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2451114ab1
freebsd/sys/kern/sysv_sem.c
Robert Watson 53d0031d37 Correct two incorrectly merged changes introduced in sysv_sem.c:1.71: 
return EINVAL rather than setting error, and don't free sops
unconditionally.  The first change was merged accidentally as part of
the larger set of changes to introduce MAC labels and access control,
and potentially lead to continued processing of a request even after
it was determined to be invalid.  The second change was due to changes
in the semaphore code since the original work was performed.

Pointed out by:	truckman
2004-11-13 08:06:40 +00:00

1249 lines
31 KiB
C
Raw Blame History

/*
* Implementation of SVID semaphores
*
* Author: Daniel Boulet
*
* This software is provided ``AS IS'' without any warranties of any kind.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_sysvipc.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/sem.h>
#include <sys/syscall.h>
#include <sys/sysent.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <sys/jail.h>
static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores");
#ifdef SEM_DEBUG
#define DPRINTF(a) printf a
#else
#define DPRINTF(a)
#endif
static void seminit(void);
static int sysvsem_modload(struct module *, int, void *);
static int semunload(void);
static void semexit_myhook(void *arg, struct proc *p);
static int sysctl_sema(SYSCTL_HANDLER_ARGS);
static int semvalid(int semid, struct semid_kernel *semakptr);
#ifndef _SYS_SYSPROTO_H_
struct __semctl_args;
int __semctl(struct thread *td, struct __semctl_args *uap);
struct semget_args;
int semget(struct thread *td, struct semget_args *uap);
struct semop_args;
int semop(struct thread *td, struct semop_args *uap);
#endif
static struct sem_undo *semu_alloc(struct thread *td);
static int semundo_adjust(struct thread *td, struct sem_undo **supptr,
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 struct mtx sem_mtx; /* semaphore global lock */
static int semtot = 0;
static struct semid_kernel *sema; /* semaphore id pool */
static struct mtx *sema_mtx; /* semaphore id pool mutexes*/
static struct sem *sem; /* semaphore pool */
SLIST_HEAD(, sem_undo) semu_list; /* list of active undo structures */
static int *semu; /* undo structure pool */
static eventhandler_tag semexit_tag;
#define SEMUNDO_MTX sem_mtx
#define SEMUNDO_LOCK() mtx_lock(&SEMUNDO_MTX);
#define SEMUNDO_UNLOCK() mtx_unlock(&SEMUNDO_MTX);
#define SEMUNDO_LOCKASSERT(how) mtx_assert(&SEMUNDO_MTX, (how));
struct sem {
u_short semval; /* semaphore value */
pid_t sempid; /* pid of last operation */
u_short semncnt; /* # awaiting semval > cval */
u_short semzcnt; /* # awaiting semval = 0 */
};
/*
* Undo structure (one per process)
*/
struct sem_undo {
SLIST_ENTRY(sem_undo) un_next; /* ptr to next active undo structure */
struct proc *un_proc; /* owner of this structure */
short un_cnt; /* # of active entries */
struct undo {
short un_adjval; /* adjust on exit values */
short un_num; /* semaphore # */
int un_id; /* semid */
} un_ent[1]; /* undo entries */
};
/*
* Configuration parameters
*/
#ifndef SEMMNI
#define SEMMNI 10 /* # of semaphore identifiers */
#endif
#ifndef SEMMNS
#define SEMMNS 60 /* # of semaphores in system */
#endif
#ifndef SEMUME
#define SEMUME 10 /* max # of undo entries per process */
#endif
#ifndef SEMMNU
#define SEMMNU 30 /* # of undo structures in system */
#endif
/* shouldn't need tuning */
#ifndef SEMMAP
#define SEMMAP 30 /* # of entries in semaphore map */
#endif
#ifndef SEMMSL
#define SEMMSL SEMMNS /* max # of semaphores per id */
#endif
#ifndef SEMOPM
#define SEMOPM 100 /* max # of operations per semop call */
#endif
#define SEMVMX 32767 /* semaphore maximum value */
#define SEMAEM 16384 /* adjust on exit max value */
/*
* Due to the way semaphore memory is allocated, we have to ensure that
* SEMUSZ is properly aligned.
*/
#define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1))
/* actual size of an undo structure */
#define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME]))
/*
* Macro to find a particular sem_undo vector
*/
#define SEMU(ix) \
((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz))
/*
* semaphore info struct
*/
struct seminfo seminfo = {
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 */
};
SYSCTL_DECL(_kern_ipc);
SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "");
SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "");
SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD,
NULL, 0, sysctl_sema, "", "");
static void
seminit(void)
{
int i;
TUNABLE_INT_FETCH("kern.ipc.semmap", &seminfo.semmap);
TUNABLE_INT_FETCH("kern.ipc.semmni", &seminfo.semmni);
TUNABLE_INT_FETCH("kern.ipc.semmns", &seminfo.semmns);
TUNABLE_INT_FETCH("kern.ipc.semmnu", &seminfo.semmnu);
TUNABLE_INT_FETCH("kern.ipc.semmsl", &seminfo.semmsl);
TUNABLE_INT_FETCH("kern.ipc.semopm", &seminfo.semopm);
TUNABLE_INT_FETCH("kern.ipc.semume", &seminfo.semume);
TUNABLE_INT_FETCH("kern.ipc.semusz", &seminfo.semusz);
TUNABLE_INT_FETCH("kern.ipc.semvmx", &seminfo.semvmx);
TUNABLE_INT_FETCH("kern.ipc.semaem", &seminfo.semaem);
sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK);
sema = malloc(sizeof(struct semid_kernel) * seminfo.semmni, M_SEM,
M_WAITOK);
sema_mtx = malloc(sizeof(struct mtx) * seminfo.semmni, M_SEM,
M_WAITOK | M_ZERO);
semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK);
for (i = 0; i < seminfo.semmni; i++) {
sema[i].u.sem_base = 0;
sema[i].u.sem_perm.mode = 0;
sema[i].u.sem_perm.seq = 0;
}
for (i = 0; i < seminfo.semmni; i++)
mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF);
for (i = 0; i < seminfo.semmnu; i++) {
struct sem_undo *suptr = SEMU(i);
suptr->un_proc = NULL;
}
SLIST_INIT(&semu_list);
mtx_init(&sem_mtx, "sem", NULL, MTX_DEF);
semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL,
EVENTHANDLER_PRI_ANY);
}
static int
semunload(void)
{
int i;
if (semtot != 0)
return (EBUSY);
EVENTHANDLER_DEREGISTER(process_exit, semexit_tag);
free(sem, M_SEM);
free(sema, M_SEM);
free(semu, M_SEM);
for (i = 0; i < seminfo.semmni; i++)
mtx_destroy(&sema_mtx[i]);
mtx_destroy(&sem_mtx);
return (0);
}
static int
sysvsem_modload(struct module *module, int cmd, void *arg)
{
int error = 0;
switch (cmd) {
case MOD_LOAD:
seminit();
break;
case MOD_UNLOAD:
error = semunload();
break;
case MOD_SHUTDOWN:
break;
default:
error = EINVAL;
break;
}
return (error);
}
static moduledata_t sysvsem_mod = {
"sysvsem",
&sysvsem_modload,
NULL
};
SYSCALL_MODULE_HELPER(semsys);
SYSCALL_MODULE_HELPER(__semctl);
SYSCALL_MODULE_HELPER(semget);
SYSCALL_MODULE_HELPER(semop);
DECLARE_MODULE(sysvsem, sysvsem_mod,
SI_SUB_SYSV_SEM, SI_ORDER_FIRST);
MODULE_VERSION(sysvsem, 1);
/*
* Entry point for all SEM calls
*
* MPSAFE
*/
int
semsys(td, uap)
struct thread *td;
/* XXX actually varargs. */
struct semsys_args /* {
int which;
int a2;
int a3;
int a4;
int a5;
} */ *uap;
{
int error;
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
if (uap->which < 0 ||
uap->which >= sizeof(semcalls)/sizeof(semcalls[0]))
return (EINVAL);
error = (*semcalls[uap->which])(td, &uap->a2);
return (error);
}
/*
* Allocate a new sem_undo structure for a process
* (returns ptr to structure or NULL if no more room)
*/
static struct sem_undo *
semu_alloc(td)
struct thread *td;
{
int i;
struct sem_undo *suptr;
struct sem_undo **supptr;
int attempt;
SEMUNDO_LOCKASSERT(MA_OWNED);
/*
* Try twice to allocate something.
* (we'll purge an empty structure 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) {
SLIST_INSERT_HEAD(&semu_list, suptr, un_next);
suptr->un_cnt = 0;
suptr->un_proc = td->td_proc;
return(suptr);
}
}
/*
* We didn't find a free one, if this is the first attempt
* then try to free a structure.
*/
if (attempt == 0) {
/* All the structures are in use - try to free one */
int did_something = 0;
SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list,
un_next) {
if (suptr->un_cnt == 0) {
suptr->un_proc = NULL;
did_something = 1;
*supptr = SLIST_NEXT(suptr, un_next);
break;
}
}
/* If we didn't free anything then just give-up */
if (!did_something)
return(NULL);
} else {
/*
* The second pass failed even though we freed
* something after the first pass!
* This is IMPOSSIBLE!
*/
panic("semu_alloc - second attempt failed");
}
}
return (NULL);
}
/*
* Adjust a particular entry for a particular proc
*/
static int
semundo_adjust(td, supptr, semid, semnum, adjval)
struct thread *td;
struct sem_undo **supptr;
int semid, semnum;
int adjval;
{
struct proc *p = td->td_proc;
struct sem_undo *suptr;
struct undo *sunptr;
int i;
SEMUNDO_LOCKASSERT(MA_OWNED);
/* Look for and remember the sem_undo if the caller doesn't provide
it */
suptr = *supptr;
if (suptr == NULL) {
SLIST_FOREACH(suptr, &semu_list, un_next) {
if (suptr->un_proc == p) {
*supptr = suptr;
break;
}
}
if (suptr == NULL) {
if (adjval == 0)
return(0);
suptr = semu_alloc(td);
if (suptr == NULL)
return(ENOSPC);
*supptr = suptr;
}
}
/*
* Look for the requested entry and adjust it (delete if adjval becomes
* 0).
*/
sunptr = &suptr->un_ent[0];
for (i = 0; i < suptr->un_cnt; i++, sunptr++) {
if (sunptr->un_id != semid || sunptr->un_num != semnum)
continue;
if (adjval != 0) {
adjval += sunptr->un_adjval;
if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
return (ERANGE);
}
sunptr->un_adjval = adjval;
if (sunptr->un_adjval == 0) {
suptr->un_cnt--;
if (i < suptr->un_cnt)
suptr->un_ent[i] =
suptr->un_ent[suptr->un_cnt];
}
return(0);
}
/* Didn't find the right entry - create it */
if (adjval == 0)
return(0);
if (adjval > seminfo.semaem || adjval < -seminfo.semaem)
return (ERANGE);
if (suptr->un_cnt != seminfo.semume) {
sunptr = &suptr->un_ent[suptr->un_cnt];
suptr->un_cnt++;
sunptr->un_adjval = adjval;
sunptr->un_id = semid; sunptr->un_num = semnum;
} else
return(EINVAL);
return(0);
}
static void
semundo_clear(semid, semnum)
int semid, semnum;
{
struct sem_undo *suptr;
SEMUNDO_LOCKASSERT(MA_OWNED);
SLIST_FOREACH(suptr, &semu_list, un_next) {
struct undo *sunptr = &suptr->un_ent[0];
int i = 0;
while (i < suptr->un_cnt) {
if (sunptr->un_id == semid) {
if (semnum == -1 || sunptr->un_num == semnum) {
suptr->un_cnt--;
if (i < suptr->un_cnt) {
suptr->un_ent[i] =
suptr->un_ent[suptr->un_cnt];
continue;
}
}
if (semnum != -1)
break;
}
i++, sunptr++;
}
}
}
static int
semvalid(semid, semakptr)
int semid;
struct semid_kernel *semakptr;
{
return ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
semakptr->u.sem_perm.seq != IPCID_TO_SEQ(semid) ? EINVAL : 0);
}
/*
* Note that the user-mode half of this passes a union, not a pointer
*/
#ifndef _SYS_SYSPROTO_H_
struct __semctl_args {
int semid;
int semnum;
int cmd;
union semun *arg;
};
#endif
/*
* MPSAFE
*/
int
__semctl(td, uap)
struct thread *td;
struct __semctl_args *uap;
{
int semid = uap->semid;
int semnum = uap->semnum;
int cmd = uap->cmd;
u_short *array;
union semun *arg = uap->arg;
union semun real_arg;
struct ucred *cred = td->td_ucred;
int i, rval, error;
struct semid_ds sbuf;
struct semid_kernel *semakptr;
struct mtx *sema_mtxp;
u_short usval, count;
DPRINTF(("call to semctl(%d, %d, %d, 0x%x)\n",
semid, semnum, cmd, arg));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
array = NULL;
switch(cmd) {
case SEM_STAT:
if (semid < 0 || semid >= seminfo.semmni)
return (EINVAL);
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
return (error);
semakptr = &sema[semid];
sema_mtxp = &sema_mtx[semid];
mtx_lock(sema_mtxp);
if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
error = EINVAL;
goto done2;
}
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
mtx_unlock(sema_mtxp);
error = copyout(&semakptr->u, real_arg.buf,
sizeof(struct semid_ds));
rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm);
if (error == 0)
td->td_retval[0] = rval;
return (error);
}
semid = IPCID_TO_IX(semid);
if (semid < 0 || semid >= seminfo.semmni)
return (EINVAL);
semakptr = &sema[semid];
sema_mtxp = &sema_mtx[semid];
error = 0;
rval = 0;
switch (cmd) {
case IPC_RMID:
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
goto done2;
semakptr->u.sem_perm.cuid = cred->cr_uid;
semakptr->u.sem_perm.uid = cred->cr_uid;
semtot -= semakptr->u.sem_nsems;
for (i = semakptr->u.sem_base - sem; i < semtot; i++)
sem[i] = sem[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;
SEMUNDO_LOCK();
semundo_clear(semid, -1);
SEMUNDO_UNLOCK();
wakeup(semakptr);
break;
case IPC_SET:
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
goto done2;
if ((error = copyin(real_arg.buf, &sbuf, sizeof(sbuf))) != 0)
goto done2;
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M)))
goto done2;
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 = time_second;
break;
case IPC_STAT:
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
goto done2;
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
sbuf = semakptr->u;
mtx_unlock(sema_mtxp);
error = copyout(&semakptr->u, real_arg.buf,
sizeof(struct semid_ds));
break;
case GETNCNT:
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
error = EINVAL;
goto done2;
}
rval = semakptr->u.sem_base[semnum].semncnt;
break;
case GETPID:
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
error = EINVAL;
goto done2;
}
rval = semakptr->u.sem_base[semnum].sempid;
break;
case GETVAL:
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
error = EINVAL;
goto done2;
}
rval = semakptr->u.sem_base[semnum].semval;
break;
case GETALL:
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
goto done2;
array = malloc(sizeof(*array) * semakptr->u.sem_nsems, M_TEMP,
M_WAITOK);
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
for (i = 0; i < semakptr->u.sem_nsems; i++)
array[i] = semakptr->u.sem_base[i].semval;
mtx_unlock(sema_mtxp);
error = copyout(array, real_arg.array,
i * sizeof(real_arg.array[0]));
break;
case GETZCNT:
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R)))
goto done2;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
error = EINVAL;
goto done2;
}
rval = semakptr->u.sem_base[semnum].semzcnt;
break;
case SETVAL:
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
goto done2;
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
goto done2;
if (semnum < 0 || semnum >= semakptr->u.sem_nsems) {
error = EINVAL;
goto done2;
}
if (real_arg.val < 0 || real_arg.val > seminfo.semvmx) {
error = ERANGE;
goto done2;
}
semakptr->u.sem_base[semnum].semval = real_arg.val;
SEMUNDO_LOCK();
semundo_clear(semid, semnum);
SEMUNDO_UNLOCK();
wakeup(semakptr);
break;
case SETALL:
mtx_lock(sema_mtxp);
raced:
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
count = semakptr->u.sem_nsems;
mtx_unlock(sema_mtxp);
if ((error = copyin(arg, &real_arg, sizeof(real_arg))) != 0)
goto done2;
array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK);
copyin(real_arg.array, array, count * sizeof(*array));
if (error)
break;
mtx_lock(sema_mtxp);
if ((error = semvalid(uap->semid, semakptr)) != 0)
goto done2;
/* we could have raced? */
if (count != semakptr->u.sem_nsems) {
free(array, M_TEMP);
array = NULL;
goto raced;
}
if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_W)))
goto done2;
for (i = 0; i < semakptr->u.sem_nsems; i++) {
usval = array[i];
if (usval > seminfo.semvmx) {
error = ERANGE;
break;
}
semakptr->u.sem_base[i].semval = usval;
}
SEMUNDO_LOCK();
semundo_clear(semid, -1);
SEMUNDO_UNLOCK();
wakeup(semakptr);
break;
default:
error = EINVAL;
break;
}
if (error == 0)
td->td_retval[0] = rval;
done2:
if (mtx_owned(sema_mtxp))
mtx_unlock(sema_mtxp);
if (array != NULL)
free(array, M_TEMP);
return(error);
}
#ifndef _SYS_SYSPROTO_H_
struct semget_args {
key_t key;
int nsems;
int semflg;
};
#endif
/*
* MPSAFE
*/
int
semget(td, uap)
struct thread *td;
struct semget_args *uap;
{
int semid, error = 0;
int key = uap->key;
int nsems = uap->nsems;
int semflg = uap->semflg;
struct ucred *cred = td->td_ucred;
DPRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
mtx_lock(&Giant);
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) {
DPRINTF(("found public key\n"));
if ((error = ipcperm(td, &sema[semid].u.sem_perm,
semflg & 0700))) {
goto done2;
}
if (nsems > 0 && sema[semid].u.sem_nsems < nsems) {
DPRINTF(("too small\n"));
error = EINVAL;
goto done2;
}
if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) {
DPRINTF(("not exclusive\n"));
error = EEXIST;
goto done2;
}
goto found;
}
}
DPRINTF(("need to allocate the semid_kernel\n"));
if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) {
if (nsems <= 0 || nsems > seminfo.semmsl) {
DPRINTF(("nsems out of range (0<%d<=%d)\n", nsems,
seminfo.semmsl));
error = EINVAL;
goto done2;
}
if (nsems > seminfo.semmns - semtot) {
DPRINTF((
"not enough semaphores left (need %d, got %d)\n",
nsems, seminfo.semmns - semtot));
error = ENOSPC;
goto done2;
}
for (semid = 0; semid < seminfo.semmni; semid++) {
if ((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0)
break;
}
if (semid == seminfo.semmni) {
DPRINTF(("no more semid_kernel's available\n"));
error = ENOSPC;
goto done2;
}
DPRINTF(("semid %d is available\n", semid));
sema[semid].u.sem_perm.key = key;
sema[semid].u.sem_perm.cuid = cred->cr_uid;
sema[semid].u.sem_perm.uid = cred->cr_uid;
sema[semid].u.sem_perm.cgid = cred->cr_gid;
sema[semid].u.sem_perm.gid = cred->cr_gid;
sema[semid].u.sem_perm.mode = (semflg & 0777) | SEM_ALLOC;
sema[semid].u.sem_perm.seq =
(sema[semid].u.sem_perm.seq + 1) & 0x7fff;
sema[semid].u.sem_nsems = nsems;
sema[semid].u.sem_otime = 0;
sema[semid].u.sem_ctime = time_second;
sema[semid].u.sem_base = &sem[semtot];
semtot += nsems;
bzero(sema[semid].u.sem_base,
sizeof(sema[semid].u.sem_base[0])*nsems);
DPRINTF(("sembase = 0x%x, next = 0x%x\n",
sema[semid].u.sem_base, &sem[semtot]));
} else {
DPRINTF(("didn't find it and wasn't asked to create it\n"));
error = ENOENT;
goto done2;
}
found:
td->td_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].u.sem_perm);
done2:
mtx_unlock(&Giant);
return (error);
}
#ifndef _SYS_SYSPROTO_H_
struct semop_args {
int semid;
struct sembuf *sops;
size_t nsops;
};
#endif
/*
* MPSAFE
*/
int
semop(td, uap)
struct thread *td;
struct semop_args *uap;
{
#define SMALL_SOPS 8
struct sembuf small_sops[SMALL_SOPS];
int semid = uap->semid;
size_t nsops = uap->nsops;
struct sembuf *sops;
struct semid_kernel *semakptr;
struct sembuf *sopptr = 0;
struct sem *semptr = 0;
struct sem_undo *suptr;
struct mtx *sema_mtxp;
size_t i, j, k;
int error;
int do_wakeup, do_undos;
DPRINTF(("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops));
if (!jail_sysvipc_allowed && jailed(td->td_ucred))
return (ENOSYS);
semid = IPCID_TO_IX(semid); /* Convert back to zero origin */
if (semid < 0 || semid >= seminfo.semmni)
return (EINVAL);
/* Allocate memory for sem_ops */
if (nsops <= SMALL_SOPS)
sops = small_sops;
else if (nsops <= seminfo.semopm)
sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK);
else {
DPRINTF(("too many sops (max=%d, nsops=%d)\n", seminfo.semopm,
nsops));
return (E2BIG);
}
if ((error = copyin(uap->sops, sops, nsops * sizeof(sops[0]))) != 0) {
DPRINTF(("error = %d from copyin(%08x, %08x, %d)\n", error,
uap->sops, sops, nsops * sizeof(sops[0])));
if (sops != small_sops)
free(sops, M_SEM);
return (error);
}
semakptr = &sema[semid];
sema_mtxp = &sema_mtx[semid];
mtx_lock(sema_mtxp);
if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0) {
error = EINVAL;
goto done2;
}
if (semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
error = EINVAL;
goto done2;
}
/*
* Initial pass thru sops to see what permissions are needed.
* Also perform any checks that don't need repeating on each
* attempt to satisfy the request vector.
*/
j = 0; /* permission needed */
do_undos = 0;
for (i = 0; i < nsops; i++) {
sopptr = &sops[i];
if (sopptr->sem_num >= semakptr->u.sem_nsems) {
error = EFBIG;
goto done2;
}
if (sopptr->sem_flg & SEM_UNDO && sopptr->sem_op != 0)
do_undos = 1;
j |= (sopptr->sem_op == 0) ? SEM_R : SEM_A;
}
if ((error = ipcperm(td, &semakptr->u.sem_perm, j))) {
DPRINTF(("error = %d from ipaccess\n", error));
goto done2;
}
/*
* Loop trying to satisfy the vector of requests.
* If we reach a point where we must wait, any requests already
* performed are rolled back and we go to sleep until some other
* process wakes us up. At this point, we start all over again.
*
* This ensures that from the perspective of other tasks, a set
* of requests is atomic (never partially satisfied).
*/
for (;;) {
do_wakeup = 0;
error = 0; /* error return if necessary */
for (i = 0; i < nsops; i++) {
sopptr = &sops[i];
semptr = &semakptr->u.sem_base[sopptr->sem_num];
DPRINTF((
"semop: semakptr=%x, sem_base=%x, "
"semptr=%x, sem[%d]=%d : op=%d, flag=%s\n",
semakptr, semakptr->u.sem_base, semptr,
sopptr->sem_num, semptr->semval, sopptr->sem_op,
(sopptr->sem_flg & IPC_NOWAIT) ?
"nowait" : "wait"));
if (sopptr->sem_op < 0) {
if (semptr->semval + sopptr->sem_op < 0) {
DPRINTF(("semop: can't do it now\n"));
break;
} else {
semptr->semval += sopptr->sem_op;
if (semptr->semval == 0 &&
semptr->semzcnt > 0)
do_wakeup = 1;
}
} else if (sopptr->sem_op == 0) {
if (semptr->semval != 0) {
DPRINTF(("semop: not zero now\n"));
break;
}
} else if (semptr->semval + sopptr->sem_op >
seminfo.semvmx) {
error = ERANGE;
break;
} else {
if (semptr->semncnt > 0)
do_wakeup = 1;
semptr->semval += sopptr->sem_op;
}
}
/*
* Did we get through the entire vector?
*/
if (i >= nsops)
goto done;
/*
* No ... rollback anything that we've already done
*/
DPRINTF(("semop: rollback 0 through %d\n", i-1));
for (j = 0; j < i; j++)
semakptr->u.sem_base[sops[j].sem_num].semval -=
sops[j].sem_op;
/* If we detected an error, return it */
if (error != 0)
goto done2;
/*
* If the request that we couldn't satisfy has the
* NOWAIT flag set then return with EAGAIN.
*/
if (sopptr->sem_flg & IPC_NOWAIT) {
error = EAGAIN;
goto done2;
}
if (sopptr->sem_op == 0)
semptr->semzcnt++;
else
semptr->semncnt++;
DPRINTF(("semop: good night!\n"));
error = msleep(semakptr, sema_mtxp, (PZERO - 4) | PCATCH,
"semwait", 0);
DPRINTF(("semop: good morning (error=%d)!\n", error));
/* return code is checked below, after sem[nz]cnt-- */
/*
* Make sure that the semaphore still exists
*/
if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 ||
semakptr->u.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) {
error = EIDRM;
goto done2;
}
/*
* The semaphore is still alive. Readjust the count of
* waiting processes.
*/
if (sopptr->sem_op == 0)
semptr->semzcnt--;
else
semptr->semncnt--;
/*
* Is it really morning, or was our sleep interrupted?
* (Delayed check of msleep() return code because we
* need to decrement sem[nz]cnt either way.)
*/
if (error != 0) {
error = EINTR;
goto done2;
}
DPRINTF(("semop: good morning!\n"));
}
done:
/*
* Process any SEM_UNDO requests.
*/
if (do_undos) {
SEMUNDO_LOCK();
suptr = NULL;
for (i = 0; i < nsops; i++) {
/*
* We only need to deal with SEM_UNDO's for non-zero
* op's.
*/
int adjval;
if ((sops[i].sem_flg & SEM_UNDO) == 0)
continue;
adjval = sops[i].sem_op;
if (adjval == 0)
continue;
error = semundo_adjust(td, &suptr, semid,
sops[i].sem_num, -adjval);
if (error == 0)
continue;
/*
* Oh-Oh! We ran out of either sem_undo's or undo's.
* Rollback the adjustments to this point and then
* rollback the semaphore ups and down so we can return
* with an error with all structures restored. We
* rollback the undo's in the exact reverse order that
* we applied them. This guarantees that we won't run
* out of space as we roll things back out.
*/
for (j = 0; j < i; j++) {
k = i - j - 1;
if ((sops[k].sem_flg & SEM_UNDO) == 0)
continue;
adjval = sops[k].sem_op;
if (adjval == 0)
continue;
if (semundo_adjust(td, &suptr, semid,
sops[k].sem_num, adjval) != 0)
panic("semop - can't undo undos");
}
for (j = 0; j < nsops; j++)
semakptr->u.sem_base[sops[j].sem_num].semval -=
sops[j].sem_op;
DPRINTF(("error = %d from semundo_adjust\n", error));
SEMUNDO_UNLOCK();
goto done2;
} /* loop through the sops */
SEMUNDO_UNLOCK();
} /* if (do_undos) */
/* We're definitely done - set the sempid's and time */
for (i = 0; i < nsops; i++) {
sopptr = &sops[i];
semptr = &semakptr->u.sem_base[sopptr->sem_num];
semptr->sempid = td->td_proc->p_pid;
}
semakptr->u.sem_otime = time_second;
/*
* Do a wakeup if any semaphore was up'd whilst something was
* sleeping on it.
*/
if (do_wakeup) {
DPRINTF(("semop: doing wakeup\n"));
wakeup(semakptr);
DPRINTF(("semop: back from wakeup\n"));
}
DPRINTF(("semop: done\n"));
td->td_retval[0] = 0;
done2:
mtx_unlock(sema_mtxp);
if (sops != small_sops)
free(sops, M_SEM);
return (error);
}
/*
* Go through the undo structures for this process and apply the adjustments to
* semaphores.
*/
static void
semexit_myhook(arg, p)
void *arg;
struct proc *p;
{
struct sem_undo *suptr;
struct sem_undo **supptr;
/*
* Go through the chain of undo vectors looking for one
* associated with this process.
*/
SEMUNDO_LOCK();
SLIST_FOREACH_PREVPTR(suptr, supptr, &semu_list, un_next) {
if (suptr->un_proc == p)
break;
}
SEMUNDO_UNLOCK();
if (suptr == NULL)
return;
DPRINTF(("proc @%08x has undo structure with %d entries\n", p,
suptr->un_cnt));
/*
* If there are any active undo elements then process them.
*/
if (suptr->un_cnt > 0) {
int ix;
for (ix = 0; ix < suptr->un_cnt; ix++) {
int semid = suptr->un_ent[ix].un_id;
int semnum = suptr->un_ent[ix].un_num;
int adjval = suptr->un_ent[ix].un_adjval;
struct semid_kernel *semakptr;
struct mtx *sema_mtxp;
semakptr = &sema[semid];
sema_mtxp = &sema_mtx[semid];
mtx_lock(sema_mtxp);
SEMUNDO_LOCK();
if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0)
panic("semexit - semid not allocated");
if (semnum >= semakptr->u.sem_nsems)
panic("semexit - semnum out of range");
DPRINTF((
"semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n",
suptr->un_proc, suptr->un_ent[ix].un_id,
suptr->un_ent[ix].un_num,
suptr->un_ent[ix].un_adjval,
semakptr->u.sem_base[semnum].semval));
if (adjval < 0) {
if (semakptr->u.sem_base[semnum].semval <
-adjval)
semakptr->u.sem_base[semnum].semval = 0;
else
semakptr->u.sem_base[semnum].semval +=
adjval;
} else
semakptr->u.sem_base[semnum].semval += adjval;
wakeup(semakptr);
DPRINTF(("semexit: back from wakeup\n"));
mtx_unlock(sema_mtxp);
SEMUNDO_UNLOCK();
}
}
/*
* Deallocate the undo vector.
*/
DPRINTF(("removing vector\n"));
suptr->un_proc = NULL;
*supptr = SLIST_NEXT(suptr, un_next);
}
static int
sysctl_sema(SYSCTL_HANDLER_ARGS)
{
return (SYSCTL_OUT(req, sema,
sizeof(struct semid_kernel) * seminfo.semmni));
}
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