1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * lib/hexdump.c
4 */
5
6 #include <linux/types.h>
7 #include <linux/ctype.h>
8 #include <linux/errno.h>
9 #include <linux/kernel.h>
10 #include <linux/minmax.h>
11 #include <linux/export.h>
12 #include <asm/unaligned.h>
13
14 const char hex_asc[] = "0123456789abcdef";
15 EXPORT_SYMBOL(hex_asc);
16 const char hex_asc_upper[] = "0123456789ABCDEF";
17 EXPORT_SYMBOL(hex_asc_upper);
18
19 /**
20 * hex_to_bin - convert a hex digit to its real value
21 * @ch: ascii character represents hex digit
22 *
23 * hex_to_bin() converts one hex digit to its actual value or -1 in case of bad
24 * input.
25 *
26 * This function is used to load cryptographic keys, so it is coded in such a
27 * way that there are no conditions or memory accesses that depend on data.
28 *
29 * Explanation of the logic:
30 * (ch - '9' - 1) is negative if ch <= '9'
31 * ('' - 1 - ch) is negative if ch >= ''
32 * we "and" these two values, so the result is negative if ch is in the range
33 * '' ... '9'
34 * we are only interested in the sign, so we do a shift ">> 8"; note that right
35 * shift of a negative value is implementation-defined, so we cast the
36 * value to (unsigned) before the shift --- we have 0xffffff if ch is in
37 * the range '' ... '9', 0 otherwise
38 * we "and" this value with (ch - '' + 1) --- we have a value 1 ... 10 if ch is
39 * in the range '' ... '9', 0 otherwise
40 * we add this value to -1 --- we have a value 0 ... 9 if ch is in the range ''
41 * ... '9', -1 otherwise
42 * the next line is similar to the previous one, but we need to decode both
43 * uppercase and lowercase letters, so we use (ch & 0xdf), which converts
44 * lowercase to uppercase
45 */
46 int hex_to_bin(unsigned char ch)
47 {
48 unsigned char cu = ch & 0xdf;
49 return -1 +
50 ((ch - '' + 1) & (unsigned)((ch - '9' - 1) & ('' - 1 - ch)) >> 8) +
51 ((cu - 'A' + 11) & (unsigned)((cu - 'F' - 1) & ('A' - 1 - cu)) >> 8);
52 }
53 EXPORT_SYMBOL(hex_to_bin);
54
55 /**
56 * hex2bin - convert an ascii hexadecimal string to its binary representation
57 * @dst: binary result
58 * @src: ascii hexadecimal string
59 * @count: result length
60 *
61 * Return 0 on success, -EINVAL in case of bad input.
62 */
63 int hex2bin(u8 *dst, const char *src, size_t count)
64 {
65 while (count--) {
66 int hi, lo;
67
68 hi = hex_to_bin(*src++);
69 if (unlikely(hi < 0))
70 return -EINVAL;
71 lo = hex_to_bin(*src++);
72 if (unlikely(lo < 0))
73 return -EINVAL;
74
75 *dst++ = (hi << 4) | lo;
76 }
77 return 0;
78 }
79 EXPORT_SYMBOL(hex2bin);
80
81 /**
82 * bin2hex - convert binary data to an ascii hexadecimal string
83 * @dst: ascii hexadecimal result
84 * @src: binary data
85 * @count: binary data length
86 */
87 char *bin2hex(char *dst, const void *src, size_t count)
88 {
89 const unsigned char *_src = src;
90
91 while (count--)
92 dst = hex_byte_pack(dst, *_src++);
93 return dst;
94 }
95 EXPORT_SYMBOL(bin2hex);
96
97 /**
98 * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
99 * @buf: data blob to dump
100 * @len: number of bytes in the @buf
101 * @rowsize: number of bytes to print per line; must be 16 or 32
102 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
103 * @linebuf: where to put the converted data
104 * @linebuflen: total size of @linebuf, including space for terminating NUL
105 * @ascii: include ASCII after the hex output
106 *
107 * hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
108 * 16 or 32 bytes of input data converted to hex + ASCII output.
109 *
110 * Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
111 * to a hex + ASCII dump at the supplied memory location.
112 * The converted output is always NUL-terminated.
113 *
114 * E.g.:
115 * hex_dump_to_buffer(frame->data, frame->len, 16, 1,
116 * linebuf, sizeof(linebuf), true);
117 *
118 * example output buffer:
119 * 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
120 *
121 * Return:
122 * The amount of bytes placed in the buffer without terminating NUL. If the
123 * output was truncated, then the return value is the number of bytes
124 * (excluding the terminating NUL) which would have been written to the final
125 * string if enough space had been available.
126 */
127 int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
128 char *linebuf, size_t linebuflen, bool ascii)
129 {
130 const u8 *ptr = buf;
131 int ngroups;
132 u8 ch;
133 int j, lx = 0;
134 int ascii_column;
135 int ret;
136
137 if (rowsize != 16 && rowsize != 32)
138 rowsize = 16;
139
140 if (len > rowsize) /* limit to one line at a time */
141 len = rowsize;
142 if (!is_power_of_2(groupsize) || groupsize > 8)
143 groupsize = 1;
144 if ((len % groupsize) != 0) /* no mixed size output */
145 groupsize = 1;
146
147 ngroups = len / groupsize;
148 ascii_column = rowsize * 2 + rowsize / groupsize + 1;
149
150 if (!linebuflen)
151 goto overflow1;
152
153 if (!len)
154 goto nil;
155
156 if (groupsize == 8) {
157 const u64 *ptr8 = buf;
158
159 for (j = 0; j < ngroups; j++) {
160 ret = snprintf(linebuf + lx, linebuflen - lx,
161 "%s%16.16llx", j ? " " : "",
162 get_unaligned(ptr8 + j));
163 if (ret >= linebuflen - lx)
164 goto overflow1;
165 lx += ret;
166 }
167 } else if (groupsize == 4) {
168 const u32 *ptr4 = buf;
169
170 for (j = 0; j < ngroups; j++) {
171 ret = snprintf(linebuf + lx, linebuflen - lx,
172 "%s%8.8x", j ? " " : "",
173 get_unaligned(ptr4 + j));
174 if (ret >= linebuflen - lx)
175 goto overflow1;
176 lx += ret;
177 }
178 } else if (groupsize == 2) {
179 const u16 *ptr2 = buf;
180
181 for (j = 0; j < ngroups; j++) {
182 ret = snprintf(linebuf + lx, linebuflen - lx,
183 "%s%4.4x", j ? " " : "",
184 get_unaligned(ptr2 + j));
185 if (ret >= linebuflen - lx)
186 goto overflow1;
187 lx += ret;
188 }
189 } else {
190 for (j = 0; j < len; j++) {
191 if (linebuflen < lx + 2)
192 goto overflow2;
193 ch = ptr[j];
194 linebuf[lx++] = hex_asc_hi(ch);
195 if (linebuflen < lx + 2)
196 goto overflow2;
197 linebuf[lx++] = hex_asc_lo(ch);
198 if (linebuflen < lx + 2)
199 goto overflow2;
200 linebuf[lx++] = ' ';
201 }
202 if (j)
203 lx--;
204 }
205 if (!ascii)
206 goto nil;
207
208 while (lx < ascii_column) {
209 if (linebuflen < lx + 2)
210 goto overflow2;
211 linebuf[lx++] = ' ';
212 }
213 for (j = 0; j < len; j++) {
214 if (linebuflen < lx + 2)
215 goto overflow2;
216 ch = ptr[j];
217 linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
218 }
219 nil:
220 linebuf[lx] = '\0';
221 return lx;
222 overflow2:
223 linebuf[lx++] = '\0';
224 overflow1:
225 return ascii ? ascii_column + len : (groupsize * 2 + 1) * ngroups - 1;
226 }
227 EXPORT_SYMBOL(hex_dump_to_buffer);
228
229 #ifdef CONFIG_PRINTK
230 /**
231 * print_hex_dump - print a text hex dump to syslog for a binary blob of data
232 * @level: kernel log level (e.g. KERN_DEBUG)
233 * @prefix_str: string to prefix each line with;
234 * caller supplies trailing spaces for alignment if desired
235 * @prefix_type: controls whether prefix of an offset, address, or none
236 * is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
237 * @rowsize: number of bytes to print per line; must be 16 or 32
238 * @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
239 * @buf: data blob to dump
240 * @len: number of bytes in the @buf
241 * @ascii: include ASCII after the hex output
242 *
243 * Given a buffer of u8 data, print_hex_dump() prints a hex + ASCII dump
244 * to the kernel log at the specified kernel log level, with an optional
245 * leading prefix.
246 *
247 * print_hex_dump() works on one "line" of output at a time, i.e.,
248 * 16 or 32 bytes of input data converted to hex + ASCII output.
249 * print_hex_dump() iterates over the entire input @buf, breaking it into
250 * "line size" chunks to format and print.
251 *
252 * E.g.:
253 * print_hex_dump(KERN_DEBUG, "raw data: ", DUMP_PREFIX_ADDRESS,
254 * 16, 1, frame->data, frame->len, true);
255 *
256 * Example output using %DUMP_PREFIX_OFFSET and 1-byte mode:
257 * 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
258 * Example output using %DUMP_PREFIX_ADDRESS and 4-byte mode:
259 * ffffffff88089af0: 73727170 77767574 7b7a7978 7f7e7d7c pqrstuvwxyz{|}~.
260 */
261 void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
262 int rowsize, int groupsize,
263 const void *buf, size_t len, bool ascii)
264 {
265 const u8 *ptr = buf;
266 int i, linelen, remaining = len;
267 unsigned char linebuf[32 * 3 + 2 + 32 + 1];
268
269 if (rowsize != 16 && rowsize != 32)
270 rowsize = 16;
271
272 for (i = 0; i < len; i += rowsize) {
273 linelen = min(remaining, rowsize);
274 remaining -= rowsize;
275
276 hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
277 linebuf, sizeof(linebuf), ascii);
278
279 switch (prefix_type) {
280 case DUMP_PREFIX_ADDRESS:
281 printk("%s%s%p: %s\n",
282 level, prefix_str, ptr + i, linebuf);
283 break;
284 case DUMP_PREFIX_OFFSET:
285 printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
286 break;
287 default:
288 printk("%s%s%s\n", level, prefix_str, linebuf);
289 break;
290 }
291 }
292 }
293 EXPORT_SYMBOL(print_hex_dump);
294
295 #endif /* defined(CONFIG_PRINTK) */
296
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