[systemd-devel] [PATCH] cryptsetup: fix keyfile size option processing

[Milan Broz]

/etc/crypttab uses "size" argument only for plain crypt mapping
(and input is limited to volume key size)

For LUKS it always read whole keyfile (no arguments except "luks"
should be in crypttab).

Because of bug in cryptsetup 1.2.0 (fixed in 1.3.0) library
did not enforced keyfile size argument, so this bug was
hidden for some time.

Patch also converts size in bits to bytes like excepted
by libcryptsetup api.

Fixes https://bugs.freedesktop.org/show_bug.cgi?id=36264

Signed-off-by: Milan Broz <mbroz at redhat.com>
---
 src/cryptsetup.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/src/cryptsetup.c b/src/cryptsetup.c
index 4ef9606..c0caf9a 100644
--- a/src/cryptsetup.c
+++ b/src/cryptsetup.c
@@ -225,6 +225,7 @@ int main(int argc, char *argv[]) {
         char **passwords = NULL, *truncated_cipher = NULL;
         const char *cipher = NULL, *cipher_mode = NULL, *hash = NULL, *name = NULL;
         char *description = NULL, *name_buffer = NULL, *mount_point = NULL;
+        unsigned keyfile_size = 0;
 
         if (argc <= 1) {
                 help();
@@ -433,6 +434,10 @@ int main(int argc, char *argv[]) {
                                                  &params);
 
                                 pass_volume_key = streq(hash, "plain");
+
+                               /* for CRYPT_PLAIN limit reads
+                                * from keyfile to key length */
+                                keyfile_size = opt_key_size / 8;
                         }
 
                         if (k < 0) {
@@ -447,7 +452,7 @@ int main(int argc, char *argv[]) {
                                  argv[3]);
 
                         if (key_file)
-                                k = crypt_activate_by_keyfile(cd, argv[2], CRYPT_ANY_SLOT, key_file, opt_key_size, flags);
+                                k = crypt_activate_by_keyfile(cd, argv[2], CRYPT_ANY_SLOT, key_file, keyfile_size, flags);
                         else {
                                 char **p;
 
-- 
1.7.4.4