Commit 31c213f2 authored by Dominik Brodowski's avatar Dominik Brodowski
Browse files

ipc: add msgsnd syscall/compat_syscall wrappers 

Provide ksys_msgsnd() and compat_ksys_msgsnd() wrappers to avoid in-kernel
calls to these syscalls. The ksys_ prefix denotes that these functions are
meant as a drop-in replacement for the syscalls. In particular, they use
the same calling convention as sys_msgsnd() and compat_sys_msgsnd().

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: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarDominik Brodowski <linux@dominikbrodowski.net>
parent 078faac9

ipc/msg.c

+16 −4
Original line number Diff line number Diff line
@@ -867,8 +867,8 @@ static long do_msgsnd(int msqid, long mtype, void __user *mtext, 
	return err;

}



SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,

		int, msgflg)

long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,

		 int msgflg)

{

	long mtype;
@@ -877,6 +877,12 @@ SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, 
	return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg);

}



SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,

		int, msgflg)

{

	return ksys_msgsnd(msqid, msgp, msgsz, msgflg);

}



#ifdef CONFIG_COMPAT



struct compat_msgbuf {
@@ -884,8 +890,8 @@ struct compat_msgbuf { 
	char mtext[1];

};



COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,

		       compat_ssize_t, msgsz, int, msgflg)

long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,

		       compat_ssize_t msgsz, int msgflg)

{

	struct compat_msgbuf __user *up = compat_ptr(msgp);

	compat_long_t mtype;
@@ -894,6 +900,12 @@ COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp, 
		return -EFAULT;

	return do_msgsnd(msqid, mtype, up->mtext, (ssize_t)msgsz, msgflg);

}



COMPAT_SYSCALL_DEFINE4(msgsnd, int, msqid, compat_uptr_t, msgp,

		       compat_ssize_t, msgsz, int, msgflg)

{

	return compat_ksys_msgsnd(msqid, msgp, msgsz, msgflg);

}

#endif



static inline int convert_mode(long *msgtyp, int msgflg)

ipc/syscall.c

+2 −2
Original line number Diff line number Diff line
@@ -46,7 +46,7 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second, 
	}



	case MSGSND:

		return sys_msgsnd(first, (struct msgbuf __user *) ptr,

		return ksys_msgsnd(first, (struct msgbuf __user *) ptr,

				  second, third);

	case MSGRCV:

		switch (version) {
@@ -142,7 +142,7 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second, 
		return compat_ksys_semctl(first, second, third, pad);



	case MSGSND:

		return compat_sys_msgsnd(first, ptr, second, third);

		return compat_ksys_msgsnd(first, ptr, second, third);



	case MSGRCV: {

		void __user *uptr = compat_ptr(ptr);

ipc/util.h

+4 −0
Original line number Diff line number Diff line
@@ -246,6 +246,8 @@ long ksys_msgget(key_t key, int msgflg); 
long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf);

long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,

		 long msgtyp, int msgflg);

long ksys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz,

		 int msgflg);

long ksys_shmget(key_t key, size_t size, int shmflg);

long ksys_shmdt(char __user *shmaddr);

long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf);
@@ -259,6 +261,8 @@ long compat_ksys_semctl(int semid, int semnum, int cmd, int arg); 
long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr);

long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,

			compat_long_t msgtyp, int msgflg);

long compat_ksys_msgsnd(int msqid, compat_uptr_t msgp,

		       compat_ssize_t msgsz, int msgflg);

long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr);

#endif /* CONFIG_COMPAT */