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