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 | { | |
63 | /* Intentionally crossing kernel/user memory boundary. */ | |
64 | void (*func)(void) = dst; | |
65 | ||
66 | pr_info("attempting ok execution at %p\n", do_nothing); | |
67 | do_nothing(); | |
68 | ||
69 | if (copy_to_user((void __user *)dst, do_nothing, EXEC_SIZE)) | |
70 | return; | |
71 | flush_icache_range((unsigned long)dst, (unsigned long)dst + EXEC_SIZE); | |
72 | pr_info("attempting bad execution at %p\n", func); | |
73 | func(); | |
74 | } | |
75 | ||
76 | void lkdtm_WRITE_RO(void) | |
77 | { | |
78 | /* Explicitly cast away "const" for the test. */ | |
79 | unsigned long *ptr = (unsigned long *)&rodata; | |
80 | ||
81 | pr_info("attempting bad rodata write at %p\n", ptr); | |
82 | *ptr ^= 0xabcd1234; | |
83 | } | |
84 | ||
85 | void lkdtm_WRITE_RO_AFTER_INIT(void) | |
86 | { | |
87 | unsigned long *ptr = &ro_after_init; | |
88 | ||
89 | /* | |
90 | * Verify we were written to during init. Since an Oops | |
91 | * is considered a "success", a failure is to just skip the | |
92 | * real test. | |
93 | */ | |
94 | if ((*ptr & 0xAA) != 0xAA) { | |
95 | pr_info("%p was NOT written during init!?\n", ptr); | |
96 | return; | |
97 | } | |
98 | ||
99 | pr_info("attempting bad ro_after_init write at %p\n", ptr); | |
100 | *ptr ^= 0xabcd1234; | |
101 | } | |
102 | ||
103 | void lkdtm_WRITE_KERN(void) | |
104 | { | |
105 | size_t size; | |
106 | unsigned char *ptr; | |
107 | ||
108 | size = (unsigned long)do_overwritten - (unsigned long)do_nothing; | |
109 | ptr = (unsigned char *)do_overwritten; | |
110 | ||
111 | pr_info("attempting bad %zu byte write at %p\n", size, ptr); | |
112 | memcpy(ptr, (unsigned char *)do_nothing, size); | |
113 | flush_icache_range((unsigned long)ptr, (unsigned long)(ptr + size)); | |
114 | ||
115 | do_overwritten(); | |
116 | } | |
117 | ||
118 | void lkdtm_EXEC_DATA(void) | |
119 | { | |
120 | execute_location(data_area, CODE_WRITE); | |
121 | } | |
122 | ||
123 | void lkdtm_EXEC_STACK(void) | |
124 | { | |
125 | u8 stack_area[EXEC_SIZE]; | |
126 | execute_location(stack_area, CODE_WRITE); | |
127 | } | |
128 | ||
129 | void lkdtm_EXEC_KMALLOC(void) | |
130 | { | |
131 | u32 *kmalloc_area = kmalloc(EXEC_SIZE, GFP_KERNEL); | |
132 | execute_location(kmalloc_area, CODE_WRITE); | |
133 | kfree(kmalloc_area); | |
134 | } | |
135 | ||
136 | void lkdtm_EXEC_VMALLOC(void) | |
137 | { | |
138 | u32 *vmalloc_area = vmalloc(EXEC_SIZE); | |
139 | execute_location(vmalloc_area, CODE_WRITE); | |
140 | vfree(vmalloc_area); | |
141 | } | |
142 | ||
143 | void lkdtm_EXEC_RODATA(void) | |
144 | { | |
145 | execute_location(lkdtm_rodata_do_nothing, CODE_AS_IS); | |
146 | } | |
147 | ||
148 | void lkdtm_EXEC_USERSPACE(void) | |
149 | { | |
150 | unsigned long user_addr; | |
151 | ||
152 | user_addr = vm_mmap(NULL, 0, PAGE_SIZE, | |
153 | PROT_READ | PROT_WRITE | PROT_EXEC, | |
154 | MAP_ANONYMOUS | MAP_PRIVATE, 0); | |
155 | if (user_addr >= TASK_SIZE) { | |
156 | pr_warn("Failed to allocate user memory\n"); | |
157 | return; | |
158 | } | |
159 | execute_user_location((void *)user_addr); | |
160 | vm_munmap(user_addr, PAGE_SIZE); | |
161 | } | |
162 | ||
163 | void lkdtm_ACCESS_USERSPACE(void) | |
164 | { | |
165 | unsigned long user_addr, tmp = 0; | |
166 | unsigned long *ptr; | |
167 | ||
168 | user_addr = vm_mmap(NULL, 0, PAGE_SIZE, | |
169 | PROT_READ | PROT_WRITE | PROT_EXEC, | |
170 | MAP_ANONYMOUS | MAP_PRIVATE, 0); | |
171 | if (user_addr >= TASK_SIZE) { | |
172 | pr_warn("Failed to allocate user memory\n"); | |
173 | return; | |
174 | } | |
175 | ||
176 | if (copy_to_user((void __user *)user_addr, &tmp, sizeof(tmp))) { | |
177 | pr_warn("copy_to_user failed\n"); | |
178 | vm_munmap(user_addr, PAGE_SIZE); | |
179 | return; | |
180 | } | |
181 | ||
182 | ptr = (unsigned long *)user_addr; | |
183 | ||
184 | pr_info("attempting bad read at %p\n", ptr); | |
185 | tmp = *ptr; | |
186 | tmp += 0xc0dec0de; | |
187 | ||
188 | pr_info("attempting bad write at %p\n", ptr); | |
189 | *ptr = tmp; | |
190 | ||
191 | vm_munmap(user_addr, PAGE_SIZE); | |
192 | } | |
193 | ||
194 | void __init lkdtm_perms_init(void) | |
195 | { | |
196 | /* Make sure we can write to __ro_after_init values during __init */ | |
197 | ro_after_init |= 0xAA; | |
198 | ||
199 | } |