1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef __TRACE_PROBE_KERNEL_H_
3 #define __TRACE_PROBE_KERNEL_H_
4 
5 #define FAULT_STRING "(fault)"
6 
7 /*
8  * This depends on trace_probe.h, but can not include it due to
9  * the way trace_probe_tmpl.h is used by trace_kprobe.c and trace_eprobe.c.
10  * Which means that any other user must include trace_probe.h before including
11  * this file.
12  */
13 /* Return the length of string -- including null terminal byte */
14 static nokprobe_inline int
15 fetch_store_strlen_user(unsigned long addr)
16 {
17 	const void __user *uaddr =  (__force const void __user *)addr;
18 	int ret;
19 
20 	ret = strnlen_user_nofault(uaddr, MAX_STRING_SIZE);
21 	/*
22 	 * strnlen_user_nofault returns zero on fault, insert the
23 	 * FAULT_STRING when that occurs.
24 	 */
25 	if (ret <= 0)
26 		return strlen(FAULT_STRING) + 1;
27 	return ret;
28 }
29 
30 /* Return the length of string -- including null terminal byte */
31 static nokprobe_inline int
32 fetch_store_strlen(unsigned long addr)
33 {
34 	int ret, len = 0;
35 	u8 c;
36 
37 #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
38 	if (addr < TASK_SIZE)
39 		return fetch_store_strlen_user(addr);
40 #endif
41 
42 	do {
43 		ret = copy_from_kernel_nofault(&c, (u8 *)addr + len, 1);
44 		len++;
45 	} while (c && ret == 0 && len < MAX_STRING_SIZE);
46 
47 	/* For faults, return enough to hold the FAULT_STRING */
48 	return (ret < 0) ? strlen(FAULT_STRING) + 1 : len;
49 }
50 
51 static nokprobe_inline void set_data_loc(int ret, void *dest, void *__dest, void *base, int len)
52 {
53 	if (ret >= 0) {
54 		*(u32 *)dest = make_data_loc(ret, __dest - base);
55 	} else {
56 		strscpy(__dest, FAULT_STRING, len);
57 		ret = strlen(__dest) + 1;
58 	}
59 }
60 
61 /*
62  * Fetch a null-terminated string from user. Caller MUST set *(u32 *)buf
63  * with max length and relative data location.
64  */
65 static nokprobe_inline int
66 fetch_store_string_user(unsigned long addr, void *dest, void *base)
67 {
68 	const void __user *uaddr =  (__force const void __user *)addr;
69 	int maxlen = get_loc_len(*(u32 *)dest);
70 	void *__dest;
71 	long ret;
72 
73 	if (unlikely(!maxlen))
74 		return -ENOMEM;
75 
76 	__dest = get_loc_data(dest, base);
77 
78 	ret = strncpy_from_user_nofault(__dest, uaddr, maxlen);
79 	set_data_loc(ret, dest, __dest, base, maxlen);
80 
81 	return ret;
82 }
83 
84 /*
85  * Fetch a null-terminated string. Caller MUST set *(u32 *)buf with max
86  * length and relative data location.
87  */
88 static nokprobe_inline int
89 fetch_store_string(unsigned long addr, void *dest, void *base)
90 {
91 	int maxlen = get_loc_len(*(u32 *)dest);
92 	void *__dest;
93 	long ret;
94 
95 #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
96 	if ((unsigned long)addr < TASK_SIZE)
97 		return fetch_store_string_user(addr, dest, base);
98 #endif
99 
100 	if (unlikely(!maxlen))
101 		return -ENOMEM;
102 
103 	__dest = get_loc_data(dest, base);
104 
105 	/*
106 	 * Try to get string again, since the string can be changed while
107 	 * probing.
108 	 */
109 	ret = strncpy_from_kernel_nofault(__dest, (void *)addr, maxlen);
110 	set_data_loc(ret, dest, __dest, base, maxlen);
111 
112 	return ret;
113 }
114 
115 static nokprobe_inline int
116 probe_mem_read_user(void *dest, void *src, size_t size)
117 {
118 	const void __user *uaddr =  (__force const void __user *)src;
119 
120 	return copy_from_user_nofault(dest, uaddr, size);
121 }
122 
123 static nokprobe_inline int
124 probe_mem_read(void *dest, void *src, size_t size)
125 {
126 #ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
127 	if ((unsigned long)src < TASK_SIZE)
128 		return probe_mem_read_user(dest, src, size);
129 #endif
130 	return copy_from_kernel_nofault(dest, src, size);
131 }
132 
133 #endif /* __TRACE_PROBE_KERNEL_H_ */
134