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ipc: add msgsnd syscall/compat_syscall wrappers

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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: Dominik Brodowski <linux@dominikbrodowski.net>
This commit is contained in:
Dominik Brodowski 2018-03-20 21:29:00 +01:00
parent 078faac9e8
commit 31c213f210
3 changed files with 22 additions and 6 deletions
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20
ipc/msg.c
View File

@ -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)

4
ipc/syscall.c
View File

@ -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);

4
ipc/util.h
View File

@ -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 */