/* Copyright (C) 2014 Stony Brook University
This file is part of Graphene Library OS.
Graphene Library OS is free software: you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License
as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.
Graphene Library OS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see . */
/*
* shim_exec.c
*
* Implementation of system call "execve".
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
/* returns 0 if normalized URIs are the same; assumes file URIs */
static int normalize_and_cmp_uris(const char* uri1, const char* uri2) {
char norm1[STR_SIZE];
char norm2[STR_SIZE];
size_t len;
int ret;
if (!strstartswith_static(uri1, URI_PREFIX_FILE) ||
!strstartswith_static(uri2, URI_PREFIX_FILE))
return -1;
uri1 += URI_PREFIX_FILE_LEN;
len = sizeof(norm1);
ret = get_norm_path(uri1, norm1, &len);
if (ret < 0)
return ret;
uri2 += URI_PREFIX_FILE_LEN;
len = sizeof(norm2);
ret = get_norm_path(uri2, norm2, &len);
if (ret < 0)
return ret;
return memcmp(norm1, norm2, len + 1);
}
static int close_on_exec(struct shim_fd_handle* fd_hdl, struct shim_handle_map* map) {
if (fd_hdl->flags & FD_CLOEXEC) {
struct shim_handle* hdl = __detach_fd_handle(fd_hdl, NULL, map);
put_handle(hdl);
}
return 0;
}
static int close_cloexec_handle(struct shim_handle_map* map) {
return walk_handle_map(&close_on_exec, map);
}
DEFINE_PROFILE_CATEGORY(exec_rtld, exec);
DEFINE_PROFILE_INTERVAL(alloc_new_stack_for_exec, exec_rtld);
DEFINE_PROFILE_INTERVAL(arrange_arguments_for_exec, exec_rtld);
DEFINE_PROFILE_INTERVAL(unmap_executable_for_exec, exec_rtld);
DEFINE_PROFILE_INTERVAL(unmap_loaded_binaries_for_exec, exec_rtld);
DEFINE_PROFILE_INTERVAL(unmap_all_vmas_for_exec, exec_rtld);
DEFINE_PROFILE_INTERVAL(load_new_executable_for_exec, exec_rtld);
int init_brk_from_executable(struct shim_handle* exec);
struct execve_rtld_arg {
void* old_stack_top;
void* old_stack;
void* old_stack_red;
const char** new_argp;
int* new_argcp;
elf_auxv_t* new_auxp;
};
noreturn static void __shim_do_execve_rtld(struct execve_rtld_arg* __arg) {
struct execve_rtld_arg arg;
memcpy(&arg, __arg, sizeof(arg));
void* old_stack_top = arg.old_stack_top;
void* old_stack = arg.old_stack;
void* old_stack_red = arg.old_stack_red;
const char** new_argp = arg.new_argp;
int* new_argcp = arg.new_argcp;
elf_auxv_t* new_auxp = arg.new_auxp;
struct shim_thread* cur_thread = get_cur_thread();
int ret = 0;
unsigned long fs_base = 0;
update_fs_base(fs_base);
debug("set fs_base to 0x%lx\n", fs_base);
UPDATE_PROFILE_INTERVAL();
DkVirtualMemoryFree(old_stack, old_stack_top - old_stack);
DkVirtualMemoryFree(old_stack_red, old_stack - old_stack_red);
if (bkeep_munmap(old_stack, old_stack_top - old_stack, 0) < 0 ||
bkeep_munmap(old_stack_red, old_stack - old_stack_red, 0) < 0)
BUG();
remove_loaded_libraries();
clean_link_map_list();
SAVE_PROFILE_INTERVAL(unmap_loaded_binaries_for_exec);
reset_brk();
size_t count = DEFAULT_VMA_COUNT;
struct shim_vma_val* vmas = malloc(sizeof(struct shim_vma_val) * count);
if (!vmas) {
ret = -ENOMEM;
goto error;
}
retry_dump_vmas:
ret = dump_all_vmas(vmas, count);
if (ret == -EOVERFLOW) {
struct shim_vma_val* new_vmas = malloc(sizeof(struct shim_vma_val) * count * 2);
if (!new_vmas) {
free(vmas);
ret = -ENOMEM;
goto error;
}
free(vmas);
vmas = new_vmas;
count *= 2;
goto retry_dump_vmas;
}
if (ret < 0) {
free(vmas);
goto error;
}
count = ret;
for (struct shim_vma_val* vma = vmas; vma < vmas + count; vma++) {
/* Don't free the current stack */
if (vma->addr == cur_thread->stack)
continue;
/* Free all the mapped VMAs */
if (!(vma->flags & VMA_UNMAPPED))
DkVirtualMemoryFree(vma->addr, vma->length);
/* Remove the VMAs */
bkeep_munmap(vma->addr, vma->length, vma->flags);
}
free_vma_val_array(vmas, count);
SAVE_PROFILE_INTERVAL(unmap_all_vmas_for_exec);
if ((ret = load_elf_object(cur_thread->exec, NULL, 0)) < 0)
goto error;
if ((ret = init_brk_from_executable(cur_thread->exec)) < 0)
goto error;
load_elf_interp(cur_thread->exec);
SAVE_PROFILE_INTERVAL(load_new_executable_for_exec);
cur_thread->robust_list = NULL;
#ifdef PROFILE
if (ENTER_TIME)
SAVE_PROFILE_INTERVAL_SINCE(syscall_execve, ENTER_TIME);
#endif
debug("execve: start execution\n");
execute_elf_object(cur_thread->exec, new_argcp, new_argp, new_auxp);
/* NOTREACHED */
error:
debug("execve: failed %d\n", ret);
shim_clean_and_exit(ret);
}
static int shim_do_execve_rtld(struct shim_handle* hdl, const char** argv, const char** envp) {
BEGIN_PROFILE_INTERVAL();
struct shim_thread* cur_thread = get_cur_thread();
int ret;
if ((ret = close_cloexec_handle(cur_thread->handle_map)) < 0)
return ret;
SAVE_PROFILE_INTERVAL(close_CLOEXEC_files_for_exec);
put_handle(cur_thread->exec);
get_handle(hdl);
cur_thread->exec = hdl;
void* old_stack_top = cur_thread->stack_top;
void* old_stack = cur_thread->stack;
void* old_stack_red = cur_thread->stack_red;
cur_thread->stack_top = NULL;
cur_thread->stack = NULL;
cur_thread->stack_red = NULL;
initial_envp = NULL;
int new_argc = 0;
for (const char** a = argv; *a; a++, new_argc++)
;
int* new_argcp = &new_argc;
const char** new_argp;
elf_auxv_t* new_auxp;
if ((ret = init_stack(argv, envp, &new_argcp, &new_argp, &new_auxp)) < 0)
return ret;
__disable_preempt(shim_get_tcb()); // Temporarily disable preemption during execve().
SAVE_PROFILE_INTERVAL(alloc_new_stack_for_exec);
struct execve_rtld_arg arg = {
.old_stack_top = old_stack_top,
.old_stack = old_stack,
.old_stack_red = old_stack_red,
.new_argp = new_argp,
.new_argcp = new_argcp,
.new_auxp = new_auxp
};
__SWITCH_STACK(new_argcp, &__shim_do_execve_rtld, &arg);
return 0;
}
#include
DEFINE_PROFILE_CATEGORY(exec, );
DEFINE_PROFILE_INTERVAL(search_and_check_file_for_exec, exec);
DEFINE_PROFILE_INTERVAL(open_file_for_exec, exec);
DEFINE_PROFILE_INTERVAL(close_CLOEXEC_files_for_exec, exec);
static BEGIN_MIGRATION_DEF(execve, struct shim_thread* thread, struct shim_process* proc,
const char** envp) {
DEFINE_MIGRATE(process, proc, sizeof(struct shim_process));
DEFINE_MIGRATE(all_mounts, NULL, 0);
DEFINE_MIGRATE(running_thread, thread, sizeof(struct shim_thread));
DEFINE_MIGRATE(handle_map, thread->handle_map, sizeof(struct shim_handle_map));
DEFINE_MIGRATE(migratable, NULL, 0);
DEFINE_MIGRATE(environ, envp, 0);
}
END_MIGRATION_DEF(execve)
/* thread is cur_thread stripped off stack & tcb (see below func);
* process is new process which is forked and waits for checkpoint. */
static int migrate_execve(struct shim_cp_store* cpstore, struct shim_thread* thread,
struct shim_process* process, va_list ap) {
struct shim_handle_map* handle_map;
const char** envp = va_arg(ap, const char**);
int ret;
BEGIN_PROFILE_INTERVAL();
if ((ret = dup_handle_map(&handle_map, thread->handle_map)) < 0)
return ret;
set_handle_map(thread, handle_map);
if ((ret = close_cloexec_handle(handle_map)) < 0)
return ret;
SAVE_PROFILE_INTERVAL(close_CLOEXEC_files_for_exec);
return START_MIGRATE(cpstore, execve, thread, process, envp);
}
int shim_do_execve(const char* file, const char** argv, const char** envp) {
struct shim_thread* cur_thread = get_cur_thread();
struct shim_dentry* dent = NULL;
int ret = 0, argc = 0;
if (test_user_string(file))
return -EFAULT;
for (const char** a = argv; /* no condition*/; a++, argc++) {
if (test_user_memory(a, sizeof(*a), false))
return -EFAULT;
if (*a == NULL)
break;
if (test_user_string(*a))
return -EFAULT;
}
if (!envp)
envp = initial_envp;
for (const char** e = envp; /* no condition*/; e++) {
if (test_user_memory(e, sizeof(*e), false))
return -EFAULT;
if (*e == NULL)
break;
if (test_user_string(*e))
return -EFAULT;
}
BEGIN_PROFILE_INTERVAL();
DEFINE_LIST(sharg);
struct sharg {
LIST_TYPE(sharg) list;
int len;
char arg[0];
};
DEFINE_LISTP(sharg);
LISTP_TYPE(sharg) shargs;
INIT_LISTP(&shargs);
reopen:
/* XXX: Not sure what to do here yet */
assert(cur_thread);
if ((ret = path_lookupat(NULL, file, LOOKUP_OPEN, &dent, NULL)) < 0)
return ret;
struct shim_mount* fs = dent->fs;
get_dentry(dent);
if (!fs->d_ops->open) {
ret = -EACCES;
err:
put_dentry(dent);
return ret;
}
if (fs->d_ops->mode) {
__kernel_mode_t mode;
if ((ret = fs->d_ops->mode(dent, &mode)) < 0)
goto err;
}
SAVE_PROFILE_INTERVAL(search_and_check_file_for_exec);
struct shim_handle* exec = NULL;
if (!(exec = get_new_handle())) {
ret = -ENOMEM;
goto err;
}
set_handle_fs(exec, fs);
exec->flags = O_RDONLY;
exec->acc_mode = MAY_READ;
ret = fs->d_ops->open(exec, dent, O_RDONLY);
if (qstrempty(&exec->uri)) {
put_handle(exec);
return -EACCES;
}
size_t pathlen;
char* path = dentry_get_path(dent, true, &pathlen);
qstrsetstr(&exec->path, path, pathlen);
if ((ret = check_elf_object(exec)) < 0 && ret != -EINVAL) {
put_handle(exec);
return ret;
}
if (ret == -EINVAL) { /* it's a shebang */
LISTP_TYPE(sharg) new_shargs = LISTP_INIT;
struct sharg* next = NULL;
bool ended = false, started = false;
char buf[80];
do {
ret = do_handle_read(exec, buf, 80);
if (ret <= 0)
break;
char* s = buf;
char* c = buf;
char* e = buf + ret;
if (!started) {
if (ret < 2 || buf[0] != '#' || buf[1] != '!')
break;
s += 2;
c += 2;
started = true;
}
for (; c < e; c++) {
if (*c == ' ' || *c == '\n' || c == e - 1) {
int l = (*c == ' ' || *c == '\n') ? c - s : e - s;
if (next) {
struct sharg* sh = __alloca(sizeof(struct sharg) + next->len + l + 1);
sh->len = next->len + l;
memcpy(sh->arg, next->arg, next->len);
memcpy(sh->arg + next->len, s, l);
sh->arg[next->len + l] = 0;
next = sh;
} else {
next = __alloca(sizeof(struct sharg) + l + 1);
next->len = l;
memcpy(next->arg, s, l);
next->arg[l] = 0;
}
if (*c == ' ' || *c == '\n') {
INIT_LIST_HEAD(next, list);
LISTP_ADD_TAIL(next, &new_shargs, list);
next = NULL;
s = c + 1;
if (*c == '\n') {
ended = true;
break;
}
}
}
}
} while (!ended);
if (started) {
if (next) {
INIT_LIST_HEAD(next, list);
LISTP_ADD_TAIL(next, &new_shargs, list);
}
struct sharg* first = LISTP_FIRST_ENTRY(&new_shargs, struct sharg, list);
assert(first);
debug("detected as script: run by %s\n", first->arg);
file = first->arg;
LISTP_SPLICE(&new_shargs, &shargs, list, sharg);
put_handle(exec);
goto reopen;
}
}
SAVE_PROFILE_INTERVAL(open_file_for_exec);
bool use_same_process = check_last_thread(cur_thread) == 0;
if (use_same_process && !strcmp_static(PAL_CB(host_type), "Linux-SGX")) {
/* for SGX PALs, can use same process only if it is the same executable (because a different
* executable has a different measurement and thus requires a new enclave); this special
* case is to correctly handle e.g. Bash process replacing itself */
assert(cur_thread->exec);
if (normalize_and_cmp_uris(qstrgetstr(&cur_thread->exec->uri), qstrgetstr(&exec->uri))) {
/* it is not the same executable, definitely cannot use same process */
use_same_process = false;
}
}
if (use_same_process) {
debug("execve() in the same process\n");
return shim_do_execve_rtld(exec, argv, envp);
}
debug("execve() in a new process\n");
INC_PROFILE_OCCURENCE(syscall_use_ipc);
if (!LISTP_EMPTY(&shargs)) {
struct sharg* sh;
int shargc = 0, cnt = 0;
LISTP_FOR_EACH_ENTRY(sh, &shargs, list) {
shargc++;
}
const char** new_argv = __alloca(sizeof(const char*) * (argc + shargc + 1));
LISTP_FOR_EACH_ENTRY(sh, &shargs, list) {
new_argv[cnt++] = sh->arg;
}
for (cnt = 0; cnt < argc; cnt++)
new_argv[shargc + cnt] = argv[cnt];
new_argv[shargc + argc] = NULL;
argv = new_argv;
}
lock(&cur_thread->lock);
put_handle(cur_thread->exec);
cur_thread->exec = exec;
void* stack = cur_thread->stack;
void* stack_top = cur_thread->stack_top;
shim_tcb_t* shim_tcb = cur_thread->shim_tcb;
void* frameptr = cur_thread->frameptr;
cur_thread->stack = NULL;
cur_thread->stack_top = NULL;
cur_thread->frameptr = NULL;
cur_thread->shim_tcb = NULL;
cur_thread->in_vm = false;
unlock(&cur_thread->lock);
ret = do_migrate_process(&migrate_execve, exec, argv, cur_thread, envp);
lock(&cur_thread->lock);
cur_thread->stack = stack;
cur_thread->stack_top = stack_top;
cur_thread->frameptr = frameptr;
cur_thread->shim_tcb = shim_tcb;
if (ret < 0) {
/* execve failed, so reanimate this thread as if nothing happened */
cur_thread->in_vm = true;
unlock(&cur_thread->lock);
return ret;
}
/* this "temporary" process must die quietly, not sending any messages to not confuse the parent
* and the execve'ed child, but it must still be around until the child finally exits (because
* its parent in turn may wait on it, e.g., `bash -c ls`) */
debug(
"Temporary process %u is exiting after emulating execve (by forking new process to replace"
" this one); will wait for forked process to exit...\n", cur_process.vmid & 0xFFFF);
MASTER_LOCK();
DkProcessExit(PAL_WAIT_FOR_CHILDREN_EXIT);
return 0;
}