[PATCH 37/45] ipc: add msgctl syscall/compat_syscall wrappers

From: Dominik Brodowski
Date: Thu Mar 22 2018 - 05:10:49 EST


Provide ksys_msgctl() and compat_ksys_msgctl() 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_msgctl() and compat_sys_msgctl().

This patch is part of a series which tries to remove in-kernel calls to
syscalls. On this basis, the syscall entry path can be streamlined.

Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
---
ipc/msg.c | 14 ++++++++++++--
ipc/syscall.c | 5 +++--
ipc/util.h | 2 ++
3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/ipc/msg.c b/ipc/msg.c
index 64e8276be164..5b026868df07 100644
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -538,7 +538,7 @@ static int msgctl_stat(struct ipc_namespace *ns, int msqid,
return err;
}

-SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
+long ksys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
{
int version;
struct ipc_namespace *ns;
@@ -581,6 +581,11 @@ SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
}
}

+SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
+{
+ return ksys_msgctl(msqid, cmd, buf);
+}
+
#ifdef CONFIG_COMPAT

struct compat_msqid_ds {
@@ -651,7 +656,7 @@ static int copy_compat_msqid_to_user(void __user *buf, struct msqid64_ds *in,
}
}

-COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
+long compat_ksys_msgctl(int msqid, int cmd, void __user *uptr)
{
struct ipc_namespace *ns;
int err;
@@ -692,6 +697,11 @@ COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
return -EINVAL;
}
}
+
+COMPAT_SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, void __user *, uptr)
+{
+ return compat_ksys_msgctl(msqid, cmd, uptr);
+}
#endif

static int testmsg(struct msg_msg *msg, long type, int mode)
diff --git a/ipc/syscall.c b/ipc/syscall.c
index 34bbabc9e672..aa29b0802e26 100644
--- a/ipc/syscall.c
+++ b/ipc/syscall.c
@@ -70,7 +70,8 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
case MSGGET:
return ksys_msgget((key_t) first, second);
case MSGCTL:
- return sys_msgctl(first, second, (struct msqid_ds __user *)ptr);
+ return ksys_msgctl(first, second,
+ (struct msqid_ds __user *)ptr);

case SHMAT:
switch (version) {
@@ -163,7 +164,7 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
case MSGGET:
return ksys_msgget(first, second);
case MSGCTL:
- return compat_sys_msgctl(first, second, compat_ptr(ptr));
+ return compat_ksys_msgctl(first, second, compat_ptr(ptr));

case SHMAT: {
int err;
diff --git a/ipc/util.h b/ipc/util.h
index 16e8b5b8c416..47837b4af3f2 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -243,6 +243,7 @@ long ksys_semtimedop(int semid, struct sembuf __user *tsops,
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_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);
@@ -253,6 +254,7 @@ long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
unsigned int nsops,
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_shmctl(int shmid, int cmd, void __user *uptr);
#endif /* CONFIG_COMPAT */

--
2.16.2