// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2016-20 Intel Corporation. */
#include <assert.h>
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include "defines.h"
#include "main.h"
void encl_delete(struct encl *encl)
{
struct encl_segment *heap_seg;
if (encl->encl_base)
munmap((void *)encl->encl_base, encl->encl_size);
if (encl->bin)
munmap(encl->bin, encl->bin_size);
if (encl->fd)
close(encl->fd);
if (encl->segment_tbl) {
heap_seg = &encl->segment_tbl[encl->nr_segments - 1];
munmap(heap_seg->src, heap_seg->size);
free(encl->segment_tbl);
}
memset(encl, 0, sizeof(*encl));
}
static bool encl_map_bin(const char *path, struct encl *encl)
{
struct stat sb;
void *bin;
int ret;
int fd;
fd = open(path, O_RDONLY);
if (fd == -1) {
perror("enclave executable open()");
return false;
}
ret = stat(path, &sb);
if (ret) {
perror("enclave executable stat()");
goto err;
}
bin = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (bin == MAP_FAILED) {
perror("enclave executable mmap()");
goto err;
}
encl->bin = bin;
encl->bin_size = sb.st_size;
close(fd);
return true;
err:
close(fd);
return false;
}
static bool encl_ioc_create(struct encl *encl)
{
struct sgx_secs *secs = &encl->secs;
struct sgx_enclave_create ioc;
int rc;
assert(encl->encl_base != 0);
memset(secs, 0, sizeof(*secs));
secs->ssa_frame_size = 1;
secs->attributes = SGX_ATTR_MODE64BIT;
secs->xfrm = 3;
secs->base = encl->encl_base;
secs->size = encl->encl_size;
ioc.src = (unsigned long)secs;
rc = ioctl(encl->fd, SGX_IOC_ENCLAVE_CREATE, &ioc);
if (rc) {
perror("SGX_IOC_ENCLAVE_CREATE failed");
munmap((void *)secs->base, encl->encl_size);
return false;
}
return true;
}
static bool encl_ioc_add_pages(struct encl *encl, struct encl_segment *seg)
{
struct sgx_enclave_add_pages ioc;
struct sgx_secinfo secinfo;
int rc;
memset(&secinfo, 0, sizeof(secinfo));
secinfo.flags = seg->flags;
ioc.src = (uint64_t)seg->src;
ioc.offset = seg->offset;
ioc.length = seg->size;
ioc.secinfo = (unsigned long)&secinfo;
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) {
perror("SGX_IOC_ENCLAVE_ADD_PAGES failed");
return false;
}
return true;
}
/*
* Parse the enclave code's symbol table to locate and return address of
* the provided symbol
*/
uint64_t encl_get_entry(struct encl *encl, const char *symbol)
{
Elf64_Sym *symtab = NULL;
char *sym_names = NULL;
Elf64_Shdr *sections;
Elf64_Ehdr *ehdr;
int num_sym = 0;
int i;
ehdr = encl->bin;
sections = encl->bin + ehdr->e_shoff;
for (i = 0; i < ehdr->e_shnum; i++) {
if (sections[i].sh_type == SHT_SYMTAB) {
symtab = (Elf64_Sym *)((char *)encl->bin + sections[i].sh_offset);
num_sym = sections[i].sh_size / sections[i].sh_entsize;
break;
}
}
for (i = 0; i < ehdr->e_shnum; i++) {
if (sections[i].sh_type == SHT_STRTAB) {
sym_names = (char *)encl->bin + sections[i].sh_offset;
break;
}
}
if (!symtab || !sym_names)
return 0;
for (i = 0; i < num_sym; i++) {
Elf64_Sym *sym = &symtab[i];
if (!strcmp(symbol, sym_names + sym->st_name))
return (uint64_t)sym->st_value;
}
return 0;
}
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;
struct stat sb;
void *ptr;
int i, j;
int ret;
int fd = -1;
memset(encl, 0, sizeof(*encl));
fd = open(device_path, O_RDWR);
if (fd < 0) {
perror("Unable to open /dev/sgx_enclave");
goto err;
}
ret = stat(device_path, &sb);
if (ret) {
perror("device file stat()");
goto err;
}
ptr = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_SHARED, fd, 0);
if (ptr == (void *)-1) {
perror("mmap for read");
goto err;
}
munmap(ptr, PAGE_SIZE);
#define ERR_MSG \
"mmap() succeeded for PROT_READ, but failed for PROT_EXEC.\n" \
" Check that /dev does not have noexec set:\n" \
" \tmount | grep \"/dev .*noexec\"\n" \
" If so, remount it executable: mount -o remount,exec /dev\n\n"
ptr = mmap(NULL, PAGE_SIZE, PROT_EXEC, MAP_SHARED, fd, 0);
if (ptr == (void *)-1) {
fprintf(stderr, ERR_MSG);
goto err;
}
munmap(ptr, PAGE_SIZE);
encl->fd = fd;
if (!encl_map_bin(path, encl))
goto err;
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];
if (phdr->p_type == PT_LOAD)
encl->nr_segments++;
}
encl->segment_tbl = calloc(encl->nr_segments,
sizeof(struct encl_segment));
if (!encl->segment_tbl)
goto err;
for (i = 0, j = 0; i < ehdr->e_phnum; i++) {
Elf64_Phdr *phdr = &phdr_tbl[i];
unsigned int flags = phdr->p_flags;
if (phdr->p_type != PT_LOAD)
continue;
seg = &encl->segment_tbl[j];
if (!!(flags & ~(PF_R | PF_W | PF_X))) {
fprintf(stderr,
"%d has invalid segment flags 0x%02x.\n", i,
phdr->p_flags);
goto err;
}
if (j == 0 && flags != (PF_R | PF_W)) {
fprintf(stderr,
"TCS has invalid segment flags 0x%02x.\n",
phdr->p_flags);
goto err;
}
if (j == 0) {
src_offset = phdr->p_offset & PAGE_MASK;
encl->src = encl->bin + src_offset;
seg->prot = PROT_READ | PROT_WRITE;
seg->flags = SGX_PAGE_TYPE_TCS << 8;
} else {
seg->prot = (phdr->p_flags & PF_R) ? PROT_READ : 0;
seg->prot |= (phdr->p_flags & PF_W) ? PROT_WRITE : 0;
seg->prot |= (phdr->p_flags & PF_X) ? PROT_EXEC : 0;
seg->flags = (SGX_PAGE_TYPE_REG << 8) | seg->prot;
}
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 - 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].offset + encl->segment_tbl[j].size;
for (encl->encl_size = 4096; encl->encl_size < encl->src_size; )
encl->encl_size <<= 1;
return true;
err:
if (fd != -1)
close(fd);
encl_delete(encl);
return false;
}
static bool encl_map_area(struct encl *encl)
{
size_t encl_size = encl->encl_size;
void *area;
area = mmap(NULL, encl_size * 2, PROT_NONE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (area == MAP_FAILED) {
perror("reservation mmap()");
return false;
}
encl->encl_base = ((uint64_t)area + encl_size - 1) & ~(encl_size - 1);
munmap(area, encl->encl_base - (uint64_t)area);
munmap((void *)(encl->encl_base + encl_size),
(uint64_t)area + encl_size - encl->encl_base);
return true;
}
bool encl_build(struct encl *encl)
{
struct sgx_enclave_init ioc;
int ret;
int i;
if (!encl_map_area(encl))
return false;
if (!encl_ioc_create(encl))
return false;
/*
* Pages must be added before mapping VMAs because their permissions
* cap the VMA permissions.
*/
for (i = 0; i < encl->nr_segments; i++) {
struct encl_segment *seg = &encl->segment_tbl[i];
if (!encl_ioc_add_pages(encl, seg))
return false;
}
ioc.sigstruct = (uint64_t)&encl->sigstruct;
ret = ioctl(encl->fd, SGX_IOC_ENCLAVE_INIT, &ioc);
if (ret) {
perror("SGX_IOC_ENCLAVE_INIT failed");
return false;
}
return true;
}
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