59 lines
2.2 KiB
Diff
59 lines
2.2 KiB
Diff
From: Salvatore Bonaccorso <carnil@debian.org>
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Date: Sat, 28 Jul 2018 16:48:31 +0200
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Subject: [PATCH] Revert "net: increase fragment memory usage limits"
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This reverts commit c2a936600f78aea00d3312ea4b66a79a4619f9b4.
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Revert commit as mitigation to FragmentSmack (CVE-2018-5391)
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[bwh: Adjust context to apply to sid]
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---
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include/net/ipv6.h | 4 ++--
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net/ipv4/ip_fragment.c | 22 +++++++---------------
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2 files changed, 9 insertions(+), 17 deletions(-)
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--- a/include/net/ipv6.h
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+++ b/include/net/ipv6.h
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@@ -379,8 +379,8 @@ static inline bool ipv6_accept_ra(struct
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idev->cnf.accept_ra;
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}
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-#define IPV6_FRAG_HIGH_THRESH (4 * 1024*1024) /* 4194304 */
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-#define IPV6_FRAG_LOW_THRESH (3 * 1024*1024) /* 3145728 */
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+#define IPV6_FRAG_HIGH_THRESH (256 * 1024) /* 262144 */
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+#define IPV6_FRAG_LOW_THRESH (192 * 1024) /* 196608 */
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#define IPV6_FRAG_TIMEOUT (60 * HZ) /* 60 seconds */
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int __ipv6_addr_type(const struct in6_addr *addr);
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--- a/net/ipv4/ip_fragment.c
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+++ b/net/ipv4/ip_fragment.c
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@@ -788,22 +788,14 @@ static int __net_init ipv4_frags_init_ne
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{
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int res;
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- /* Fragment cache limits.
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- *
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- * The fragment memory accounting code, (tries to) account for
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- * the real memory usage, by measuring both the size of frag
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- * queue struct (inet_frag_queue (ipv4:ipq/ipv6:frag_queue))
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- * and the SKB's truesize.
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- *
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- * A 64K fragment consumes 129736 bytes (44*2944)+200
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- * (1500 truesize == 2944, sizeof(struct ipq) == 200)
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- *
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- * We will commit 4MB at one time. Should we cross that limit
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- * we will prune down to 3MB, making room for approx 8 big 64K
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- * fragments 8x128k.
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+ /*
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+ * Fragment cache limits. We will commit 256K at one time. Should we
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+ * cross that limit we will prune down to 192K. This should cope with
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+ * even the most extreme cases without allowing an attacker to
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+ * measurably harm machine performance.
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*/
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- net->ipv4.frags.high_thresh = 4 * 1024 * 1024;
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- net->ipv4.frags.low_thresh = 3 * 1024 * 1024;
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+ net->ipv4.frags.high_thresh = 256 * 1024;
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+ net->ipv4.frags.low_thresh = 192 * 1024;
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/*
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* Important NOTE! Fragment queue must be destroyed before MSL expires.
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* RFC791 is wrong proposing to prolongate timer each fragment arrival
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