1 # |
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2 # Replace arc4random* calls with FIPS compliant implementation in FIPS mode. |
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3 # |
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4 # Once libc:arc4random* are FIPS compliant (20816957), this patch will be |
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5 # dropped. |
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6 # |
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7 # This is a temporary patch and is not intented for upstream contribution. |
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8 # |
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9 diff -pur old/misc.c new/misc.c |
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10 --- old/misc.c |
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11 +++ new/misc.c |
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12 @@ -1164,3 +1164,87 @@ sock_set_v6only(int s) |
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13 error("setsockopt IPV6_V6ONLY: %s", strerror(errno)); |
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14 #endif |
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15 } |
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16 + |
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17 +#ifdef ENABLE_OPENSSL_FIPS |
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18 +/* cancel arc4random* -> fips_arc4random* defines from misc.h */ |
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19 +#undef arc4random |
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20 +#undef arc4random_buf |
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21 +#undef arc4random_stir |
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22 +#undef arc4random_uniform |
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23 + |
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24 +/* FIPS compliant alternative for arc4random */ |
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25 +static uint32_t |
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26 +fips_arc4random_impl() |
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27 +{ |
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28 + unsigned int r = 0; |
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29 + |
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30 + if (RAND_bytes((unsigned char *)&r, sizeof (r)) <= 0) { |
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31 + fatal("RAND_bytes() failed. Aborting the process"); |
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32 + } |
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33 + |
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34 + return (r); |
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35 +} |
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36 + |
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37 +uint32_t |
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38 +fips_arc4random() |
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39 +{ |
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40 + if (!ssh_FIPS_mode()) |
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41 + return arc4random(); |
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42 + else |
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43 + return fips_arc4random_impl(); |
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44 +} |
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45 + |
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46 +/* implementation taken from openbsd-compat/arc4random.c */ |
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47 +void |
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48 +fips_arc4random_buf(void *_buf, size_t n) |
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49 +{ |
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50 + size_t i; |
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51 + uint32_t r = 0; |
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52 + char *buf = (char *)_buf; |
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53 + |
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54 + if (!ssh_FIPS_mode()) |
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55 + return arc4random_buf(_buf, n); |
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56 + |
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57 + for (i = 0; i < n; i++) { |
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58 + if (i % 4 == 0) |
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59 + r = fips_arc4random_impl(); |
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60 + buf[i] = r & 0xff; |
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61 + r >>= 8; |
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62 + } |
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63 + explicit_bzero(&r, sizeof(r)); |
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64 +} |
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65 + |
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66 +void |
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67 +fips_arc4random_stir(void) |
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68 +{ |
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69 + if (!ssh_FIPS_mode()) |
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70 + return arc4random_stir(); |
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71 +} |
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72 + |
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73 +/* implementation taken from openbsd-compat/arc4random.c */ |
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74 +uint32_t |
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75 +fips_arc4random_uniform(uint32_t upper_bound) |
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76 +{ |
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77 + uint32_t r, min; |
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78 + |
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79 + if (upper_bound < 2) |
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80 + return 0; |
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81 + |
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82 + /* 2**32 % x == (2**32 - x) % x */ |
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83 + min = -upper_bound % upper_bound; |
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84 + |
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85 + /* |
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86 + * This could theoretically loop forever but each retry has |
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87 + * p > 0.5 (worst case, usually far better) of selecting a |
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88 + * number inside the range we need, so it should rarely need |
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89 + * to re-roll. |
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90 + */ |
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91 + for (;;) { |
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92 + r = fips_arc4random_impl(); |
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93 + if (r >= min) |
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94 + break; |
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95 + } |
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96 + |
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97 + return r % upper_bound; |
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98 +} |
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99 +#endif /* ENABLE_OPENSSL_FIPS */ |
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100 diff -pur old/misc.h new/misc.h |
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101 --- old/misc.h |
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102 +++ new/misc.h |
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103 @@ -140,4 +140,16 @@ char *read_passphrase(const char *, int) |
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104 int ask_permission(const char *, ...) __attribute__((format(printf, 1, 2))); |
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105 int read_keyfile_line(FILE *, const char *, char *, size_t, u_long *); |
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106 |
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107 +#ifdef ENABLE_OPENSSL_FIPS |
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108 +/* arc4random* FIPS alternatives */ |
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109 +uint32_t fips_arc4random(void); |
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110 +void fips_arc4random_buf(void *, size_t); |
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111 +void fips_arc4random_stir(void); |
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112 +uint32_t fips_arc4random_uniform(uint32_t upper_bound); |
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113 +#define arc4random fips_arc4random |
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114 +#define arc4random_buf fips_arc4random_buf |
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115 +#define arc4random_stir fips_arc4random_stir |
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116 +#define arc4random_uniform fips_arc4random_uniform |
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117 +#endif /* ENABLE_OPENSSL_FIPS */ |
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118 + |
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119 #endif /* _MISC_H */ |
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