On Sun, Oct 23, 2022 at 08:18:58AM +0300, Jarkko Sakkinen wrote:
> On Thu, Oct 13, 2022 at 08:39:58AM +0200, Nikolaus Voss wrote:
> > Commit cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-provided
> > decrypted data") added key instantiation with user provided decrypted data.
> > The user data is hex-ascii-encoded but was just memcpy'ed to the binary buffer.
> > Fix this to use hex2bin instead.
> >
> > Old keys created from user provided decrypted data saved with "keyctl pipe"
> > are still valid, however if the key is recreated from decrypted data the
> > old key must be converted to the correct format. This can be done with a
> > small shell script, e.g.:
> >
> > BROKENKEY=abcdefABCDEF1234567890aaaaaaaaaa
> > NEWKEY=$(echo -ne $BROKENKEY | xxd -p -c32)
> > keyctl add user masterkey "$(cat masterkey.bin)" @u
> > keyctl add encrypted testkey "new user:masterkey 32 $NEWKEY" @u
> >
> > It is encouraged to switch to a new key because the effective key size
> > of the old keys is only half of the specified size.
> >
> > The corresponding test for the Linux Test Project ltp has also been
> > fixed (see link below).
> >
> > Fixes: cd3bc044af48 ("KEYS: encrypted: Instantiate key with user-provided decrypted data")
> > Cc: stable <stable@xxxxxxxxxx>
> > Link: https://lore.kernel.org/ltp/20221006081709.92303897@xxxxxxxxxxxxxxxxxxx/
> > Signed-off-by: Nikolaus Voss <nikolaus.voss@xxxxxxxxxxxxxxx>
> > ---
> > Changes
> > =======
> > v4: - fixed link
> > v3: - use generated random key in example, reformat commit message
> > v2: - clarify commit message, add example to recover old/broken keys
> > - improve example in Documentation/security/keys/trusted-encrypted.rst
> > - add link to ltp patch
> >
> > Documentation/security/keys/trusted-encrypted.rst | 3 ++-
> > security/keys/encrypted-keys/encrypted.c | 6 +++---
> > 2 files changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
> > index 0bfb4c339748..9bc9db8ec651 100644
> > --- a/Documentation/security/keys/trusted-encrypted.rst
> > +++ b/Documentation/security/keys/trusted-encrypted.rst
> > @@ -350,7 +350,8 @@ Load an encrypted key "evm" from saved blob::
> >
> > Instantiate an encrypted key "evm" using user-provided decrypted data::
> >
> > - $ keyctl add encrypted evm "new default user:kmk 32 `cat evm_decrypted_data.blob`" @u
> > + $ evmkey=$(dd if=/dev/urandom bs=1 count=32 | xxd -c32 -p)
> > + $ keyctl add encrypted evm "new default user:kmk 32 $evmkey" @u
> > 794890253
> >
> > $ keyctl print 794890253
> > diff --git a/security/keys/encrypted-keys/encrypted.c b/security/keys/encrypted-keys/encrypted.c
> > index e05cfc2e49ae..1e313982af02 100644
> > --- a/security/keys/encrypted-keys/encrypted.c
> > +++ b/security/keys/encrypted-keys/encrypted.c
> > @@ -627,7 +627,7 @@ static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
> > pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n");
> > return ERR_PTR(-EINVAL);
> > }
> > - if (strlen(decrypted_data) != decrypted_datalen) {
> > + if (strlen(decrypted_data) != decrypted_datalen * 2) {
> > pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n");
> > return ERR_PTR(-EINVAL);
> > }
> > @@ -791,8 +791,8 @@ static int encrypted_init(struct encrypted_key_payload *epayload,
> > ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
> > } else if (decrypted_data) {
> > get_random_bytes(epayload->iv, ivsize);
> > - memcpy(epayload->decrypted_data, decrypted_data,
> > - epayload->decrypted_datalen);
> > + ret = hex2bin(epayload->decrypted_data, decrypted_data,
> > + epayload->decrypted_datalen);
> > } else {
> > get_random_bytes(epayload->iv, ivsize);
> > get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);
> > --
> > 2.34.1
> >
>
>
> Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>
>
> Unless there is opposing views, I can pick this.
Actually, taking this back: please fix the checkpatch warnings first.
BR, Jarkko
