@@ -33,6 +33,8 @@ enum sgx_page_flags {
_IOWR(SGX_MAGIC, 0x05, struct sgx_enclave_restrict_permissions)
#define SGX_IOC_ENCLAVE_MODIFY_TYPES \
_IOWR(SGX_MAGIC, 0x06, struct sgx_enclave_modify_type)
+#define SGX_IOC_ENCLAVE_REMOVE_PAGES \
+ _IOWR(SGX_MAGIC, 0x07, struct sgx_enclave_remove_pages)
/**
* struct sgx_enclave_create - parameter structure for the
@@ -116,6 +118,25 @@ struct sgx_enclave_modify_type {
__u64 count;
};
+/**
+ * struct sgx_enclave_remove_pages - %SGX_IOC_ENCLAVE_REMOVE_PAGES parameters
+ * @offset: starting page offset (page aligned relative to enclave base
+ * address defined in SECS)
+ * @length: length of memory (multiple of the page size)
+ * @count: (output) bytes successfully changed (multiple of page size)
+ *
+ * Regular (PT_REG) or TCS (PT_TCS) can be removed from an initialized
+ * enclave if the system supports SGX2. First, the %SGX_IOC_ENCLAVE_MODIFY_TYPES
+ * ioctl() should be used to change the page type to PT_TRIM. After that
+ * succeeds ENCLU[EACCEPT] should be run from within the enclave and then
+ * %SGX_IOC_ENCLAVE_REMOVE_PAGES can be used to complete the page removal.
+ */
+struct sgx_enclave_remove_pages {
+ __u64 offset;
+ __u64 length;
+ __u64 count;
+};
+
struct sgx_enclave_run;
/**
@@ -1070,6 +1070,148 @@ static long sgx_ioc_enclave_modify_type(struct sgx_encl *encl, void __user *arg)
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;
+
+ 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(¶ms, 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, ¶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;
@@ -1098,6 +1240,9 @@ long sgx_ioctl(struct file *filep, unsigned int cmd, unsigned long arg)
case SGX_IOC_ENCLAVE_MODIFY_TYPES:
ret = sgx_ioc_enclave_modify_type(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;