net/ceph/armor.c

   1 // SPDX-License-Identifier: GPL-2.0
   2
   3 #include <linux/errno.h>
   4
   5 int ceph_armor(char *dst, const char *src, const char *end);
   6 int ceph_unarmor(char *dst, const char *src, const char *end);
   7
   8 /*
   9  * base64 encode/decode.
  10  */
  11
  12 static const char *pem_key =
  13         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  14
  15 static int encode_bits(int c)
  16 {
  17         return pem_key[c];
  18 }
  19
  20 static int decode_bits(char c)
  21 {
  22         if (c >= 'A' && c <= 'Z')
  23                 return c - 'A';
  24         if (c >= 'a' && c <= 'z')
  25                 return c - 'a' + 26;
  26         if (c >= '0' && c <= '9')
  27                 return c - '0' + 52;
  28         if (c == '+')
  29                 return 62;
  30         if (c == '/')
  31                 return 63;
  32         if (c == '=')
  33                 return 0; /* just non-negative, please */
  34         return -EINVAL;
  35 }
  36
  37 int ceph_armor(char *dst, const char *src, const char *end)
  38 {
  39         int olen = 0;
  40         int line = 0;
  41
  42         while (src < end) {
  43                 unsigned char a, b, c;
  44
  45                 a = *src++;
  46                 *dst++ = encode_bits(a >> 2);
  47                 if (src < end) {
  48                         b = *src++;
  49                         *dst++ = encode_bits(((a & 3) << 4) | (b >> 4));
  50                         if (src < end) {
  51                                 c = *src++;
  52                                 *dst++ = encode_bits(((b & 15) << 2) |
  53                                                      (c >> 6));
  54                                 *dst++ = encode_bits(c & 63);
  55                         } else {
  56                                 *dst++ = encode_bits((b & 15) << 2);
  57                                 *dst++ = '=';
  58                         }
  59                 } else {
  60                         *dst++ = encode_bits(((a & 3) << 4));
  61                         *dst++ = '=';
  62                         *dst++ = '=';
  63                 }
  64                 olen += 4;
  65                 line += 4;
  66                 if (line == 64) {
  67                         line = 0;
  68                         *(dst++) = '\n';
  69                         olen++;
  70                 }
  71         }
  72         return olen;
  73 }
  74
  75 int ceph_unarmor(char *dst, const char *src, const char *end)
  76 {
  77         int olen = 0;
  78
  79         while (src < end) {
  80                 int a, b, c, d;
  81
  82                 if (src[0] == '\n') {
  83                         src++;
  84                         continue;
  85                 }
  86                 if (src + 4 > end)
  87                         return -EINVAL;
  88                 a = decode_bits(src[0]);
  89                 b = decode_bits(src[1]);
  90                 c = decode_bits(src[2]);
  91                 d = decode_bits(src[3]);
  92                 if (a < 0 || b < 0 || c < 0 || d < 0)
  93                         return -EINVAL;
  94
  95                 *dst++ = (a << 2) | (b >> 4);
  96                 if (src[2] == '=')
  97                         return olen + 1;
  98                 *dst++ = ((b & 15) << 4) | (c >> 2);
  99                 if (src[3] == '=')
 100                         return olen + 2;
 101                 *dst++ = ((c & 3) << 6) | d;
 102                 olen += 3;
 103                 src += 4;
 104         }
 105         return olen;
 106 }