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* [PATCH v2 0/3] netlink: allow NLA_BINARY length range validation
@ 2020-08-18  8:17 Johannes Berg
  2020-08-18  8:17 ` [PATCH v2 1/3] netlink: consistently use NLA_POLICY_EXACT_LEN() Johannes Berg
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Johannes Berg @ 2020-08-18  8:17 UTC (permalink / raw)
  To: netdev

In quite a few places (perhaps particularly in wireless) we need to
validation an NLA_BINARY attribute with both a minimum and a maximum
length. Currently, we can do either of the two, but not both, given
that we have NLA_MIN_LEN (minimum length) and NLA_BINARY (maximum).

Extend the range mechanisms that we use for integer validation to
apply to NLA_BINARY as well.

After converting everything to use NLA_POLICY_MIN_LEN() we can thus
get rid of the NLA_MIN_LEN type since that's now a special case of
NLA_BINARY with a minimum length validation. Similarly, NLA_EXACT_LEN
can be specified using NLA_POLICY_EXACT_LEN() and also maps to the
new NLA_BINARY validation (min == max == desired length).

Finally, NLA_POLICY_EXACT_LEN_WARN() also gets to be a somewhat
special case of this.

I haven't included the patch here now that converts nl82011 to use
this because it doesn't apply without another cleanup patch, but
we can remove a number of hand-coded min/max length checks and get
better error messages from the general validation code while doing
that.

As I had originally built the netlink policy export to userspace in
a way that has min/max length for NLA_BINARY (for the types that we
used to call NLA_MIN_LEN, NLA_BINARY and NLA_EXACT_LEN) anyway, it
doesn't really change anything there except that now there's a chance
that userspace sees min length < max length, which previously wasn't
possible.


v2:
 * fix the min<max comment to correctly say min<=max

johannes



^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2020-08-18 19:29 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-08-18  8:17 [PATCH v2 0/3] netlink: allow NLA_BINARY length range validation Johannes Berg
2020-08-18  8:17 ` [PATCH v2 1/3] netlink: consistently use NLA_POLICY_EXACT_LEN() Johannes Berg
2020-08-18  8:53   ` Matthieu Baerts
2020-08-18  8:17 ` [PATCH v2 2/3] netlink: consistently use NLA_POLICY_MIN_LEN() Johannes Berg
2020-08-18  8:17 ` [PATCH v2 3/3] netlink: make NLA_BINARY validation more flexible Johannes Berg
2020-08-18 19:29 ` [PATCH v2 0/3] netlink: allow NLA_BINARY length range validation David Miller

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