[PATCH 4/4] selftests/sgx: Trigger the reclaimer and #PF handler

Jarkko Sakkinen
2021-07-05T14:37:10Z

Create a heap for the test enclave, which has the same size as all
available Enclave Page Cache (EPC) pages in the system. This will guarantee
that all test_encl.elf pages *and* SGX Enclave Control Structure (SECS)
have been swapped out by the page reclaimer during the load time. Actually,
this adds a bit more stress than that since part of the EPC gets reserved
for the Version Array (VA) pages.

For each test, the page fault handler gets triggered in two occasions:

- When SGX_IOC_ENCLAVE_INIT is performed, SECS gets swapped in by the
page fault handler.
- During the execution, each page that is referenced gets swapped in
by the page fault handler.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
tools/testing/selftests/sgx/load.c | 33 +++++++++++++++----
tools/testing/selftests/sgx/main.c | 42 ++++++++++++++++++++++++-
tools/testing/selftests/sgx/main.h | 3 +-
tools/testing/selftests/sgx/sigstruct.c | 6 ++--
4 files changed, 74 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/sgx/load.c b/tools/testing/selftests/sgx/load.c
index 9946fab2a3d6..a312a132ac33 100644
--- a/tools/testing/selftests/sgx/load.c
+++ b/tools/testing/selftests/sgx/load.c
@@ -21,6 +21,8 @@

void encl_delete(struct encl *encl)
{
+ struct encl_segment *heap_seg = &encl->segment_tbl[encl->nr_segments - 1];
+
if (encl->encl_base)
munmap((void *)encl->encl_base, encl->encl_size);

@@ -30,6 +32,8 @@ void encl_delete(struct encl *encl)
if (encl->fd)
close(encl->fd);

+ munmap(heap_seg->src, heap_seg->size);
+
if (encl->segment_tbl)
free(encl->segment_tbl);

@@ -111,7 +115,10 @@ static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)
ioc.offset = seg->offset;
ioc.length = seg->size;
ioc.secinfo = (unsigned long)&secinfo;
- ioc.flags = SGX_PAGE_MEASURE;
+ if (seg->measure)
+ ioc.flags = SGX_PAGE_MEASURE;
+ else
+ ioc.flags = 0;

rc = ioctl(encl->fd, SGX_IOC_ENCLAVE_ADD_PAGES, &ioc);
if (rc < 0) {
@@ -124,9 +131,10 @@ static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)

-bool encl_load(const char *path, struct encl *encl)
+bool encl_load(const char *path, struct encl *encl, unsigned long heap_size)
{
const char device_path[] = "/dev/sgx_enclave";
+ struct encl_segment *seg;
Elf64_Phdr *phdr_tbl;
off_t src_offset;
Elf64_Ehdr *ehdr;
@@ -188,6 +196,8 @@ bool encl_load(const char *path, struct encl *encl)
ehdr = encl->bin;
phdr_tbl = encl->bin + ehdr->e_phoff;

+ encl->nr_segments = 1; /* one for the heap */
+
for (i = 0; i < ehdr->e_phnum; i++) {
Elf64_Phdr *phdr = &phdr_tbl[i];

@@ -203,7 +213,6 @@ bool encl_load(const char *path, struct encl *encl)
for (i = 0, j = 0; i < ehdr->e_phnum; i++) {
Elf64_Phdr *phdr = &phdr_tbl[i];
unsigned int flags = phdr->p_flags;
- struct encl_segment *seg;

if (phdr->p_type != PT_LOAD)
continue;
@@ -240,14 +249,26 @@ bool encl_load(const char *path, struct encl *encl)
seg->offset = (phdr->p_offset & PAGE_MASK) - src_offset;
seg->size = (phdr->p_filesz + PAGE_SIZE - 1) & PAGE_MASK;
seg->src = encl->src + seg->offset;
+ seg->measure = true;

j++;
}

- assert(j == encl->nr_segments);
+ assert(j == encl->nr_segments - 1);
+
+ seg = &encl->segment_tbl[j];
+ seg->offset = encl->segment_tbl[j - 1].offset + encl->segment_tbl[j - 1].size;
+ seg->size = heap_size;
+ seg->src = mmap(NULL, heap_size, PROT_READ | PROT_WRITE,
+ MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+ seg->prot = PROT_READ | PROT_WRITE;
+ seg->flags = (SGX_PAGE_TYPE_REG << 8) | seg->prot;
+ seg->measure = false;
+
+ if (seg->src == MAP_FAILED)
+ goto err;

- encl->src_size = encl->segment_tbl[j - 1].offset +
- encl->segment_tbl[j - 1].size;
+ encl->src_size = encl->segment_tbl[j].offset + encl->segment_tbl[j].size;

for (encl->encl_size = 4096; encl->encl_size < encl->src_size; )
encl->encl_size <<= 1;
diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c
index e252015e0c15..772ba1d72619 100644
--- a/tools/testing/selftests/sgx/main.c
+++ b/tools/testing/selftests/sgx/main.c
@@ -112,17 +112,57 @@ FIXTURE(enclave) {
struct sgx_enclave_run run;
};

+#define SGX_NR_ALL_PAGES_PATH "/sys/kernel/debug/x86/sgx_nr_all_pages"
+
+static int sysfs_get_ulong(const char *path, unsigned long *value)
+{
+ struct stat sbuf;
+ ssize_t ret = 0;
+ char buf[128];
+ int fd;
+
+ ret = stat(path, &sbuf);
+ if (ret)
+ return ret;
+
+ fd = open(path, O_RDONLY);
+ if (fd < 0)
+ return fd;
+
+ ret = read(fd, buf, sizeof(buf));
+ if (ret < 0)
+ goto out;
+
+ /* Clear the read bytes count. */
+ ret = 0;
+
+ errno = 0;
+ *value = strtoul(buf, NULL, 0);
+ if (errno)
+ ret = -1;
+
+out:
+ close(fd);
+ return ret;
+}
+
FIXTURE_SETUP(enclave)
{
Elf64_Sym *sgx_enter_enclave_sym = NULL;
+ unsigned long nr_all_pages;
struct vdso_symtab symtab;
struct encl_segment *seg;
char maps_line[256];
FILE *maps_file;
unsigned int i;
void *addr;
+ int ret;
+
+ ret = sysfs_get_ulong(SGX_NR_ALL_PAGES_PATH, &nr_all_pages);
+ if (ret)
+ ksft_exit_skip("Failed to read " SGX_NR_ALL_PAGES_PATH "\n");

- if (!encl_load("test_encl.elf", &self->encl)) {
+ if (!encl_load("test_encl.elf", &self->encl, nr_all_pages * 4096)) {
encl_delete(&self->encl);
ksft_exit_skip("cannot load enclaves\n");
}
diff --git a/tools/testing/selftests/sgx/main.h b/tools/testing/selftests/sgx/main.h
index 452d11dc4889..a286861dc289 100644
--- a/tools/testing/selftests/sgx/main.h
+++ b/tools/testing/selftests/sgx/main.h
@@ -12,6 +12,7 @@ struct encl_segment {
size_t size;
unsigned int prot;
unsigned int flags;
+ bool measure;
};

struct encl {
@@ -32,7 +33,7 @@ extern unsigned char sign_key[];
extern unsigned char sign_key_end[];

void encl_delete(struct encl *ctx);
-bool encl_load(const char *path, struct encl *encl);
+bool encl_load(const char *path, struct encl *encl, unsigned long heap_size);
bool encl_measure(struct encl *encl);
bool encl_build(struct encl *encl);

diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c
index 202a96fd81bf..50c5ab1aa6fa 100644
--- a/tools/testing/selftests/sgx/sigstruct.c
+++ b/tools/testing/selftests/sgx/sigstruct.c
@@ -296,8 +296,10 @@ static bool mrenclave_segment(EVP_MD_CTX *ctx, struct encl *encl,
if (!mrenclave_eadd(ctx, seg->offset + offset, seg->flags))
return false;

- if (!mrenclave_eextend(ctx, seg->offset + offset, seg->src + offset))
- return false;
+ if (seg->measure) {
+ if (!mrenclave_eextend(ctx, seg->offset + offset, seg->src + offset))
+ return false;
+ }
}

return true;
--
2.32.0