3 files changed, 169 insertions, 0 deletions

diff --git a/tools/testing/selftests/sgx/defines.h b/tools/testing/selftests/sgx/defines.h
index 9ea0c7882dfb..0bbda6f0c7d3 100644
--- a/tools/testing/selftests/sgx/defines.h
+++ b/tools/testing/selftests/sgx/defines.h
@@ -21,6 +21,8 @@
 enum encl_op_type {
 	ENCL_OP_PUT_TO_BUFFER,
 	ENCL_OP_GET_FROM_BUFFER,
+	ENCL_OP_PUT_TO_ADDRESS,
+	ENCL_OP_GET_FROM_ADDRESS,
 	ENCL_OP_MAX,
 };
 
@@ -38,4 +40,16 @@ struct encl_op_get_from_buf {
 	uint64_t value;
 };
 
+struct encl_op_put_to_addr {
+	struct encl_op_header header;
+	uint64_t value;
+	uint64_t addr;
+};
+
+struct encl_op_get_from_addr {
+	struct encl_op_header header;
+	uint64_t value;
+	uint64_t addr;
+};
+
 #endif /* DEFINES_H */
diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index 61321229e485..1b4858f8ca4e 100644
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -21,6 +21,7 @@
 #include "main.h"
 
 static const uint64_t MAGIC = 0x1122334455667788ULL;
+static const uint64_t MAGIC2 = 0x8877665544332211ULL;
 vdso_sgx_enter_enclave_t vdso_sgx_enter_enclave;
 
 struct vdso_symtab {
@@ -107,6 +108,25 @@ static Elf64_Sym *vdso_symtab_get(struct vdso_symtab *symtab, const char *name)
 	return NULL;
 }
 
+/*
+ * Return the offset in the enclave where the data segment can be found.
+ * The first RW segment loaded is the TCS, skip that to get info on the
+ * data segment.
+ */
+static off_t encl_get_data_offset(struct encl *encl)
+{
+	int i;
+
+	for (i = 1; i < encl->nr_segments; i++) {
+		struct encl_segment *seg = &encl->segment_tbl[i];
+
+		if (seg->prot == (PROT_READ | PROT_WRITE))
+			return seg->offset;
+	}
+
+	return -1;
+}
+
 FIXTURE(enclave) {
 	struct encl encl;
 	struct sgx_enclave_run run;
@@ -389,4 +409,118 @@ TEST_F(enclave, clobbered_vdso_and_user_function)
 	EXPECT_EQ(self->run.user_data, 0);
 }
 
+/*
+ * Second page of .data segment is used to test changing PTE permissions.
+ * This spans the local encl_buffer within the test enclave.
+ *
+ * 1) Start with a sanity check: a value is written to the target page within
+ *    the enclave and read back to ensure target page can be written to.
+ * 2) Change PTE permissions (RW -> RO) of target page within enclave.
+ * 3) Repeat (1) - this time expecting a regular #PF communicated via the
+ *    vDSO.
+ * 4) Change PTE permissions of target page within enclave back to be RW.
+ * 5) Repeat (1) by resuming enclave, now expected to be possible to write to
+ *    and read from target page within enclave.
+ */
+TEST_F(enclave, pte_permissions)
+{
+	struct encl_op_get_from_addr get_addr_op;
+	struct encl_op_put_to_addr put_addr_op;
+	unsigned long data_start;
+	int ret;
+
+	ASSERT_TRUE(setup_test_encl(ENCL_HEAP_SIZE_DEFAULT, &self->encl, _metadata));
+
+	memset(&self->run, 0, sizeof(self->run));
+	self->run.tcs = self->encl.encl_base;
+
+	data_start = self->encl.encl_base +
+		     encl_get_data_offset(&self->encl) +
+		     PAGE_SIZE;
+
+	/*
+	 * Sanity check to ensure it is possible to write to page that will
+	 * have its permissions manipulated.
+	 */
+
+	/* Write MAGIC to page */
+	put_addr_op.value = MAGIC;
+	put_addr_op.addr = data_start;
+	put_addr_op.header.type = ENCL_OP_PUT_TO_ADDRESS;
+
+	EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0);
+
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+
+	/*
+	 * Read memory that was just written to, confirming that it is the
+	 * value previously written (MAGIC).
+	 */
+	get_addr_op.value = 0;
+	get_addr_op.addr = data_start;
+	get_addr_op.header.type = ENCL_OP_GET_FROM_ADDRESS;
+
+	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);
+
+	EXPECT_EQ(get_addr_op.value, MAGIC);
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+
+	/* Change PTE permissions of target page within the enclave */
+	ret = mprotect((void *)data_start, PAGE_SIZE, PROT_READ);
+	if (ret)
+		perror("mprotect");
+
+	/*
+	 * PTE permissions of target page changed to read-only, EPCM
+	 * permissions unchanged (EPCM permissions are RW), attempt to
+	 * write to the page, expecting a regular #PF.
+	 */
+
+	put_addr_op.value = MAGIC2;
+
+	EXPECT_EQ(ENCL_CALL(&put_addr_op, &self->run, true), 0);
+
+	EXPECT_EQ(self->run.exception_vector, 14);
+	EXPECT_EQ(self->run.exception_error_code, 0x7);
+	EXPECT_EQ(self->run.exception_addr, data_start);
+
+	self->run.exception_vector = 0;
+	self->run.exception_error_code = 0;
+	self->run.exception_addr = 0;
+
+	/*
+	 * Change PTE permissions back to enable enclave to write to the
+	 * target page and resume enclave - do not expect any exceptions this
+	 * time.
+	 */
+	ret = mprotect((void *)data_start, PAGE_SIZE, PROT_READ | PROT_WRITE);
+	if (ret)
+		perror("mprotect");
+
+	EXPECT_EQ(vdso_sgx_enter_enclave((unsigned long)&put_addr_op, 0,
+					 0, ERESUME, 0, 0, &self->run),
+		 0);
+
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+
+	get_addr_op.value = 0;
+
+	EXPECT_EQ(ENCL_CALL(&get_addr_op, &self->run, true), 0);
+
+	EXPECT_EQ(get_addr_op.value, MAGIC2);
+	EXPECT_EEXIT(&self->run);
+	EXPECT_EQ(self->run.exception_vector, 0);
+	EXPECT_EQ(self->run.exception_error_code, 0);
+	EXPECT_EQ(self->run.exception_addr, 0);
+}
+
 TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c
index 4e8da738173f..5d86e3e6456a 100644
--- a/tools/testing/selftests/sgx/test_encl.c
+++ b/tools/testing/selftests/sgx/test_encl.c
@@ -4,6 +4,11 @@
 #include <stddef.h>
 #include "defines.h"
 
+/*
+ * Data buffer spanning two pages that will be placed first in .data
+ * segment. Even if not used internally the second page is needed by
+ * external test manipulating page permissions.
+ */
 static uint8_t encl_buffer[8192] = { 1 };
 
 static void *memcpy(void *dest, const void *src, size_t n)
@@ -30,11 +35,27 @@ static void do_encl_op_get_from_buf(void *op)
 	memcpy(&op2->value, &encl_buffer[0], 8);
 }
 
+static void do_encl_op_put_to_addr(void *_op)
+{
+	struct encl_op_put_to_addr *op = _op;
+
+	memcpy((void *)op->addr, &op->value, 8);
+}
+
+static void do_encl_op_get_from_addr(void *_op)
+{
+	struct encl_op_get_from_addr *op = _op;
+
+	memcpy(&op->value, (void *)op->addr, 8);
+}
+
 void encl_body(void *rdi,  void *rsi)
 {
 	const void (*encl_op_array[ENCL_OP_MAX])(void *) = {
 		do_encl_op_put_to_buf,
 		do_encl_op_get_from_buf,
+		do_encl_op_put_to_addr,
+		do_encl_op_get_from_addr,
 	};
 
 	struct encl_op_header *op = (struct encl_op_header *)rdi;