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ipc: add msgrcv syscall/compat_syscall wrappers

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Provide ksys_msgrcv() and compat_ksys_msgrcv() 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_msgrcv() and compat_sys_msgrcv().

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 21:25:57 +01:00
parent e340db5648
commit 078faac9e8
3 changed files with 24 additions and 7 deletions
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19
ipc/msg.c
View File

@ -1150,10 +1150,16 @@ static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, in
return bufsz;
}
long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
long msgtyp, int msgflg)
{
return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
}
SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz,
long, msgtyp, int, msgflg)
{
return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
return ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#ifdef CONFIG_COMPAT
@ -1171,12 +1177,19 @@ static long compat_do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bu
return msgsz;
}
COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, compat_long_t, msgtyp, int, msgflg)
long compat_ksys_msgrcv(int msqid, compat_uptr_t msgp, compat_ssize_t msgsz,
compat_long_t msgtyp, int msgflg)
{
return do_msgrcv(msqid, compat_ptr(msgp), (ssize_t)msgsz, (long)msgtyp,
msgflg, compat_do_msg_fill);
}
COMPAT_SYSCALL_DEFINE5(msgrcv, int, msqid, compat_uptr_t, msgp,
compat_ssize_t, msgsz, compat_long_t, msgtyp,
int, msgflg)
{
return compat_ksys_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);
}
#endif
int msg_init_ns(struct ipc_namespace *ns)

8
ipc/syscall.c
View File

@ -59,11 +59,11 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
(struct ipc_kludge __user *) ptr,
sizeof(tmp)))
return -EFAULT;
return sys_msgrcv(first, tmp.msgp, second,
return ksys_msgrcv(first, tmp.msgp, second,
tmp.msgtyp, third);
}
default:
return sys_msgrcv(first,
return ksys_msgrcv(first,
(struct msgbuf __user *) ptr,
second, fifth, third);
}
@ -156,10 +156,10 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
return -EINVAL;
if (copy_from_user(&ipck, uptr, sizeof(ipck)))
return -EFAULT;
return compat_sys_msgrcv(first, ipck.msgp, second,
return compat_ksys_msgrcv(first, ipck.msgp, second,
ipck.msgtyp, third);
}
return compat_sys_msgrcv(first, ptr, second, fifth, third);
return compat_ksys_msgrcv(first, ptr, second, fifth, third);
}
case MSGGET:
return ksys_msgget(first, second);

4
ipc/util.h
View File

@ -244,6 +244,8 @@ long ksys_semget(key_t key, int nsems, int semflg);
long ksys_semctl(int semid, int semnum, int cmd, unsigned long arg);
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_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);
@ -255,6 +257,8 @@ long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
const struct compat_timespec __user *timeout);
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_shmctl(int shmid, int cmd, void __user *uptr);
#endif /* CONFIG_COMPAT */