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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
0d9eb29b KC |
2 | /* |
3 | * This is for all the tests related to validating kernel memory | |
4 | * permissions: non-executable regions, non-writable regions, and | |
5 | * even non-readable regions. | |
6 | */ | |
6d2e91a6 | 7 | #include "lkdtm.h" |
0d9eb29b KC |
8 | #include <linux/slab.h> |
9 | #include <linux/vmalloc.h> | |
10 | #include <linux/mman.h> | |
11 | #include <linux/uaccess.h> | |
12 | #include <asm/cacheflush.h> | |
13 | ||
0d9eb29b KC |
14 | /* Whether or not to fill the target memory area with do_nothing(). */ |
15 | #define CODE_WRITE true | |
16 | #define CODE_AS_IS false | |
17 | ||
18 | /* How many bytes to copy to be sure we've copied enough of do_nothing(). */ | |
19 | #define EXEC_SIZE 64 | |
20 | ||
21 | /* This is non-const, so it will end up in the .data section. */ | |
22 | static u8 data_area[EXEC_SIZE]; | |
23 | ||
24 | /* This is cost, so it will end up in the .rodata section. */ | |
25 | static const unsigned long rodata = 0xAA55AA55; | |
26 | ||
27 | /* This is marked __ro_after_init, so it should ultimately be .rodata. */ | |
28 | static unsigned long ro_after_init __ro_after_init = 0x55AA5500; | |
29 | ||
30 | /* | |
31 | * This just returns to the caller. It is designed to be copied into | |
32 | * non-executable memory regions. | |
33 | */ | |
34 | static void do_nothing(void) | |
35 | { | |
36 | return; | |
37 | } | |
38 | ||
39 | /* Must immediately follow do_nothing for size calculuations to work out. */ | |
40 | static void do_overwritten(void) | |
41 | { | |
42 | pr_info("do_overwritten wasn't overwritten!\n"); | |
43 | return; | |
44 | } | |
45 | ||
46 | static noinline void execute_location(void *dst, bool write) | |
47 | { | |
48 | void (*func)(void) = dst; | |
49 | ||
50 | pr_info("attempting ok execution at %p\n", do_nothing); | |
51 | do_nothing(); | |
52 | ||
53 | if (write == CODE_WRITE) { | |
54 | memcpy(dst, do_nothing, EXEC_SIZE); | |
55 | flush_icache_range((unsigned long)dst, | |
56 | (unsigned long)dst + EXEC_SIZE); | |
57 | } | |
58 | pr_info("attempting bad execution at %p\n", func); | |
59 | func(); | |
60 | } | |
61 | ||
62 | static void execute_user_location(void *dst) | |
63 | { | |
fcd35857 CM |
64 | int copied; |
65 | ||
0d9eb29b KC |
66 | /* Intentionally crossing kernel/user memory boundary. */ |
67 | void (*func)(void) = dst; | |
68 | ||
69 | pr_info("attempting ok execution at %p\n", do_nothing); | |
70 | do_nothing(); | |
71 | ||
fcd35857 CM |
72 | copied = access_process_vm(current, (unsigned long)dst, do_nothing, |
73 | EXEC_SIZE, FOLL_WRITE); | |
74 | if (copied < EXEC_SIZE) | |
0d9eb29b | 75 | return; |
0d9eb29b KC |
76 | pr_info("attempting bad execution at %p\n", func); |
77 | func(); | |
78 | } | |
79 | ||
80 | void lkdtm_WRITE_RO(void) | |
81 | { | |
82 | /* Explicitly cast away "const" for the test. */ | |
83 | unsigned long *ptr = (unsigned long *)&rodata; | |
84 | ||
85 | pr_info("attempting bad rodata write at %p\n", ptr); | |
86 | *ptr ^= 0xabcd1234; | |
87 | } | |
88 | ||
89 | void lkdtm_WRITE_RO_AFTER_INIT(void) | |
90 | { | |
91 | unsigned long *ptr = &ro_after_init; | |
92 | ||
93 | /* | |
94 | * Verify we were written to during init. Since an Oops | |
95 | * is considered a "success", a failure is to just skip the | |
96 | * real test. | |
97 | */ | |
98 | if ((*ptr & 0xAA) != 0xAA) { | |
99 | pr_info("%p was NOT written during init!?\n", ptr); | |
100 | return; | |
101 | } | |
102 | ||
103 | pr_info("attempting bad ro_after_init write at %p\n", ptr); | |
104 | *ptr ^= 0xabcd1234; | |
105 | } | |
106 | ||
107 | void lkdtm_WRITE_KERN(void) | |
108 | { | |
109 | size_t size; | |
110 | unsigned char *ptr; | |
111 | ||
112 | size = (unsigned long)do_overwritten - (unsigned long)do_nothing; | |
113 | ptr = (unsigned char *)do_overwritten; | |
114 | ||
115 | pr_info("attempting bad %zu byte write at %p\n", size, ptr); | |
116 | memcpy(ptr, (unsigned char *)do_nothing, size); | |
117 | flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size)); | |
118 | ||
119 | do_overwritten(); | |
120 | } | |
121 | ||
122 | void lkdtm_EXEC_DATA(void) | |
123 | { | |
124 | execute_location(data_area, CODE_WRITE); | |
125 | } | |
126 | ||
127 | void lkdtm_EXEC_STACK(void) | |
128 | { | |
129 | u8 stack_area[EXEC_SIZE]; | |
130 | execute_location(stack_area, CODE_WRITE); | |
131 | } | |
132 | ||
133 | void lkdtm_EXEC_KMALLOC(void) | |
134 | { | |
135 | u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL); | |
136 | execute_location(kmalloc_area, CODE_WRITE); | |
137 | kfree(kmalloc_area); | |
138 | } | |
139 | ||
140 | void lkdtm_EXEC_VMALLOC(void) | |
141 | { | |
142 | u32 *vmalloc_area = vmalloc(EXEC_SIZE); | |
143 | execute_location(vmalloc_area, CODE_WRITE); | |
144 | vfree(vmalloc_area); | |
145 | } | |
146 | ||
147 | void lkdtm_EXEC_RODATA(void) | |
148 | { | |
149 | execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); | |
150 | } | |
151 | ||
152 | void lkdtm_EXEC_USERSPACE(void) | |
153 | { | |
154 | unsigned long user_addr; | |
155 | ||
156 | user_addr = vm_mmap(NULL, 0, PAGE_SIZE, | |
157 | PROT_READ | PROT_WRITE | PROT_EXEC, | |
158 | MAP_ANONYMOUS | MAP_PRIVATE, 0); | |
159 | if (user_addr >= TASK_SIZE) { | |
160 | pr_warn("Failed to allocate user memory\n"); | |
161 | return; | |
162 | } | |
163 | execute_user_location((void *)user_addr); | |
164 | vm_munmap(user_addr, PAGE_SIZE); | |
165 | } | |
166 | ||
167 | void lkdtm_ACCESS_USERSPACE(void) | |
168 | { | |
169 | unsigned long user_addr, tmp = 0; | |
170 | unsigned long *ptr; | |
171 | ||
172 | user_addr = vm_mmap(NULL, 0, PAGE_SIZE, | |
173 | PROT_READ | PROT_WRITE | PROT_EXEC, | |
174 | MAP_ANONYMOUS | MAP_PRIVATE, 0); | |
175 | if (user_addr >= TASK_SIZE) { | |
176 | pr_warn("Failed to allocate user memory\n"); | |
177 | return; | |
178 | } | |
179 | ||
180 | if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) { | |
181 | pr_warn("copy_to_user failed\n"); | |
182 | vm_munmap(user_addr, PAGE_SIZE); | |
183 | return; | |
184 | } | |
185 | ||
186 | ptr = (unsigned long *)user_addr; | |
187 | ||
188 | pr_info("attempting bad read at %p\n", ptr); | |
189 | tmp = *ptr; | |
190 | tmp += 0xc0dec0de; | |
191 | ||
192 | pr_info("attempting bad write at %p\n", ptr); | |
193 | *ptr = tmp; | |
194 | ||
195 | vm_munmap(user_addr, PAGE_SIZE); | |
196 | } | |
197 | ||
198 | void __init lkdtm_perms_init(void) | |
199 | { | |
200 | /* Make sure we can write to __ro_after_init values during __init */ | |
201 | ro_after_init |= 0xAA; | |
202 | ||
203 | } |