lib/hexdump.c

   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 <linux/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  */
  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  */
  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) */