On Wed, 2022-10-19 at 18:38 +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 > > However, NEWKEY is still broken: If for BROKENKEY 32 bytes were > specified, a brute force attacker knowing the key properties would only > need to try at most 2^(16*8) keys, as if the key was only 16 bytes long. > > The security issue is a result of the combination of limiting the input > range to hex-ascii and using memcpy() instead of hex2bin(). It could > have been fixed either by allowing binary input or using hex2bin() (and > doubling the ascii input key length). This patch implements the latter. > > 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@xxxxxxxxxx > Link: https://lore.kernel.org/ltp/20221006081709.92303897@xxxxxxxxxxxxxxxxxxx/ > Reviewed-by: Mimi Zohar <zohar@xxxxxxxxxxxxx> > Signed-off-by: Nikolaus Voss <nikolaus.voss@xxxxxxxxxxxxxxx> Thanks! This patch is now queued in next-integrity/next-integrity- testing. -- thanks, Mimi