From 71338aa7d050c86d8765cd36e46be514fb0ebbce Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Mon, 23 May 2011 12:17:35 +0000 Subject: net: convert %p usage to %pK The %pK format specifier is designed to hide exposed kernel pointers, specifically via /proc interfaces. Exposing these pointers provides an easy target for kernel write vulnerabilities, since they reveal the locations of writable structures containing easily triggerable function pointers. The behavior of %pK depends on the kptr_restrict sysctl. If kptr_restrict is set to 0, no deviation from the standard %p behavior occurs. If kptr_restrict is set to 1, the default, if the current user (intended to be a reader via seq_printf(), etc.) does not have CAP_SYSLOG (currently in the LSM tree), kernel pointers using %pK are printed as 0's. If kptr_restrict is set to 2, kernel pointers using %pK are printed as 0's regardless of privileges. Replacing with 0's was chosen over the default "(null)", which cannot be parsed by userland %p, which expects "(nil)". The supporting code for kptr_restrict and %pK are currently in the -mm tree. This patch converts users of %p in net/ to %pK. Cases of printing pointers to the syslog are not covered, since this would eliminate useful information for postmortem debugging and the reading of the syslog is already optionally protected by the dmesg_restrict sysctl. Signed-off-by: Dan Rosenberg Cc: James Morris Cc: Eric Dumazet Cc: Thomas Graf Cc: Eugene Teo Cc: Kees Cook Cc: Ingo Molnar Cc: David S. Miller Cc: Peter Zijlstra Cc: Eric Paris Signed-off-by: Andrew Morton Signed-off-by: David S. Miller --- net/packet/af_packet.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/packet') diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 549527bca87..925f715686a 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2706,7 +2706,7 @@ static int packet_seq_show(struct seq_file *seq, void *v) const struct packet_sock *po = pkt_sk(s); seq_printf(seq, - "%p %-6d %-4d %04x %-5d %1d %-6u %-6u %-6lu\n", + "%pK %-6d %-4d %04x %-5d %1d %-6u %-6u %-6lu\n", s, atomic_read(&s->sk_refcnt), s->sk_type, -- cgit v1.2.3-18-g5258