1/* Check getcontext and setcontext on the context from makecontext
2 with shadow stack.
3 Copyright (C) 2018-2022 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5
6 The GNU C Library is free software; you can redistribute it and/or
7 modify it under the terms of the GNU Lesser General Public
8 License as published by the Free Software Foundation; either
9 version 2.1 of the License, or (at your option) any later version.
10
11 The GNU C Library is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public
17 License along with the GNU C Library; if not, see
18 <https://www.gnu.org/licenses/>. */
19
20#include <stdio.h>
21#include <stdint.h>
22#include <stdlib.h>
23#include <ucontext.h>
24#include <unistd.h>
25#include <sys/mman.h>
26#include <stdatomic.h>
27#include <x86intrin.h>
28
29static ucontext_t ctx[5];
30static atomic_int done;
31
32static void
33__attribute__((noinline, noclone))
34f2 (void)
35{
36 printf (format: "start f2\n");
37 done++;
38 if (setcontext (&ctx[2]) != 0)
39 {
40 printf (format: "%s: setcontext: %m\n", __FUNCTION__);
41 exit (EXIT_FAILURE);
42 }
43}
44
45static void
46f1 (void)
47{
48 printf (format: "start f1\n");
49 if (getcontext (ucp: &ctx[2]) != 0)
50 {
51 printf (format: "%s: getcontext: %m\n", __FUNCTION__);
52 exit (EXIT_FAILURE);
53 }
54 if (done)
55 exit (EXIT_SUCCESS);
56 f2 ();
57}
58
59static int
60do_test (void)
61{
62 char st1[32768];
63 puts (s: "making contexts");
64 if (getcontext (ucp: &ctx[0]) != 0)
65 {
66 printf (format: "%s: getcontext: %m\n", __FUNCTION__);
67 exit (EXIT_FAILURE);
68 }
69 if (getcontext (ucp: &ctx[1]) != 0)
70 {
71 printf (format: "%s: getcontext: %m\n", __FUNCTION__);
72 exit (EXIT_FAILURE);
73 }
74
75 ctx[3].uc_stack.ss_sp = st1;
76 ctx[3].uc_stack.ss_size = sizeof st1;
77 ctx[3].uc_link = &ctx[0];
78 makecontext (ucp: &ctx[3], func: (void (*) (void)) f1, argc: 0);
79
80 ctx[1].uc_stack.ss_sp = st1;
81 ctx[1].uc_stack.ss_size = sizeof st1;
82 ctx[1].uc_link = &ctx[0];
83 makecontext (ucp: &ctx[1], func: (void (*) (void)) f1, argc: 0);
84
85 ctx[4].uc_stack.ss_sp = st1;
86 ctx[4].uc_stack.ss_size = sizeof st1;
87 ctx[4].uc_link = &ctx[0];
88 makecontext (ucp: &ctx[4], func: (void (*) (void)) f1, argc: 0);
89
90 /* NB: When shadow stack is enabled, makecontext calls arch_prctl
91 with ARCH_CET_ALLOC_SHSTK to allocate a new shadow stack which
92 can be unmapped. The base address and size of the new shadow
93 stack are returned in __ssp[1] and __ssp[2]. makecontext is
94 called for CTX1, CTX3 and CTX4. But only CTX1 is used. New
95 shadow stacks are allocated in the order of CTX3, CTX1, CTX4.
96 It is very likely that CTX1's shadow stack is placed between
97 CTX3 and CTX4. We munmap CTX3's and CTX4's shadow stacks to
98 create gaps above and below CTX1's shadow stack. We check
99 that setcontext CTX1 works correctly in this case. */
100 if (_get_ssp () != 0)
101 {
102 if (ctx[3].__ssp[1] != 0
103 && munmap (addr: (void *) (uintptr_t) ctx[3].__ssp[1],
104 len: (size_t) ctx[3].__ssp[2]) != 0)
105 {
106 printf (format: "%s: munmap: %m\n", __FUNCTION__);
107 exit (EXIT_FAILURE);
108 }
109
110 if (ctx[4].__ssp[1] != 0
111 && munmap (addr: (void *) (uintptr_t) ctx[4].__ssp[1],
112 len: (size_t) ctx[4].__ssp[2]) != 0)
113 {
114 printf (format: "%s: munmap: %m\n", __FUNCTION__);
115 exit (EXIT_FAILURE);
116 }
117 }
118
119 if (setcontext (&ctx[1]) != 0)
120 {
121 printf (format: "%s: setcontext: %m\n", __FUNCTION__);
122 exit (EXIT_FAILURE);
123 }
124 exit (EXIT_FAILURE);
125}
126
127#include <support/test-driver.c>
128

source code of glibc/sysdeps/unix/sysv/linux/x86/tst-cet-setcontext-1.c