Static-pie binaries normally include a startup routine to perform any ELF
relocations from .rela.dyn. Since the enclave loading process is different
and glibc is not included, do the necessary relocation for encl_op_array
entries manually at runtime relative to the enclave base to ensure correct
function pointers.
Signed-off-by: Jo Van Bulck <jo.vanbulck@xxxxxxxxxxxxxx>
---
tools/testing/selftests/sgx/test_encl.c | 49 ++++++++++++++++-------
tools/testing/selftests/sgx/test_encl.lds | 2 +
2 files changed, 36 insertions(+), 15 deletions(-)
diff --git a/tools/testing/selftests/sgx/test_encl.c b/tools/testing/selftests/sgx/test_encl.c
index c0d639729..7633fb7cb 100644
--- a/tools/testing/selftests/sgx/test_encl.c
+++ b/tools/testing/selftests/sgx/test_encl.c
@@ -119,21 +119,40 @@ static void do_encl_op_nop(void *_op)
}
+/*
+ * Symbol placed at the start of the enclave image by the linker script.
+ * Declare this extern symbol with visibility "hidden" to ensure the
+ * compiler does not access it through the GOT.
+ */
+extern const uint8_t __attribute__((visibility("hidden"))) __encl_base;
+static const uint64_t encl_base = (uint64_t)&__encl_base;
+
+typedef void (*encl_op_t)(void *);
+const encl_op_t encl_op_array[ENCL_OP_MAX] = {
+ do_encl_op_put_to_buf,
+ do_encl_op_get_from_buf,
+ do_encl_op_put_to_addr,
+ do_encl_op_get_from_addr,
+ do_encl_op_nop,
+ do_encl_eaccept,
+ do_encl_emodpe,
+ do_encl_init_tcs_page,
+};
+
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,
- do_encl_op_nop,
- do_encl_eaccept,
- do_encl_emodpe,
- do_encl_init_tcs_page,
- };
-
- struct encl_op_header *op = (struct encl_op_header *)rdi;
-
- if (op->type < ENCL_OP_MAX)
- (*encl_op_array[op->type])(op);
+ struct encl_op_header *header = (struct encl_op_header *)rdi;
+ encl_op_t op;
+
+ if (header->type >= ENCL_OP_MAX)
+ return;
+
+ /*
+ * "encl_base" needs to be added, as this call site *cannot be*
+ * made rip-relative by the compiler, or fixed up by any other
+ * possible means.
+ */
+ op = encl_base + encl_op_array[header->type];
+
+ (*op)(header);
}
diff --git a/tools/testing/selftests/sgx/test_encl.lds b/tools/testing/selftests/sgx/test_encl.lds
index 62d37160f..b86c86060 100644
--- a/tools/testing/selftests/sgx/test_encl.lds
+++ b/tools/testing/selftests/sgx/test_encl.lds
@@ -32,6 +32,8 @@ SECTIONS
*(.note*)
*(.debug*)
*(.eh_frame*)
+ *(.dyn*)
+ *(.gnu.hash)
}
}
--
2.25.1
