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cryptsetup: modify keyfile search logic to use read_file_full() too 

Let's move the 3rd way how cryptsetup acquires key files to
read_file_full() too.

Since load_key_file()'s raison d'etre now is just the search path logic,
let's rename the function to find_key_file().
This commit is contained in:
Lennart Poettering 2020-11-04 18:15:42 +01:00
parent e2c2f868b2
commit e060ed32e4
3 changed files with 42 additions and 90 deletions
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113
src/cryptsetup/cryptsetup-keyfile.c
View File

@ -1,29 +1,18 @@
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <unistd.h>
#include "cryptsetup-keyfile.h"
#include "fd-util.h"
#include "format-util.h"
#include "memory-util.h"
#include "fileio.h"
#include "path-util.h"
#include "stat-util.h"
#include "strv.h"
#define KEY_FILE_SIZE_MAX (16U*1024U*1024U) /* 16 MiB */
int load_key_file(
int find_key_file(
const char *key_file,
char **search_path,
size_t key_file_size,
uint64_t key_file_offset,
const char *bindname,
void **ret_key,
size_t *ret_key_size) {
_cleanup_(erase_and_freep) char *buffer = NULL;
_cleanup_free_ char *discovered_path = NULL;
_cleanup_close_ int fd = -1;
ssize_t n;
char **i;
int r;
assert(key_file);
@ -31,80 +20,38 @@ int load_key_file(
assert(ret_key_size);
if (strv_isempty(search_path) || path_is_absolute(key_file)) {
fd = open(key_file, O_RDONLY|O_CLOEXEC);
if (fd < 0)
return log_error_errno(errno, "Failed to load key file '%s': %m", key_file);
} else {
char **i;
STRV_FOREACH(i, search_path) {
_cleanup_free_ char *joined;
joined = path_join(*i, key_file);
if (!joined)
return log_oom();
fd = open(joined, O_RDONLY|O_CLOEXEC);
if (fd >= 0) {
discovered_path = TAKE_PTR(joined);
break;
}
if (errno != ENOENT)
return log_error_errno(errno, "Failed to load key file '%s': %m", joined);
}
if (!discovered_path) {
/* Search path supplied, but file not found, report by returning NULL, but not failing */
*ret_key = NULL;
*ret_key_size = 0;
return 0;
}
assert(fd >= 0);
key_file = discovered_path;
}
if (key_file_size == 0) {
struct stat st;
if (fstat(fd, &st) < 0)
return log_error_errno(errno, "Failed to stat key file '%s': %m", key_file);
r = stat_verify_regular(&st);
r = read_full_file_full(
AT_FDCWD, key_file, UINT64_MAX, SIZE_MAX,
READ_FULL_FILE_SECURE|READ_FULL_FILE_WARN_WORLD_READABLE|READ_FULL_FILE_CONNECT_SOCKET,
bindname,
(char**) ret_key, ret_key_size);
if (r < 0)
return log_error_errno(r, "Key file is not a regular file: %m");
return log_error_errno(r, "Failed to load key file '%s': %m", key_file);
if (st.st_size == 0)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Key file is empty, refusing.");
if ((uint64_t) st.st_size > KEY_FILE_SIZE_MAX) {
char buf1[FORMAT_BYTES_MAX], buf2[FORMAT_BYTES_MAX];
return log_error_errno(SYNTHETIC_ERRNO(ERANGE),
"Key file larger (%s) than allowed maximum size (%s), refusing.",
format_bytes(buf1, sizeof(buf1), st.st_size),
format_bytes(buf2, sizeof(buf2), KEY_FILE_SIZE_MAX));
}
if (key_file_offset >= (uint64_t) st.st_size)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Key file offset too large for file, refusing.");
key_file_size = st.st_size - key_file_offset;
return 1;
}
buffer = malloc(key_file_size);
if (!buffer)
return log_oom();
STRV_FOREACH(i, search_path) {
_cleanup_free_ char *joined;
if (key_file_offset > 0)
n = pread(fd, buffer, key_file_size, key_file_offset);
else
n = read(fd, buffer, key_file_size);
if (n < 0)
return log_error_errno(errno, "Failed to read key file '%s': %m", key_file);
if (n == 0)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Empty encrypted key found, refusing.");
joined = path_join(*i, key_file);
if (!joined)
return log_oom();
*ret_key = TAKE_PTR(buffer);
*ret_key_size = (size_t) n;
r = read_full_file_full(
AT_FDCWD, joined, UINT64_MAX, SIZE_MAX,
READ_FULL_FILE_SECURE|READ_FULL_FILE_WARN_WORLD_READABLE|READ_FULL_FILE_CONNECT_SOCKET,
bindname,
(char**) ret_key, ret_key_size);
if (r >= 0)
return 1;
if (r != -ENOENT)
return log_error_errno(r, "Failed to load key file '%s': %m", key_file);
}
return 1;
/* Search path supplied, but file not found, report by returning NULL, but not failing */
*ret_key = NULL;
*ret_key_size = 0;
return 0;
}

5
src/cryptsetup/cryptsetup-keyfile.h
View File

@ -4,10 +4,9 @@
#include <inttypes.h>
#include <sys/types.h>
int load_key_file(
int find_key_file(
const char *key_file,
char **search_path,
size_t key_file_size,
uint64_t key_file_offset,
const char *bindname,
void **ret_key,
size_t *ret_key_size);

14
src/cryptsetup/cryptsetup.c
View File

@ -908,16 +908,22 @@ static int run(int argc, char *argv[]) {
(void) mlockall(MCL_FUTURE);
if (!key_file) {
_cleanup_free_ char *bindname = NULL;
const char *fn;
bindname = make_bindname(argv[2]);
if (!bindname)
return log_oom();
/* If a key file is not explicitly specified, search for a key in a well defined
* search path, and load it. */
fn = strjoina(argv[2], ".key");
r = load_key_file(fn,
STRV_MAKE("/etc/cryptsetup-keys.d", "/run/cryptsetup-keys.d"),
0, 0, /* Note we leave arg_keyfile_offset/arg_keyfile_size as something that only applies to arg_keyfile! */
&key_data, &key_data_size);
r = find_key_file(
fn,
STRV_MAKE("/etc/cryptsetup-keys.d", "/run/cryptsetup-keys.d"),
bindname,
&key_data, &key_data_size);
if (r < 0)
return r;
if (r > 0)