On Saturday 16 May 2015 00:46:44 Thomas Gleixner wrote:
On Wed, 6 May 2015, Arnd Bergmann wrote:
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops,
unsigned, nsops,const struct __kernel_timespec __user *, timeout)+{
- unsigned long jiffies_left = 0;
- if (timeout) {
struct timespec64 _timeout;if (get_timespec64(&_timeout, timeout))Moo. I had to look 3 times to get not confused by the extra underscore. What's wrong with a proper variable name which is easy to distinguish?
return -EFAULT;
if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 ||_timeout.tv_nsec >= 1000000000L)return -EINVAL;We have proper helper functions to validate time specs.
I ended up fixing both issues you noticed in the same patch after all, and also simplified it slightly more.
Finally, I also noticed that I had not done a timespec64_to_jiffies() call at the time when I wrote this patch, but it actually exists now, so I've reordered my series and am using it in the new version, as I should have done to start with.
Arnd
8<----
From e04b14d49273c27d92f1799233b82bcdafb43d9a Mon Sep 17 00:00:00 2001
From: Arnd Bergmann arnd@arndb.de Date: Mon, 27 Apr 2015 23:30:39 +0200 Subject: [UPDATED PATCH] y2038: add compat handling for sys_semtimedop
This moves the compat_sys_semtimedop function to ipc/sem.c so it can be shared with 32-bit architectures efficiently. Instead of copying the timespec back to user space, we take a shortcut and pass the kernel timespec64 value to the low-level implementation directly.
The native sys_semtimedop() function is modified to take a __kernel_timespec structure, which will be based on a 64-bit time_t in the future.
There is a small API change here: if multiple errors are present, and the timespec argument is an invalid pointer, we now return -EFAULT before checking any of the other error conditions. This is what the compat version has always done, but if it is a problem, we need a more sophisticated approach.
Signed-off-by: Arnd Bergmann arnd@arndb.de
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index f3fdc312627b..c2a70a8f907d 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -665,7 +665,7 @@ asmlinkage long sys_semop(int semid, struct sembuf __user *sops, asmlinkage long sys_semctl(int semid, int semnum, int cmd, unsigned long arg); asmlinkage long sys_semtimedop(int semid, struct sembuf __user *sops, unsigned nsops, - const struct timespec __user *timeout); + const struct __kernel_timespec __user *timeout); asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg); asmlinkage long sys_shmget(key_t key, size_t size, int flag); asmlinkage long sys_shmdt(char __user *shmaddr); diff --git a/ipc/compat.c b/ipc/compat.c index 9b3c85f8a538..2bbdb093d1be 100644 --- a/ipc/compat.c +++ b/ipc/compat.c @@ -745,13 +745,3 @@ COMPAT_SYSCALL_DEFINE3(shmctl, int, first, int, second, void __user *, uptr) } return err; } - -COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsems, - unsigned, nsops, - const struct compat_timespec __user *, timeout) -{ - struct timespec __user *ts64; - if (compat_convert_timespec(&ts64, timeout)) - return -EFAULT; - return sys_semtimedop(semid, tsems, nsops, ts64); -} diff --git a/ipc/sem.c b/ipc/sem.c index d1a6edd17eba..84d354a34df3 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -72,6 +72,7 @@ * The worst-case behavior is nevertheless O(N^2) for N wakeups. */
+#include <linux/compat.h> #include <linux/slab.h> #include <linux/spinlock.h> #include <linux/init.h> @@ -1779,8 +1780,8 @@ static int get_queue_result(struct sem_queue *q) return error; }
-SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, - unsigned, nsops, const struct timespec __user *, timeout) +static long semtimedop(int semid, struct sembuf __user * tsops, + unsigned nsops, struct timespec64 *timeout) { int error = -EINVAL; struct sem_array *sma; @@ -1809,17 +1810,11 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, goto out_free; } if (timeout) { - struct timespec _timeout; - if (copy_from_user(&_timeout, timeout, sizeof(*timeout))) { - error = -EFAULT; - goto out_free; - } - if (_timeout.tv_sec < 0 || _timeout.tv_nsec < 0 || - _timeout.tv_nsec >= 1000000000L) { + if (!timespec64_valid(timeout)) { error = -EINVAL; goto out_free; } - jiffies_left = timespec_to_jiffies(&_timeout); + jiffies_left = timespec64_to_jiffies(timeout); } max = 0; for (sop = sops; sop < sops + nsops; sop++) { @@ -2014,10 +2009,36 @@ out_free: return error; }
+SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, + unsigned, nsops, + const struct __kernel_timespec __user *, p) +{ + struct timespec64 timeout; + + if (p && get_timespec64(&timeout, p)) + return -EFAULT; + + return semtimedop(semid, tsops, nsops, p ? &timeout : NULL); +} + +#ifdef CONFIG_COMPAT_TIME +COMPAT_SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, + unsigned, nsops, + const struct compat_timespec __user *, p) +{ + struct timespec64 timeout; + + if (p && compat_get_timespec64(&timeout, p)) + return -EFAULT; + + return semtimedop(semid, tsops, nsops, p ? &timeout : NULL); +} +#endif + SYSCALL_DEFINE3(semop, int, semid, struct sembuf __user *, tsops, unsigned, nsops) { - return sys_semtimedop(semid, tsops, nsops, NULL); + return semtimedop(semid, tsops, nsops, NULL); }
/* If CLONE_SYSVSEM is set, establish sharing of SEM_UNDO state between diff --git a/ipc/syscall.c b/ipc/syscall.c index 52429489cde0..d7b17355d870 100644 --- a/ipc/syscall.c +++ b/ipc/syscall.c @@ -7,6 +7,7 @@ #include <linux/unistd.h>
#ifdef __ARCH_WANT_SYS_IPC +#include <linux/compat_time.h> #include <linux/errno.h> #include <linux/ipc.h> #include <linux/shm.h> @@ -26,9 +27,15 @@ SYSCALL_DEFINE6(ipc, unsigned int, call, int, first, unsigned long, second, return sys_semtimedop(first, (struct sembuf __user *)ptr, second, NULL); case SEMTIMEDOP: +#if defined(CONFIG_ARCH_HAS_COMPAT_TIME) && !defined(CONFIG_64BIT) + return compat_sys_semtimedop(first, (struct sembuf __user *)ptr, + second, + (const struct compat_timespec __user *)fifth); +#else return sys_semtimedop(first, (struct sembuf __user *)ptr, second, (const struct timespec __user *)fifth); +#endif
case SEMGET: return sys_semget(first, second, third);