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psd: add basic validation of userspace matchinfo data

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psd multiplies weight_thresh by HZ, so it could overflow.

Userspace libxt_psd refuses values exceeding PSD_MAX_RATE, so check
that on kernel side, too.

Also, setting 0 weight for both privileged and highports will cause
psd to never match at all.

Reject 0 weight threshold, too because it makes no sense (triggers
match for every initial packet).
This commit is contained in:
Florian Westphal
2012-06-02 21:13:58 +02:00
committed by Jan Engelhardt
parent ac58f2e94b
commit f6b8767228
2 changed files with 30 additions and 6 deletions
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2
doc/changelog.txt
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@@ -3,6 +3,8 @@ HEAD
==== ====
Fixes: Fixes:
- xt_psd: avoid crash due to curr->next corruption - xt_psd: avoid crash due to curr->next corruption
Changes:
- xt_psd: reject invalid match options
v1.42 (2012-04-05) v1.42 (2012-04-05)

34
extensions/xt_psd.c
View File

@@ -278,13 +278,35 @@ out_match:
return true; return true;
} }
static int psd_mt_check(const struct xt_mtchk_param *par)
{
const struct xt_psd_info *info = par->matchinfo;
if (info->weight_threshold == 0)
/* 0 would match on every 1st packet */
return -EINVAL;
if ((info->lo_ports_weight | info->hi_ports_weight) == 0)
/* would never match */
return -EINVAL;
if (info->delay_threshold > PSD_MAX_RATE ||
info->weight_threshold > PSD_MAX_RATE ||
info->lo_ports_weight > PSD_MAX_RATE ||
info->hi_ports_weight > PSD_MAX_RATE)
return -EINVAL;
return 0;
}
static struct xt_match xt_psd_reg __read_mostly = { static struct xt_match xt_psd_reg __read_mostly = {
.name = "psd", .name = "psd",
.family = NFPROTO_IPV4, .family = NFPROTO_IPV4,
.revision = 1, .revision = 1,
.match = xt_psd_match, .checkentry = psd_mt_check,
.matchsize = sizeof(struct xt_psd_info), .match = xt_psd_match,
.me = THIS_MODULE, .matchsize = sizeof(struct xt_psd_info),
.me = THIS_MODULE,
}; };
static int __init xt_psd_init(void) static int __init xt_psd_init(void)