From acc738fec03bdaa5b77340c32a82fbfedaaabef0 Mon Sep 17 00:00:00 2001 From: Jan Engelhardt Date: Mon, 16 Mar 2009 15:35:29 +0100 Subject: [PATCH] netfilter: xtables: avoid pointer to self Commit 784544739a25c30637397ace5489eeb6e15d7d49 (netfilter: iptables: lock free counters) broke a number of modules whose rule data referenced itself. A reallocation would not reestablish the correct references, so it is best to use a separate struct that does not fall under RCU. Signed-off-by: Jan Engelhardt Signed-off-by: Patrick McHardy --- include/linux/netfilter/xt_limit.h | 9 ++++---- include/linux/netfilter/xt_quota.h | 4 +++- include/linux/netfilter/xt_statistic.h | 7 +++--- net/netfilter/xt_limit.c | 40 ++++++++++++++++++++++++---------- net/netfilter/xt_quota.c | 31 ++++++++++++++++++++------ net/netfilter/xt_statistic.c | 28 +++++++++++++++++++----- 6 files changed, 88 insertions(+), 31 deletions(-) diff --git a/include/linux/netfilter/xt_limit.h b/include/linux/netfilter/xt_limit.h index b3ce653..fda222c 100644 --- a/include/linux/netfilter/xt_limit.h +++ b/include/linux/netfilter/xt_limit.h @@ -4,6 +4,8 @@ /* timings are in milliseconds. */ #define XT_LIMIT_SCALE 10000 +struct xt_limit_priv; + /* 1/10,000 sec period => max of 10,000/sec. Min rate is then 429490 seconds, or one every 59 hours. */ struct xt_rateinfo { @@ -11,11 +13,10 @@ struct xt_rateinfo { u_int32_t burst; /* Period multiplier for upper limit. */ /* Used internally by the kernel */ - unsigned long prev; - u_int32_t credit; + unsigned long prev; /* moved to xt_limit_priv */ + u_int32_t credit; /* moved to xt_limit_priv */ u_int32_t credit_cap, cost; - /* Ugly, ugly fucker. */ - struct xt_rateinfo *master; + struct xt_limit_priv *master; }; #endif /*_XT_RATE_H*/ diff --git a/include/linux/netfilter/xt_quota.h b/include/linux/netfilter/xt_quota.h index 4c8368d..8dc89df 100644 --- a/include/linux/netfilter/xt_quota.h +++ b/include/linux/netfilter/xt_quota.h @@ -6,13 +6,15 @@ enum xt_quota_flags { }; #define XT_QUOTA_MASK 0x1 +struct xt_quota_priv; + struct xt_quota_info { u_int32_t flags; u_int32_t pad; /* Used internally by the kernel */ aligned_u64 quota; - struct xt_quota_info *master; + struct xt_quota_priv *master; }; #endif /* _XT_QUOTA_H */ diff --git a/include/linux/netfilter/xt_statistic.h b/include/linux/netfilter/xt_statistic.h index 3d38bc9..8f521ab 100644 --- a/include/linux/netfilter/xt_statistic.h +++ b/include/linux/netfilter/xt_statistic.h @@ -13,6 +13,8 @@ enum xt_statistic_flags { }; #define XT_STATISTIC_MASK 0x1 +struct xt_statistic_priv; + struct xt_statistic_info { u_int16_t mode; u_int16_t flags; @@ -23,11 +25,10 @@ struct xt_statistic_info { struct { u_int32_t every; u_int32_t packet; - /* Used internally by the kernel */ - u_int32_t count; + u_int32_t count; /* unused */ } nth; } u; - struct xt_statistic_info *master __attribute__((aligned(8))); + struct xt_statistic_priv *master __attribute__((aligned(8))); }; #endif /* _XT_STATISTIC_H */ diff --git a/net/netfilter/xt_limit.c b/net/netfilter/xt_limit.c index c908d69..2e8089e 100644 --- a/net/netfilter/xt_limit.c +++ b/net/netfilter/xt_limit.c @@ -14,6 +14,11 @@ #include #include +struct xt_limit_priv { + unsigned long prev; + uint32_t credit; +}; + MODULE_LICENSE("GPL"); MODULE_AUTHOR("Herve Eychenne "); MODULE_DESCRIPTION("Xtables: rate-limit match"); @@ -60,18 +65,18 @@ static DEFINE_SPINLOCK(limit_lock); static bool limit_mt(const struct sk_buff *skb, const struct xt_match_param *par) { - struct xt_rateinfo *r = - ((const struct xt_rateinfo *)par->matchinfo)->master; + const struct xt_rateinfo *r = par->matchinfo; + struct xt_limit_priv *priv = r->master; unsigned long now = jiffies; spin_lock_bh(&limit_lock); - r->credit += (now - xchg(&r->prev, now)) * CREDITS_PER_JIFFY; - if (r->credit > r->credit_cap) - r->credit = r->credit_cap; + priv->credit += (now - xchg(&priv->prev, now)) * CREDITS_PER_JIFFY; + if (priv->credit > r->credit_cap) + priv->credit = r->credit_cap; - if (r->credit >= r->cost) { + if (priv->credit >= r->cost) { /* We're not limited. */ - r->credit -= r->cost; + priv->credit -= r->cost; spin_unlock_bh(&limit_lock); return true; } @@ -95,6 +100,7 @@ user2credits(u_int32_t user) static bool limit_mt_check(const struct xt_mtchk_param *par) { struct xt_rateinfo *r = par->matchinfo; + struct xt_limit_priv *priv; /* Check for overflow. */ if (r->burst == 0 @@ -104,19 +110,30 @@ static bool limit_mt_check(const struct xt_mtchk_param *par) return false; } - /* For SMP, we only want to use one set of counters. */ - r->master = r; + priv = kmalloc(sizeof(*priv), GFP_KERNEL); + if (priv == NULL) + return -ENOMEM; + + /* For SMP, we only want to use one set of state. */ + r->master = priv; if (r->cost == 0) { /* User avg in seconds * XT_LIMIT_SCALE: convert to jiffies * 128. */ - r->prev = jiffies; - r->credit = user2credits(r->avg * r->burst); /* Credits full. */ + priv->prev = jiffies; + priv->credit = user2credits(r->avg * r->burst); /* Credits full. */ r->credit_cap = user2credits(r->avg * r->burst); /* Credits full. */ r->cost = user2credits(r->avg); } return true; } +static void limit_mt_destroy(const struct xt_mtdtor_param *par) +{ + const struct xt_rateinfo *info = par->matchinfo; + + kfree(info->master); +} + #ifdef CONFIG_COMPAT struct compat_xt_rateinfo { u_int32_t avg; @@ -167,6 +184,7 @@ static struct xt_match limit_mt_reg __read_mostly = { .family = NFPROTO_UNSPEC, .match = limit_mt, .checkentry = limit_mt_check, + .destroy = limit_mt_destroy, .matchsize = sizeof(struct xt_rateinfo), #ifdef CONFIG_COMPAT .compatsize = sizeof(struct compat_xt_rateinfo), diff --git a/net/netfilter/xt_quota.c b/net/netfilter/xt_quota.c index c84fce5..01dd07b 100644 --- a/net/netfilter/xt_quota.c +++ b/net/netfilter/xt_quota.c @@ -9,6 +9,10 @@ #include #include +struct xt_quota_priv { + uint64_t quota; +}; + MODULE_LICENSE("GPL"); MODULE_AUTHOR("Sam Johnston "); MODULE_DESCRIPTION("Xtables: countdown quota match"); @@ -20,18 +24,20 @@ static DEFINE_SPINLOCK(quota_lock); static bool quota_mt(const struct sk_buff *skb, const struct xt_match_param *par) { - struct xt_quota_info *q = - ((const struct xt_quota_info *)par->matchinfo)->master; + struct xt_quota_info *q = (void *)par->matchinfo; + struct xt_quota_priv *priv = q->master; bool ret = q->flags & XT_QUOTA_INVERT; spin_lock_bh("a_lock); - if (q->quota >= skb->len) { - q->quota -= skb->len; + if (priv->quota >= skb->len) { + priv->quota -= skb->len; ret = !ret; } else { /* we do not allow even small packets from now on */ - q->quota = 0; + priv->quota = 0; } + /* Copy quota back to matchinfo so that iptables can display it */ + q->quota = priv->quota; spin_unlock_bh("a_lock); return ret; @@ -43,17 +49,28 @@ static bool quota_mt_check(const struct xt_mtchk_param *par) if (q->flags & ~XT_QUOTA_MASK) return false; - /* For SMP, we only want to use one set of counters. */ - q->master = q; + + q->master = kmalloc(sizeof(*q->master), GFP_KERNEL); + if (q->master == NULL) + return -ENOMEM; + return true; } +static void quota_mt_destroy(const struct xt_mtdtor_param *par) +{ + const struct xt_quota_info *q = par->matchinfo; + + kfree(q->master); +} + static struct xt_match quota_mt_reg __read_mostly = { .name = "quota", .revision = 0, .family = NFPROTO_UNSPEC, .match = quota_mt, .checkentry = quota_mt_check, + .destroy = quota_mt_destroy, .matchsize = sizeof(struct xt_quota_info), .me = THIS_MODULE, }; diff --git a/net/netfilter/xt_statistic.c b/net/netfilter/xt_statistic.c index 0d75141..d8c0f8f 100644 --- a/net/netfilter/xt_statistic.c +++ b/net/netfilter/xt_statistic.c @@ -16,6 +16,10 @@ #include #include +struct xt_statistic_priv { + uint32_t count; +}; + MODULE_LICENSE("GPL"); MODULE_AUTHOR("Patrick McHardy "); MODULE_DESCRIPTION("Xtables: statistics-based matching (\"Nth\", random)"); @@ -27,7 +31,7 @@ static DEFINE_SPINLOCK(nth_lock); static bool statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) { - struct xt_statistic_info *info = (void *)par->matchinfo; + const struct xt_statistic_info *info = par->matchinfo; bool ret = info->flags & XT_STATISTIC_INVERT; switch (info->mode) { @@ -36,10 +40,9 @@ statistic_mt(const struct sk_buff *skb, const struct xt_match_param *par) ret = !ret; break; case XT_STATISTIC_MODE_NTH: - info = info->master; spin_lock_bh(&nth_lock); - if (info->u.nth.count++ == info->u.nth.every) { - info->u.nth.count = 0; + if (info->master->count++ == info->u.nth.every) { + info->master->count = 0; ret = !ret; } spin_unlock_bh(&nth_lock); @@ -56,16 +59,31 @@ static bool statistic_mt_check(const struct xt_mtchk_param *par) if (info->mode > XT_STATISTIC_MODE_MAX || info->flags & ~XT_STATISTIC_MASK) return false; - info->master = info; + + info->master = kzalloc(sizeof(*info->master), GFP_KERNEL); + if (info->master == NULL) { + printk(KERN_ERR KBUILD_MODNAME ": Out of memory\n"); + return false; + } + info->master->count = info->u.nth.count; + return true; } +static void statistic_mt_destroy(const struct xt_mtdtor_param *par) +{ + const struct xt_statistic_info *info = par->matchinfo; + + kfree(info->master); +} + static struct xt_match xt_statistic_mt_reg __read_mostly = { .name = "statistic", .revision = 0, .family = NFPROTO_UNSPEC, .match = statistic_mt, .checkentry = statistic_mt_check, + .destroy = statistic_mt_destroy, .matchsize = sizeof(struct xt_statistic_info), .me = THIS_MODULE, }; -- 1.8.2.3