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  * ('0' - 1 - ch) is negative if ch >= '0'
32  * we "and" these two values, so the result is negative if ch is in the range
33  *	'0' ... '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 '0' ... '9', 0 otherwise
38  * we "and" this value with (ch - '0' + 1) --- we have a value 1 ... 10 if ch is
39  *	in the range '0' ... '9', 0 otherwise
40  * we add this value to -1 --- we have a value 0 ... 9 if ch is in the range '0'
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  */
hex_to_bin(unsigned char ch)46 int hex_to_bin(unsigned char ch)
47 {
48 	unsigned char cu = ch & 0xdf;
49 	return -1 +
50 		((ch - '0' +  1) & (unsigned)((ch - '9' - 1) & ('0' - 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  */
hex2bin(u8 * dst,const char * src,size_t count)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  */
bin2hex(char * dst,const void * src,size_t count)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  */
hex_dump_to_buffer(const void * buf,size_t len,int rowsize,int groupsize,char * linebuf,size_t linebuflen,bool ascii)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  */
print_hex_dump(const char * level,const char * prefix_str,int prefix_type,int rowsize,int groupsize,const void * buf,size_t len,bool ascii)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