systemd/use-rndaddentropy-ioctl-to-load-random-seed.patch

156 lines
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Simply writing /var/lib/systemd/random-seed back to /dev/(u)random does not
increase the entropy bit count. Therefore use the RNDADDENTROPY ioctl to
write back the bytes and increase the entropy bit counter.
Related to bnc#892096
---
systemd-210/src/random-seed/random-seed.c | 73 +++++++++++++++++++++++++-----
1 file changed, 62 insertions(+), 11 deletions(-)
--- systemd-210/src/random-seed/random-seed.c
+++ systemd-210/src/random-seed/random-seed.c 2015-04-14 11:38:08.617519434 +0000
@@ -22,7 +22,9 @@
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
+#include <linux/random.h>
#include <string.h>
+#include <sys/ioctl.h>
#include <sys/stat.h>
#include "log.h"
@@ -32,8 +34,8 @@
#define POOL_SIZE_MIN 512
int main(int argc, char *argv[]) {
- _cleanup_close_ int seed_fd = -1, random_fd = -1;
- _cleanup_free_ void* buf = NULL;
+ _cleanup_close_ int seed_fd = -1, random_fd = -1, entropy_fd = -1;
+ _cleanup_free_ struct rand_pool_info *entropy = NULL;
size_t buf_size = 0;
ssize_t k;
int r;
@@ -64,11 +66,12 @@ int main(int argc, char *argv[]) {
if (buf_size <= POOL_SIZE_MIN)
buf_size = POOL_SIZE_MIN;
- buf = malloc(buf_size);
- if (!buf) {
+ entropy = (struct rand_pool_info*) malloc(sizeof(struct rand_pool_info) + buf_size);
+ if (!entropy) {
r = log_oom();
goto finish;
}
+ entropy->buf_size = buf_size;
r = mkdir_parents_label(RANDOM_SEED, 0755);
if (r < 0) {
@@ -82,6 +85,23 @@ int main(int argc, char *argv[]) {
if (streq(argv[1], "load")) {
+ entropy_fd = open(RANDOM_SEED_DIR "entropy_count", O_RDONLY|O_CLOEXEC|O_NOCTTY, 0600);
+ if (entropy_fd < 0) {
+ entropy->entropy_count = 0;
+ if (errno != ENOENT) {
+ log_error("Failed to open " RANDOM_SEED "/entropy_count: %m");
+ r = -errno;
+ goto finish;
+ }
+ } else {
+ r = read(entropy_fd, &entropy->entropy_count, sizeof(entropy->entropy_count));
+ if (r < 0) {
+ log_error("Failed to read entropy count file: %m");
+ r = -errno;
+ goto finish;
+ }
+ }
+
seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
if (seed_fd < 0) {
seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY);
@@ -102,7 +122,7 @@ int main(int argc, char *argv[]) {
}
}
- k = loop_read(seed_fd, buf, buf_size, false);
+ k = loop_read(seed_fd, entropy->buf, entropy->buf_size, false);
if (k <= 0) {
if (r != 0)
@@ -113,16 +133,32 @@ int main(int argc, char *argv[]) {
} else {
lseek(seed_fd, 0, SEEK_SET);
- k = loop_write(random_fd, buf, (size_t) k, false);
- if (k <= 0) {
- log_error("Failed to write seed to /dev/urandom: %s", r < 0 ? strerror(-r) : "short write");
+ if (entropy->entropy_count && (size_t) k == entropy->buf_size) {
+ r = ioctl(random_fd, RNDADDENTROPY, entropy);
+ if (r < 0) {
+ log_error("Failed to write seed to /dev/urandom: %m");
+ r = -errno;
+ }
+ } else {
+ k = loop_write(random_fd, entropy->buf, (size_t) k, false);
+ if (k <= 0) {
+ log_error("Failed to write seed to /dev/urandom: %s", r < 0 ? strerror(-r) : "short write");
- r = k == 0 ? -EIO : (int) k;
+ r = k == 0 ? -EIO : (int) k;
+ }
}
}
} else if (streq(argv[1], "save")) {
+ /* Read available entropy count, if possible */
+ f = fopen("/proc/sys/kernel/random/entropy_avail", "re");
+ if (f) {
+ if (fscanf(f, "%zu", &entropy->entropy_count) < 0)
+ entropy->entropy_count = 0;
+ fclose(f);
+ }
+
seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
if (seed_fd < 0) {
log_error("Failed to open " RANDOM_SEED ": %m");
@@ -137,6 +173,21 @@ int main(int argc, char *argv[]) {
goto finish;
}
+ if (entropy->entropy_count) {
+ entropy_fd = open(RANDOM_SEED_DIR "entropy_count", O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600);
+ if (seed_fd < 0) {
+ log_error("Failed to open " RANDOM_SEED_DIR "entropy_count: %m");
+ r = -errno;
+ goto finish;
+ }
+ r = write(entropy_fd, &entropy->entropy_count, sizeof(entropy->entropy_count));
+ if (r < 0) {
+ log_error("Failed to write entropy count file: %m");
+ r = -errno;
+ goto finish;
+ }
+ }
+
} else {
log_error("Unknown verb %s.", argv[1]);
r = -EINVAL;
@@ -149,12 +200,12 @@ int main(int argc, char *argv[]) {
fchmod(seed_fd, 0600);
fchown(seed_fd, 0, 0);
- k = loop_read(random_fd, buf, buf_size, false);
+ k = loop_read(random_fd, entropy->buf, entropy->buf_size, false);
if (k <= 0) {
log_error("Failed to read new seed from /dev/urandom: %s", r < 0 ? strerror(-r) : "EOF");
r = k == 0 ? -EIO : (int) k;
} else {
- r = loop_write(seed_fd, buf, (size_t) k, false);
+ r = loop_write(seed_fd, entropy->buf, (size_t) k, false);
if (r <= 0) {
log_error("Failed to write new random seed file: %s", r < 0 ? strerror(-r) : "short write");
r = r == 0 ? -EIO : r;