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Using /dev/urandom for our random source

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This commit is contained in:
Nicolas Viennot 2013-06-22 01:00:47 -04:00
parent 761d68bfff
commit d02e97c206
2 changed files with 27 additions and 2 deletions
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26
tmate-slave.c
View File

@ -13,6 +13,8 @@
#include <ncurses.h> #include <ncurses.h>
#endif #endif
#include <term.h> #include <term.h>
#include <time.h>
#include <fcntl.h>
#include "tmate.h" #include "tmate.h"
struct tmate_encoder *tmate_encoder; struct tmate_encoder *tmate_encoder;
@ -22,6 +24,7 @@ const char *tmate_session_token = "main";
static char *log_path; /* NULL means stderr */ static char *log_path; /* NULL means stderr */
static char *cmdline; static char *cmdline;
static char *cmdline_end; static char *cmdline_end;
static int dev_urandom_fd;
extern FILE *log_file; extern FILE *log_file;
extern int server_create_socket(void); extern int server_create_socket(void);
@ -37,6 +40,19 @@ void tmate_reopen_logfile(void)
log_open(debug_level, log_path); log_open(debug_level, log_path);
} }
void tmate_get_random_bytes(void *buffer, ssize_t len)
{
if (read(dev_urandom_fd, buffer, len) != len)
tmate_fatal("Cannot read from /dev/urandom");
}
long tmate_get_random_long(void)
{
long val;
tmate_get_random_bytes(&val, sizeof(val));
return val;
}
int main(int argc, char **argv, char **envp) int main(int argc, char **argv, char **envp)
{ {
int opt; int opt;
@ -68,6 +84,9 @@ int main(int argc, char **argv, char **envp)
tmate_reopen_logfile(); tmate_reopen_logfile();
if ((dev_urandom_fd = open("/dev/urandom", O_RDONLY)) < 0)
tmate_fatal("Cannot open /dev/urandom");
if ((mkdir(TMATE_WORKDIR, 0700) < 0 && errno != EEXIST) || if ((mkdir(TMATE_WORKDIR, 0700) < 0 && errno != EEXIST) ||
(mkdir(TMATE_WORKDIR "/sessions", 0700) < 0 && errno != EEXIST) || (mkdir(TMATE_WORKDIR "/sessions", 0700) < 0 && errno != EEXIST) ||
(mkdir(TMATE_WORKDIR "/jail", 0700) < 0 && errno != EEXIST)) (mkdir(TMATE_WORKDIR "/jail", 0700) < 0 && errno != EEXIST))
@ -102,7 +121,7 @@ static char *get_random_token(void)
int i; int i;
char *token = xmalloc(TMATE_TOKEN_LEN + 1); char *token = xmalloc(TMATE_TOKEN_LEN + 1);
ssh_get_random(token, TMATE_TOKEN_LEN, 0); tmate_get_random_bytes(token, TMATE_TOKEN_LEN);
for (i = 0; i < TMATE_TOKEN_LEN; i++) for (i = 0; i < TMATE_TOKEN_LEN; i++)
token[i] = tmate_token_digits[token[i] % NUM_DIGITS]; token[i] = tmate_token_digits[token[i] % NUM_DIGITS];
token[i] = 0; token[i] = 0;
@ -132,7 +151,10 @@ static int validate_token(const char *token)
static void random_sleep(void) static void random_sleep(void)
{ {
usleep(50000 + (rand() % 50000)); struct timespec ts;
ts.tv_sec = 0;
ts.tv_nsec = 50000000 + (tmate_get_random_long() % 150000000);
nanosleep(&ts, NULL);
} }
static void ssh_echo(struct tmate_ssh_client *ssh_client, static void ssh_echo(struct tmate_ssh_client *ssh_client,

3
tmate.h
View File

@ -137,6 +137,9 @@ extern struct tmate_encoder *tmate_encoder;
extern int tmux_socket_fd; extern int tmux_socket_fd;
extern const char *tmate_session_token; extern const char *tmate_session_token;
extern void tmate_get_random_bytes(void *buffer, ssize_t len);
extern long tmate_get_random_long(void);
extern void tmate_reopen_logfile(void); extern void tmate_reopen_logfile(void);
extern void tmate_spawn_slave(struct tmate_ssh_client *client); extern void tmate_spawn_slave(struct tmate_ssh_client *client);