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exec_loadvm: Isolate stack size calc logic into separate functions.

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This commit is contained in:
uebayasi 2014-04-15 15:50:16 +00:00
parent db08ffef5a
commit 9605f3cc61
1 changed files with 60 additions and 42 deletions
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102
sys/kern/kern_exec.c
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@ -1,4 +1,4 @@
/* $NetBSD: kern_exec.c,v 1.395 2014/04/14 13:14:38 uebayasi Exp $ */
/* $NetBSD: kern_exec.c,v 1.396 2014/04/15 15:50:16 uebayasi Exp $ */
/*-
* Copyright (c) 2008 The NetBSD Foundation, Inc.
@ -59,7 +59,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.395 2014/04/14 13:14:38 uebayasi Exp $");
__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.396 2014/04/15 15:50:16 uebayasi Exp $");
#include "opt_exec.h"
#include "opt_execfmt.h"
@ -122,6 +122,8 @@ __KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.395 2014/04/14 13:14:38 uebayasi Exp
struct execve_data;
static size_t calcargs(struct execve_data * restrict, const size_t);
static size_t calcstack(struct execve_data * restrict, const size_t);
static int copyinargs(struct execve_data * restrict, char * const *,
char * const *, execve_fetch_element_t, char **);
static int copyinargstrs(struct execve_data * restrict, char * const *,
@ -250,6 +252,7 @@ struct execve_data {
char *ed_resolvedpathbuf;
size_t ed_ps_strings_sz;
int ed_szsigcode;
size_t ed_argslen;
long ed_argc;
long ed_envc;
};
@ -700,29 +703,10 @@ execve_loadvm(struct lwp *l, const char *path, char * const *args,
* Calculate the new stack size.
*/
const size_t nargenvptrs =
data->ed_argc + /* char *argv[] */
1 + /* \0 */
data->ed_envc + /* char *env[] */
1 + /* \0 */
epp->ep_esch->es_arglen; /* auxinfo */
const size_t ptrsz = (epp->ep_flags & EXEC_32) ?
sizeof(int) : sizeof(char *);
const size_t argenvstrlen = (char *)ALIGN(dp) - data->ed_argp;
data->ed_szsigcode = epp->ep_esch->es_emul->e_esigcode -
epp->ep_esch->es_emul->e_sigcode;
data->ed_ps_strings_sz = (epp->ep_flags & EXEC_32) ?
sizeof(struct ps_strings32) : sizeof(struct ps_strings);
const size_t aslrgap =
#ifdef PAX_ASLR
pax_aslr_active(l) ? (cprng_fast32() % PAGE_SIZE) : 0;
#define ASLR_GAP(l) (pax_aslr_active(l) ? (cprng_fast32() % PAGE_SIZE) : 0)
#else
0;
#define ASLR_GAP(l) 0
#endif
#ifdef __MACHINE_STACK_GROWS_UP
@ -736,32 +720,19 @@ execve_loadvm(struct lwp *l, const char *path, char * const *args,
#define RTLD_GAP 0
#endif
const size_t argenvlen =
RTLD_GAP + /* reserved for _rtld() */
sizeof(int) + /* XXX argc in stack is long, not int */
(nargenvptrs * ptrsz); /* XXX auxinfo multiplied by ptr size? */
const size_t argenvstrlen = (char *)ALIGN(dp) - data->ed_argp;
const size_t sigcode_psstr_sz =
data->ed_szsigcode + /* sigcode */
data->ed_ps_strings_sz + /* ps_strings */
STACK_PTHREADSPACE; /* pthread space */
data->ed_argslen = calcargs(data, argenvstrlen);
const size_t stacklen =
argenvlen +
argenvstrlen +
aslrgap +
sigcode_psstr_sz;
const size_t len = calcstack(data, ASLR_GAP(l) + RTLD_GAP);
/* make the stack "safely" aligned */
const size_t aligned_stacklen = STACK_LEN_ALIGN(stacklen, STACK_ALIGNBYTES);
if (aligned_stacklen > epp->ep_ssize) {
if (len > epp->ep_ssize) {
/* in effect, compare to initial limit */
DPRINTF(("%s: stack limit exceeded %zu\n", __func__, aligned_stacklen));
DPRINTF(("%s: stack limit exceeded %zu\n", __func__, len));
goto bad;
}
/* adjust "active stack depth" for process VSZ */
epp->ep_ssize = aligned_stacklen;
epp->ep_ssize = len;
return 0;
@ -1397,6 +1368,53 @@ execve1(struct lwp *l, const char *path, char * const *args,
return error;
}
static size_t
calcargs(struct execve_data * restrict data, const size_t argenvstrlen)
{
struct exec_package * const epp = &data->ed_pack;
const size_t nargenvptrs =
data->ed_argc + /* char *argv[] */
1 + /* \0 */
data->ed_envc + /* char *env[] */
1 + /* \0 */
epp->ep_esch->es_arglen; /* auxinfo */
const size_t ptrsz = (epp->ep_flags & EXEC_32) ?
sizeof(int) : sizeof(char *);
const size_t argenvlen =
sizeof(int) + /* XXX argc in stack is long, not int */
(nargenvptrs * ptrsz); /* XXX auxinfo multiplied by ptr size? */
return argenvlen + argenvstrlen;
}
static size_t
calcstack(struct execve_data * restrict data, const size_t gaplen)
{
struct exec_package * const epp = &data->ed_pack;
data->ed_szsigcode = epp->ep_esch->es_emul->e_esigcode -
epp->ep_esch->es_emul->e_sigcode;
data->ed_ps_strings_sz = (epp->ep_flags & EXEC_32) ?
sizeof(struct ps_strings32) : sizeof(struct ps_strings);
const size_t sigcode_psstr_sz =
data->ed_szsigcode + /* sigcode */
data->ed_ps_strings_sz + /* ps_strings */
STACK_PTHREADSPACE; /* pthread space */
const size_t stacklen =
data->ed_argslen +
gaplen +
sigcode_psstr_sz;
/* make the stack "safely" aligned */
return STACK_LEN_ALIGN(stacklen, STACK_ALIGNBYTES);
}
static int
copyinargs(struct execve_data * restrict data, char * const *args,
char * const *envs, execve_fetch_element_t fetch_element, char **dpp)