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shared: add random-util.[ch]

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This commit is contained in:
Ronny Chevalier
2015-04-11 00:11:13 +02:00
parent 0b452006de
commit 3df3e884ae
24 changed files with 188 additions and 111 deletions
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src/shared/ask-password-api.c
+1
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@@ -35,6 +35,7 @@
#include "formats-util.h"
#include "mkdir.h"
#include "strv.h"
#include "random-util.h"
#include "ask-password-api.h"
src/shared/hashmap.c
+1
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@@ -30,6 +30,7 @@
#include "siphash24.h"
#include "strv.h"
#include "mempool.h"
#include "random-util.h"
#ifdef ENABLE_DEBUG_HASHMAP
#include "list.h"
src/shared/random-util.c
+127
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@@ -0,0 +1,127 @@
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdint.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <time.h>
#include <sys/auxv.h>
#include <linux/random.h>
#include "random-util.h"
#include "time-util.h"
#include "missing.h"
#include "util.h"
int dev_urandom(void *p, size_t n) {
static int have_syscall = -1;
_cleanup_close_ int fd = -1;
int r;
/* Gathers some randomness from the kernel. This call will
* never block, and will always return some data from the
* kernel, regardless if the random pool is fully initialized
* or not. It thus makes no guarantee for the quality of the
* returned entropy, but is good enough for or usual usecases
* of seeding the hash functions for hashtable */
/* Use the getrandom() syscall unless we know we don't have
* it, or when the requested size is too large for it. */
if (have_syscall != 0 || (size_t) (int) n != n) {
r = getrandom(p, n, GRND_NONBLOCK);
if (r == (int) n) {
have_syscall = true;
return 0;
}
if (r < 0) {
if (errno == ENOSYS)
/* we lack the syscall, continue with
* reading from /dev/urandom */
have_syscall = false;
else if (errno == EAGAIN)
/* not enough entropy for now. Let's
* remember to use the syscall the
* next time, again, but also read
* from /dev/urandom for now, which
* doesn't care about the current
* amount of entropy. */
have_syscall = true;
else
return -errno;
} else
/* too short read? */
return -ENODATA;
}
fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0)
return errno == ENOENT ? -ENOSYS : -errno;
return loop_read_exact(fd, p, n, true);
}
void initialize_srand(void) {
static bool srand_called = false;
unsigned x;
#ifdef HAVE_SYS_AUXV_H
void *auxv;
#endif
if (srand_called)
return;
x = 0;
#ifdef HAVE_SYS_AUXV_H
/* The kernel provides us with a bit of entropy in auxv, so
* let's try to make use of that to seed the pseudo-random
* generator. It's better than nothing... */
auxv = (void*) getauxval(AT_RANDOM);
if (auxv)
x ^= *(unsigned*) auxv;
#endif
x ^= (unsigned) now(CLOCK_REALTIME);
x ^= (unsigned) gettid();
srand(x);
srand_called = true;
}
void random_bytes(void *p, size_t n) {
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. */
initialize_srand();
for (q = p; q < (uint8_t*) p + n; q ++)
*q = rand();
}
src/shared/random-util.h
+38
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@@ -0,0 +1,38 @@
#pragma once
/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <stdint.h>
int dev_urandom(void *p, size_t n);
void random_bytes(void *p, size_t n);
void initialize_srand(void);
static inline uint64_t random_u64(void) {
uint64_t u;
random_bytes(&u, sizeof(u));
return u;
}
static inline uint32_t random_u32(void) {
uint32_t u;
random_bytes(&u, sizeof(u));
return u;
}
src/shared/util.c
+1 -95
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@@ -94,6 +94,7 @@
#include "sparse-endian.h"
#include "formats-util.h"
#include "process-util.h"
#include "random-util.h"
/* Put this test here for a lack of better place */
assert_cc(EAGAIN == EWOULDBLOCK);
@@ -2387,101 +2388,6 @@ char* dirname_malloc(const char *path) {
return dir;
}
int dev_urandom(void *p, size_t n) {
static int have_syscall = -1;
_cleanup_close_ int fd = -1;
int r;
/* Gathers some randomness from the kernel. This call will
* never block, and will always return some data from the
* kernel, regardless if the random pool is fully initialized
* or not. It thus makes no guarantee for the quality of the
* returned entropy, but is good enough for or usual usecases
* of seeding the hash functions for hashtable */
/* Use the getrandom() syscall unless we know we don't have
* it, or when the requested size is too large for it. */
if (have_syscall != 0 || (size_t) (int) n != n) {
r = getrandom(p, n, GRND_NONBLOCK);
if (r == (int) n) {
have_syscall = true;
return 0;
}
if (r < 0) {
if (errno == ENOSYS)
/* we lack the syscall, continue with
* reading from /dev/urandom */
have_syscall = false;
else if (errno == EAGAIN)
/* not enough entropy for now. Let's
* remember to use the syscall the
* next time, again, but also read
* from /dev/urandom for now, which
* doesn't care about the current
* amount of entropy. */
have_syscall = true;
else
return -errno;
} else
/* too short read? */
return -ENODATA;
}
fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY);
if (fd < 0)
return errno == ENOENT ? -ENOSYS : -errno;
return loop_read_exact(fd, p, n, true);
}
void initialize_srand(void) {
static bool srand_called = false;
unsigned x;
#ifdef HAVE_SYS_AUXV_H
void *auxv;
#endif
if (srand_called)
return;
x = 0;
#ifdef HAVE_SYS_AUXV_H
/* The kernel provides us with a bit of entropy in auxv, so
* let's try to make use of that to seed the pseudo-random
* generator. It's better than nothing... */
auxv = (void*) getauxval(AT_RANDOM);
if (auxv)
x ^= *(unsigned*) auxv;
#endif
x ^= (unsigned) now(CLOCK_REALTIME);
x ^= (unsigned) gettid();
srand(x);
srand_called = true;
}
void random_bytes(void *p, size_t n) {
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. */
initialize_srand();
for (q = p; q < (uint8_t*) p + n; q ++)
*q = rand();
}
void rename_process(const char name[8]) {
assert(name);
src/shared/util.h
-16
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@@ -283,22 +283,6 @@ int make_stdio(int fd);
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);
void initialize_srand(void);
static inline uint64_t random_u64(void) {
uint64_t u;
random_bytes(&u, sizeof(u));
return u;
}
static inline uint32_t random_u32(void) {
uint32_t u;
random_bytes(&u, sizeof(u));
return u;
}
/* For basic lookup tables with strictly enumerated entries */
#define _DEFINE_STRING_TABLE_LOOKUP_TO_STRING(name,type,scope) \
scope const char *name##_to_string(type i) { \