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sysv_sem.c
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/*
* Copyright (c) 2000-2007 Apple Inc. All rights reserved.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. The rights granted to you under the License
* may not be used to create, or enable the creation or redistribution of,
* unlawful or unlicensed copies of an Apple operating system, or to
* circumvent, violate, or enable the circumvention or violation of, any
* terms of an Apple operating system software license agreement.
*
* Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
*/
/*
* Implementation of SVID semaphores
*
* Author: Daniel Boulet
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
/*
* John Bellardo modified the implementation for Darwin. 12/2000
*/
/*
* NOTICE: This file was modified by McAfee Research in 2004 to introduce
* support for mandatory and extensible security protections. This notice
* is included in support of clause 2.2 (b) of the Apple Public License,
* Version 2.0.
* Copyright (c) 2005-2006 SPARTA, Inc.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc_internal.h>
#include <sys/kauth.h>
#include <sys/sem_internal.h>
#include <sys/malloc.h>
#include <mach/mach_types.h>
#include <sys/filedesc.h>
#include <sys/file_internal.h>
#include <sys/sysctl.h>
#include <sys/ipcs.h>
#include <sys/sysent.h>
#include <sys/sysproto.h>
#if CONFIG_MACF
#include <security/mac_framework.h>
#endif
#include <security/audit/audit.h>
#if SYSV_SEM
/* Uncomment this line to see the debugging output */
/* #define SEM_DEBUG */
/* Uncomment this line to see MAC debugging output. */
/* #define MAC_DEBUG */
#if CONFIG_MACF_DEBUG
#define MPRINTF(a) printf(a)
#else
#define MPRINTF(a)
#endif
#define M_SYSVSEM M_TEMP
/* Hard system limits to avoid resource starvation / DOS attacks.
* These are not needed if we can make the semaphore pages swappable.
*/
static struct seminfo limitseminfo = {
SEMMAP, /* # of entries in semaphore map */
SEMMNI, /* # of semaphore identifiers */
SEMMNS, /* # of semaphores in system */
SEMMNU, /* # of undo structures in system */
SEMMSL, /* max # of semaphores per id */
SEMOPM, /* max # of operations per semop call */
SEMUME, /* max # of undo entries per process */
SEMUSZ, /* size in bytes of undo structure */
SEMVMX, /* semaphore maximum value */
SEMAEM /* adjust on exit max value */
};
/* Current system allocations. We use this structure to track how many
* resources we have allocated so far. This way we can set large hard limits
* and not allocate the memory for them up front.
*/
struct seminfo seminfo = {
SEMMAP, /* Unused, # of entries in semaphore map */
0, /* # of semaphore identifiers */
0, /* # of semaphores in system */
0, /* # of undo entries in system */
SEMMSL, /* max # of semaphores per id */
SEMOPM, /* max # of operations per semop call */
SEMUME, /* max # of undo entries per process */
SEMUSZ, /* size in bytes of undo structure */
SEMVMX, /* semaphore maximum value */
SEMAEM /* adjust on exit max value */
};
static int semu_alloc(struct proc *p);
static int semundo_adjust(struct proc *p, int *supidx,
int semid, int semnum, int adjval);
static void semundo_clear(int semid, int semnum);
/* XXX casting to (sy_call_t *) is bogus, as usual. */
static sy_call_t *semcalls[] = {
(sy_call_t *)semctl, (sy_call_t *)semget,
(sy_call_t *)semop
};
static int semtot = 0; /* # of used semaphores */
struct semid_kernel *sema = NULL; /* semaphore id pool */
struct sem *sem_pool = NULL; /* semaphore pool */
static int semu_list_idx = -1; /* active undo structures */
struct sem_undo *semu = NULL; /* semaphore undo pool */
void sysv_sem_lock_init(void);
static lck_grp_t *sysv_sem_subsys_lck_grp;
static lck_grp_attr_t *sysv_sem_subsys_lck_grp_attr;
static lck_attr_t *sysv_sem_subsys_lck_attr;
static lck_mtx_t sysv_sem_subsys_mutex;
#define SYSV_SEM_SUBSYS_LOCK() lck_mtx_lock(&sysv_sem_subsys_mutex)
#define SYSV_SEM_SUBSYS_UNLOCK() lck_mtx_unlock(&sysv_sem_subsys_mutex)
__private_extern__ void
sysv_sem_lock_init( void )
{
sysv_sem_subsys_lck_grp_attr = lck_grp_attr_alloc_init();
sysv_sem_subsys_lck_grp = lck_grp_alloc_init("sysv_sem_subsys_lock", sysv_sem_subsys_lck_grp_attr);
sysv_sem_subsys_lck_attr = lck_attr_alloc_init();
lck_mtx_init(&sysv_sem_subsys_mutex, sysv_sem_subsys_lck_grp, sysv_sem_subsys_lck_attr);
}
static __inline__ user_time_t
sysv_semtime(void)
{
struct timeval tv;
microtime(&tv);
return (tv.tv_sec);
}
/*
* XXX conversion of internal user_time_t to external tume_t loses
* XXX precision; not an issue for us now, since we are only ever
* XXX setting 32 bits worth of time into it.
*
* pad field contents are not moved correspondingly; contents will be lost
*
* NOTE: Source and target may *NOT* overlap! (target is smaller)
*/
static void
semid_ds_kernelto32(struct user_semid_ds *in, struct user32_semid_ds *out)
{
out->sem_perm = in->sem_perm;
out->sem_base = CAST_DOWN_EXPLICIT(__int32_t,in->sem_base);
out->sem_nsems = in->sem_nsems;
out->sem_otime = in->sem_otime; /* XXX loses precision */
out->sem_ctime = in->sem_ctime; /* XXX loses precision */
}
static void
semid_ds_kernelto64(struct user_semid_ds *in, struct user64_semid_ds *out)
{
out->sem_perm = in->sem_perm;
out->sem_base = CAST_DOWN_EXPLICIT(__int32_t,in->sem_base);
out->sem_nsems = in->sem_nsems;
out->sem_otime = in->sem_otime; /* XXX loses precision */
out->sem_ctime = in->sem_ctime; /* XXX loses precision */
}
/*
* pad field contents are not moved correspondingly; contents will be lost
*
* NOTE: Source and target may are permitted to overlap! (source is smaller);
* this works because we copy fields in order from the end of the struct to
* the beginning.
*
* XXX use CAST_USER_ADDR_T() for lack of a CAST_USER_TIME_T(); net effect
* XXX is the same.
*/
static void
semid_ds_32tokernel(struct user32_semid_ds *in, struct user_semid_ds *out)
{
out->sem_ctime = in->sem_ctime;
out->sem_otime = in->sem_otime;
out->sem_nsems = in->sem_nsems;
out->sem_base = (void *)(uintptr_t)in->sem_base;
out->sem_perm = in->sem_perm;
}
static void
semid_ds_64tokernel(struct user64_semid_ds *in, struct user_semid_ds *out)
{
out->sem_ctime = in->sem_ctime;
out->sem_otime = in->sem_otime;
out->sem_nsems = in->sem_nsems;
out->sem_base = (void *)(uintptr_t)in->sem_base;
out->sem_perm = in->sem_perm;
}
/*
* semsys
*
* Entry point for all SEM calls: semctl, semget, semop
*
* Parameters: p Process requesting the call
* uap User argument descriptor (see below)
* retval Return value of the selected sem call
*
* Indirect parameters: uap->which sem call to invoke (index in array of sem calls)
* uap->a2 User argument descriptor
*
* Returns: 0 Success
* !0 Not success
*
* Implicit returns: retval Return value of the selected sem call
*
* DEPRECATED: This interface should not be used to call the other SEM
* functions (semctl, semget, semop). The correct usage is
* to call the other SEM functions directly.
*
*/
int
semsys(struct proc *p, struct semsys_args *uap, int32_t *retval)
{
/* The individual calls handling the locking now */
if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
return (EINVAL);
return ((*semcalls[uap->which])(p, &uap->a2, retval));
}
/*
* Expand the semu array to the given capacity. If the expansion fails
* return 0, otherwise return 1.
*
* Assumes we already have the subsystem lock.
*/
static int
grow_semu_array(int newSize)
{
int i;
struct sem_undo *newSemu;
if (newSize <= seminfo.semmnu)
return 1;
if (newSize > limitseminfo.semmnu) /* enforce hard limit */
{
#ifdef SEM_DEBUG
printf("undo structure hard limit of %d reached, requested %d\n",
limitseminfo.semmnu, newSize);
#endif
return 0;
}
newSize = (newSize/SEMMNU_INC + 1) * SEMMNU_INC;
newSize = newSize > limitseminfo.semmnu ? limitseminfo.semmnu : newSize;
#ifdef SEM_DEBUG
printf("growing semu[] from %d to %d\n", seminfo.semmnu, newSize);
#endif
MALLOC(newSemu, struct sem_undo *, sizeof (struct sem_undo) * newSize,
M_SYSVSEM, M_WAITOK | M_ZERO);
if (NULL == newSemu)
{
#ifdef SEM_DEBUG
printf("allocation failed. no changes made.\n");
#endif
return 0;
}
/* copy the old data to the new array */
for (i = 0; i < seminfo.semmnu; i++)
{
newSemu[i] = semu[i];
}
/*
* The new elements (from newSemu[i] to newSemu[newSize-1]) have their
* "un_proc" set to 0 (i.e. NULL) by the M_ZERO flag to MALLOC() above,
* so they're already marked as "not in use".
*/
/* Clean up the old array */
if (semu)
FREE(semu, M_SYSVSEM);
semu = newSemu;
seminfo.semmnu = newSize;
#ifdef SEM_DEBUG
printf("expansion successful\n");
#endif
return 1;
}
/*
* Expand the sema array to the given capacity. If the expansion fails
* we return 0, otherwise we return 1.
*
* Assumes we already have the subsystem lock.
*/
static int
grow_sema_array(int newSize)
{
struct semid_kernel *newSema;
int i;
if (newSize <= seminfo.semmni)
return 0;
if (newSize > limitseminfo.semmni) /* enforce hard limit */
{
#ifdef SEM_DEBUG
printf("identifier hard limit of %d reached, requested %d\n",
limitseminfo.semmni, newSize);
#endif
return 0;
}
newSize = (newSize/SEMMNI_INC + 1) * SEMMNI_INC;
newSize = newSize > limitseminfo.semmni ? limitseminfo.semmni : newSize;
#ifdef SEM_DEBUG
printf("growing sema[] from %d to %d\n", seminfo.semmni, newSize);
#endif
MALLOC(newSema, struct semid_kernel *,
sizeof (struct semid_kernel) * newSize,
M_SYSVSEM, M_WAITOK | M_ZERO);
if (NULL == newSema)
{
#ifdef SEM_DEBUG
printf("allocation failed. no changes made.\n");
#endif
return 0;
}
/* copy over the old ids */
for (i = 0; i < seminfo.semmni; i++)
{
newSema[i] = sema[i];
/* This is a hack. What we really want to be able to
* do is change the value a process is waiting on
* without waking it up, but I don't know how to do
* this with the existing code, so we wake up the
* process and let it do a lot of work to determine the
* semaphore set is really not available yet, and then
* sleep on the correct, reallocated semid_kernel pointer.
*/
if (sema[i].u.sem_perm.mode & SEM_ALLOC)
wakeup((caddr_t)&sema[i]);
}
#if CONFIG_MACF
for (i = seminfo.semmni; i < newSize; i++)
{
mac_sysvsem_label_init(&newSema[i]);
}
#endif
/*
* The new elements (from newSema[i] to newSema[newSize-1]) have their
* "sem_base" and "sem_perm.mode" set to 0 (i.e. NULL) by the M_ZERO
* flag to MALLOC() above, so they're already marked as "not in use".
*/
/* Clean up the old array */
if (sema)
FREE(sema, M_SYSVSEM);
sema = newSema;
seminfo.semmni = newSize;
#ifdef SEM_DEBUG
printf("expansion successful\n");
#endif
return 1;
}
/*
* Expand the sem_pool array to the given capacity. If the expansion fails
* we return 0 (fail), otherwise we return 1 (success).
*
* Assumes we already hold the subsystem lock.
*/
static int
grow_sem_pool(int new_pool_size)
{
struct sem *new_sem_pool = NULL;
struct sem *sem_free;
int i;
if (new_pool_size < semtot)
return 0;
/* enforce hard limit */
if (new_pool_size > limitseminfo.semmns) {
#ifdef SEM_DEBUG
printf("semaphore hard limit of %d reached, requested %d\n",
limitseminfo.semmns, new_pool_size);
#endif
return 0;
}
new_pool_size = (new_pool_size/SEMMNS_INC + 1) * SEMMNS_INC;
new_pool_size = new_pool_size > limitseminfo.semmns ? limitseminfo.semmns : new_pool_size;
#ifdef SEM_DEBUG
printf("growing sem_pool array from %d to %d\n", seminfo.semmns, new_pool_size);
#endif
MALLOC(new_sem_pool, struct sem *, sizeof (struct sem) * new_pool_size,
M_SYSVSEM, M_WAITOK | M_ZERO | M_NULL);
if (NULL == new_sem_pool) {
#ifdef SEM_DEBUG
printf("allocation failed. no changes made.\n");
#endif
return 0;
}
/* We have our new memory, now copy the old contents over */
if (sem_pool)
for(i = 0; i < seminfo.semmns; i++)
new_sem_pool[i] = sem_pool[i];
/* Update our id structures to point to the new semaphores */
for(i = 0; i < seminfo.semmni; i++) {
if (sema[i].u.sem_perm.mode & SEM_ALLOC) /* ID in use */
sema[i].u.sem_base = new_sem_pool +
(sema[i].u.sem_base - sem_pool);
}
sem_free = sem_pool;
sem_pool = new_sem_pool;
/* clean up the old array */
if (sem_free != NULL)
FREE(sem_free, M_SYSVSEM);
seminfo.semmns = new_pool_size;
#ifdef SEM_DEBUG
printf("expansion complete\n");
#endif
return 1;
}
/*
* Allocate a new sem_undo structure for a process
* (returns ptr to structure or NULL if no more room)
*
* Assumes we already hold the subsystem lock.
*/
static int
semu_alloc(struct proc *p)
{
int i;
struct sem_undo *suptr;
int *supidx;
int attempt;
/*
* Try twice to allocate something.
* (we'll purge any empty structures after the first pass so
* two passes are always enough)
*/
for (attempt = 0; attempt < 2; attempt++) {
/*
* Look for a free structure.
* Fill it in and return it if we find one.
*/
for (i = 0; i < seminfo.semmnu; i++) {
suptr = SEMU(i);
if (suptr->un_proc == NULL) {
suptr->un_next_idx = semu_list_idx;
semu_list_idx = i;
suptr->un_cnt = 0;
suptr->un_ent = NULL;
suptr->un_proc = p;
return i;
}
}
/*
* We didn't find a free one, if this is the first attempt
* then try to free some structures.
*/
if (attempt == 0) {
/* All the structures are in use - try to free some */
int did_something = 0;
supidx = &semu_list_idx;
while (*supidx != -1) {
suptr = SEMU(*supidx);
if (suptr->un_cnt == 0) {
suptr->un_proc = NULL;
*supidx = suptr->un_next_idx;
did_something = 1;
} else
supidx = &(suptr->un_next_idx);
}
/* If we didn't free anything. Try expanding
* the semu[] array. If that doesn't work
* then fail. We expand last to get the
* most reuse out of existing resources.
*/
if (!did_something)
if (!grow_semu_array(seminfo.semmnu + 1))
return -1;
} else {
/*
* The second pass failed even though we freed
* something after the first pass!
* This is IMPOSSIBLE!
*/
panic("semu_alloc - second attempt failed");
}
}
return -1;
}
/*
* Adjust a particular entry for a particular proc
*
* Assumes we already hold the subsystem lock.
*/
static int
semundo_adjust(struct proc *p, int *supidx, int semid,
int semnum, int adjval)
{
struct sem_undo *suptr;
int suidx;
struct undo *sueptr, **suepptr, *new_sueptr;
int i;
/*
* Look for and remember the sem_undo if the caller doesn't provide it
*/
suidx = *supidx;
if (suidx == -1) {
for (suidx = semu_list_idx; suidx != -1;
suidx = suptr->un_next_idx) {
suptr = SEMU(suidx);
if (suptr->un_proc == p) {
*supidx = suidx;
break;
}
}
if (suidx == -1) {
if (adjval == 0)
return(0);
suidx = semu_alloc(p);
if (suidx == -1)
return(ENOSPC);
*supidx = suidx;
}
}
/*
* Look for the requested entry and adjust it (delete if adjval becomes
* 0).
*/
suptr = SEMU(suidx);
new_sueptr = NULL;
for (i = 0, suepptr = &suptr->un_ent, sueptr = suptr->un_ent;
i < suptr->un_cnt;
i++, suepptr = &sueptr->une_next, sueptr = sueptr->une_next) {
if (sueptr->une_id != semid || sueptr->une_num != semnum)
continue;
if (adjval == 0)
sueptr->une_adjval = 0;
else
sueptr->une_adjval += adjval;
if (sueptr->une_adjval == 0) {
suptr->un_cnt--;
*suepptr = sueptr->une_next;
FREE(sueptr, M_SYSVSEM);
sueptr = NULL;
}
return 0;
}
/* Didn't find the right entry - create it */
if (adjval == 0) {
/* no adjustment: no need for a new entry */
return 0;
}
if (suptr->un_cnt == limitseminfo.semume) {
/* reached the limit number of semaphore undo entries */
return EINVAL;
}
/* allocate a new semaphore undo entry */
MALLOC(new_sueptr, struct undo *, sizeof (struct undo),
M_SYSVSEM, M_WAITOK);
if (new_sueptr == NULL) {
return ENOMEM;
}
/* fill in the new semaphore undo entry */
new_sueptr->une_next = suptr->un_ent;
suptr->un_ent = new_sueptr;
suptr->un_cnt++;
new_sueptr->une_adjval = adjval;
new_sueptr->une_id = semid;
new_sueptr->une_num = semnum;
return 0;
}
/* Assumes we already hold the subsystem lock.
*/
static void
semundo_clear(int semid, int semnum)
{
struct sem_undo *suptr;
int suidx;
for (suidx = semu_list_idx; suidx != -1; suidx = suptr->un_next_idx) {
struct undo *sueptr;
struct undo **suepptr;
int i = 0;
suptr = SEMU(suidx);
sueptr = suptr->un_ent;
suepptr = &suptr->un_ent;
while (i < suptr->un_cnt) {
if (sueptr->une_id == semid) {
if (semnum == -1 || sueptr->une_num == semnum) {
suptr->un_cnt--;
*suepptr = sueptr->une_next;
FREE(sueptr, M_SYSVSEM);
sueptr = *suepptr;
continue;
}
if (semnum != -1)
break;
}
i++;
suepptr = &sueptr->une_next;
sueptr = sueptr->une_next;
}
}
}
/*
* Note that the user-mode half of this passes a union coerced to a
* user_addr_t. The union contains either an int or a pointer, and
* so we have to coerce it back, variant on whether the calling
* process is 64 bit or not. The coercion works for the 'val' element
* because the alignment is the same in user and kernel space.
*/
int
semctl(struct proc *p, struct semctl_args *uap, int32_t *retval)
{
int semid = uap->semid;
int semnum = uap->semnum;
int cmd = uap->cmd;
user_semun_t user_arg = (user_semun_t)uap->arg;
kauth_cred_t cred = kauth_cred_get();
int i, rval, eval;
struct user_semid_ds sbuf;
struct semid_kernel *semakptr;
AUDIT_ARG(svipc_cmd, cmd);
AUDIT_ARG(svipc_id, semid);
SYSV_SEM_SUBSYS_LOCK();
#ifdef SEM_DEBUG
printf("call to semctl(%d, %d, %d, 0x%qx)\n", semid, semnum, cmd, user_arg);
#endif
semid = IPCID_TO_IX(semid);
if (semid < 0 || semid >= seminfo.semmni) {
#ifdef SEM_DEBUG
printf("Invalid semid\n");
#endif
eval = EINVAL;
goto semctlout;
}
semakptr = &sema[semid];
if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
semakptr->u.sem_perm._seq != IPCID_TO_SEQ(uap->semid)) {
eval = EINVAL;
goto semctlout;
}
#if CONFIG_MACF
eval = mac_sysvsem_check_semctl(cred, semakptr, cmd);
if (eval)
goto semctlout;
#endif
eval = 0;
rval = 0;
switch (cmd) {
case IPC_RMID:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_M)))
goto semctlout;
semakptr->u.sem_perm.cuid = kauth_cred_getuid(cred);
semakptr->u.sem_perm.uid = kauth_cred_getuid(cred);
semtot -= semakptr->u.sem_nsems;
for (i = semakptr->u.sem_base - sem_pool; i < semtot; i++)
sem_pool[i] = sem_pool[i + semakptr->u.sem_nsems];
for (i = 0; i < seminfo.semmni; i++) {
if ((sema[i].u.sem_perm.mode & SEM_ALLOC) &&
sema[i].u.sem_base > semakptr->u.sem_base)
sema[i].u.sem_base -= semakptr->u.sem_nsems;
}
semakptr->u.sem_perm.mode = 0;
#if CONFIG_MACF
mac_sysvsem_label_recycle(semakptr);
#endif
semundo_clear(semid, -1);
wakeup((caddr_t)semakptr);
break;
case IPC_SET:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_M)))
goto semctlout;
if (IS_64BIT_PROCESS(p)) {
struct user64_semid_ds ds64;
eval = copyin(user_arg.buf, &ds64, sizeof(ds64));
semid_ds_64tokernel(&ds64, &sbuf);
} else {
struct user32_semid_ds ds32;
eval = copyin(user_arg.buf, &ds32, sizeof(ds32));
semid_ds_32tokernel(&ds32, &sbuf);
}
if (eval != 0) {
goto semctlout;
}
semakptr->u.sem_perm.uid = sbuf.sem_perm.uid;
semakptr->u.sem_perm.gid = sbuf.sem_perm.gid;
semakptr->u.sem_perm.mode = (semakptr->u.sem_perm.mode &
~0777) | (sbuf.sem_perm.mode & 0777);
semakptr->u.sem_ctime = sysv_semtime();
break;
case IPC_STAT:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
if (IS_64BIT_PROCESS(p)) {
struct user64_semid_ds semid_ds64;
bzero(&semid_ds64, sizeof(semid_ds64));
semid_ds_kernelto64(&semakptr->u, &semid_ds64);
eval = copyout(&semid_ds64, user_arg.buf, sizeof(semid_ds64));
} else {
struct user32_semid_ds semid_ds32;
bzero(&semid_ds32, sizeof(semid_ds32));
semid_ds_kernelto32(&semakptr->u, &semid_ds32);
eval = copyout(&semid_ds32, user_arg.buf, sizeof(semid_ds32));
}
break;
case GETNCNT:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
eval = EINVAL;
goto semctlout;
}
rval = semakptr->u.sem_base[semnum].semncnt;
break;
case GETPID:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
eval = EINVAL;
goto semctlout;
}
rval = semakptr->u.sem_base[semnum].sempid;
break;
case GETVAL:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
eval = EINVAL;
goto semctlout;
}
rval = semakptr->u.sem_base[semnum].semval;
break;
case GETALL:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
/* XXXXXXXXXXXXXXXX TBD XXXXXXXXXXXXXXXX */
for (i = 0; i < semakptr->u.sem_nsems; i++) {
/* XXX could be done in one go... */
eval = copyout((caddr_t)&semakptr->u.sem_base[i].semval,
user_arg.array + (i * sizeof(unsigned short)),
sizeof(unsigned short));
if (eval != 0)
break;
}
break;
case GETZCNT:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_R)))
goto semctlout;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
eval = EINVAL;
goto semctlout;
}
rval = semakptr->u.sem_base[semnum].semzcnt;
break;
case SETVAL:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_W)))
{
#ifdef SEM_DEBUG
printf("Invalid credentials for write\n");
#endif
goto semctlout;
}
if (semnum < 0 || semnum >= semakptr->u.sem_nsems)
{
#ifdef SEM_DEBUG
printf("Invalid number out of range for set\n");
#endif
eval = EINVAL;
goto semctlout;
}
/*
* Cast down a pointer instead of using 'val' member directly
* to avoid introducing endieness and a pad field into the
* header file. Ugly, but it works.
*/
u_int newsemval = CAST_DOWN_EXPLICIT(u_int, user_arg.buf);
/*
* The check is being performed as unsigned values to match
* eventual destination
*/
if (newsemval > (u_int)seminfo.semvmx)
{
#ifdef SEM_DEBUG
printf("Out of range sem value for set\n");
#endif
eval = ERANGE;
goto semctlout;
}
semakptr->u.sem_base[semnum].semval = newsemval;
semakptr->u.sem_base[semnum].sempid = p->p_pid;
/* XXX scottl Should there be a MAC call here? */
semundo_clear(semid, semnum);
wakeup((caddr_t)semakptr);
break;
case SETALL:
if ((eval = ipcperm(cred, &semakptr->u.sem_perm, IPC_W)))
goto semctlout;
/*** XXXXXXXXXXXX TBD ********/
for (i = 0; i < semakptr->u.sem_nsems; i++) {
/* XXX could be done in one go... */
eval = copyin(user_arg.array + (i * sizeof(unsigned short)),
(caddr_t)&semakptr->u.sem_base[i].semval,
sizeof(unsigned short));
if (eval != 0)
break;
semakptr->u.sem_base[i].sempid = p->p_pid;
}
/* XXX scottl Should there be a MAC call here? */
semundo_clear(semid, -1);
wakeup((caddr_t)semakptr);
break;
default:
eval = EINVAL;
goto semctlout;
}
if (eval == 0)
*retval = rval;
semctlout:
SYSV_SEM_SUBSYS_UNLOCK();
return(eval);
}
int
semget(__unused struct proc *p, struct semget_args *uap, int32_t *retval)
{
int semid, eval;
int key = uap->key;
int nsems = uap->nsems;
int semflg = uap->semflg;
kauth_cred_t cred = kauth_cred_get();
#ifdef SEM_DEBUG
if (key != IPC_PRIVATE)
printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg);
else
printf("semget(IPC_PRIVATE, %d, 0%o)\n", nsems, semflg);
#endif
SYSV_SEM_SUBSYS_LOCK();
if (key != IPC_PRIVATE) {
for (semid = 0; semid < seminfo.semmni; semid++) {
if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) &&
sema[semid].u.sem_perm._key == key)
break;
}
if (semid < seminfo.semmni) {
#ifdef SEM_DEBUG
printf("found public key\n");
#endif
if ((eval = ipcperm(cred, &sema[semid].u.sem_perm,
semflg & 0700)))
goto semgetout;
if (nsems < 0 || sema[semid].u.sem_nsems < nsems) {
#ifdef SEM_DEBUG
printf("too small\n");
#endif
eval = EINVAL;
goto semgetout;
}
if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
#ifdef SEM_DEBUG
printf("not exclusive\n");
#endif
eval = EEXIST;
goto semgetout;
}
#if CONFIG_MACF
eval = mac_sysvsem_check_semget(cred, &sema[semid]);
if (eval)
goto semgetout;
#endif
goto found;
}
}
#ifdef SEM_DEBUG
printf("need to allocate an id for the request\n");
#endif
if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
if (nsems <= 0 || nsems > limitseminfo.semmsl) {
#ifdef SEM_DEBUG
printf("nsems out of range (0<%d<=%d)\n", nsems,
seminfo.semmsl);
#endif
eval = EINVAL;
goto semgetout;
}
if (nsems > seminfo.semmns - semtot) {
#ifdef SEM_DEBUG
printf("not enough semaphores left (need %d, got %d)\n",
nsems, seminfo.semmns - semtot);
#endif
if (!grow_sem_pool(semtot + nsems)) {
#ifdef SEM_DEBUG
printf("failed to grow the sem array\n");
#endif
eval = ENOSPC;
goto semgetout;
}
}
for (semid = 0; semid < seminfo.semmni; semid++) {
if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0)
break;
}