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net: socket: move check for forbid_cmsg_compat to __sys_...msg() 

The non-compat codepaths for sys_...msg() verify that MSG_CMSG_COMPAT
is not set. By moving this check to the __sys_...msg() functions
(and making it dependent on a static flag passed to this function), we
can call the __sys...msg() functions instead of the syscall functions
in all cases. __sys_recvmmsg() does not need this trickery, as the
check is handled within the do_sys_recvmmsg() function internal to
net/socket.c.

This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net

Cc: David S. Miller <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski 2018-03-13 20:35:57 +01:00
parent 1255e26906
commit e1834a329d
3 changed files with 37 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/linux/socket.h
View File

@ -346,13 +346,18 @@ extern int put_cmsg(struct msghdr*, int level, int type, int len, void *data);
struct timespec;
/* The __sys_...msg variants allow MSG_CMSG_COMPAT */
extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags);
extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags);
/* The __sys_...msg variants allow MSG_CMSG_COMPAT iff
* forbid_cmsg_compat==false
*/
extern long __sys_recvmsg(int fd, struct user_msghdr __user *msg,
unsigned int flags, bool forbid_cmsg_compat);
extern long __sys_sendmsg(int fd, struct user_msghdr __user *msg,
unsigned int flags, bool forbid_cmsg_compat);
extern int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
unsigned int flags, struct timespec *timeout);
extern int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg,
unsigned int vlen, unsigned int flags);
unsigned int vlen, unsigned int flags,
bool forbid_cmsg_compat);
/* helpers which do the actual work for syscalls */
extern int __sys_recvfrom(int fd, void __user *ubuf, size_t size,

8
net/compat.c
View File

@ -736,19 +736,21 @@ static unsigned char nas[21] = {
COMPAT_SYSCALL_DEFINE3(sendmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)
{
return __sys_sendmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
return __sys_sendmsg(fd, (struct user_msghdr __user *)msg,
flags | MSG_CMSG_COMPAT, false);
}
COMPAT_SYSCALL_DEFINE4(sendmmsg, int, fd, struct compat_mmsghdr __user *, mmsg,
unsigned int, vlen, unsigned int, flags)
{
return __sys_sendmmsg(fd, (struct mmsghdr __user *)mmsg, vlen,
flags | MSG_CMSG_COMPAT);
flags | MSG_CMSG_COMPAT, false);
}
COMPAT_SYSCALL_DEFINE3(recvmsg, int, fd, struct compat_msghdr __user *, msg, unsigned int, flags)
{
return __sys_recvmsg(fd, (struct user_msghdr __user *)msg, flags | MSG_CMSG_COMPAT);
return __sys_recvmsg(fd, (struct user_msghdr __user *)msg,
flags | MSG_CMSG_COMPAT, false);
}
COMPAT_SYSCALL_DEFINE4(recv, int, fd, void __user *, buf, compat_size_t, len, unsigned int, flags)

38
net/socket.c
View File

@ -2137,12 +2137,16 @@ out_freeiov:
* BSD sendmsg interface
*/
long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned flags)
long __sys_sendmsg(int fd, struct user_msghdr __user *msg, unsigned int flags,
bool forbid_cmsg_compat)
{
int fput_needed, err;
struct msghdr msg_sys;
struct socket *sock;
if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))
return -EINVAL;
sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
goto out;
@ -2156,9 +2160,7 @@ out:
SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int, flags)
{
if (flags & MSG_CMSG_COMPAT)
return -EINVAL;
return __sys_sendmsg(fd, msg, flags);
return __sys_sendmsg(fd, msg, flags, true);
}
/*
@ -2166,7 +2168,7 @@ SYSCALL_DEFINE3(sendmsg, int, fd, struct user_msghdr __user *, msg, unsigned int
*/
int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
unsigned int flags)
unsigned int flags, bool forbid_cmsg_compat)
{
int fput_needed, err, datagrams;
struct socket *sock;
@ -2176,6 +2178,9 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
struct used_address used_address;
unsigned int oflags = flags;
if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))
return -EINVAL;
if (vlen > UIO_MAXIOV)
vlen = UIO_MAXIOV;
@ -2232,9 +2237,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
SYSCALL_DEFINE4(sendmmsg, int, fd, struct mmsghdr __user *, mmsg,
unsigned int, vlen, unsigned int, flags)
{
if (flags & MSG_CMSG_COMPAT)
return -EINVAL;
return __sys_sendmmsg(fd, mmsg, vlen, flags);
return __sys_sendmmsg(fd, mmsg, vlen, flags, true);
}
static int ___sys_recvmsg(struct socket *sock, struct user_msghdr __user *msg,
@ -2307,12 +2310,16 @@ out_freeiov:
* BSD recvmsg interface
*/
long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned flags)
long __sys_recvmsg(int fd, struct user_msghdr __user *msg, unsigned int flags,
bool forbid_cmsg_compat)
{
int fput_needed, err;
struct msghdr msg_sys;
struct socket *sock;
if (forbid_cmsg_compat && (flags & MSG_CMSG_COMPAT))
return -EINVAL;
sock = sockfd_lookup_light(fd, &err, &fput_needed);
if (!sock)
goto out;
@ -2327,9 +2334,7 @@ out:
SYSCALL_DEFINE3(recvmsg, int, fd, struct user_msghdr __user *, msg,
unsigned int, flags)
{
if (flags & MSG_CMSG_COMPAT)
return -EINVAL;
return __sys_recvmsg(fd, msg, flags);
return __sys_recvmsg(fd, msg, flags, true);
}
/*
@ -2580,13 +2585,16 @@ SYSCALL_DEFINE2(socketcall, int, call, unsigned long __user *, args)
(int __user *)a[4]);
break;
case SYS_SENDMSG:
err = sys_sendmsg(a0, (struct user_msghdr __user *)a1, a[2]);
err = __sys_sendmsg(a0, (struct user_msghdr __user *)a1,
a[2], true);
break;
case SYS_SENDMMSG:
err = sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2], a[3]);
err = __sys_sendmmsg(a0, (struct mmsghdr __user *)a1, a[2],
a[3], true);
break;
case SYS_RECVMSG:
err = sys_recvmsg(a0, (struct user_msghdr __user *)a1, a[2]);
err = __sys_recvmsg(a0, (struct user_msghdr __user *)a1,
a[2], true);
break;
case SYS_RECVMMSG:
err = do_sys_recvmmsg(a0, (struct mmsghdr __user *)a1, a[2],