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rngd.c
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rngd.c
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/*
* rngd.c -- Random Number Generator daemon
*
* rngd reads data from a hardware random number generator, verifies it
* looks like random data, and adds it to /dev/random's entropy store.
*
* In theory, this should allow you to read very quickly from
* /dev/random; rngd also adds bytes to the entropy store periodically
* when it's full, which makes predicting the entropy store's contents
* harder.
*
* Copyright (C) 2001 Philipp Rumpf
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*/
#define _GNU_SOURCE
#ifndef HAVE_CONFIG_H
#error Invalid or missing autoconf build environment
#endif
#include "rng-tools-config.h"
#include <unistd.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/capability.h>
#include <sys/prctl.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <argp.h>
#include <syslog.h>
#include <signal.h>
#include <limits.h>
#include <ctype.h>
#include <time.h>
#include <pwd.h>
#include <grp.h>
#include <sched.h>
#include "rngd.h"
#include "fips.h"
#include "exits.h"
#include "rngd_entsource.h"
#include "rngd_linux.h"
/*
* Globals
*/
int kent_pool_size;
/* Background/daemon mode */
bool am_daemon = false; /* True if we went daemon */
bool msg_squash = false; /* True if we want no messages on the console */
bool quiet = false; /* True if we want no console output at all */
volatile bool server_running = true; /* set to false, to stop daemon */
bool do_reseed = false; /* force a reseed event */
bool ignorefail = false; /* true if we ignore MAX_RNG_FAILURES */
/* Command line arguments and processing */
const char *rngd_program_version =
"rngd " VERSION "\n"
"Copyright 2001-2004 Jeff Garzik\n"
"Copyright 2017 Neil Horman\n"
"Copyright (c) 2001 by Philipp Rumpf\n"
"This is free software; see the source for copying conditions. There is NO "
"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.";
const char *argp_program_bug_address = PACKAGE_BUGREPORT;
static char doc[] =
"Check and feed random data from hardware device to kernel entropy pool.\n";
static struct argp_option options[] = {
{ "debug", 'd', 0, 0, "Enable debug output" },
{ "foreground", 'f', 0, 0, "Do not fork and become a daemon" },
{ "ignorefail", 'i', 0, 0, "Ignore repeated fips failures" },
{ "background", 'b', 0, 0, "Become a daemon (default)" },
{ "exclude", 'x', "n", 0, "Disable the numbered entropy source specified" },
{ "include", 'n', "n", 0, "Enable the numbered entropy source specified" },
{ "list", 'l', 0, 0, "List the operational entropy sources on this system and exit" },
{ "option", 'O', "options", 0, "rng specific options in the form source:key:value"},
{ "random-device", 'o', "file", 0,
"Kernel device used for random number output (default: /dev/random)" },
{ "rng-device", 'r', "file", 0,
"Kernel device used for random number input (default: /dev/hwrng)" },
{ "test", 't', 0, 0, "Enter test mode and report entropy production rates" },
{ "pid-file", 'p', "file", 0,
"File used for recording daemon PID, and multiple exclusion (default: /var/run/rngd.pid)" },
{ "random-step", 's', "nnn", 0,
"Number of bytes written to random-device at a time (default: 64)" },
{ "fill-watermark", 'W', "n", 0,
"Do not stop feeding entropy to random-device until at least n bits of entropy are available in the pool (default: 3/4 of poolsize), 0 <= n <= 256" },
{ "quiet", 'q', 0, 0, "Suppress all messages" },
{ "version" ,'v', 0, 0, "List rngd version" },
{ "entropy-count", 'e', "n", 0, "Number of entropy bits to support (default: 8), 1 <= n <= 8" },
{ "force-reseed", 'R', "n", 0, "Time in seconds to force adding entropy to the random device" },
{ "use-slow-sources", 'u', 0, 0, "Always gather entropy from sources considered as \"slow\" too" },
{ "drop-privileges", 'D', "user:group", 0, "Drop privileges to a user and group specified" },
{ 0 },
};
static struct arguments default_arguments = {
.random_name = "/dev/random",
.pid_file = "/var/run/rngd.pid",
.random_step = 64,
.fill_watermark = -1,
.daemon = true,
.test = false,
.list = false,
.ignorefail = false,
.entropy_count = 8,
.force_reseed = 60 * 5,
.use_slow_sources = false,
.drop_privs = false,
};
struct arguments *arguments = &default_arguments;
static unsigned long ent_gathered = 0;
static unsigned long test_iterations = 0;
static double sum_entropy = 0;
static struct timespec start_test, end_test;
static bool test_running = false;
static enum {
ENT_HWRNG = 0,
ENT_TPM = 1,
ENT_RDRAND,
ENT_DARN,
ENT_RNDR,
ENT_NISTBEACON,
ENT_JITTER,
ENT_PKCS11,
ENT_RTLSDR,
ENT_QRYPT,
ENT_NAMEDPIPE,
ENT_MAX
} entropy_indexes __attribute__((used));
static struct rng_option drng_options[] = {
[DRNG_OPT_AES] = {
.key = "use_aes",
.type = VAL_INT,
.int_val = 0,
},
{
.key = NULL,
},
};
static struct rng_option darn_options[] = {
[DARN_OPT_AES] = {
.key = "use_aes",
.type = VAL_INT,
.int_val = 1,
},
{
.key = NULL,
}
};
static struct rng_option jitter_options[] = {
[JITTER_OPT_THREADS] = {
.key = "thread_count",
.type = VAL_INT,
.int_val = 4,
},
[JITTER_OPT_BUF_SZ] = {
.key = "buffer_size",
.type = VAL_INT,
.int_val = 16535,
},
[JITTER_OPT_REFILL] = {
.key = "refill_thresh",
.type = VAL_INT,
.int_val = 16535,
},
[JITTER_OPT_RETRY_COUNT] = {
.key = "retry_count",
.type = VAL_INT,
.int_val = 1,
},
[JITTER_OPT_RETRY_DELAY] = {
.key = "retry_delay",
.type = VAL_INT,
.int_val = -1,
},
[JITTER_OPT_USE_AES] = {
.key = "use_aes",
.type = VAL_INT,
.int_val = 1,
},
[JITTER_OPT_FORCE_INT_TIMER] = {
.key = "force_soft_timer",
.type = VAL_INT,
.int_val = 0,
},
[JITTER_OPT_TIMEOUT] = {
.key = "timeout",
.type = VAL_INT,
.int_val = 5,
},
{
.key = NULL,
}
};
#ifndef DEFAULT_PKCS11_ENGINE
#define DEFAULT_PKCS11_ENGINE "/usr/lib64/opensc-pkcs11.so"
#endif
static struct rng_option pkcs11_options[] = {
[PKCS11_OPT_ENGINE] = {
.key = "engine_path",
.type = VAL_STRING,
.str_val = DEFAULT_PKCS11_ENGINE,
},
[PKCS11_OPT_CHUNK] = {
.key = "chunk_size",
.type = VAL_INT,
.int_val = 1,
},
{
.key = NULL,
}
};
static struct rng_option nist_options[] = {
[NIST_OPT_USE_AES] = {
.key = "use_aes",
.type = VAL_INT,
.int_val = 1,
},
{
.key = NULL,
}
};
static struct rng_option rtlsdr_options[] = {
[RTLSDR_OPT_DEVID] = {
.key = "device_id",
.type = VAL_INT,
.int_val = 0,
},
[RTLSDR_OPT_FREQ_MIN] = {
.key = "freq_min",
.type = VAL_INT,
.int_val = 90000000,
},
[RTLSDR_OPT_FREQ_MAX] = {
.key = "freq_max",
.type = VAL_INT,
.int_val = 110000000,
},
[RTLSDR_OPT_SRATE_MIN] = {
.key = "sample_min",
.type = VAL_INT,
.int_val = 1000000,
},
[RTLSDR_OPT_SRATE_MAX] = {
.key = "sample_max",
.type = VAL_INT,
.int_val = 2800000,
},
{
.key = NULL,
}
};
static struct rng_option qrypt_options[] = {
[QRYPT_OPT_TOKEN_FILE] = {
.key = "tokenfile",
.type = VAL_STRING,
.str_val = "/etc/qrypt.token",
},
[QRYPT_OPT_MAX_ERROR_DELAY] {
.key = "delay",
.type = VAL_INT,
.int_val = 28800, /* 8 hours */
},
{
.key = NULL,
}
};
static struct rng_option namedpipe_options[] = {
[NAMEDPIPE_OPT_PATH] = {
.key = "path",
.type = VAL_STRING,
.str_val = "",
},
[NAMEDPIPE_OPT_TIMEOUT] {
.key = "timeout",
.type = VAL_INT,
.int_val = 5, /* 5 seconds */
},
{
.key = NULL,
}
};
static struct rng entropy_sources[ENT_MAX] = {
/* Note, the special char dev must be the first entry */
{
.rng_name = "Hardware RNG Device",
.rng_sname = "hwrng",
.rng_fname = "/dev/hwrng",
.rng_fd = -1,
.flags = { 0 },
.xread = xread,
.init = init_entropy_source,
.rng_options = NULL,
},
/* must be at index 1 */
{
.rng_name = "TPM RNG Device",
.rng_sname = "tpm",
.rng_fname = "/dev/tpm0",
.rng_fd = -1,
.flags = { 0 },
.xread = xread_tpm,
.init = init_tpm_entropy_source,
.rng_options = NULL,
.disabled = true,
},
{
.rng_name = "Intel RDRAND Instruction RNG",
.rng_sname = "rdrand",
.rng_fd = -1,
.flags = { 0 },
#ifdef HAVE_RDRAND
.xread = xread_drng,
.init = init_drng_entropy_source,
#else
.disabled = true,
#endif
.rng_options = drng_options,
},
{
.rng_name = "Power9 DARN Instruction RNG",
.rng_sname = "darn",
.rng_fd = -1,
.flags = { 0 },
#ifdef HAVE_DARN
.xread = xread_darn,
.init = init_darn_entropy_source,
#else
.disabled = true,
#endif
.rng_options = darn_options,
},
{
.rng_name = "ARM v8.5 RNDR Instruction RNG",
.rng_sname = "rndr",
.rng_fd = -1,
.flags = { 0 },
#ifdef HAVE_RNDR
.xread = xread_rndr,
.init = init_rndr_entropy_source,
#else
.disabled = true,
#endif
.rng_options = drng_options,
},
{
.rng_name = "NIST Network Entropy Beacon",
.rng_sname = "nist",
.rng_fd = -1,
.flags = {
.slow_source = 1,
.intermittent_source = 1,
},
#ifdef HAVE_NISTBEACON
.xread = xread_nist,
.init = init_nist_entropy_source,
#endif
.disabled = true,
.rng_options = nist_options,
},
{
.rng_name = "JITTER Entropy generator",
.rng_sname = "jitter",
.rng_fd = -1,
.flags = {
.slow_source = 1,
},
#ifdef HAVE_JITTER
.xread = xread_jitter,
.init = init_jitter_entropy_source,
.close = close_jitter_entropy_source,
#else
.disabled = true,
#endif
.rng_options = jitter_options,
},
{
.rng_name = "PKCS11 Entropy generator",
.rng_sname = "pkcs11",
.rng_fd = -1,
.flags = {
.slow_source = 1,
},
#ifdef HAVE_PKCS11
.xread = xread_pkcs11,
.init = init_pkcs11_entropy_source,
.close = close_pkcs11_entropy_source,
#else
.disabled = true,
#endif
.rng_options = pkcs11_options,
},
{
.rng_name = "RTLSDR software defined radio generator",
.rng_sname = "rtlsdr",
.rng_fd = -1,
.flags = { 0 },
#ifdef HAVE_RTLSDR
.xread = xread_rtlsdr,
.init = init_rtlsdr_entropy_source,
.close = close_rtlsdr_entropy_source,
#else
.disabled = true,
#endif
.rng_options = rtlsdr_options,
},
{
.rng_name = "Qrypt quantum entropy beacon",
.rng_sname = "qrypt",
.rng_fd = -1,
.flags = {
.intermittent_source = 1,
},
#ifdef HAVE_QRYPT
.xread = xread_qrypt,
.init = init_qrypt_entropy_source,
.close = close_qrypt_entropy_source,
#endif
.disabled = true,
.rng_options = qrypt_options,
},
{
.rng_name = "Named pipe entropy input",
.rng_sname = "namedpipe",
.rng_fd = -1,
.flags = { 0 },
.xread = xread_namedpipe,
.init = init_namedpipe_entropy_source,
.rng_options = namedpipe_options,
}
};
static int find_ent_src_idx_by_sname(const char *sname)
{
int i;
for (i = 0; i < ENT_MAX; i++) {
if (!strncmp(sname, entropy_sources[i].rng_sname,
strlen(entropy_sources[i].rng_sname)))
return i;
}
return -1;
}
static int find_ent_src_idx(const char *name_idx)
{
int idx;
if (isalpha(name_idx[0])) {
idx = find_ent_src_idx_by_sname(name_idx);
if (idx == -1) {
message(LOG_CONS|LOG_WARNING, "Unknown entropy source %s\n", name_idx);
return -EINVAL;
}
} else {
idx = strtoul(name_idx, NULL, 10);
if ((idx == LONG_MAX) || (idx >= ENT_MAX)) {
message(LOG_CONS|LOG_INFO, "option index out of range: %d\n", idx);
return -ERANGE;
}
message(LOG_CONS|LOG_INFO, "Note, reference of entropy sources by index "
"is deprecated, use entropy source short name instead\n");
}
return idx;
}
/*
* command line processing
*/
static error_t parse_opt (int key, char *arg, struct argp_state *state)
{
char *optkey;
long int idx;
long int val;
char *strval;
bool restore = false;
char *search, *last_search;
struct rng_option *options;
switch(key) {
case 'd':
arguments->debug = true;
break;
case 'o':
arguments->random_name = arg;
break;
case 'O':
search = strchrnul(arg, ':');
if (*search != '\0') {
*search = '\0';
restore = true;
}
idx = find_ent_src_idx(arg);
if (idx < 0)
return idx;
if (restore == true)
*search = ':';
if (*search == '\0') {
message(LOG_CONS|LOG_INFO, "Available options for %s (%s)\n",
entropy_sources[idx].rng_name, entropy_sources[idx].rng_sname);
options = entropy_sources[idx].rng_options;
while (options && options->key) {
if (options->type == VAL_INT)
message(LOG_CONS|LOG_INFO, "key: [%s]\tdefault value: [%d]\n", options->key, options->int_val);
else
message(LOG_CONS|LOG_INFO, "key: [%s]\tdefault value: [%s]\n", options->key, options->str_val);
options++;
}
return -ERANGE;
}
last_search = search = search + 1;
search = strchr(search, ':');
if (!search) {
message(LOG_CONS|LOG_ERR, "Options tuple not specified correctly\n");
return -EINVAL;
}
*search = '\0';
optkey = strdupa(last_search);
*search = ':';
last_search = search + 1;
strval = last_search;
val = strtoul(last_search, NULL, 10);
if (val == LONG_MAX) {
message(LOG_CONS|LOG_INFO, "rng option was not parsable\n");
return -ERANGE;
}
options = entropy_sources[idx].rng_options;
while (options && options->key) {
if (!strcmp(optkey, options->key)) {
if (options->type == VAL_INT)
options->int_val = val;
else
options->str_val = strdup(strval);
return 0;
}
options++;
}
message(LOG_CONS|LOG_INFO, "Option %s not found for source idx %ld\n", optkey, idx);
return -ERANGE;
break;
case 'x':
idx = find_ent_src_idx(arg);
if (idx < 0)
return idx;
entropy_sources[idx].disabled = true;
message(LOG_CONS|LOG_INFO, "Disabling %ld: %s (%s)\n", idx,
entropy_sources[idx].rng_name, entropy_sources[idx].rng_sname);
break;
case 'n':
idx = find_ent_src_idx(arg);
if (idx < 0)
return idx;
entropy_sources[idx].disabled = false;
message(LOG_CONS|LOG_INFO, "Enabling %ld: %s (%s)\n", idx,
entropy_sources[idx].rng_name, entropy_sources[idx].rng_sname);
break;
case 'l':
arguments->list = true;
break;
case 'p':
arguments->pid_file = arg;
break;
case 'r':
entropy_sources[ENT_HWRNG].rng_fname = arg;
break;
case 'f':
arguments->daemon = false;
break;
case 't':
arguments->daemon = false;
arguments->test = true;
break;
case 'b':
arguments->daemon = true;
break;
case 'i':
arguments->ignorefail = true;
break;
case 's':
if (sscanf(arg, "%i", &arguments->random_step) == 0)
argp_usage(state);
if (arguments->random_step > FIPS_RNG_BUFFER_SIZE || arguments->random_step < 0)
arguments->random_step = FIPS_RNG_BUFFER_SIZE;
break;
case 'W': {
int n;
if ((sscanf(arg, "%i", &n) == 0) || (n < 0) || (n > 256))
argp_usage(state);
else
arguments->fill_watermark = n;
break;
}
case 'q':
quiet = true;
break;
case 'v':
message(LOG_CONS|LOG_INFO, "%s\n", rngd_program_version);
exit(0);
break;
case 'e': {
int e;
if ((sscanf(arg,"%i", &e) == 0) || (e < 0) || (e > 8))
argp_usage(state);
else
arguments->entropy_count = e;
break;
}
case 'R': {
int R;
if ((sscanf(arg,"%i", &R) == 0) || (R < 0))
argp_usage(state);
else
arguments->force_reseed = R;
break;
}
case 'u': {
arguments->use_slow_sources = true;
break;
}
case 'D': {
struct passwd *usrent;
struct group *grpent;
char *endptr;
long int nuid, ngid;
search = strchr(arg, ':');
/* Check for corner cases */
if (search == NULL) {
message(LOG_CONS|LOG_ERR, "No colon found in user:group tuple\n");
return -EINVAL;
}
if (search == arg || search[1] == '\0') {
message(LOG_CONS|LOG_ERR, "No user or group name found in user:group tuple\n");
return -EINVAL;
}
*search = '\0';
/* Translate user argument into a user struct pointer.
* First, try to get it as specified. If that fails,
* try it as a number.
*/
usrent = getpwnam(arg);
if (usrent == NULL) {
/* Try as a number */
nuid = strtol(arg, &endptr, 10);
if (*endptr || !(usrent = getpwuid(nuid))) {
message(LOG_CONS|LOG_ERR, "User '%s' not found\n", arg);
*search = ':';
return -EINVAL;
}
}
*search = ':';
/* Do the same with a group name or number */
grpent = getgrnam(search + 1);
if (grpent == NULL) {
/* Try as a number */
ngid = strtol(search + 1, &endptr, 10);
if (*endptr || !(grpent = getgrgid(ngid))) {
message(LOG_CONS|LOG_ERR, "Group '%s' not found\n", search + 1);
return -EINVAL;
}
}
/* Found both user and group in a system */
arguments->drop_uid = usrent->pw_uid;
arguments->drop_gid = grpent->gr_gid;
arguments->drop_privs = true;
message(LOG_CONS|LOG_DEBUG, "Trying to drop privileges to %s(%d)/%s(%d)\n",
usrent->pw_name, usrent->pw_uid, grpent->gr_name, grpent->gr_gid);
break;
}
default:
return ARGP_ERR_UNKNOWN;
}
return 0;
}
static struct argp argp = { options, parse_opt, NULL, doc };
static int update_kernel_random(int random_step)
{
unsigned char buf[FIPS_RNG_BUFFER_SIZE]; /* random_step was checked to be <= FIPS_RNG_BUFFER_SIZE */
int rc;
struct rng *iter;
message(LOG_DAEMON|LOG_DEBUG, "entropy successfully gathered, preparing it for the kernel\n");
while(true) {
if (!server_running)
return 0;
if (do_reseed) {
do_reseed = false;
alarm(arguments->force_reseed);
}
/* mix the sources on byte-level: ensure we always feed data from all available sources to the kernel
* helps to mitigate problems should a source not be as random as expected */
int p = 0;
while(p < random_step) {
int progress = p;
for (int i = 0; i < ENT_MAX; ++i) {
iter = &entropy_sources[i];
if (!iter->entropy_buf.valid)
continue;
buf[p++] = iter->entropy_buf.entropy[iter->entropy_buf.used_pos++];
if (iter->entropy_buf.used_pos == FIPS_RNG_BUFFER_SIZE)
iter->entropy_buf.valid = false;
if(p >= random_step)
break;
}
/* abort data preparation when no data was added to the buffer in one loop = no valid sources left
* this wastes a few bytes when FIPS_RNG_BUFFER_SIZE is not a multiple of random_step
* but it makes the logic easier to implement and read */
if (p == progress)
return 0;
}
rc = random_add_entropy(buf, random_step);
if (rc == -1) {
/* feeding the entropy to the kernel failed, not much we can do, wait and try again later */
random_sleep();
continue;
}
message(LOG_DAEMON|LOG_DEBUG, "Added %d/%d bits entropy\n", rc, kent_pool_size);
if (rc >= kent_pool_size-64) {
message(LOG_DAEMON|LOG_DEBUG, "Pool full at %d, sleeping!\n",
kent_pool_size);
random_sleep();
}
}
}
static int random_test_sink(int random_step)
{
struct rng *iter;
if (!ent_gathered)
alarm(1);
for (int i = 0; i < ENT_MAX; ++i) {
iter = &entropy_sources[i];
if (iter->entropy_buf.valid)
ent_gathered += FIPS_RNG_BUFFER_SIZE;
}
return 0;
}
static int drop_privileges(uid_t drop_uid, gid_t drop_gid)
{
cap_value_t ioctl_caps[1] = { CAP_SYS_ADMIN };
cap_t caps;
uid_t curr_uid = geteuid();
gid_t curr_gid = getegid(), supp_gid = drop_gid;
/* We need CAP_SYS_ADMIN capability to perform privileged
* ioctl(2) operations on the /dev/random device (see random(4)).
*/
if (!CAP_IS_SUPPORTED(CAP_SYS_ADMIN)) {
message(LOG_DAEMON|LOG_ERR, "Capability CAP_SYS_ADMIN is not present\n");
return 1;
}
/* We wish to retain the capabilities across the identity change,
* so we need to tell the kernel. See prctl(2).
*/
if (prctl(PR_SET_KEEPCAPS, 1L)) {
message(LOG_DAEMON|LOG_ERR, "Cannot keep capabilities after dropping privileges: %s\n",
strerror(errno));
return 1;
}
/* Actually try to drop privileges */
if (setgroups(1, &supp_gid)) {
message(LOG_DAEMON|LOG_ERR, "setgroups() failed: %s\n", strerror(errno));
return 1;
}
if (setresgid(drop_gid, drop_gid, drop_gid)) {
message(LOG_DAEMON|LOG_ERR, "setresgid() failed: %s\n", strerror(errno));
return 1;
}
if (setresuid(drop_uid, drop_uid, drop_uid)) {
message(LOG_DAEMON|LOG_ERR, "setresuid() failed: %s\n", strerror(errno));
return 1;
}
/* Drop all the capabilities except CAP_SYS_ADMIN. We can do this only
* if CAP_SYS_ADMIN is present in the PERMITTED subset initially.
*/
caps = cap_init();
if (caps == NULL) {
message(LOG_DAEMON|LOG_ERR, "cap_init() failed: %s\n", strerror(errno));
return 1;
}
/* We need CAP_SYS_ADMIN capability in the EFFECTIVE and PERMITTED subsets */
if (cap_set_flag(caps, CAP_PERMITTED, 1, ioctl_caps, CAP_SET) ||
cap_set_flag(caps, CAP_EFFECTIVE, 1, ioctl_caps, CAP_SET)) {
message(LOG_DAEMON|LOG_ERR, "Cannot manipulate capability data structure: %s\n",
strerror(errno));
cap_free(caps);
return 1;
}
/* Above, we just manipulated the data structure describing the flags,
* not the capabilities themselves. So, set those capabilities now.
*/
if (cap_set_proc(caps)) {
message(LOG_DAEMON|LOG_ERR, "Cannot set CAP_SYS_ADMIN capability: %s\n",
strerror(errno));
cap_free(caps);
return 1;
}
/* Free capabilities data */
if (cap_free(caps))
message(LOG_DAEMON|LOG_DEBUG, "cap_free() failed: %s\n", strerror(errno));
/* We can continue with this error */
/* Tell the kernel we do not want to retain the capability over
* any further identity changes (be paranoid)
*/
if (prctl(PR_SET_KEEPCAPS, 0L)) {
message(LOG_DAEMON|LOG_ERR, "prctl() failed: %s\n", strerror(errno));
return 1;
}
/* Be paranoid, verify that the changes were successful.
* Fail if current user or group is not ones to drop to
* or if older user or group can be obtained.
*/
if (curr_gid != drop_gid && (getegid() != drop_gid || setegid(curr_gid) >= 0)) {
message(LOG_DAEMON|LOG_ERR, "Group privileges drop was not successfull\n");
return 1;
}
if (curr_uid != drop_uid && (geteuid() != drop_uid || seteuid(curr_uid) >= 0)) {
message(LOG_DAEMON|LOG_ERR, "User privileges drop was not successfull\n");
return 1;
}
/* The same check for supplemental groups */
int ret = getgroups(1, &supp_gid);
if (ret < 0 || ret > 1 || (ret == 1 && supp_gid != drop_gid)) {
message(LOG_DAEMON|LOG_ERR, "Supplemental groups drop was not successfull\n");
return 1;
}
message(LOG_DAEMON|LOG_INFO, "Process privileges have been dropped to %d:%d\n",
geteuid(), getegid());
return 0;
}
static void do_loop(int random_step)
{
int buffers_filled;
int no_work;
bool work_done;
int sources_left;
int i;
int retval;
struct rng *iter;
bool try_slow_sources = false;
int (*random_add_fn)(int random_step);
random_add_fn = arguments->test ? random_test_sink : update_kernel_random;
continue_trying:
for (no_work = 0; no_work < 100; no_work = (work_done ? 0 : no_work+1)) {
work_done = false;
buffers_filled = 0;
/*
* Exclude slow sources when faster sources are working well
* sources like jitterentropy can provide some entropy when needed
* but can actually hinder performance when large amounts of entropy are needed
* owing to the fact that they may block while generating said entropy
* So, lets prioritize the faster sources. Start by only trying to collect
* entropy from the fast sources, then iff that fails, start including the slower
* sources as well. Once we get some entropy, return to only using fast sources
*/
if (no_work) {
message(LOG_DAEMON|LOG_DEBUG, "Couldn't get entropy in last loop, enabling slow sources\n");
try_slow_sources = true;
} else {
try_slow_sources = false;
}
for (i = 0; i < ENT_MAX; ++i) {
/*message(LOG_CONS|LOG_INFO, "I is %d\n", i);*/
iter = &entropy_sources[i];
/* empty the buffer for each source before gathering new entropy, even when some bytes are left */
iter->entropy_buf.valid = false;
iter->entropy_buf.used_pos = 0;
if (!try_slow_sources && !arguments->use_slow_sources && iter->flags.slow_source)
continue;
retry_same:
if (!server_running)
return;
if (iter->disabled)
continue; /* failed, no work */
message(LOG_DAEMON|LOG_DEBUG, "Reading entropy from %s\n", iter->rng_name);
retval = iter->xread(iter->entropy_buf.entropy, sizeof(iter->entropy_buf.entropy), iter);
if (retval)
continue; /* failed, no work */