util: introduce new dev_urandom() call that is like random_bytes() but doesn't fall...

diff --git a/src/shared/util.c b/src/shared/util.c
index 945f1525a266d73e70b4b188d3aac2da0bf27792..f452431c6701a2ea56398de2c62116d7b513475b 100644 (file)
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2255,25 +2255,37 @@ char* dirname_malloc(const char *path) {
         return dir;
 }
 
         return dir;
 }
 

-void random_bytes(void *p, size_t n) {
-        static bool srand_called = false;
+int dev_urandom(void *p, size_t n) {

         _cleanup_close_ int fd;
         ssize_t k;
         _cleanup_close_ int fd;
         ssize_t k;

-        uint8_t *q;

 
         fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
         if (fd < 0)
 
         fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
         if (fd < 0)

-                goto fallback;
+                return errno == ENOENT ? -ENOSYS : -errno;

 
         k = loop_read(fd, p, n, true);
 
         k = loop_read(fd, p, n, true);

-        if (k < 0 || (size_t) k != n)
-                goto fallback;
+        if (k < 0)
+                return (int) k;
+        if ((size_t) k != n)
+                return -EIO;

 
 

-        return;
+        return 0;
+}

 
 

-fallback:
+void random_bytes(void *p, size_t n) {
+        static bool srand_called = false;
+        uint8_t *q;
+        int r;
+
+        r = dev_urandom(p, n);
+        if (r >= 0)
+                return;
+
+        /* If some idiot made /dev/urandom unavailable to us, he'll
+         * get a PRNG instead. */

 
         if (!srand_called) {
 
         if (!srand_called) {

+                unsigned x = 0;

 
 #ifdef HAVE_SYS_AUXV_H
                 /* The kernel provides us with a bit of entropy in
 
 #ifdef HAVE_SYS_AUXV_H
                 /* The kernel provides us with a bit of entropy in


@@ -2285,16 +2297,16 @@ fallback:
 
                 auxv = (void*) getauxval(AT_RANDOM);
                 if (auxv)
 
                 auxv = (void*) getauxval(AT_RANDOM);
                 if (auxv)

-                        srand(*(unsigned*) auxv);
-                else
+                        x ^= *(unsigned*) auxv;

 #endif
 #endif

-                        srand(time(NULL) + gettid());

 
 

+                x ^= (unsigned) now(CLOCK_REALTIME);
+                x ^= (unsigned) gettid();
+
+                srand(x);

                 srand_called = true;
         }
 
                 srand_called = true;
         }
 

-        /* If some idiot made /dev/urandom unavailable to us, he'll
-         * get a PRNG instead. */

         for (q = p; q < (uint8_t*) p + n; q ++)
                 *q = rand();
 }
         for (q = p; q < (uint8_t*) p + n; q ++)
                 *q = rand();
 }

diff --git a/src/shared/util.h b/src/shared/util.h
index 1169864c3a5853f0d301855253616d0cd346fac9..117855de819933fc173e6e9d9e7073ea00bb8501 100644 (file)
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -272,6 +272,7 @@ int make_stdio(int fd);
 int make_null_stdio(void);
 int make_console_stdio(void);
 
 int make_null_stdio(void);
 int make_console_stdio(void);
 

+int dev_urandom(void *p, size_t n);

 void random_bytes(void *p, size_t n);
 
 static inline uint64_t random_u64(void) {
 void random_bytes(void *p, size_t n);
 
 static inline uint64_t random_u64(void) {