x86/sgx: Add SGX_IOC_ENCLAVE_ADD_PAGES

SGX enclave pages are inaccessible to normal software. They must be
populated with data by copying from normal memory with the help of the
EADD and EEXTEND functions of the ENCLS instruction.

Add an ioctl() which performs EADD that adds new data to an enclave, and
optionally EEXTEND functions that hash the page contents and use the
hash as part of enclave “measurement” to ensure enclave integrity.

The enclave author gets to decide which pages will be included in the
enclave measurement with EEXTEND. Measurement is very slow and has
sometimes has very little value. For instance, an enclave _could_
measure every page of data and code, but would be slow to initialize.
Or, it might just measure its code and then trust that code to
initialize the bulk of its data after it starts running.

Co-developed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Tested-by: Jethro Beekman <jethro@fortanix.com>
Link: https://lkml.kernel.org/r/20201112220135.165028-14-jarkko@kernel.org

1 files changed, 30 insertions, 0 deletions

diff --git a/arch/x86/include/uapi/asm/sgx.h b/arch/x86/include/uapi/asm/sgx.h
index f31bb17e27c3..835f7e588f0d 100644
--- a/arch/x86/include/uapi/asm/sgx.h
+++ b/arch/x86/include/uapi/asm/sgx.h
@@ -8,10 +8,21 @@
 #include <linux/types.h>
 #include <linux/ioctl.h>
 
+/**
+ * enum sgx_epage_flags - page control flags
+ * %SGX_PAGE_MEASURE:	Measure the page contents with a sequence of
+ *			ENCLS[EEXTEND] operations.
+ */
+enum sgx_page_flags {
+	SGX_PAGE_MEASURE	= 0x01,
+};
+
 #define SGX_MAGIC 0xA4
 
 #define SGX_IOC_ENCLAVE_CREATE \
 	_IOW(SGX_MAGIC, 0x00, struct sgx_enclave_create)
+#define SGX_IOC_ENCLAVE_ADD_PAGES \
+	_IOWR(SGX_MAGIC, 0x01, struct sgx_enclave_add_pages)
 
 /**
  * struct sgx_enclave_create - parameter structure for the
@@ -22,4 +33,23 @@ struct sgx_enclave_create  {
 	__u64	src;
 };
 
+/**
+ * struct sgx_enclave_add_pages - parameter structure for the
+ *                                %SGX_IOC_ENCLAVE_ADD_PAGE ioctl
+ * @src:	start address for the page data
+ * @offset:	starting page offset
+ * @length:	length of the data (multiple of the page size)
+ * @secinfo:	address for the SECINFO data
+ * @flags:	page control flags
+ * @count:	number of bytes added (multiple of the page size)
+ */
+struct sgx_enclave_add_pages {
+	__u64 src;
+	__u64 offset;
+	__u64 length;
+	__u64 secinfo;
+	__u64 flags;
+	__u64 count;
+};
+
 #endif /* _UAPI_ASM_X86_SGX_H */