xiaomi-sm8450/android_kernel_xiaomi_sm8450
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

net: cleanly handle kernel vs user buffers for ->msg_control

Browse Source 
The msg_control field in struct msghdr can either contain a user
pointer when used with the recvmsg system call, or a kernel pointer
when used with sendmsg.  To complicate things further kernel_recvmsg
can stuff a kernel pointer in and then use set_fs to make the uaccess
helpers accept it.

Replace it with a union of a kernel pointer msg_control field, and
a user pointer msg_control_user one, and allow kernel_recvmsg operate
on a proper kernel pointer using a bitfield to override the normal
choice of a user pointer for recvmsg.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Christoph Hellwig
2020-05-11 13:59:13 +02:00
committed by David S. Miller
parent 2618d530dd
commit 1f466e1f15
5 changed files with 49 additions and 40 deletions
Download Patch File Download Diff File Expand all files Collapse all files

12
include/linux/socket.h
View File

@@ -50,7 +50,17 @@ struct msghdr {
void *msg_name; /* ptr to socket address structure */
int msg_namelen; /* size of socket address structure */
struct iov_iter msg_iter; /* data */
void *msg_control; /* ancillary data */
/*
* Ancillary data. msg_control_user is the user buffer used for the
* recv* side when msg_control_is_user is set, msg_control is the kernel
* buffer used for all other cases.
*/
union {
void *msg_control;
void __user *msg_control_user;
};
bool msg_control_is_user : 1;
__kernel_size_t msg_controllen; /* ancillary data buffer length */
unsigned int msg_flags; /* flags on received message */
struct kiocb *msg_iocb; /* ptr to iocb for async requests */