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1 | /* |
2 | * Noise generation for PuTTY's cryptographic random number |
3 | * generator. |
4 | */ |
5 | |
6 | #include <stdio.h> |
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7 | #include <stdlib.h> |
8 | #include <errno.h> |
9 | |
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10 | #include <fcntl.h> |
11 | #include <unistd.h> |
12 | #include <sys/time.h> |
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13 | #include <sys/resource.h> |
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14 | |
15 | #include "putty.h" |
16 | #include "ssh.h" |
17 | #include "storage.h" |
18 | |
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19 | static int read_dev_urandom(char *buf, int len) |
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20 | { |
21 | int fd; |
22 | int ngot, ret; |
23 | |
24 | fd = open("/dev/urandom", O_RDONLY); |
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25 | if (fd < 0) |
26 | return 0; |
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27 | |
28 | ngot = 0; |
29 | while (ngot < len) { |
30 | ret = read(fd, buf+ngot, len-ngot); |
31 | if (ret < 0) { |
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32 | close(fd); |
33 | return 0; |
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34 | } |
35 | ngot += ret; |
36 | } |
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37 | |
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38 | close(fd); |
39 | |
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40 | return 1; |
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41 | } |
42 | |
43 | /* |
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44 | * This function is called once, at PuTTY startup. It will do some |
45 | * slightly silly things such as fetching an entire process listing |
46 | * and scanning /tmp, load the saved random seed from disk, and |
47 | * also read 32 bytes out of /dev/urandom. |
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48 | */ |
49 | |
50 | void noise_get_heavy(void (*func) (void *, int)) |
51 | { |
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52 | char buf[512]; |
53 | FILE *fp; |
54 | int ret; |
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55 | int got_dev_urandom = 0; |
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56 | |
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57 | if (read_dev_urandom(buf, 32)) { |
58 | got_dev_urandom = 1; |
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59 | func(buf, 32); |
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60 | } |
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61 | |
62 | fp = popen("ps -axu 2>/dev/null", "r"); |
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63 | if (fp) { |
64 | while ( (ret = fread(buf, 1, sizeof(buf), fp)) > 0) |
65 | func(buf, ret); |
66 | pclose(fp); |
67 | } else if (!got_dev_urandom) { |
68 | fprintf(stderr, "popen: %s\n" |
69 | "Unable to access fallback entropy source\n", strerror(errno)); |
70 | exit(1); |
71 | } |
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72 | |
73 | fp = popen("ls -al /tmp 2>/dev/null", "r"); |
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74 | if (fp) { |
75 | while ( (ret = fread(buf, 1, sizeof(buf), fp)) > 0) |
76 | func(buf, ret); |
77 | pclose(fp); |
78 | } else if (!got_dev_urandom) { |
79 | fprintf(stderr, "popen: %s\n" |
80 | "Unable to access fallback entropy source\n", strerror(errno)); |
81 | exit(1); |
82 | } |
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83 | |
84 | read_random_seed(func); |
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85 | random_save_seed(); |
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86 | } |
87 | |
88 | void random_save_seed(void) |
89 | { |
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90 | int len; |
91 | void *data; |
92 | |
93 | if (random_active) { |
94 | random_get_savedata(&data, &len); |
95 | write_random_seed(data, len); |
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96 | sfree(data); |
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97 | } |
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98 | } |
99 | |
100 | /* |
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101 | * This function is called every time the random pool needs |
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102 | * stirring, and will acquire the system time. |
103 | */ |
104 | void noise_get_light(void (*func) (void *, int)) |
105 | { |
106 | struct timeval tv; |
107 | gettimeofday(&tv, NULL); |
108 | func(&tv, sizeof(tv)); |
109 | } |
110 | |
111 | /* |
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112 | * This function is called on a timer, and grabs as much changeable |
113 | * system data as it can quickly get its hands on. |
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114 | */ |
115 | void noise_regular(void) |
116 | { |
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117 | int fd; |
118 | int ret; |
119 | char buf[512]; |
120 | struct rusage rusage; |
121 | |
122 | if ((fd = open("/proc/meminfo", O_RDONLY)) >= 0) { |
123 | while ( (ret = read(fd, buf, sizeof(buf))) > 0) |
124 | random_add_noise(buf, ret); |
125 | close(fd); |
126 | } |
127 | if ((fd = open("/proc/stat", O_RDONLY)) >= 0) { |
128 | while ( (ret = read(fd, buf, sizeof(buf))) > 0) |
129 | random_add_noise(buf, ret); |
130 | close(fd); |
131 | } |
132 | getrusage(RUSAGE_SELF, &rusage); |
133 | random_add_noise(&rusage, sizeof(rusage)); |
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134 | } |
135 | |
136 | /* |
137 | * This function is called on every keypress or mouse move, and |
138 | * will add the current time to the noise pool. It gets the scan |
139 | * code or mouse position passed in, and adds that too. |
140 | */ |
141 | void noise_ultralight(unsigned long data) |
142 | { |
143 | struct timeval tv; |
144 | gettimeofday(&tv, NULL); |
145 | random_add_noise(&tv, sizeof(tv)); |
146 | random_add_noise(&data, sizeof(data)); |
147 | } |