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: Dominik Brodowski <linux@dominikbrodowski.net>

diff --git a/ipc/msg.c b/ipc/msg.c
index abc5826..9de4806 100644 (file)
--- a/ipc/msg.c
+++ b/ipc/msg.c
@@ -867,8 +867,8 @@ out_unlock1:
        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)

diff --git a/ipc/syscall.c b/ipc/syscall.c
index 0228c7a..77a883e 100644 (file)
--- a/ipc/syscall.c
+++ b/ipc/syscall.c
@@ -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);

diff --git a/ipc/util.h b/ipc/util.h
index c16aceb..51853dc 100644 (file)
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -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 */