netdev - [PATCH net-next] filter: do not output bpf image address for security reason

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Date:	Fri, 17 May 2013 16:31:39 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Daniel Borkmann <dborkman@...hat.com>
Subject: [PATCH net-next] filter: do not output bpf image address for
 security reason

From: Eric Dumazet <edumazet@...gle.com>

Do not leak starting address of BPF JIT code, as it might help
intruders to perform an attack.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Daniel Borkmann <dborkman@...hat.com>
---
 include/linux/filter.h |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index c050dcc..08cda1c 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -58,10 +58,11 @@ extern void bpf_jit_free(struct sk_filter *fp);
 static inline void bpf_jit_dump(unsigned int flen, unsigned int proglen,
 				u32 pass, void *image)
 {
-	pr_err("flen=%u proglen=%u pass=%u image=%p\n",
-	       flen, proglen, pass, image);
+	/* Do not output address (image) for security reason */
+	pr_err("flen=%u proglen=%u pass=%u image=10\n",
+	       flen, proglen, pass);
 	if (image)
-		print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_ADDRESS,
+		print_hex_dump(KERN_ERR, "JIT code: ", DUMP_PREFIX_OFFSET,
 			       16, 1, image, proglen, false);
 }
 #define SK_RUN_FILTER(FILTER, SKB) (*FILTER->bpf_func)(SKB, FILTER->insns)


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