px5g-mbedtls: Use getrandom()

Instead of accessing /dev/urandom use the getrandom syscall. This way we
do not have to keep the file open all the time.
This also fixes a compile error with glibc:

--------
px5g-mbedtls.c: In function '_urandom':
px5g-mbedtls.c:48:9: error: ignoring return value of 'read' declared with attribute 'warn_unused_result' [-Werror=unused-result]
   48 |         read(urandom_fd, out, len);
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
--------

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

diff --git a/package/utils/px5g-mbedtls/px5g-mbedtls.c b/package/utils/px5g-mbedtls/px5g-mbedtls.c
index 0b72154509a8c84577a877f6b13e4243b3dc58d1..4e0a73ab0a7034ba5f217b65bcffa58d76140688 100644 (file)
--- a/package/utils/px5g-mbedtls/px5g-mbedtls.c
+++ b/package/utils/px5g-mbedtls/px5g-mbedtls.c
@@ -20,6 +20,7 @@
  */
 
 #include <sys/types.h>
+#include <sys/random.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -31,6 +32,7 @@
 #include <stdbool.h>
 
 #include <mbedtls/bignum.h>
+#include <mbedtls/entropy.h>
 #include <mbedtls/x509_crt.h>
 #include <mbedtls/ecp.h>
 #include <mbedtls/rsa.h>
@@ -40,12 +42,16 @@
 #define PX5G_COPY "Copyright (c) 2009 Steven Barth <steven@midlink.org>"
 #define PX5G_LICENSE "Licensed under the GNU Lesser General Public License v2.1"
 
-static int urandom_fd;
 static char buf[16384];
 
 static int _urandom(void *ctx, unsigned char *out, size_t len)
 {
-       read(urandom_fd, out, len);
+       ssize_t ret;
+
+       ret = getrandom(out, len, 0);
+       if (ret < 0 || (size_t)ret != len)
+               return MBEDTLS_ERR_ENTROPY_SOURCE_FAILED;
+
        return 0;
 }
 
@@ -306,8 +312,6 @@ int selfsigned(char **arg)
 
 int main(int argc, char *argv[])
 {
-       urandom_fd = open("/dev/urandom", O_RDONLY);
-
        if (!argv[1]) {
                //Usage
        } else if (!strcmp(argv[1], "eckey")) {