blob: b65ab214bdf57d97c07454969a3511fe64e4cfd3 [file] [log] [blame]
// 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;
}