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pf: Make tag hashing more robust

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tagname2tag() hashes the tag name before truncating it to 63 characters.
tag_unref() removes the tag from the name hash by computing the hash
over the truncated name.  Ensure that both operations compute the same
hash for a given tag.

The larger issue is a lack of string validation in pf(4) ioctl handlers.
This is intended to be fixed with some future work, but an extra safety
belt in tagname2hashindex() is worthwhile regardless.

Reported by:	syzbot+a0988828aafb00de7d68@syzkaller.appspotmail.com
Reviewed by:	kp
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D27346
This commit is contained in:
Mark Johnston 2020-11-24 16:18:47 +00:00
parent 384d27e04d
commit 5d49283f88
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=367987
1 changed files with 3 additions and 1 deletions
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4
sys/netpfil/pf/pf_ioctl.c
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@ -512,8 +512,10 @@ pf_cleanup_tagset(struct pf_tagset *ts)
static uint16_t
tagname2hashindex(const struct pf_tagset *ts, const char *tagname)
{
size_t len;
return (murmur3_32_hash(tagname, strlen(tagname), ts->seed) & ts->mask);
len = strnlen(tagname, PF_TAG_NAME_SIZE - 1);
return (murmur3_32_hash(tagname, len, ts->seed) & ts->mask);
}
static uint16_t