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, 16 insertions, 20 deletions

diff --git a/net/sunrpc/sysctl.c b/net/sunrpc/sysctl.c
index d75f17b56f0e..999eee1ed61c 100644
--- a/net/sunrpc/sysctl.c
+++ b/net/sunrpc/sysctl.c
@@ -60,7 +60,7 @@ rpc_unregister_sysctl(void)
 }
 
 static int proc_do_xprt(struct ctl_table *table, int write,
-			void __user *buffer, size_t *lenp, loff_t *ppos)
+			void *buffer, size_t *lenp, loff_t *ppos)
 {
 	char tmpbuf[256];
 	size_t len;
@@ -70,15 +70,15 @@ static int proc_do_xprt(struct ctl_table *table, int write,
 		return 0;
 	}
 	len = svc_print_xprts(tmpbuf, sizeof(tmpbuf));
-	return simple_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
+	return memory_read_from_buffer(buffer, *lenp, ppos, tmpbuf, len);
 }
 
 static int
-proc_dodebug(struct ctl_table *table, int write,
-				void __user *buffer, size_t *lenp, loff_t *ppos)
+proc_dodebug(struct ctl_table *table, int write, void *buffer, size_t *lenp,
+	     loff_t *ppos)
 {
-	char		tmpbuf[20], c, *s = NULL;
-	char __user *p;
+	char		tmpbuf[20], *s = NULL;
+	char *p;
 	unsigned int	value;
 	size_t		left, len;
 
@@ -90,18 +90,17 @@ proc_dodebug(struct ctl_table *table, int write,
 	left = *lenp;
 
 	if (write) {
-		if (!access_ok(buffer, left))
-			return -EFAULT;
 		p = buffer;
-		while (left && __get_user(c, p) >= 0 && isspace(c))
-			left--, p++;
+		while (left && isspace(*p)) {
+			left--;
+			p++;
+		}
 		if (!left)
 			goto done;
 
 		if (left > sizeof(tmpbuf) - 1)
 			return -EINVAL;
-		if (copy_from_user(tmpbuf, p, left))
-			return -EFAULT;
+		memcpy(tmpbuf, p, left);
 		tmpbuf[left] = '\0';
 
 		value = simple_strtol(tmpbuf, &s, 0);
@@ -121,11 +120,9 @@ proc_dodebug(struct ctl_table *table, int write,
 		len = sprintf(tmpbuf, "0x%04x", *(unsigned int *) table->data);
 		if (len > left)
 			len = left;
-		if (copy_to_user(buffer, tmpbuf, len))
-			return -EFAULT;
+		memcpy(buffer, tmpbuf, len);
 		if ((left -= len) > 0) {
-			if (put_user('\n', (char __user *)buffer + len))
-				return -EFAULT;
+			*((char *)buffer + len) = '\n';
 			left--;
 		}
 	}
diff --git a/net/sunrpc/xprtrdma/svc_rdma.c b/net/sunrpc/xprtrdma/svc_rdma.c
index 97bca509a391..526da5d4710b 100644
--- a/net/sunrpc/xprtrdma/svc_rdma.c
+++ b/net/sunrpc/xprtrdma/svc_rdma.c
@@ -80,8 +80,7 @@ atomic_t rdma_stat_sq_prod;
  * current value.
  */
 static int read_reset_stat(struct ctl_table *table, int write,
-			   void __user *buffer, size_t *lenp,
-			   loff_t *ppos)
+			   void *buffer, size_t *lenp, loff_t *ppos)
 {
 	atomic_t *stat = (atomic_t *)table->data;
 
@@ -103,8 +102,8 @@ static int read_reset_stat(struct ctl_table *table, int write,
 		len -= *ppos;
 		if (len > *lenp)
 			len = *lenp;
-		if (len && copy_to_user(buffer, str_buf, len))
-			return -EFAULT;
+		if (len)
+			memcpy(buffer, str_buf, len);
 		*lenp = len;
 		*ppos += len;
 	}