ipc: add semtimedop syscall/compat_syscall wrappers

Provide ksys_semtimedop() and compat_ksys_semtimedop() 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_semtimedop() and
compat_sys_semtimedop().

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/sem.c b/ipc/sem.c
index a4af049..e21ceb8 100644 (file)
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -2120,8 +2120,8 @@ out_free:
        return error;
 }
 
-SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
-               unsigned, nsops, const struct timespec __user *, timeout)
+long ksys_semtimedop(int semid, struct sembuf __user *tsops,
+                    unsigned int nsops, const struct timespec __user *timeout)
 {
        if (timeout) {
                struct timespec64 ts;
@@ -2132,10 +2132,16 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
        return do_semtimedop(semid, tsops, nsops, NULL);
 }
 
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
+               unsigned int, nsops, const struct timespec __user *, timeout)
+{
+       return ksys_semtimedop(semid, tsops, nsops, timeout);
+}
+
 #ifdef CONFIG_COMPAT
-COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
-                      unsigned, nsops,
-                      const struct compat_timespec __user *, timeout)
+long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
+                           unsigned int nsops,
+                           const struct compat_timespec __user *timeout)
 {
        if (timeout) {
                struct timespec64 ts;
@@ -2145,6 +2151,13 @@ COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
        }
        return do_semtimedop(semid, tsems, nsops, NULL);
 }
+
+COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems,
+                      unsigned int, nsops,
+                      const struct compat_timespec __user *, timeout)
+{
+       return compat_ksys_semtimedop(semid, tsems, nsops, timeout);
+}
 #endif
 
 SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops,

diff --git a/ipc/syscall.c b/ipc/syscall.c
index 3763b42..84d6a76 100644 (file)
--- a/ipc/syscall.c
+++ b/ipc/syscall.c
@@ -7,6 +7,9 @@
  */
 #include <linux/unistd.h>
 #include <linux/syscalls.h>
+#include <linux/security.h>
+#include <linux/ipc_namespace.h>
+#include "util.h"
 
 #ifdef __ARCH_WANT_SYS_IPC
 #include <linux/errno.h>
@@ -24,12 +27,12 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second,
 
        switch (call) {
        case SEMOP:
-               return sys_semtimedop(first, (struct sembuf __user *)ptr,
-                                     second, NULL);
+               return ksys_semtimedop(first, (struct sembuf __user *)ptr,
+                                      second, NULL);
        case SEMTIMEDOP:
-               return sys_semtimedop(first, (struct sembuf __user *)ptr,
-                                     second,
-                                     (const struct timespec __user *)fifth);
+               return ksys_semtimedop(first, (struct sembuf __user *)ptr,
+                                      second,
+                                      (const struct timespec __user *)fifth);
 
        case SEMGET:
                return sys_semget(first, second, third);
@@ -124,9 +127,9 @@ COMPAT_SYSCALL_DEFINE6(ipc, u32, call, int, first, int, second,
        switch (call) {
        case SEMOP:
                /* struct sembuf is the same on 32 and 64bit :)) */
-               return sys_semtimedop(first, compat_ptr(ptr), second, NULL);
+               return ksys_semtimedop(first, compat_ptr(ptr), second, NULL);
        case SEMTIMEDOP:
-               return compat_sys_semtimedop(first, compat_ptr(ptr), second,
+               return compat_ksys_semtimedop(first, compat_ptr(ptr), second,
                                                compat_ptr(fifth));
        case SEMGET:
                return sys_semget(first, second, third);

diff --git a/ipc/util.h b/ipc/util.h
index 89b8ec1..6deadf7 100644 (file)
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -235,4 +235,17 @@ static inline int compat_ipc_parse_version(int *cmd)
 #endif
 }
 #endif
+
+/* for __ARCH_WANT_SYS_IPC */
+long ksys_semtimedop(int semid, struct sembuf __user *tsops,
+                    unsigned int nsops,
+                    const struct timespec __user *timeout);
+
+/* for CONFIG_ARCH_WANT_OLD_COMPAT_IPC */
+#ifdef CONFIG_COMPAT
+long compat_ksys_semtimedop(int semid, struct sembuf __user *tsems,
+                           unsigned int nsops,
+                           const struct compat_timespec __user *timeout);
+#endif /* CONFIG_COMPAT */
+
 #endif