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edb5e0c8f9
Sync with Linux kernel 6.6 shadow stack interface. Since only x86-64 is supported, i386 shadow stack codes are unchanged and CET shouldn't be enabled for i386. 1. When the shadow stack base in TCB is unset, the default shadow stack is in use. Use the current shadow stack pointer as the marker for the default shadow stack. It is used to identify if the current shadow stack is the same as the target shadow stack when switching ucontexts. If yes, INCSSP will be used to unwind shadow stack. Otherwise, shadow stack restore token will be used. 2. Allocate shadow stack with the map_shadow_stack syscall. Since there is no function to explicitly release ucontext, there is no place to release shadow stack allocated by map_shadow_stack in ucontext functions. Such shadow stacks will be leaked. 3. Rename arch_prctl CET commands to ARCH_SHSTK_XXX. 4. Rewrite the CET control functions with the current kernel shadow stack interface. Since CET is no longer enabled by kernel, a separate patch will enable shadow stack during startup.
126 lines
3.5 KiB
C
126 lines
3.5 KiB
C
/* Check getcontext and setcontext on the context from makecontext
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with shadow stack.
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Copyright (C) 2018-2023 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <ucontext.h>
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#include <unistd.h>
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#include <sys/mman.h>
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#include <stdatomic.h>
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#include <x86intrin.h>
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static ucontext_t ctx[5];
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static atomic_int done;
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static void
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__attribute__((noinline, noclone))
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f2 (void)
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{
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printf ("start f2\n");
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done++;
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if (setcontext (&ctx[2]) != 0)
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{
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printf ("%s: setcontext: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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}
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static void
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f1 (void)
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{
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printf ("start f1\n");
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if (getcontext (&ctx[2]) != 0)
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{
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printf ("%s: getcontext: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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if (done)
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exit (EXIT_SUCCESS);
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f2 ();
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}
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static int
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do_test (void)
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{
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char st1[32768];
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puts ("making contexts");
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if (getcontext (&ctx[0]) != 0)
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{
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printf ("%s: getcontext: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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if (getcontext (&ctx[1]) != 0)
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{
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printf ("%s: getcontext: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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ctx[3].uc_stack.ss_sp = st1;
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ctx[3].uc_stack.ss_size = sizeof st1;
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ctx[3].uc_link = &ctx[0];
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makecontext (&ctx[3], (void (*) (void)) f1, 0);
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ctx[1].uc_stack.ss_sp = st1;
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ctx[1].uc_stack.ss_size = sizeof st1;
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ctx[1].uc_link = &ctx[0];
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makecontext (&ctx[1], (void (*) (void)) f1, 0);
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ctx[4].uc_stack.ss_sp = st1;
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ctx[4].uc_stack.ss_size = sizeof st1;
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ctx[4].uc_link = &ctx[0];
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makecontext (&ctx[4], (void (*) (void)) f1, 0);
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/* NB: When shadow stack is enabled, makecontext calls map_shadow_stack
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to allocate a new shadow stack which can be unmapped. The base
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address and size of the new shadow stack are returned in __ssp[1]
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and __ssp[2]. makecontext is called for CTX1, CTX3 and CTX4. But
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only CTX1 is used. New shadow stacks are allocated in the order
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of CTX3, CTX1, CTX4. It is very likely that CTX1's shadow stack is
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placed between CTX3 and CTX4. We munmap CTX3's and CTX4's shadow
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stacks to create gaps above and below CTX1's shadow stack. We check
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that setcontext CTX1 works correctly in this case. */
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if (_get_ssp () != 0)
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{
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if (ctx[3].__ssp[1] != 0
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&& munmap ((void *) (uintptr_t) ctx[3].__ssp[1],
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(size_t) ctx[3].__ssp[2]) != 0)
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{
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printf ("%s: munmap: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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if (ctx[4].__ssp[1] != 0
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&& munmap ((void *) (uintptr_t) ctx[4].__ssp[1],
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(size_t) ctx[4].__ssp[2]) != 0)
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{
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printf ("%s: munmap: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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}
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if (setcontext (&ctx[1]) != 0)
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{
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printf ("%s: setcontext: %m\n", __FUNCTION__);
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exit (EXIT_FAILURE);
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}
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exit (EXIT_FAILURE);
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}
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#include <support/test-driver.c>
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