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 | |
29 | static ucontext_t ctx[5]; |
30 | static atomic_int done; |
31 | |
32 | static void |
33 | __attribute__((noinline, noclone)) |
34 | f2 (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 | |
45 | static void |
46 | f1 (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 | |
59 | static int |
60 | do_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 | |