diff options
| -rw-r--r-- | util-linux/seedrng.c | 26 |
1 files changed, 18 insertions, 8 deletions
diff --git a/util-linux/seedrng.c b/util-linux/seedrng.c index a02609a..c07bf84 100644 --- a/util-linux/seedrng.c +++ b/util-linux/seedrng.c @@ -190,9 +190,17 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) if (mkdir(seed_dir, 0700) < 0 && errno != EEXIST) bb_perror_msg_and_die("can't create directory '%s'", seed_dir); dfd = xopen(seed_dir, O_DIRECTORY | O_RDONLY); - if (flock(dfd, LOCK_EX) < 0) - bb_perror_msg_and_die("can't lock seed directory"); xfchdir(dfd); + /* Concurrent runs of this tool might feed the same data to RNG twice. + * Avoid concurrent runs by taking a blocking lock on the directory. + * Not checking for errors. Looking at manpage, + * ENOLCK "The kernel ran out of memory for allocating lock records" + * seems to be the only one which is likely - and if that happens, + * machine is OOMing (much worse problem than inability to lock...). + * Also, typically configured Linux machines do not fail GFP_KERNEL + * allocations (they trigger memory reclaim instead). + */ + flock(dfd, LOCK_EX); /* would block while another copy runs */ sha256_begin(&hash); sha256_hash(&hash, "SeedRNG v1 Old+New Prefix", 25); @@ -204,7 +212,7 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) for (int i = 1; i < 3; ++i) { seed_from_file_if_exists(i == 1 ? NON_CREDITABLE_SEED_NAME : CREDITABLE_SEED_NAME, dfd, - i == 1 ? false : !skip_credit, + /* credit? */ i == 1 ? false : !skip_credit, &hash); } @@ -218,11 +226,13 @@ int seedrng_main(int argc UNUSED_PARAM, char *argv[]) (unsigned)new_seed_len * 8, new_seed_creditable ? "" : "non-"); fd = xopen3(NON_CREDITABLE_SEED_NAME, O_WRONLY | O_CREAT | O_TRUNC, 0400); xwrite(fd, new_seed, new_seed_len); - if (fsync(fd) < 0) { - bb_perror_msg("can't%s seed", " write"); - return (1 << 4); - } - if (new_seed_creditable) + if (new_seed_creditable) { + /* More paranoia when we create a file which we believe contains + * genuine entropy: make sure disk is not full, quota was't esceeded, etc: + */ + if (fsync(fd) < 0) + bb_perror_msg_and_die("can't write '%s'", NON_CREDITABLE_SEED_NAME); xrename(NON_CREDITABLE_SEED_NAME, CREDITABLE_SEED_NAME); + } return EXIT_SUCCESS; } |