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