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seedrng: further reduce size

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- Remove all games with errno to further reduce code size.
- Combine error messages that don't benefit from being separated.
- Lock directory fd instead of separate file.

function                                             old     new   delta
static.longopts                                       38      26     -12
seed_from_file_if_exists                             426     413     -13
packed_usage                                       34519   34480     -39
.rodata                                           108484  108407     -77
seedrng_main                                        1088    1000     -88
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/5 up/down: 0/-229)           Total: -229 bytes
   text	   data	    bss	    dec	    hex	filename
 976208	   4227	   1816	 982251	  efceb	busybox_old
 975979	   4227	   1816	 982022	  efc06	busybox_unstripped

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>
This commit is contained in:
Jason A. Donenfeld 2022-04-20 15:34:20 +02:00 committed by Bernhard Reutner-Fischer
parent 3c60711f83
commit 398bb3861a
1 changed files with 22 additions and 55 deletions
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77
util-linux/seedrng.c
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@ -21,7 +21,7 @@
*/ */
//config:config SEEDRNG //config:config SEEDRNG
//config: bool "seedrng (2.4 kb)" //config: bool "seedrng (2.1 kb)"
//config: default y //config: default y
//config: help //config: help
//config: Seed the kernel RNG from seed files, meant to be called //config: Seed the kernel RNG from seed files, meant to be called
@ -33,12 +33,11 @@
//kbuild:lib-$(CONFIG_SEEDRNG) += seedrng.o //kbuild:lib-$(CONFIG_SEEDRNG) += seedrng.o
//usage:#define seedrng_trivial_usage //usage:#define seedrng_trivial_usage
//usage: "[-d SEED_DIRECTORY] [-l LOCK_FILE] [-n]" //usage: "[-d SEED_DIRECTORY] [-n]"
//usage:#define seedrng_full_usage "\n\n" //usage:#define seedrng_full_usage "\n\n"
//usage: "Seed the kernel RNG from seed files." //usage: "Seed the kernel RNG from seed files."
//usage: "\n" //usage: "\n"
//usage: "\n -d, --seed-dir DIR Use seed files from specified directory (default: /var/lib/seedrng)" //usage: "\n -d, --seed-dir DIR Use seed files from specified directory (default: /var/lib/seedrng)"
//usage: "\n -l, --lock-file FILE Use file as exclusive lock (default: /var/run/seedrng.lock)"
//usage: "\n -n, --skip-credit Skip crediting seeds, even if creditable" //usage: "\n -n, --skip-credit Skip crediting seeds, even if creditable"
#include "libbb.h" #include "libbb.h"
@ -65,14 +64,7 @@
#define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */ #define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
#endif #endif
#if ENABLE_PID_FILE_PATH
#define PID_FILE_PATH CONFIG_PID_FILE_PATH
#else
#define PID_FILE_PATH "/var/run"
#endif
#define DEFAULT_SEED_DIR "/var/lib/seedrng" #define DEFAULT_SEED_DIR "/var/lib/seedrng"
#define DEFAULT_LOCK_FILE PID_FILE_PATH "/seedrng.lock"
#define CREDITABLE_SEED_NAME "seed.credit" #define CREDITABLE_SEED_NAME "seed.credit"
#define NON_CREDITABLE_SEED_NAME "seed.no-credit" #define NON_CREDITABLE_SEED_NAME "seed.no-credit"
@ -116,8 +108,6 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
return 0; return 0;
if (open_read_close("/dev/urandom", seed, len) == (ssize_t)len) if (open_read_close("/dev/urandom", seed, len) == (ssize_t)len)
return 0; return 0;
if (!errno)
errno = EIO;
return -1; return -1;
} }
@ -155,34 +145,29 @@ static int seed_from_file_if_exists(const char *filename, int dfd, bool credit,
{ {
uint8_t seed[MAX_SEED_LEN]; uint8_t seed[MAX_SEED_LEN];
ssize_t seed_len; ssize_t seed_len;
int ret = 0;
seed_len = open_read_close(filename, seed, sizeof(seed)); seed_len = open_read_close(filename, seed, sizeof(seed));
if (seed_len < 0) { if (seed_len < 0) {
if (errno != ENOENT) { if (errno == ENOENT)
ret = -errno; return 0;
bb_simple_perror_msg("unable to read seed file"); bb_simple_perror_msg("unable to read seed file");
} return -1;
goto out;
} }
if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) { if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
ret = -errno;
bb_simple_perror_msg("unable to remove seed after reading, so not seeding"); bb_simple_perror_msg("unable to remove seed after reading, so not seeding");
goto out; return -1;
} } else if (!seed_len)
if (!seed_len) return 0;
goto out;
sha256_hash(hash, &seed_len, sizeof(seed_len)); sha256_hash(hash, &seed_len, sizeof(seed_len));
sha256_hash(hash, seed, seed_len); sha256_hash(hash, seed, seed_len);
printf("Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without"); printf("Seeding %zd bits %s crediting\n", seed_len * 8, credit ? "and" : "without");
ret = seed_rng(seed, seed_len, credit); if (seed_rng(seed, seed_len, credit) < 0) {
if (ret < 0)
bb_simple_perror_msg("unable to seed"); bb_simple_perror_msg("unable to seed");
out: return -1;
errno = -ret; }
return ret ? -1 : 0; return 0;
} }
int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE; int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
@ -190,8 +175,8 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
{ {
static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix"; static const char seedrng_prefix[] = "SeedRNG v1 Old+New Prefix";
static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure"; static const char seedrng_failure[] = "SeedRNG v1 No New Seed Failure";
char *seed_dir, *lock_file, *creditable_seed, *non_creditable_seed; char *seed_dir, *creditable_seed, *non_creditable_seed;
int ret, fd = -1, dfd = -1, lock, program_ret = 0; int ret, fd = -1, dfd = -1, program_ret = 0;
uint8_t new_seed[MAX_SEED_LEN]; uint8_t new_seed[MAX_SEED_LEN];
size_t new_seed_len; size_t new_seed_len;
bool new_seed_creditable; bool new_seed_creditable;
@ -202,22 +187,18 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
int opt; int opt;
enum { enum {
OPT_d = (1 << 0), OPT_d = (1 << 0),
OPT_l = (1 << 1), OPT_n = (1 << 1)
OPT_n = (1 << 2)
}; };
#if ENABLE_LONG_OPTS #if ENABLE_LONG_OPTS
static const char longopts[] ALIGN1 = static const char longopts[] ALIGN1 =
"seed-dir\0" Required_argument "d" "seed-dir\0" Required_argument "d"
"lock-file\0" Required_argument "l"
"skip-credit\0" No_argument "n" "skip-credit\0" No_argument "n"
; ;
#endif #endif
opt = getopt32long(argv, "d:l:n", longopts, &seed_dir, &lock_file); opt = getopt32long(argv, "d:n", longopts, &seed_dir);
if (!(opt & OPT_d) || !seed_dir) if (!(opt & OPT_d) || !seed_dir)
seed_dir = xstrdup(DEFAULT_SEED_DIR); seed_dir = xstrdup(DEFAULT_SEED_DIR);
if (!(opt & OPT_l) || !lock_file)
lock_file = xstrdup(DEFAULT_LOCK_FILE);
skip_credit = opt & OPT_n; skip_credit = opt & OPT_n;
creditable_seed = concat_path_file(seed_dir, CREDITABLE_SEED_NAME); creditable_seed = concat_path_file(seed_dir, CREDITABLE_SEED_NAME);
non_creditable_seed = concat_path_file(seed_dir, NON_CREDITABLE_SEED_NAME); non_creditable_seed = concat_path_file(seed_dir, NON_CREDITABLE_SEED_NAME);
@ -229,16 +210,9 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
bb_simple_perror_msg_and_die("unable to create seed directory"); bb_simple_perror_msg_and_die("unable to create seed directory");
lock = open(lock_file, O_WRONLY | O_CREAT, 0000);
if (lock < 0 || flock(lock, LOCK_EX) < 0) {
bb_simple_perror_msg("unable to open lock file");
program_ret = 1;
goto out;
}
dfd = open(seed_dir, O_DIRECTORY | O_RDONLY); dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
if (dfd < 0) { if (dfd < 0 || flock(dfd, LOCK_EX) < 0) {
bb_simple_perror_msg("unable to open seed directory"); bb_simple_perror_msg("unable to open and lock seed directory");
program_ret = 1; program_ret = 1;
goto out; goto out;
} }
@ -271,26 +245,19 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
printf("Saving %zu bits of %s seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable"); printf("Saving %zu bits of %s seed for next boot\n", new_seed_len * 8, new_seed_creditable ? "creditable" : "non-creditable");
fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400); fd = open(non_creditable_seed, O_WRONLY | O_CREAT | O_TRUNC, 0400);
if (fd < 0) { if (fd < 0 || full_write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
bb_simple_perror_msg("unable to open seed file for writing");
program_ret |= 1 << 4;
goto out;
}
if (write(fd, new_seed, new_seed_len) != (ssize_t)new_seed_len || fsync(fd) < 0) {
bb_simple_perror_msg("unable to write seed file"); bb_simple_perror_msg("unable to write seed file");
program_ret |= 1 << 5; program_ret |= 1 << 4;
goto out; goto out;
} }
if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) { if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) {
bb_simple_perror_msg("unable to make new seed creditable"); bb_simple_perror_msg("unable to make new seed creditable");
program_ret |= 1 << 6; program_ret |= 1 << 5;
} }
out: out:
if (ENABLE_FEATURE_CLEAN_UP && fd >= 0) if (ENABLE_FEATURE_CLEAN_UP && fd >= 0)
close(fd); close(fd);
if (ENABLE_FEATURE_CLEAN_UP && dfd >= 0) if (ENABLE_FEATURE_CLEAN_UP && dfd >= 0)
close(dfd); close(dfd);
if (ENABLE_FEATURE_CLEAN_UP && lock >= 0)
close(lock);
return program_ret; return program_ret;
} }