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authorChristoph Hellwig <hch@lst.de>2020-07-23 08:09:08 +0200
committerDavid S. Miller <davem@davemloft.net>2020-07-24 15:41:54 -0700
commit6d04fe15f78acdf8e32329e208552e226f7a8ae6 (patch)
tree90ff9c419f8244651aa420349756cc371d539646
parenta7b75c5a8c41445f33efb663887ff5f5c3b4454b (diff)
downloadlinux-6d04fe15f78acdf8e32329e208552e226f7a8ae6.tar.bz2
net: optimize the sockptr_t for unified kernel/user address spaces
For architectures like x86 and arm64 we don't need the separate bit to indicate that a pointer is a kernel pointer as the address spaces are unified. That way the sockptr_t can be reduced to a union of two pointers, which leads to nicer calling conventions. The only caveat is that we need to check that users don't pass in kernel address and thus gain access to kernel memory. Thus the USER_SOCKPTR helper is replaced with a init_user_sockptr function that does this check and returns an error if it fails. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/linux/sockptr.h32
-rw-r--r--net/ipv4/bpfilter/sockopt.c14
-rw-r--r--net/socket.c6
3 files changed, 43 insertions, 9 deletions
diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
index 700856e13ea0..7d5cdb2b30b5 100644
--- a/include/linux/sockptr.h
+++ b/include/linux/sockptr.h
@@ -8,9 +8,34 @@
#ifndef _LINUX_SOCKPTR_H
#define _LINUX_SOCKPTR_H
+#include <linux/compiler.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
+#ifdef CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
+typedef union {
+ void *kernel;
+ void __user *user;
+} sockptr_t;
+
+static inline bool sockptr_is_kernel(sockptr_t sockptr)
+{
+ return (unsigned long)sockptr.kernel >= TASK_SIZE;
+}
+
+static inline sockptr_t KERNEL_SOCKPTR(void *p)
+{
+ return (sockptr_t) { .kernel = p };
+}
+
+static inline int __must_check init_user_sockptr(sockptr_t *sp, void __user *p)
+{
+ if ((unsigned long)p >= TASK_SIZE)
+ return -EFAULT;
+ sp->user = p;
+ return 0;
+}
+#else /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
typedef struct {
union {
void *kernel;
@@ -29,10 +54,13 @@ static inline sockptr_t KERNEL_SOCKPTR(void *p)
return (sockptr_t) { .kernel = p, .is_kernel = true };
}
-static inline sockptr_t USER_SOCKPTR(void __user *p)
+static inline int __must_check init_user_sockptr(sockptr_t *sp, void __user *p)
{
- return (sockptr_t) { .user = p };
+ sp->user = p;
+ sp->is_kernel = false;
+ return 0;
}
+#endif /* CONFIG_ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE */
static inline bool sockptr_is_null(sockptr_t sockptr)
{
diff --git a/net/ipv4/bpfilter/sockopt.c b/net/ipv4/bpfilter/sockopt.c
index 1b34cb9a7708..94f18d2352d0 100644
--- a/net/ipv4/bpfilter/sockopt.c
+++ b/net/ipv4/bpfilter/sockopt.c
@@ -57,16 +57,18 @@ int bpfilter_ip_set_sockopt(struct sock *sk, int optname, sockptr_t optval,
return bpfilter_mbox_request(sk, optname, optval, optlen, true);
}
-int bpfilter_ip_get_sockopt(struct sock *sk, int optname, char __user *optval,
- int __user *optlen)
+int bpfilter_ip_get_sockopt(struct sock *sk, int optname,
+ char __user *user_optval, int __user *optlen)
{
- int len;
+ sockptr_t optval;
+ int err, len;
if (get_user(len, optlen))
return -EFAULT;
-
- return bpfilter_mbox_request(sk, optname, USER_SOCKPTR(optval), len,
- false);
+ err = init_user_sockptr(&optval, user_optval);
+ if (err)
+ return err;
+ return bpfilter_mbox_request(sk, optname, optval, len, false);
}
static int __init bpfilter_sockopt_init(void)
diff --git a/net/socket.c b/net/socket.c
index e44b8ac47f6f..94ca4547cd7c 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2097,7 +2097,7 @@ static bool sock_use_custom_sol_socket(const struct socket *sock)
int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
int optlen)
{
- sockptr_t optval = USER_SOCKPTR(user_optval);
+ sockptr_t optval;
char *kernel_optval = NULL;
int err, fput_needed;
struct socket *sock;
@@ -2105,6 +2105,10 @@ int __sys_setsockopt(int fd, int level, int optname, char __user *user_optval,
if (optlen < 0)
return -EINVAL;
+ err = init_user_sockptr(&optval, user_optval);
+ if (err)
+ return err;
+
sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
return err;