@@ -31,6 +31,8 @@ enum sgx_page_flags {
_IO(SGX_MAGIC, 0x04)
#define SGX_IOC_ENCLAVE_RESTRICT_PERMISSIONS \
_IOWR(SGX_MAGIC, 0x05, struct sgx_enclave_restrict_permissions)
+#define SGX_IOC_ENCLAVE_MODIFY_TYPES \
+ _IOWR(SGX_MAGIC, 0x06, struct sgx_enclave_modify_types)
/**
* struct sgx_enclave_create - parameter structure for the
@@ -97,6 +99,24 @@ struct sgx_enclave_restrict_permissions {
__u64 count;
};
+/**
+ * struct sgx_enclave_modify_types - parameters for ioctl
+ * %SGX_IOC_ENCLAVE_MODIFY_TYPES
+ * @offset: starting page offset (page aligned relative to enclave base
+ * address defined in SECS)
+ * @length: length of memory (multiple of the page size)
+ * @page_type: new type for pages in range described by @offset and @length
+ * @result: (output) SGX result code of ENCLS[EMODT] function
+ * @count: (output) bytes successfully changed (multiple of page size)
+ */
+struct sgx_enclave_modify_types {
+ __u64 offset;
+ __u64 length;
+ __u64 page_type;
+ __u64 result;
+ __u64 count;
+};
+
struct sgx_enclave_run;
/**
@@ -872,6 +872,205 @@ static long sgx_ioc_enclave_restrict_permissions(struct sgx_encl *encl,
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;
+
+ 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(¶ms, 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, ¶ms);
+
+ if (copy_to_user(arg, ¶ms, 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;
@@ -897,6 +1096,9 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
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;
default:
ret = -ENOIOCTLCMD;
break;