sysctl: pass kernel pointers to ->proc_handler

Instead of having all the sysctl handlers deal with user pointers, which
is rather hairy in terms of the BPF interaction, copy the input to and
from  userspace in common code.  This also means that the strings are
always NUL-terminated by the common code, making the API a little bit
safer.

As most handler just pass through the data to one of the common handlers
a lot of the changes are mechnical.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 11 insertions, 23 deletions

diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index cca7ae712995..65abcf1b3210 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -160,8 +160,8 @@ static int max_t3[] = { 8191 }; /* Must fit in 16 bits when multiplied by BCT3MU
 static int min_priority[1];
 static int max_priority[] = { 127 }; /* From DECnet spec */
 
-static int dn_forwarding_proc(struct ctl_table *, int,
-			void __user *, size_t *, loff_t *);
+static int dn_forwarding_proc(struct ctl_table *, int, void *, size_t *,
+		loff_t *);
 static struct dn_dev_sysctl_table {
 	struct ctl_table_header *sysctl_header;
 	struct ctl_table dn_dev_vars[5];
@@ -245,8 +245,7 @@ static void dn_dev_sysctl_unregister(struct dn_dev_parms *parms)
 }
 
 static int dn_forwarding_proc(struct ctl_table *table, int write,
-				void __user *buffer,
-				size_t *lenp, loff_t *ppos)
+		void *buffer, size_t *lenp, loff_t *ppos)
 {
 #ifdef CONFIG_DECNET_ROUTER
 	struct net_device *dev = table->extra1;
diff --git a/net/decnet/sysctl_net_decnet.c b/net/decnet/sysctl_net_decnet.c
index 55bf64a22b59..deae519bdeec 100644
--- a/net/decnet/sysctl_net_decnet.c
+++ b/net/decnet/sysctl_net_decnet.c
@@ -134,8 +134,7 @@ static int parse_addr(__le16 *addr, char *str)
 }
 
 static int dn_node_address_handler(struct ctl_table *table, int write,
-				void __user *buffer,
-				size_t *lenp, loff_t *ppos)
+		void *buffer, size_t *lenp, loff_t *ppos)
 {
 	char addr[DN_ASCBUF_LEN];
 	size_t len;
@@ -148,10 +147,7 @@ static int dn_node_address_handler(struct ctl_table *table, int write,
 
 	if (write) {
 		len = (*lenp < DN_ASCBUF_LEN) ? *lenp : (DN_ASCBUF_LEN-1);
-
-		if (copy_from_user(addr, buffer, len))
-			return -EFAULT;
-
+		memcpy(addr, buffer, len);
 		addr[len] = 0;
 		strip_it(addr);
 
@@ -173,11 +169,9 @@ static int dn_node_address_handler(struct ctl_table *table, int write,
 	len = strlen(addr);
 	addr[len++] = '\n';
 
-	if (len > *lenp) len = *lenp;
-
-	if (copy_to_user(buffer, addr, len))
-		return -EFAULT;
-
+	if (len > *lenp)
+		len = *lenp;
+	memcpy(buffer, addr, len);
 	*lenp = len;
 	*ppos += len;
 
@@ -185,8 +179,7 @@ static int dn_node_address_handler(struct ctl_table *table, int write,
 }
 
 static int dn_def_dev_handler(struct ctl_table *table, int write,
-				void __user *buffer,
-				size_t *lenp, loff_t *ppos)
+		void *buffer, size_t *lenp, loff_t *ppos)
 {
 	size_t len;
 	struct net_device *dev;
@@ -201,9 +194,7 @@ static int dn_def_dev_handler(struct ctl_table *table, int write,
 		if (*lenp > 16)
 			return -E2BIG;
 
-		if (copy_from_user(devname, buffer, *lenp))
-			return -EFAULT;
-
+		memcpy(devname, buffer, *lenp);
 		devname[*lenp] = 0;
 		strip_it(devname);
 
@@ -238,9 +229,7 @@ static int dn_def_dev_handler(struct ctl_table *table, int write,
 
 	if (len > *lenp) len = *lenp;
 
-	if (copy_to_user(buffer, devname, len))
-		return -EFAULT;
-
+	memcpy(buffer, devname, len);
 	*lenp = len;
 	*ppos += len;