diff options
Diffstat (limited to 'src/random-seed/random-seed.c')
| -rw-r--r-- | src/random-seed/random-seed.c | 88 |
1 files changed, 55 insertions, 33 deletions
diff --git a/src/random-seed/random-seed.c b/src/random-seed/random-seed.c index 223b56306c..d25ee7d80a 100644 --- a/src/random-seed/random-seed.c +++ b/src/random-seed/random-seed.c @@ -15,15 +15,17 @@ #include "util.h" #define POOL_SIZE_MIN 512 +#define POOL_SIZE_MAX (10*1024*1024) int main(int argc, char *argv[]) { _cleanup_close_ int seed_fd = -1, random_fd = -1; + bool read_seed_file, write_seed_file; _cleanup_free_ void* buf = NULL; size_t buf_size = 0; + struct stat st; ssize_t k; - int r, open_rw_error; FILE *f; - bool refresh_seed_file = true; + int r; if (argc != 2) { log_error("This program requires one argument."); @@ -46,31 +48,25 @@ int main(int argc, char *argv[]) { fclose(f); } - if (buf_size <= POOL_SIZE_MIN) + if (buf_size < POOL_SIZE_MIN) buf_size = POOL_SIZE_MIN; - buf = malloc(buf_size); - if (!buf) { - r = log_oom(); - goto finish; - } - r = mkdir_parents_label(RANDOM_SEED, 0755); if (r < 0) { log_error_errno(r, "Failed to create directory " RANDOM_SEED_DIR ": %m"); goto finish; } - /* When we load the seed we read it and write it to the device - * and then immediately update the saved seed with new data, - * to make sure the next boot gets seeded differently. */ + /* When we load the seed we read it and write it to the device and then immediately update the saved seed with + * new data, to make sure the next boot gets seeded differently. */ if (streq(argv[1], "load")) { + int open_rw_error; seed_fd = open(RANDOM_SEED, O_RDWR|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600); open_rw_error = -errno; if (seed_fd < 0) { - refresh_seed_file = false; + write_seed_file = false; seed_fd = open(RANDOM_SEED, O_RDONLY|O_CLOEXEC|O_NOCTTY); if (seed_fd < 0) { @@ -85,10 +81,13 @@ int main(int argc, char *argv[]) { goto finish; } - } + } else + write_seed_file = true; random_fd = open("/dev/urandom", O_RDWR|O_CLOEXEC|O_NOCTTY, 0600); if (random_fd < 0) { + write_seed_file = false; + random_fd = open("/dev/urandom", O_WRONLY|O_CLOEXEC|O_NOCTTY, 0600); if (random_fd < 0) { r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); @@ -96,33 +95,24 @@ int main(int argc, char *argv[]) { } } - k = loop_read(seed_fd, buf, buf_size, false); - if (k < 0) - r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m"); - else if (k == 0) { - r = 0; - log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding."); - } else { - (void) lseek(seed_fd, 0, SEEK_SET); - - r = loop_write(random_fd, buf, (size_t) k, false); - if (r < 0) - log_error_errno(r, "Failed to write seed to /dev/urandom: %m"); - } + read_seed_file = true; } else if (streq(argv[1], "save")) { + random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY); + if (random_fd < 0) { + r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); + goto finish; + } + seed_fd = open(RANDOM_SEED, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_CREAT, 0600); if (seed_fd < 0) { r = log_error_errno(errno, "Failed to open " RANDOM_SEED ": %m"); goto finish; } - random_fd = open("/dev/urandom", O_RDONLY|O_CLOEXEC|O_NOCTTY); - if (random_fd < 0) { - r = log_error_errno(errno, "Failed to open /dev/urandom: %m"); - goto finish; - } + read_seed_file = false; + write_seed_file = true; } else { log_error("Unknown verb '%s'.", argv[1]); @@ -130,7 +120,39 @@ int main(int argc, char *argv[]) { goto finish; } - if (refresh_seed_file) { + if (fstat(seed_fd, &st) < 0) { + r = log_error_errno(errno, "Failed to stat() seed file " RANDOM_SEED ": %m"); + goto finish; + } + + /* If the seed file is larger than what we expect, then honour the existing size and save/restore as much as it says */ + if ((uint64_t) st.st_size > buf_size) + buf_size = MIN(st.st_size, POOL_SIZE_MAX); + + buf = malloc(buf_size); + if (!buf) { + r = log_oom(); + goto finish; + } + + if (read_seed_file) { + + k = loop_read(seed_fd, buf, buf_size, false); + if (k < 0) + r = log_error_errno(k, "Failed to read seed from " RANDOM_SEED ": %m"); + else if (k == 0) { + r = 0; + log_debug("Seed file " RANDOM_SEED " not yet initialized, proceeding."); + } else { + (void) lseek(seed_fd, 0, SEEK_SET); + + r = loop_write(random_fd, buf, (size_t) k, false); + if (r < 0) + log_error_errno(r, "Failed to write seed to /dev/urandom: %m"); + } + } + + if (write_seed_file) { /* This is just a safety measure. Given that we are root and * most likely created the file ourselves the mode and owner |