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     close(fd);
  39
  40     return 1;
  41 }
  42
  43 /*
  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.
  48  */
  49
  50 void noise_get_heavy(void (*func) (void *, int))
  51 {
  52     char buf[512];
  53     FILE *fp;
  54     int ret;
  55     int got_dev_urandom = 0;
  56
  57     if (read_dev_urandom(buf, 32)) {
  58         got_dev_urandom = 1;
  59         func(buf, 32);
  60     }
  61
  62     fp = popen("ps -axu 2>/dev/null", "r");
  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     }
  72
  73     fp = popen("ls -al /tmp 2>/dev/null", "r");
  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     }
  83
  84     read_random_seed(func);
  85     random_save_seed();
  86 }
  87
  88 void random_save_seed(void)
  89 {
  90     int len;
  91     void *data;
  92
  93     if (random_active) {
  94         random_get_savedata(&data, &len);
  95         write_random_seed(data, len);
  96         sfree(data);
  97     }
  98 }
  99
 100 /*
 101  * This function is called every time the random pool needs
 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 /*
 112  * This function is called on a timer, and grabs as much changeable
 113  * system data as it can quickly get its hands on.
 114  */
 115 void noise_regular(void)
 116 {
 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));
 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 }