seedrng: use libbb functions

- Make extensive use of libbb.h functions, which simplify a lot of code
  and reduce binary size considerably.
- Use the already existing PID_FILE_PATH variable.

function                                             old     new   delta
seed_from_file_if_exists                             697     533    -164
.rodata                                           108665  108484    -181
seedrng_main                                        1463    1218    -245
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/3 up/down: 0/-590)           Total: -590 bytes
   text	   data	    bss	    dec	    hex	filename
 977035	   4227	   1848	 983110	  f0046	busybox_old
 976445	   4227	   1848	 982520	  efdf8	busybox_unstripped

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Bernhard Reutner-Fischer <rep.dot.nop@gmail.com>

1 files changed, 59 insertions, 89 deletions

diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c
index 2950acde0..d82a942aa 100644
--- a/util-linux/seedrng.c
+++ b/util-linux/seedrng.c
@@ -6,7 +6,7 @@
  */
 
 //config:config SEEDRNG
-//config:       bool "seedrng (3.8 kb)"
+//config:       bool "seedrng (2.6 kb)"
 //config:       default y
 //config:       help
 //config:       Seed the kernel RNG from seed files, meant to be called
@@ -50,53 +50,38 @@
 #define GRND_INSECURE 0x0004 /* Apparently some headers don't ship with this yet. */
 #endif
 
-#ifndef LOCALSTATEDIR
-#define LOCALSTATEDIR "/var/lib"
-#endif
-#ifndef RUNSTATEDIR
-#define RUNSTATEDIR "/var/run"
+#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 LOCALSTATEDIR "/seedrng"
-#define DEFAULT_LOCK_FILE RUNSTATEDIR "/seedrng.lock"
+#define DEFAULT_SEED_DIR "/var/lib/seedrng"
+#define DEFAULT_LOCK_FILE PID_FILE_PATH "/seedrng.lock"
 #define CREDITABLE_SEED_NAME "seed.credit"
 #define NON_CREDITABLE_SEED_NAME "seed.no-credit"
 
 static char *seed_dir, *lock_file, *creditable_seed, *non_creditable_seed;
 
 enum seedrng_lengths {
-        MAX_SEED_LEN = 512,
-        MIN_SEED_LEN = SHA256_OUTSIZE
+        MIN_SEED_LEN = SHA256_OUTSIZE,
+        MAX_SEED_LEN = 512
 };
 
-#ifndef DIV_ROUND_UP
-#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
-#endif
-
 static size_t determine_optimal_seed_len(void)
 {
-        size_t ret = 0;
         char poolsize_str[11] = { 0 };
-        int fd = open("/proc/sys/kernel/random/poolsize", O_RDONLY);
 
-        if (fd < 0 || read(fd, poolsize_str, sizeof(poolsize_str) - 1) < 0) {
-                fprintf(stderr, "WARNING: Unable to determine pool size, falling back to %u bits: %s\n", MIN_SEED_LEN * 8, strerror(errno));
-                ret = MIN_SEED_LEN;
-        } else
-                ret = DIV_ROUND_UP(strtoul(poolsize_str, NULL, 10), 8);
-        if (fd >= 0)
-                close(fd);
-        if (ret < MIN_SEED_LEN)
-                ret = MIN_SEED_LEN;
-        else if (ret > MAX_SEED_LEN)
-                ret = MAX_SEED_LEN;
-        return ret;
+        if (open_read_close("/proc/sys/kernel/random/poolsize", poolsize_str, sizeof(poolsize_str) - 1) < 0) {
+                bb_perror_msg("unable to determine pool size, falling back to %u bits", MIN_SEED_LEN * 8);
+                return MIN_SEED_LEN;
+        }
+        return MAX(MIN((bb_strtoul(poolsize_str, NULL, 10) + 7) / 8, MAX_SEED_LEN), MIN_SEED_LEN);
 }
 
 static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
 {
         ssize_t ret;
-        int urandom_fd;
 
         *is_creditable = false;
         ret = getrandom(seed, len, GRND_NONBLOCK);
@@ -109,21 +94,16 @@ static int read_new_seed(uint8_t *seed, size_t len, bool *is_creditable)
                         .events = POLLIN
                 };
                 if (random_fd.fd < 0)
-                        return -errno;
-                *is_creditable = poll(&random_fd, 1, 0) == 1;
+                        return -1;
+                *is_creditable = safe_poll(&random_fd, 1, 0) == 1;
                 close(random_fd.fd);
         } else if (getrandom(seed, len, GRND_INSECURE) == (ssize_t)len)
                 return 0;
-        urandom_fd = open("/dev/urandom", O_RDONLY);
-        if (urandom_fd < 0)
-                return -errno;
-        ret = read(urandom_fd, seed, len);
-        if (ret == (ssize_t)len)
-                ret = 0;
-        else
-                ret = -errno ? -errno : -EIO;
-        close(urandom_fd);
-        return ret;
+        if (open_read_close("/dev/urandom", seed, len) == (ssize_t)len)
+                return 0;
+        if (!errno)
+                errno = EIO;
+        return -1;
 }
 
 static int seed_rng(uint8_t *seed, size_t len, bool credit)
@@ -138,69 +118,63 @@ static int seed_rng(uint8_t *seed, size_t len, bool credit)
         };
         int random_fd, ret;
 
-        if (len > sizeof(req.buffer))
-                return -EFBIG;
+        if (len > sizeof(req.buffer)) {
+                errno = EFBIG;
+                return -1;
+        }
         memcpy(req.buffer, seed, len);
 
         random_fd = open("/dev/random", O_RDWR);
         if (random_fd < 0)
-                return -errno;
+                return -1;
         ret = ioctl(random_fd, RNDADDENTROPY, &req);
         if (ret)
                 ret = -errno ? -errno : -EIO;
         close(random_fd);
-        return ret;
+        errno = -ret;
+        return ret ? -1 : 0;
 }
 
 static int seed_from_file_if_exists(const char *filename, bool credit, sha256_ctx_t *hash)
 {
         uint8_t seed[MAX_SEED_LEN];
         ssize_t seed_len;
-        int fd, dfd, ret = 0;
+        int dfd = -1, ret = 0;
 
-        fd = open(filename, O_RDONLY);
-        if (fd < 0 && errno == ENOENT)
-                return 0;
-        else if (fd < 0) {
-                ret = -errno;
-                fprintf(stderr, "ERROR: Unable to open seed file: %s\n", strerror(errno));
-                return ret;
-        }
         dfd = open(seed_dir, O_DIRECTORY | O_RDONLY);
         if (dfd < 0) {
                 ret = -errno;
-                close(fd);
-                fprintf(stderr, "ERROR: Unable to open seed directory: %s\n", strerror(errno));
-                return ret;
+                bb_simple_perror_msg("unable to open seed directory");
+                goto out;
         }
-        seed_len = read(fd, seed, sizeof(seed));
+        seed_len = open_read_close(filename, seed, sizeof(seed));
         if (seed_len < 0) {
-                ret = -errno;
-                fprintf(stderr, "ERROR: Unable to read seed file: %s\n", strerror(errno));
-        }
-        close(fd);
-        if (ret) {
-                close(dfd);
-                return ret;
+                if (errno != ENOENT) {
+                        ret = -errno;
+                        bb_simple_perror_msg("unable to read seed file");
+                }
+                goto out;
         }
         if ((unlink(filename) < 0 || fsync(dfd) < 0) && seed_len) {
                 ret = -errno;
-                fprintf(stderr, "ERROR: Unable to remove seed after reading, so not seeding: %s\n", strerror(errno));
+                bb_simple_perror_msg("unable to remove seed after reading, so not seeding");
+                goto out;
         }
-        close(dfd);
-        if (ret)
-                return ret;
         if (!seed_len)
-                return 0;
+                goto out;
 
         sha256_hash(hash, &seed_len, sizeof(seed_len));
         sha256_hash(hash, seed, seed_len);
 
-        fprintf(stdout, "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 (ret < 0)
-                fprintf(stderr, "ERROR: Unable to seed: %s\n", strerror(-ret));
-        return ret;
+                bb_simple_perror_msg("unable to seed");
+out:
+        if (dfd >= 0)
+                close(dfd);
+        errno = -ret;
+        return ret ? -1 : 0;
 }
 
 int seedrng_main(int argc, char *argv[]) MAIN_EXTERNALLY_VISIBLE;
@@ -236,14 +210,12 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         if (!(opt & OPT_l) || !lock_file)
                 lock_file = xstrdup(DEFAULT_LOCK_FILE);
         skip_credit = opt & OPT_n;
-        creditable_seed = xasprintf("%s/%s", seed_dir, CREDITABLE_SEED_NAME);
-        non_creditable_seed = xasprintf("%s/%s", seed_dir, NON_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);
 
         umask(0077);
-        if (getuid()) {
-                fprintf(stderr, "ERROR: This program requires root\n");
-                return 1;
-        }
+        if (getuid())
+                bb_simple_error_msg_and_die("this program requires root");
 
         sha256_begin(&hash);
         sha256_hash(&hash, seedrng_prefix, strlen(seedrng_prefix));
@@ -252,14 +224,12 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         sha256_hash(&hash, &realtime, sizeof(realtime));
         sha256_hash(&hash, &boottime, sizeof(boottime));
 
-        if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) {
-                fprintf(stderr, "ERROR: Unable to create \"%s\" directory: %s\n", seed_dir, strerror(errno));
-                return 1;
-        }
+        if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST)
+                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) {
-                fprintf(stderr, "ERROR: Unable to open lock file: %s\n", strerror(errno));
+                bb_simple_perror_msg("unable to open lock file");
                 program_ret = 1;
                 goto out;
         }
@@ -274,7 +244,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         new_seed_len = determine_optimal_seed_len();
         ret = read_new_seed(new_seed, new_seed_len, &new_seed_creditable);
         if (ret < 0) {
-                fprintf(stderr, "ERROR: Unable to read new seed: %s\n", strerror(-ret));
+                bb_simple_perror_msg("unable to read new seed");
                 new_seed_len = SHA256_OUTSIZE;
                 strncpy((char *)new_seed, seedrng_failure, new_seed_len);
                 program_ret |= 1 << 3;
@@ -283,20 +253,20 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[])
         sha256_hash(&hash, new_seed, new_seed_len);
         sha256_end(&hash, new_seed + new_seed_len - SHA256_OUTSIZE);
 
-        fprintf(stdout, "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);
         if (fd < 0) {
-                fprintf(stderr, "ERROR: Unable to open seed file for writing: %s\n", strerror(errno));
+                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) {
-                fprintf(stderr, "ERROR: Unable to write seed file: %s\n", strerror(errno));
+                bb_simple_perror_msg("unable to write seed file");
                 program_ret |= 1 << 5;
                 goto out;
         }
         if (new_seed_creditable && rename(non_creditable_seed, creditable_seed) < 0) {
-                fprintf(stderr, "WARNING: Unable to make new seed creditable: %s\n", strerror(errno));
+                bb_simple_perror_msg("unable to make new seed creditable");
                 program_ret |= 1 << 6;
         }
 out: