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