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Use swapcontext for Intel CET

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When Intel CET is enabled, makecontext will create a different shadow
stack for each context.  async_fibre_swapcontext cannot use _longjmp.
It must call swapcontext to swap shadow stack as well as normal stack.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/10983)
This commit is contained in:
H.J. Lu 2019-12-13 16:46:07 -08:00 committed by Matt Caswell
parent 0e43960e88
commit 34675b2ba9
2 changed files with 20 additions and 1 deletions
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2
crypto/async/arch/async_posix.c
View File

@ -34,7 +34,9 @@ void async_local_cleanup(void)
int async_fibre_makecontext(async_fibre *fibre)
{
#ifndef USE_SWAPCONTEXT
fibre->env_init = 0;
#endif
if (getcontext(&fibre->fibre) == 0) {
fibre->fibre.uc_stack.ss_sp = OPENSSL_malloc(STACKSIZE);
if (fibre->fibre.uc_stack.ss_sp != NULL) {

19
crypto/async/arch/async_posix.h
View File

@ -25,17 +25,33 @@
# define ASYNC_POSIX
# define ASYNC_ARCH
# ifdef __CET__
/*
* When Intel CET is enabled, makecontext will create a different
* shadow stack for each context. async_fibre_swapcontext cannot
* use _longjmp. It must call swapcontext to swap shadow stack as
* well as normal stack.
*/
# define USE_SWAPCONTEXT
# endif
# include <ucontext.h>
# include <setjmp.h>
# ifndef USE_SWAPCONTEXT
# include <setjmp.h>
# endif
typedef struct async_fibre_st {
ucontext_t fibre;
# ifndef USE_SWAPCONTEXT
jmp_buf env;
int env_init;
# endif
} async_fibre;
static ossl_inline int async_fibre_swapcontext(async_fibre *o, async_fibre *n, int r)
{
# ifdef USE_SWAPCONTEXT
swapcontext(&o->fibre, &n->fibre);
# else
o->env_init = 1;
if (!r || !_setjmp(o->env)) {
@ -44,6 +60,7 @@ static ossl_inline int async_fibre_swapcontext(async_fibre *o, async_fibre *n, i
else
setcontext(&n->fibre);
}
# endif
return 1;
}