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, 5 insertions, 8 deletions

diff --git a/arch/mips/lasat/sysctl.c b/arch/mips/lasat/sysctl.c
index e666fe26c50d..2119541a5b8b 100644
--- a/arch/mips/lasat/sysctl.c
+++ b/arch/mips/lasat/sysctl.c
@@ -95,16 +95,15 @@ int proc_lasat_ip(struct ctl_table *table, int write,
 		len = 0;
 		p = buffer;
 		while (len < *lenp) {
-			if (get_user(c, p++))
-				return -EFAULT;
+			c = *p;
+			p++;
 			if (c == 0 || c == '\n')
 				break;
 			len++;
 		}
 		if (len >= sizeof(ipbuf)-1)
 			len = sizeof(ipbuf) - 1;
-		if (copy_from_user(ipbuf, buffer, len))
-			return -EFAULT;
+		memcpy(ipbuf, buffer, len);
 		ipbuf[len] = 0;
 		*ppos += *lenp;
 		/* Now see if we can convert it to a valid IP */
@@ -122,11 +121,9 @@ int proc_lasat_ip(struct ctl_table *table, int write,
 		if (len > *lenp)
 			len = *lenp;
 		if (len)
-			if (copy_to_user(buffer, ipbuf, len))
-				return -EFAULT;
+			memcpy(buffer, ipbuf, len);
 		if (len < *lenp) {
-			if (put_user('\n', ((char *) buffer) + len))
-				return -EFAULT;
+			*((char *)buffer + len) = '\n';
 			len++;
 		}
 		*lenp = len;