 0 instructions ENCLS[EMODPR]
 * and ENCLS[ETRACK]. An attempt to relax EPCM permissions with this call
 * will be ignored by the hardware.
 *
 * Return:
 * - 0:         Success
 * - -errno:    Otherwise
 */
static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl,
                                                 void __user *arg)
{
        struct sgx_enclave_restrict_permissions params;
        long ret;

        ret = sgx_ioc_sgx2_ready(encl);
        if (ret)
                return ret;

        if (copy_from_user(&params, arg, sizeof(params)))
                return -EFAULT;

        if (sgx_validate_offset_length(encl, params.offset, params.length))
                return -EINVAL;

        if (params.permissions & ~SGX_SECINFO_PERMISSION_MASK)
                return -EINVAL;

        /*
         * Fail early if invalid permissions requested to prevent ENCLS[EMODPR]
         * from faulting later when the CPU does the same check.
         */
        if ((params.permissions & SGX_SECINFO_W) &&
            !(params.permissions & SGX_SECINFO_R))
                return -EINVAL;

        if (params.result || params.count)
                return -EINVAL;

        ret = sgx_enclave_restrict_permissions(encl, &params);

        if (copy_to_user(arg, &params, sizeof(params)))
                return -EFAULT;

        return ret;
}

/**
 * sgx_enclave_modify_types() - Modify type of SGX enclave pages
 * @encl:       Enclave to which the pages belong.
 * @modt:       Checked parameters from user about which pages need modifying
 *              and their new page type.
 *
 * Return:
 * - 0:         Success
 * - -errno:    Otherwise
 */
static long sgx_enclave_modify_types(struct sgx_encl *encl,
                                     struct sgx_enclave_modify_types *modt)
{
        unsigned long max_prot_restore;
        enum sgx_page_type page_type;
        struct sgx_encl_page *entry;
        struct sgx_secinfo secinfo;
        unsigned long prot;
        unsigned long addr;
        unsigned long c;
        void *epc_virt;
        int ret;

        page_type = modt->page_type & SGX_PAGE_TYPE_MASK;

        /*
         * The only new page types allowed by hardware are PT_TCS and PT_TRIM.
         */
        if (page_type != SGX_PAGE_TYPE_TCS && page_type != SGX_PAGE_TYPE_TRIM)
                return -EINVAL;

        memset(&secinfo, 0, sizeof(secinfo));

        secinfo.flags = page_type << 8;

        for (c = 0 ; c < modt->length; c += PAGE_SIZE) {
                addr = encl->base + modt->offset + c;

                sgx_reclaim_direct();

                mutex_lock(&encl->lock);

                entry = sgx_encl_load_page(encl, addr);
                if (IS_ERR(entry)) {
                        ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT;
                        goto out_unlock;
                }

                /*
                 * Borrow the logic from the Intel SDM. Regular pages
                 * (SGX_PAGE_TYPE_REG) can change type to SGX_PAGE_TYPE_TCS
                 * or SGX_PAGE_TYPE_TRIM but TCS pages can only be trimmed.
                 * CET pages not supported yet.
                 */
                if (!(entry->type == SGX_PAGE_TYPE_REG ||
                      (entry->type == SGX_PAGE_TYPE_TCS &&
                       page_type == SGX_PAGE_TYPE_TRIM))) {
                        ret = -EINVAL;
                        goto out_unlock;
                }

                max_prot_restore = entry->vm_max_prot_bits;

                /*
                 * Once a regular page becomes a TCS page it cannot be
                 * changed back. So the maximum allowed protection reflects
                 * the TCS page that is always RW from kernel perspective but
                 * will be inaccessible from within enclave. Before doing
                 * so, do make sure that the new page type continues to
                 * respect the originally vetted page permissions.
                 */
                if (entry->type == SGX_PAGE_TYPE_REG &&
                    page_type == SGX_PAGE_TYPE_TCS) {
                        if (~entry->vm_max_prot_bits & (VM_READ | VM_WRITE)) {
                                ret = -EPERM;
                                goto out_unlock;
                        }
                        prot = PROT_READ | PROT_WRITE;
                        entry->vm_max_prot_bits = calc_vm_prot_bits(prot, 0);

                        /*
                         * Prevent page from being reclaimed while mutex
                         * is released.
                         */
                        if (sgx_unmark_page_reclaimable(entry->epc_page)) {
                                ret = -EAGAIN;
                                goto out_entry_changed;
                        }

                        /*
                         * Do not keep encl->lock because of dependency on
                         * mmap_lock acquired in sgx_zap_enclave_ptes().
                         */
                        mutex_unlock(&encl->lock);

                        sgx_zap_enclave_ptes(encl, addr);

                        mutex_lock(&encl->lock);

                        sgx_mark_page_reclaimable(entry->epc_page);
                }

                /* Change EPC type */
                epc_virt = sgx_get_epc_virt_addr(entry->epc_page);
                ret = __emodt(&secinfo, epc_virt);
                if (encls_faulted(ret)) {
                        /*
                         * All possible faults should be avoidable:
                         * parameters have been checked, will only change
                         * valid page types, and no concurrent
                         * SGX1/SGX2 ENCLS instructions since these are
                         * protected with mutex.
                         */
                        pr_err_once("EMODT encountered exception %d\n",
                                    ENCLS_TRAPNR(ret));
                        ret = -EFAULT;
                        goto out_entry_changed;
                }
                if (encls_failed(ret)) {
                        modt->result = ret;
                        ret = -EFAULT;
                        goto out_entry_changed;
                }

                ret = sgx_enclave_etrack(encl);
                if (ret) {
                        ret = -EFAULT;
                        goto out_unlock;
                }

                entry->type = page_type;

                mutex_unlock(&encl->lock);
        }

        ret = 0;
        goto out;

out_entry_changed:
        entry->vm_max_prot_bits = max_prot_restore;
out_unlock:
        mutex_unlock(&encl->lock);
out:
        modt->count = c;

        return ret;
}

/**
 * sgx_ioc_enclave_modify_types() - handler for %SGX_IOC_ENCLAVE_MODIFY_TYPES
 * @encl:       an enclave pointer
 * @arg:        userspace pointer to a &struct sgx_enclave_modify_types instance
 *
 * Ability to change the enclave page type supports the following use cases:
 *
 * * It is possible to add TCS pages to an enclave by changing the type of
 *   regular pages (%SGX_PAGE_TYPE_REG) to TCS (%SGX_PAGE_TYPE_TCS) pages.
 *   With this support the number of threads supported by an initialized
 *   enclave can be increased dynamically.
 *
 * * Regular or TCS pages can dynamically be removed from an initialized
 *   enclave by changing the page type to %SGX_PAGE_TYPE_TRIM. Changing the
 *   page type to %SGX_PAGE_TYPE_TRIM marks the page for removal with actual
 *   removal done by handler of %SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl() called
 *   after ENCLU[EACCEPT] is run on %SGX_PAGE_TYPE_TRIM page from within the
 *   enclave.
 *
 * Return:
 * - 0:         Success
 * - -errno:    Otherwise
 */
static long sgx_ioc_enclave_modify_types(struct sgx_encl *encl,
                                         void __user *arg)
{
        struct sgx_enclave_modify_types params;
        long ret;

        ret = sgx_ioc_sgx2_ready(encl);
        if (ret)
                return ret;

        if (copy_from_user(&params, arg, sizeof(params)))
                return -EFAULT;

        if (sgx_validate_offset_length(encl, params.offset, params.length))
                return -EINVAL;

        if (params.page_type & ~SGX_PAGE_TYPE_MASK)
                return -EINVAL;

        if (params.result || params.count)
                return -EINVAL;

        ret = sgx_enclave_modify_types(encl, &params);

        if (copy_to_user(arg, &params, sizeof(params)))
                return -EFAULT;

        return ret;
}

/**
 * sgx_encl_remove_pages() - Remove trimmed pages from SGX enclave
 * @encl:       Enclave to which the pages belong
 * @params:     Checked parameters from user on which pages need to be removed
 *
 * Return:
 * - 0:         Success.
 * - -errno:    Otherwise.
 */
static long sgx_encl_remove_pages(struct sgx_encl *encl,
                                  struct sgx_enclave_remove_pages *params)
{
        struct sgx_encl_page *entry;
        struct sgx_secinfo secinfo;
        unsigned long addr;
        unsigned long c;
        void *epc_virt;
        int ret;

        memset(&secinfo, 0, sizeof(secinfo));
        secinfo.flags = SGX_SECINFO_R | SGX_SECINFO_W | SGX_SECINFO_X;

        for (c = 0 ; c < params->length; c += PAGE_SIZE) {
                addr = encl->base + params->offset + c;

                sgx_reclaim_direct();

                mutex_lock(&encl->lock);

                entry = sgx_encl_load_page(encl, addr);
                if (IS_ERR(entry)) {
                        ret = PTR_ERR(entry) == -EBUSY ? -EAGAIN : -EFAULT;
                        goto out_unlock;
                }

                if (entry->type != SGX_PAGE_TYPE_TRIM) {
                        ret = -EPERM;
                        goto out_unlock;
                }

                /*
                 * ENCLS[EMODPR] is a no-op instruction used to inform if
                 * ENCLU[EACCEPT] was run from within the enclave. If
                 * ENCLS[EMODPR] is run with RWX on a trimmed page that is
                 * not yet accepted then it will return
                 * %SGX_PAGE_NOT_MODIFIABLE, after the trimmed page is
                 * accepted the instruction will encounter a page fault.
                 */
                epc_virt = sgx_get_epc_virt_addr(entry->epc_page);
                ret = __emodpr(&secinfo, epc_virt);
                if (!encls_faulted(ret) || ENCLS_TRAPNR(ret) != X86_TRAP_PF) {
                        ret = -EPERM;
                        goto out_unlock;
                }

                if (sgx_unmark_page_reclaimable(entry->epc_page)) {
                        ret = -EBUSY;
                        goto out_unlock;
                }

                /*
                 * Do not keep encl->lock because of dependency on
                 * mmap_lock acquired in sgx_zap_enclave_ptes().
                 */
                mutex_unlock(&encl->lock);

                sgx_zap_enclave_ptes(encl, addr);

                mutex_lock(&encl->lock);

                sgx_encl_free_epc_page(entry->epc_page);
                encl->secs_child_cnt--;
                entry->epc_page = NULL;
                xa_erase(&encl->page_array, PFN_DOWN(entry->desc));
                sgx_encl_shrink(encl, NULL);
                kfree(entry);

                mutex_unlock(&encl->lock);
        }

        ret = 0;
        goto out;

out_unlock:
        mutex_unlock(&encl->lock);
out:
        params->count = c;

        return ret;
}

/**
 * sgx_ioc_enclave_remove_pages() - handler for %SGX_IOC_ENCLAVE_REMOVE_PAGES
 * @encl:       an enclave pointer
 * @arg:        userspace pointer to &struct sgx_enclave_remove_pages instance
 *
 * Final step of the flow removing pages from an initialized enclave. The
 * complete flow is:
 *
 * 1) User changes the type of the pages to be removed to %SGX_PAGE_TYPE_TRIM
 *    using the %SGX_IOC_ENCLAVE_MODIFY_TYPES ioctl().
 * 2) User approves the page removal by running ENCLU[EACCEPT] from within
 *    the enclave.
 * 3) User initiates actual page removal using the
 *    %SGX_IOC_ENCLAVE_REMOVE_PAGES ioctl() that is handled here.
 *
 * First remove any page table entries pointing to the page and then proceed
 * with the actual removal of the enclave page and data in support of it.
 *
 * VA pages are not affected by this removal. It is thus possible that the
 * enclave may end up with more VA pages than needed to support all its
 * pages.
 *
 * Return:
 * - 0:         Success
 * - -errno:    Otherwise
 */
static long sgx_ioc_enclave_remove_pages(struct sgx_encl *encl,
                                         void __user *arg)
{
        struct sgx_enclave_remove_pages params;
        long ret;

        ret = sgx_ioc_sgx2_ready(encl);
        if (ret)
                return ret;

        if (copy_from_user(&params, arg, sizeof(params)))
                return -EFAULT;

        if (sgx_validate_offset_length(encl, params.offset, params.length))
                return -EINVAL;

        if (params.count)
                return -EINVAL;

        ret = sgx_encl_remove_pages(encl, &params);

        if (copy_to_user(arg, &params, sizeof(params)))
                return -EFAULT;

        return ret;
}

long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
{
        struct sgx_encl *encl = filep->private_data;
        int ret;

        if (test_and_set_bit(SGX_ENCL_IOCTL, &encl->flags))
                return -EBUSY;

        switch (cmd) {
        case SGX_IOC_ENCLAVE_CREATE:
                ret = sgx_ioc_enclave_create(encl, (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_ADD_PAGES:
                ret = sgx_ioc_enclave_add_pages(encl, (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_INIT:
                ret = sgx_ioc_enclave_init(encl, (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_PROVISION:
                ret = sgx_ioc_enclave_provision(encl, (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS:
                ret = sgx_ioc_enclave_restrict_permissions(encl,
                                                           (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_MODIFY_TYPES:
                ret = sgx_ioc_enclave_modify_types(encl, (void __user *)arg);
                break;
        case SGX_IOC_ENCLAVE_REMOVE_PAGES:
                ret = sgx_ioc_enclave_remove_pages(encl, (void __user *)arg);
                break;
        default:
                ret = -ENOIOCTLCMD;
                break;
        }

        clear_bit(SGX_ENCL_IOCTL, &encl->flags);
        return ret;
}