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
kern_fetch_store_strlen_user(unsigned long addr)15 kern_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
kern_fetch_store_strlen(unsigned long addr)32 kern_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 kern_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
set_data_loc(int ret,void * dest,void * __dest,void * base,int len)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
kern_fetch_store_string_user(unsigned long addr,void * dest,void * base)66 kern_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
kern_fetch_store_string(unsigned long addr,void * dest,void * base)89 kern_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 kern_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 #endif /* __TRACE_PROBE_KERNEL_H_ */
116