security: don't use a negative Opt_err token index

security: don't use a negative Opt_err token index

The code uses a bitmap to check for duplicate tokens during parsing, and
that doesn't work at all for the negative Opt_err token case.

There is absolutely no reason to make Opt_err be negative, and in fact
it only confuses things, since some of the affected functions actually
return a positive Opt_xyz enum _or_ a regular negative error code (eg
-EINVAL), and using -1 for Opt_err makes no sense.

There are similar problems in ima_policy.c and key encryption, but they
don't have the immediate bug wrt bitmap handing, and ima_policy.c in
particular needs a different patch to make the enum values match the
token array index.  Mimi is sending that separately.

Reported-by: [email protected]
Reported-by: Eric Biggers <[email protected]>
Fixes: 5208cc83423d ("keys, trusted: fix: *do not* allow duplicate key options")
Fixes: 00d60fd3b932 ("KEYS: Provide keyctls to drive the new key type ops for asymmetric keys [ver #2]")
Cc: James Morris James Morris <[email protected]>
Cc: Mimi Zohar <[email protected]>
Cc: Jarkko Sakkinen <[email protected]>
Cc: Peter Huewe <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>