git.distorted.org.uk Git - u/mdw/putty/blob - unix/uxnoise.c

   1 /*
   2  * Noise generation for PuTTY's cryptographic random number
   3  * generator.
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <errno.h>
   9
  10 #include <fcntl.h>
  11 #include <unistd.h>
  12 #include <sys/time.h>
  13 #include <sys/resource.h>
  14
  15 #include "putty.h"
  16 #include "ssh.h"
  17 #include "storage.h"
  18
  19 static int read_dev_urandom(char *buf, int len)
  20 {
  21     int fd;
  22     int ngot, ret;
  23
  24     fd = open("/dev/urandom", O_RDONLY);
  25     if (fd < 0)
  26         return 0;
  27
  28     ngot = 0;
  29     while (ngot < len) {
  30         ret = read(fd, buf+ngot, len-ngot);
  31         if (ret < 0) {
  32             close(fd);
  33             return 0;
  34         }
  35         ngot += ret;
  36     }
  37
  38     return 1;
  39 }
  40
  41 /*
  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.
  46  */
  47
  48 void noise_get_heavy(void (*func) (void *, int))
  49 {
  50     char buf[512];
  51     FILE *fp;
  52     int ret;
  53     int got_dev_urandom = 0;
  54
  55     if (read_dev_urandom(buf, 32)) {
  56         got_dev_urandom = 1;
  57         func(buf, 32);
  58     }
  59
  60     fp = popen("ps -axu 2>/dev/null", "r");
  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     }
  70
  71     fp = popen("ls -al /tmp 2>/dev/null", "r");
  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     }
  81
  82     read_random_seed(func);
  83     random_save_seed();
  84 }
  85
  86 void random_save_seed(void)
  87 {
  88     int len;
  89     void *data;
  90
  91     if (random_active) {
  92         random_get_savedata(&data, &len);
  93         write_random_seed(data, len);
  94         sfree(data);
  95     }
  96 }
  97
  98 /*
  99  * This function is called every time the random pool needs
 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 /*
 110  * This function is called on a timer, and grabs as much changeable
 111  * system data as it can quickly get its hands on.
 112  */
 113 void noise_regular(void)
 114 {
 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));
 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 }