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e843e7d2c8
a) SysV can be abused to allocate locked kernel memory. For most systems, a small limit doesn't make sense, see the discussion with regards to SHMMAX. Therefore: Increase the sysv sem limits so that all known applications will work with these defaults. b) With regards to the maximum supported: Some of the specified hard limits are not correct anymore, therefore the patch updates the documentation. - SEMMNI must stay below IPCMNI, which is 32768. As for SHMMAX: Stay a bit below this limit. - SEMMSL was limited to 8k, to ensure that the kmalloc for the kernel array was limited to 16 kB (order=2) This doesn't apply anymore: - the allocation size isn't sizeof(short)*nsems anymore. - ipc_alloc falls back to vmalloc - SEMOPM should stay below 1000, to limit the kmalloc in semtimedop() to an order=1 allocation. Therefore: Leave it at 500 (order=0 allocation). Note: If an administrator must limit the memory allocations, then he can set the values as necessary. Or he can disable sysv entirely (as e.g. done by Android). Signed-off-by: Manfred Spraul <manfred@colorfullife.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Acked-by: Rafael Aquini <aquini@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
92 lines
2.9 KiB
C
92 lines
2.9 KiB
C
#ifndef _UAPI_LINUX_SEM_H
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#define _UAPI_LINUX_SEM_H
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#include <linux/ipc.h>
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/* semop flags */
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#define SEM_UNDO 0x1000 /* undo the operation on exit */
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/* semctl Command Definitions. */
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#define GETPID 11 /* get sempid */
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#define GETVAL 12 /* get semval */
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#define GETALL 13 /* get all semval's */
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#define GETNCNT 14 /* get semncnt */
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#define GETZCNT 15 /* get semzcnt */
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#define SETVAL 16 /* set semval */
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#define SETALL 17 /* set all semval's */
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/* ipcs ctl cmds */
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#define SEM_STAT 18
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#define SEM_INFO 19
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/* Obsolete, used only for backwards compatibility and libc5 compiles */
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struct semid_ds {
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struct ipc_perm sem_perm; /* permissions .. see ipc.h */
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__kernel_time_t sem_otime; /* last semop time */
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__kernel_time_t sem_ctime; /* last change time */
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struct sem *sem_base; /* ptr to first semaphore in array */
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struct sem_queue *sem_pending; /* pending operations to be processed */
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struct sem_queue **sem_pending_last; /* last pending operation */
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struct sem_undo *undo; /* undo requests on this array */
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unsigned short sem_nsems; /* no. of semaphores in array */
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};
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/* Include the definition of semid64_ds */
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#include <asm/sembuf.h>
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/* semop system calls takes an array of these. */
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struct sembuf {
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unsigned short sem_num; /* semaphore index in array */
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short sem_op; /* semaphore operation */
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short sem_flg; /* operation flags */
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};
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/* arg for semctl system calls. */
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds __user *buf; /* buffer for IPC_STAT & IPC_SET */
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unsigned short __user *array; /* array for GETALL & SETALL */
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struct seminfo __user *__buf; /* buffer for IPC_INFO */
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void __user *__pad;
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};
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struct seminfo {
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int semmap;
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int semmni;
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int semmns;
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int semmnu;
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int semmsl;
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int semopm;
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int semume;
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int semusz;
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int semvmx;
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int semaem;
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};
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/*
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* SEMMNI, SEMMSL and SEMMNS are default values which can be
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* modified by sysctl.
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* The values has been chosen to be larger than necessary for any
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* known configuration.
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*
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* SEMOPM should not be increased beyond 1000, otherwise there is the
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* risk that semop()/semtimedop() fails due to kernel memory fragmentation when
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* allocating the sop array.
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*/
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#define SEMMNI 32000 /* <= IPCMNI max # of semaphore identifiers */
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#define SEMMSL 32000 /* <= INT_MAX max num of semaphores per id */
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#define SEMMNS (SEMMNI*SEMMSL) /* <= INT_MAX max # of semaphores in system */
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#define SEMOPM 500 /* <= 1 000 max num of ops per semop call */
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#define SEMVMX 32767 /* <= 32767 semaphore maximum value */
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#define SEMAEM SEMVMX /* adjust on exit max value */
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/* unused */
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#define SEMUME SEMOPM /* max num of undo entries per process */
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#define SEMMNU SEMMNS /* num of undo structures system wide */
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#define SEMMAP SEMMNS /* # of entries in semaphore map */
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#define SEMUSZ 20 /* sizeof struct sem_undo */
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#endif /* _UAPI_LINUX_SEM_H */
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