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/*
* FreeBSD setup_initial_stack() implementation.
*
* Copyright (c) 2013-14 Stacey D. Son
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#ifndef TARGET_OS_STACK_H
#define TARGET_OS_STACK_H
#include <sys/param.h>
#include "target_arch_sigtramp.h"
#include "qemu/guest-random.h"
#include "user/tswap-target.h"
/*
* The initial FreeBSD stack is as follows:
* (see kern/kern_exec.c exec_copyout_strings() )
*
* Hi Address -> char **ps_argvstr (struct ps_strings for ps, w, etc.)
* unsigned ps_nargvstr
* char **ps_envstr
* PS_STRINGS -> unsigned ps_nenvstr
*
* machine dependent sigcode (sv_sigcode of size
* sv_szsigcode)
*
* execpath (absolute image path for rtld)
*
* SSP Canary (sizeof(long) * 8)
*
* page sizes array (usually sizeof(u_long) )
*
* "destp" -> argv, env strings (up to 262144 bytes)
*/
static inline int setup_initial_stack(struct bsd_binprm *bprm,
abi_ulong *ret_addr, abi_ulong *stringp)
{
int i;
abi_ulong stack_hi_addr;
size_t execpath_len, stringspace;
abi_ulong destp, argvp, envp, p;
struct target_ps_strings ps_strs;
char canary[sizeof(abi_long) * 8];
stack_hi_addr = p = target_stkbas + target_stksiz;
/* Save some space for ps_strings. */
p -= sizeof(struct target_ps_strings);
/* Add machine dependent sigcode. */
p -= TARGET_SZSIGCODE;
if (setup_sigtramp(p, (unsigned)offsetof(struct target_sigframe, sf_uc),
TARGET_FREEBSD_NR_sigreturn)) {
errno = EFAULT;
return -1;
}
if (bprm->fullpath) {
execpath_len = strlen(bprm->fullpath) + 1;
p -= roundup(execpath_len, sizeof(abi_ulong));
if (memcpy_to_target(p, bprm->fullpath, execpath_len)) {
errno = EFAULT;
return -1;
}
}
/* Add canary for SSP. */
qemu_guest_getrandom_nofail(canary, sizeof(canary));
p -= roundup(sizeof(canary), sizeof(abi_ulong));
if (memcpy_to_target(p, canary, sizeof(canary))) {
errno = EFAULT;
return -1;
}
/* Add page sizes array. */
p -= sizeof(abi_ulong);
if (put_user_ual(TARGET_PAGE_SIZE, p)) {
errno = EFAULT;
return -1;
}
/*
* Deviate from FreeBSD stack layout: force stack to new page here
* so that signal trampoline is not sharing the page with user stack
* frames. This is actively harmful in qemu as it marks pages with
* code it translated as read-only, which is somewhat problematic
* for user trying to use the stack as intended.
*/
p = rounddown(p, TARGET_PAGE_SIZE);
/* Calculate the string space needed */
stringspace = 0;
for (i = 0; i < bprm->argc; ++i) {
stringspace += strlen(bprm->argv[i]) + 1;
}
for (i = 0; i < bprm->envc; ++i) {
stringspace += strlen(bprm->envp[i]) + 1;
}
if (stringspace > TARGET_ARG_MAX) {
errno = ENOMEM;
return -1;
}
/* Make room for the argv and envp strings */
destp = rounddown(p - stringspace, sizeof(abi_ulong));
p = argvp = destp - (bprm->argc + bprm->envc + 2) * sizeof(abi_ulong);
/* Remember the strings pointer */
if (stringp) {
*stringp = destp;
}
/*
* Add argv strings. Note that the argv[] vectors are added by
* loader_build_argptr()
*/
/* XXX need to make room for auxargs */
ps_strs.ps_argvstr = tswapl(argvp);
ps_strs.ps_nargvstr = tswap32(bprm->argc);
for (i = 0; i < bprm->argc; ++i) {
size_t len = strlen(bprm->argv[i]) + 1;
if (memcpy_to_target(destp, bprm->argv[i], len)) {
errno = EFAULT;
return -1;
}
if (put_user_ual(destp, argvp)) {
errno = EFAULT;
return -1;
}
argvp += sizeof(abi_ulong);
destp += len;
}
if (put_user_ual(0, argvp)) {
errno = EFAULT;
return -1;
}
/*
* Add env strings. Note that the envp[] vectors are added by
* loader_build_argptr().
*/
envp = argvp + sizeof(abi_ulong);
ps_strs.ps_envstr = tswapl(envp);
ps_strs.ps_nenvstr = tswap32(bprm->envc);
for (i = 0; i < bprm->envc; ++i) {
size_t len = strlen(bprm->envp[i]) + 1;
if (memcpy_to_target(destp, bprm->envp[i], len)) {
errno = EFAULT;
return -1;
}
if (put_user_ual(destp, envp)) {
errno = EFAULT;
return -1;
}
envp += sizeof(abi_ulong);
destp += len;
}
if (put_user_ual(0, envp)) {
errno = EFAULT;
return -1;
}
if (memcpy_to_target(stack_hi_addr - sizeof(ps_strs), &ps_strs,
sizeof(ps_strs))) {
errno = EFAULT;
return -1;
}
if (ret_addr) {
*ret_addr = p;
}
return 0;
}
#endif /* TARGET_OS_STACK_H */
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