[dm-crypt] luksDump with --master-key-file fails to create nonexisting file

[Ingo Franzki]

Hi,

I just noticed that a luksDump with option --master-key-file fails to open the file when it is not already existing.
Is this by intention?

cryptsetup luksDump <device> --dump-master-key --master-key-file mykey.bin
...
Cannot open keyfile mykey.bin for write.

When I do a "touch mykey.bin" first, above command works fine.

Funtion tools_write_mk() in utils_password.c uses open with O_WRONLY. This does not seem to create the file when it is not existing.
Maybe it should also specify O_CREAT?

Kind regards, Ingo

[Milan Broz]

Post by Ingo Franzki
Hi,
I just noticed that a luksDump with option --master-key-file fails to open the file when it is not already existing.
Is this by intention?
cryptsetup luksDump <device> --dump-master-key --master-key-file mykey.bin
...
Cannot open keyfile mykey.bin for write.
When I do a "touch mykey.bin" first, above command works fine.
Funtion tools_write_mk() in utils_password.c uses open with O_WRONLY. This does not seem to create the file when it is not existing.
Maybe it should also specify O_CREAT?

This is a quite new code (--master-key-file was previously used only for input).

I think this a mistake and it should be handled the same way as we create header backup, IOW with these flags:
open(file, O_CREAT|O_EXCL|O_WRONLY, S_IRUSR)

(do not overwrite existing, set user only, read-only acl)

Milan