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>

1 files changed, 8 insertions, 19 deletions

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;