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authorDan Rosenberg <drosenberg@vsecurity.com>2011-05-23 12:17:35 +0000
committerDavid S. Miller <davem@davemloft.net>2011-05-24 01:13:12 -0400
commit71338aa7d050c86d8765cd36e46be514fb0ebbce (patch)
tree96bacb805b939c490145b31b4e2fb9e5cea79c5d /net/atm/proc.c
parent229de618ba6ff36e382b908b7637fe56c25ae9f1 (diff)
downloadlinux-71338aa7d050c86d8765cd36e46be514fb0ebbce.tar.gz
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 <drosenberg@vsecurity.com> Cc: James Morris <jmorris@namei.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Thomas Graf <tgraf@infradead.org> Cc: Eugene Teo <eugeneteo@kernel.org> Cc: Kees Cook <kees.cook@canonical.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: David S. Miller <davem@davemloft.net> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Paris <eparis@parisplace.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/atm/proc.c')
-rw-r--r--net/atm/proc.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/net/atm/proc.c b/net/atm/proc.c
index f85da0779e5..be3afdefec5 100644
--- a/net/atm/proc.c
+++ b/net/atm/proc.c
@@ -191,7 +191,7 @@ static void vcc_info(struct seq_file *seq, struct atm_vcc *vcc)
{
struct sock *sk = sk_atm(vcc);
- seq_printf(seq, "%p ", vcc);
+ seq_printf(seq, "%pK ", vcc);
if (!vcc->dev)
seq_printf(seq, "Unassigned ");
else
@@ -218,7 +218,7 @@ static void svc_info(struct seq_file *seq, struct atm_vcc *vcc)
{
if (!vcc->dev)
seq_printf(seq, sizeof(void *) == 4 ?
- "N/A@%p%10s" : "N/A@%p%2s", vcc, "");
+ "N/A@%pK%10s" : "N/A@%pK%2s", vcc, "");
else
seq_printf(seq, "%3d %3d %5d ",
vcc->dev->number, vcc->vpi, vcc->vci);