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>

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);

net/can/bcm.c

@@ -165,9 +165,9 @@ static int bcm_proc_show(struct seq_file *m, void *v)
 	struct bcm_sock *bo = bcm_sk(sk);
 	struct bcm_op *op;
 
-	seq_printf(m, ">>> socket %p", sk->sk_socket);
-	seq_printf(m, " / sk %p", sk);
-	seq_printf(m, " / bo %p", bo);
+	seq_printf(m, ">>> socket %pK", sk->sk_socket);
+	seq_printf(m, " / sk %pK", sk);
+	seq_printf(m, " / bo %pK", bo);
 	seq_printf(m, " / dropped %lu", bo->dropped_usr_msgs);
 	seq_printf(m, " / bound %s", bcm_proc_getifname(ifname, bo->ifindex));
 	seq_printf(m, " <<<\n");

net/ipv4/raw.c

@@ -979,7 +979,7 @@ static void raw_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
 	      srcp  = inet->inet_num;
 
 	seq_printf(seq, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d\n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d\n",
 		i, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),

net/ipv4/tcp_ipv4.c

@@ -2371,7 +2371,7 @@ static void get_openreq4(struct sock *sk, struct request_sock *req,
 	int ttd = req->expires - jiffies;
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %p%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %u %d %pK%n",
 		i,
 		ireq->loc_addr,
 		ntohs(inet_sk(sk)->inet_sport),
@@ -2426,7 +2426,7 @@ static void get_tcp4_sock(struct sock *sk, struct seq_file *f, int i, int *len)
 		rx_queue = max_t(int, tp->rcv_nxt - tp->copied_seq, 0);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X %02X %08X:%08X %02X:%08lX "
-			"%08X %5d %8d %lu %d %p %lu %lu %u %u %d%n",
+			"%08X %5d %8d %lu %d %pK %lu %lu %u %u %d%n",
 		i, src, srcp, dest, destp, sk->sk_state,
 		tp->write_seq - tp->snd_una,
 		rx_queue,
@@ -2461,7 +2461,7 @@ static void get_timewait4_sock(struct inet_timewait_sock *tw,
 	srcp  = ntohs(tw->tw_sport);
 
 	seq_printf(f, "%4d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK%n",
 		i, src, srcp, dest, destp, tw->tw_substate, 0, 0,
 		3, jiffies_to_clock_t(ttd), 0, 0, 0, 0,
 		atomic_read(&tw->tw_refcnt), tw, len);

net/ipv4/udp.c

@@ -2090,7 +2090,7 @@ static void udp4_format_sock(struct sock *sp, struct seq_file *f,
 	__u16 srcp	  = ntohs(inet->inet_sport);
 
 	seq_printf(f, "%5d: %08X:%04X %08X:%04X"
-		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d%n",
+		" %02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d%n",
 		bucket, src, srcp, dest, destp, sp->sk_state,
 		sk_wmem_alloc_get(sp),
 		sk_rmem_alloc_get(sp),

net/ipv6/raw.c

@@ -1240,7 +1240,7 @@ static void raw6_sock_seq_show(struct seq_file *seq, struct sock *sp, int i)
 	srcp  = inet_sk(sp)->inet_num;
 	seq_printf(seq,
 		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
-		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d\n",
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d\n",
 		   i,
 		   src->s6_addr32[0], src->s6_addr32[1],
 		   src->s6_addr32[2], src->s6_addr32[3], srcp,

net/ipv6/tcp_ipv6.c

@@ -2036,7 +2036,7 @@ static void get_openreq6(struct seq_file *seq,
 
 	seq_printf(seq,
 		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
-		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p\n",
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
 		   i,
 		   src->s6_addr32[0], src->s6_addr32[1],
 		   src->s6_addr32[2], src->s6_addr32[3],
@@ -2087,7 +2087,7 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i)
 
 	seq_printf(seq,
 		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
-		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %lu %lu %u %u %d\n",
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %lu %lu %u %u %d\n",
 		   i,
 		   src->s6_addr32[0], src->s6_addr32[1],
 		   src->s6_addr32[2], src->s6_addr32[3], srcp,
@@ -2129,7 +2129,7 @@ static void get_timewait6_sock(struct seq_file *seq,
 
 	seq_printf(seq,
 		   "%4d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
-		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %p\n",
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %d %d %pK\n",
 		   i,
 		   src->s6_addr32[0], src->s6_addr32[1],
 		   src->s6_addr32[2], src->s6_addr32[3], srcp,

net/ipv6/udp.c

@@ -1391,7 +1391,7 @@ static void udp6_sock_seq_show(struct seq_file *seq, struct sock *sp, int bucket
 	srcp  = ntohs(inet->inet_sport);
 	seq_printf(seq,
 		   "%5d: %08X%08X%08X%08X:%04X %08X%08X%08X%08X:%04X "
-		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %p %d\n",
+		   "%02X %08X:%08X %02X:%08lX %08X %5d %8d %lu %d %pK %d\n",
 		   bucket,
 		   src->s6_addr32[0], src->s6_addr32[1],
 		   src->s6_addr32[2], src->s6_addr32[3], srcp,

net/key/af_key.c

@@ -3656,7 +3656,7 @@ static int pfkey_seq_show(struct seq_file *f, void *v)
 	if (v == SEQ_START_TOKEN)
 		seq_printf(f ,"sk       RefCnt Rmem   Wmem   User   Inode\n");
 	else
-		seq_printf(f ,"%p %-6d %-6u %-6u %-6u %-6lu\n",
+		seq_printf(f, "%pK %-6d %-6u %-6u %-6u %-6lu\n",
 			       s,
 			       atomic_read(&s->sk_refcnt),
 			       sk_rmem_alloc_get(s),

net/netlink/af_netlink.c

@@ -1985,7 +1985,7 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
 		struct sock *s = v;
 		struct netlink_sock *nlk = nlk_sk(s);
 
-		seq_printf(seq, "%p %-3d %-6d %08x %-8d %-8d %p %-8d %-8d %-8lu\n",
+		seq_printf(seq, "%pK %-3d %-6d %08x %-8d %-8d %pK %-8d %-8d %-8lu\n",
 			   s,
 			   s->sk_protocol,
 			   nlk->pid,

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,

net/phonet/socket.c

@@ -607,7 +607,7 @@ static int pn_sock_seq_show(struct seq_file *seq, void *v)
 		struct pn_sock *pn = pn_sk(sk);
 
 		seq_printf(seq, "%2d %04X:%04X:%02X %02X %08X:%08X %5d %lu "
-			"%d %p %d%n",
+			"%d %pK %d%n",
 			sk->sk_protocol, pn->sobject, pn->dobject,
 			pn->resource, sk->sk_state,
 			sk_wmem_alloc_get(sk), sk_rmem_alloc_get(sk),

net/sctp/proc.c

@@ -212,7 +212,7 @@ static int sctp_eps_seq_show(struct seq_file *seq, void *v)
 	sctp_for_each_hentry(epb, node, &head->chain) {
 		ep = sctp_ep(epb);
 		sk = epb->sk;
-		seq_printf(seq, "%8p %8p %-3d %-3d %-4d %-5d %5d %5lu ", ep, sk,
+		seq_printf(seq, "%8pK %8pK %-3d %-3d %-4d %-5d %5d %5lu ", ep, sk,
 			   sctp_sk(sk)->type, sk->sk_state, hash,
 			   epb->bind_addr.port,
 			   sock_i_uid(sk), sock_i_ino(sk));
@@ -316,7 +316,7 @@ static int sctp_assocs_seq_show(struct seq_file *seq, void *v)
 		assoc = sctp_assoc(epb);
 		sk = epb->sk;
 		seq_printf(seq,
-			   "%8p %8p %-3d %-3d %-2d %-4d "
+			   "%8pK %8pK %-3d %-3d %-2d %-4d "
 			   "%4d %8d %8d %7d %5lu %-5d %5d ",
 			   assoc, sk, sctp_sk(sk)->type, sk->sk_state,
 			   assoc->state, hash,

net/unix/af_unix.c

@@ -2254,7 +2254,7 @@ static int unix_seq_show(struct seq_file *seq, void *v)
 		struct unix_sock *u = unix_sk(s);
 		unix_state_lock(s);
 
-		seq_printf(seq, "%p: %08X %08X %08X %04X %02X %5lu",
+		seq_printf(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
 			s,
 			atomic_read(&s->sk_refcnt),
 			0,