[PATCH v25 20/21] selftests/x86: Add vDSO selftest for SGX

Jarkko Sakkinen
2020-02-04T06:07:57Z

Expand the selftest by invoking the enclave by using
__vdso_sgx_enter_enclave() in addition to direct ENCLS[EENTER].

Cc: linux-kselftest@vger.kernel.org
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
tools/testing/selftests/x86/sgx/main.c | 132 +++++++++++++++++++++
tools/testing/selftests/x86/sgx/sgx_call.S | 43 +++++++
tools/testing/selftests/x86/sgx/sgx_call.h | 3 +
3 files changed, 178 insertions(+)

diff --git a/tools/testing/selftests/x86/sgx/main.c b/tools/testing/selftests/x86/sgx/main.c
index 48ed5fdfb3cb..d97cc3cf0093 100644
--- a/tools/testing/selftests/x86/sgx/main.c
+++ b/tools/testing/selftests/x86/sgx/main.c
@@ -21,6 +21,109 @@
#define PAGE_SIZE 4096

static const uint64_t MAGIC = 0x1122334455667788ULL;
+void *eenter;
+
+struct vdso_symtab {
+ Elf64_Sym *elf_symtab;
+ const char *elf_symstrtab;
+ Elf64_Word *elf_hashtab;
+};
+
+static void *vdso_get_base_addr(char *envp[])
+{
+ Elf64_auxv_t *auxv;
+ int i;
+
+ for (i = 0; envp[i]; i++)
+ ;
+
+ auxv = (Elf64_auxv_t *)&envp[i + 1];
+
+ for (i = 0; auxv[i].a_type != AT_NULL; i++) {
+ if (auxv[i].a_type == AT_SYSINFO_EHDR)
+ return (void *)auxv[i].a_un.a_val;
+ }
+
+ return NULL;
+}
+
+static Elf64_Dyn *vdso_get_dyntab(void *addr)
+{
+ Elf64_Ehdr *ehdr = addr;
+ Elf64_Phdr *phdrtab = addr + ehdr->e_phoff;
+ int i;
+
+ for (i = 0; i < ehdr->e_phnum; i++)
+ if (phdrtab[i].p_type == PT_DYNAMIC)
+ return addr + phdrtab[i].p_offset;
+
+ return NULL;
+}
+
+static void *vdso_get_dyn(void *addr, Elf64_Dyn *dyntab, Elf64_Sxword tag)
+{
+ int i;
+
+ for (i = 0; dyntab[i].d_tag != DT_NULL; i++)
+ if (dyntab[i].d_tag == tag)
+ return addr + dyntab[i].d_un.d_ptr;
+
+ return NULL;
+}
+
+static bool vdso_get_symtab(void *addr, struct vdso_symtab *symtab)
+{
+ Elf64_Dyn *dyntab = vdso_get_dyntab(addr);
+
+ symtab->elf_symtab = vdso_get_dyn(addr, dyntab, DT_SYMTAB);
+ if (!symtab->elf_symtab)
+ return false;
+
+ symtab->elf_symstrtab = vdso_get_dyn(addr, dyntab, DT_STRTAB);
+ if (!symtab->elf_symstrtab)
+ return false;
+
+ symtab->elf_hashtab = vdso_get_dyn(addr, dyntab, DT_HASH);
+ if (!symtab->elf_hashtab)
+ return false;
+
+ return true;
+}
+
+static unsigned long elf_sym_hash(const char *name)
+{
+ unsigned long h = 0, high;
+
+ while (*name) {
+ h = (h << 4) + *name++;
+ high = h & 0xf0000000;
+
+ if (high)
+ h ^= high >> 24;
+
+ h &= ~high;
+ }
+
+ return h;
+}
+
+static Elf64_Sym *vdso_symtab_get(struct vdso_symtab *symtab, const char *name)
+{
+ Elf64_Word bucketnum = symtab->elf_hashtab[0];
+ Elf64_Word *buckettab = &symtab->elf_hashtab[2];
+ Elf64_Word *chaintab = &symtab->elf_hashtab[2 + bucketnum];
+ Elf64_Sym *sym;
+ Elf64_Word i;
+
+ for (i = buckettab[elf_sym_hash(name) % bucketnum]; i != STN_UNDEF;
+ i = chaintab[i]) {
+ sym = &symtab->elf_symtab[i];
+ if (!strcmp(name, &symtab->elf_symstrtab[sym->st_name]))
+ return sym;
+ }
+
+ return NULL;
+}

static bool encl_create(int dev_fd, unsigned long bin_size,
struct sgx_secs *secs)
@@ -218,10 +321,14 @@ bool load_sigstruct(const char *path, void *sigstruct)

int main(int argc, char *argv[], char *envp[])
{
+ struct sgx_enclave_exception exception;
struct sgx_sigstruct sigstruct;
+ struct vdso_symtab symtab;
+ Elf64_Sym *eenter_sym;
struct sgx_secs secs;
uint64_t result = 0;
off_t bin_size;
+ void *addr;
void *bin;

if (!encl_data_map("encl.bin", &bin, &bin_size))
@@ -243,5 +350,30 @@ int main(int argc, char *argv[], char *envp[])

printf("Output: 0x%lx\n", result);

+ memset(&exception, 0, sizeof(exception));
+
+ addr = vdso_get_base_addr(envp);
+ if (!addr)
+ exit(1);
+
+ if (!vdso_get_symtab(addr, &symtab))
+ exit(1);
+
+ eenter_sym = vdso_symtab_get(&symtab, "__vdso_sgx_enter_enclave");
+ if (!eenter_sym)
+ exit(1);
+ eenter = addr + eenter_sym->st_value;
+
+ printf("Input: 0x%lx\n", MAGIC);
+
+ sgx_call_vdso((void *)&MAGIC, &result, 0, NULL, NULL, NULL,
+ (void *)secs.base, &exception, NULL);
+ if (result != MAGIC) {
+ fprintf(stderr, "0x%lx != 0x%lx\n", result, MAGIC);
+ exit(1);
+ }
+
+ printf("Output: 0x%lx\n", result);
+
exit(0);
}
diff --git a/tools/testing/selftests/x86/sgx/sgx_call.S b/tools/testing/selftests/x86/sgx/sgx_call.S
index ca4c7893f9d9..e71f44f7a995 100644
--- a/tools/testing/selftests/x86/sgx/sgx_call.S
+++ b/tools/testing/selftests/x86/sgx/sgx_call.S
@@ -21,3 +21,46 @@ sgx_async_exit:
ENCLU
pop %rbx
ret
+
+ .global sgx_call_vdso
+sgx_call_vdso:
+ .cfi_startproc
+ push %r15
+ .cfi_adjust_cfa_offset 8
+ .cfi_rel_offset %r15, 0
+ push %r14
+ .cfi_adjust_cfa_offset 8
+ .cfi_rel_offset %r14, 0
+ push %r13
+ .cfi_adjust_cfa_offset 8
+ .cfi_rel_offset %r13, 0
+ push %r12
+ .cfi_adjust_cfa_offset 8
+ .cfi_rel_offset %r12, 0
+ push %rbx
+ .cfi_adjust_cfa_offset 8
+ .cfi_rel_offset %rbx, 0
+ push $0
+ .cfi_adjust_cfa_offset 8
+ push 0x48(%rsp)
+ .cfi_adjust_cfa_offset 8
+ push 0x48(%rsp)
+ .cfi_adjust_cfa_offset 8
+ push 0x48(%rsp)
+ .cfi_adjust_cfa_offset 8
+ mov $2, %eax
+ call *eenter(%rip)
+ add $0x20, %rsp
+ .cfi_adjust_cfa_offset -0x20
+ pop %rbx
+ .cfi_adjust_cfa_offset -8
+ pop %r12
+ .cfi_adjust_cfa_offset -8
+ pop %r13
+ .cfi_adjust_cfa_offset -8
+ pop %r14
+ .cfi_adjust_cfa_offset -8
+ pop %r15
+ .cfi_adjust_cfa_offset -8
+ ret
+ .cfi_endproc
diff --git a/tools/testing/selftests/x86/sgx/sgx_call.h b/tools/testing/selftests/x86/sgx/sgx_call.h
index bf72068ada23..a4072c5ecce7 100644
--- a/tools/testing/selftests/x86/sgx/sgx_call.h
+++ b/tools/testing/selftests/x86/sgx/sgx_call.h
@@ -8,4 +8,7 @@

void sgx_call_eenter(void *rdi, void *rsi, void *entry);

+int sgx_call_vdso(void *rdi, void *rsi, long rdx, void *rcx, void *r8, void *r9,
+ void *tcs, struct sgx_enclave_exception *ei, void *cb);
+
#endif /* SGX_CALL_H */
--
2.20.1