/*- * Implementation of SVID semaphores * * Author: Daniel Boulet * * This software is provided ``AS IS'' without any warranties of any kind. */ /*- * Copyright (c) 2003-2005 McAfee, Inc. * All rights reserved. * * This software was developed for the FreeBSD Project in part by McAfee * Research, the Security Research Division of McAfee, Inc under DARPA/SPAWAR * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS research * program. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); #include "opt_sysvipc.h" #include "opt_mac.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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 semseq, 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 struct mtx sem_undo_mtx; 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 */ LIST_HEAD(, sem_undo) semu_list; /* list of active undo structures */ LIST_HEAD(, sem_undo) semu_free_list; /* list of free undo structures */ static int *semu; /* undo structure pool */ static eventhandler_tag semexit_tag; #define SEMUNDO_MTX sem_undo_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 { LIST_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 */ unsigned short un_seq; } 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_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, "Number of entries in the semaphore map"); SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RDTUN, &seminfo.semmni, 0, "Number of semaphore identifiers"); SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RDTUN, &seminfo.semmns, 0, "Maximum number of semaphores in the system"); SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RDTUN, &seminfo.semmnu, 0, "Maximum number of undo structures in the system"); SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, "Max semaphores per id"); SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RDTUN, &seminfo.semopm, 0, "Max operations per semop call"); SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RDTUN, &seminfo.semume, 0, "Max undo entries per process"); SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RDTUN, &seminfo.semusz, 0, "Size in bytes of undo structure"); SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, "Semaphore maximum value"); SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, "Adjust on exit max value"); 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; #ifdef MAC mac_sysvsem_init(&sema[i]); #endif } for (i = 0; i < seminfo.semmni; i++) mtx_init(&sema_mtx[i], "semid", NULL, MTX_DEF); LIST_INIT(&semu_free_list); for (i = 0; i < seminfo.semmnu; i++) { struct sem_undo *suptr = SEMU(i); suptr->un_proc = NULL; LIST_INSERT_HEAD(&semu_free_list, suptr, un_next); } LIST_INIT(&semu_list); mtx_init(&sem_mtx, "sem", NULL, MTX_DEF); mtx_init(&sem_undo_mtx, "semu", NULL, MTX_DEF); semexit_tag = EVENTHANDLER_REGISTER(process_exit, semexit_myhook, NULL, EVENTHANDLER_PRI_ANY); } static int semunload(void) { int i; /* XXXKIB */ if (semtot != 0) return (EBUSY); EVENTHANDLER_DEREGISTER(process_exit, semexit_tag); #ifdef MAC for (i = 0; i < seminfo.semmni; i++) mac_sysvsem_destroy(&sema[i]); #endif free(sem, M_SEM); free(sema, M_SEM); free(semu, M_SEM); for (i = 0; i < seminfo.semmni; i++) mtx_destroy(&sema_mtx[i]); free(sema_mtx, M_SEM); mtx_destroy(&sem_mtx); mtx_destroy(&sem_undo_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. */ 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 (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC)) 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(struct thread *td) { struct sem_undo *suptr; SEMUNDO_LOCKASSERT(MA_OWNED); if ((suptr = LIST_FIRST(&semu_free_list)) == NULL) return (NULL); LIST_REMOVE(suptr, un_next); LIST_INSERT_HEAD(&semu_list, suptr, un_next); suptr->un_cnt = 0; suptr->un_proc = td->td_proc; return (suptr); } static int semu_try_free(struct sem_undo *suptr) { SEMUNDO_LOCKASSERT(MA_OWNED); if (suptr->un_cnt != 0) return (0); LIST_REMOVE(suptr, un_next); LIST_INSERT_HEAD(&semu_free_list, suptr, un_next); return (1); } /* * Adjust a particular entry for a particular proc */ static int semundo_adjust(struct thread *td, struct sem_undo **supptr, int semid, int semseq, int 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) { LIST_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]; if (suptr->un_cnt == 0) semu_try_free(suptr); } 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; sunptr->un_seq = semseq; } else return (EINVAL); return (0); } static void semundo_clear(int semid, int semnum) { struct sem_undo *suptr, *suptr1; struct undo *sunptr; int i; SEMUNDO_LOCKASSERT(MA_OWNED); LIST_FOREACH_SAFE(suptr, &semu_list, un_next, suptr1) { sunptr = &suptr->un_ent[0]; for (i = 0; i < suptr->un_cnt; i++, sunptr++) { if (sunptr->un_id != semid) continue; 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; } semu_try_free(suptr); } if (semnum != -1) break; } } } static int semvalid(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 int __semctl(struct thread *td, struct __semctl_args *uap) { struct semid_ds dsbuf; union semun arg, semun; register_t rval; int error; switch (uap->cmd) { case SEM_STAT: case IPC_SET: case IPC_STAT: case GETALL: case SETVAL: case SETALL: error = copyin(uap->arg, &arg, sizeof(arg)); if (error) return (error); break; } switch (uap->cmd) { case SEM_STAT: case IPC_STAT: semun.buf = &dsbuf; break; case IPC_SET: error = copyin(arg.buf, &dsbuf, sizeof(dsbuf)); if (error) return (error); semun.buf = &dsbuf; break; case GETALL: case SETALL: semun.array = arg.array; break; case SETVAL: semun.val = arg.val; break; } error = kern_semctl(td, uap->semid, uap->semnum, uap->cmd, &semun, &rval); if (error) return (error); switch (uap->cmd) { case SEM_STAT: case IPC_STAT: error = copyout(&dsbuf, arg.buf, sizeof(dsbuf)); break; } if (error == 0) td->td_retval[0] = rval; return (error); } int kern_semctl(struct thread *td, int semid, int semnum, int cmd, union semun *arg, register_t *rval) { u_short *array; struct ucred *cred = td->td_ucred; int i, error; struct semid_ds *sbuf; struct semid_kernel *semakptr; struct mtx *sema_mtxp; u_short usval, count; int semidx; DPRINTF(("call to semctl(%d, %d, %d, 0x%p)\n", semid, semnum, cmd, arg)); if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC)) return (ENOSYS); array = NULL; switch(cmd) { case SEM_STAT: /* * For this command we assume semid is an array index * rather than an IPC id. */ if (semid < 0 || semid >= seminfo.semmni) return (EINVAL); 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; #ifdef MAC error = mac_sysvsem_check_semctl(cred, semakptr, cmd); if (error != 0) goto done2; #endif bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds)); *rval = IXSEQ_TO_IPCID(semid, semakptr->u.sem_perm); mtx_unlock(sema_mtxp); return (0); } semidx = IPCID_TO_IX(semid); if (semidx < 0 || semidx >= seminfo.semmni) return (EINVAL); semakptr = &sema[semidx]; sema_mtxp = &sema_mtx[semidx]; if (cmd == IPC_RMID) mtx_lock(&sem_mtx); mtx_lock(sema_mtxp); #ifdef MAC error = mac_sysvsem_check_semctl(cred, semakptr, cmd); if (error != 0) goto done2; #endif error = 0; *rval = 0; switch (cmd) { case IPC_RMID: if ((error = semvalid(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; semakptr->u.sem_perm.mode = 0; SEMUNDO_LOCK(); semundo_clear(semidx, -1); SEMUNDO_UNLOCK(); #ifdef MAC mac_sysvsem_cleanup(semakptr); #endif wakeup(semakptr); 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) mtx_lock_flags(&sema_mtx[i], LOP_DUPOK); } 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; mtx_unlock(&sema_mtx[i]); } } semtot -= semakptr->u.sem_nsems; break; case IPC_SET: if ((error = semvalid(semid, semakptr)) != 0) goto done2; if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_M))) goto done2; sbuf = arg->buf; 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 = semvalid(semid, semakptr)) != 0) goto done2; if ((error = ipcperm(td, &semakptr->u.sem_perm, IPC_R))) goto done2; bcopy(&semakptr->u, arg->buf, sizeof(struct semid_ds)); break; case GETNCNT: if ((error = semvalid(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: if ((error = semvalid(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: if ((error = semvalid(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: /* * Unfortunately, callers of this function don't know * in advance how many semaphores are in this set. * While we could just allocate the maximum size array * and pass the actual size back to the caller, that * won't work for SETALL since we can't copyin() more * data than the user specified as we may return a * spurious EFAULT. * * Note that the number of semaphores in a set is * fixed for the life of that set. The only way that * the 'count' could change while are blocked in * malloc() is if this semaphore set were destroyed * and a new one created with the same index. * However, semvalid() will catch that due to the * sequence number unless exactly 0x8000 (or a * multiple thereof) semaphore sets for the same index * are created and destroyed while we are in malloc! * */ count = semakptr->u.sem_nsems; mtx_unlock(sema_mtxp); array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK); mtx_lock(sema_mtxp); if ((error = semvalid(semid, semakptr)) != 0) goto done2; KASSERT(count == semakptr->u.sem_nsems, ("nsems changed")); 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, arg->array, count * sizeof(*array)); mtx_lock(sema_mtxp); break; case GETZCNT: if ((error = semvalid(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 = semvalid(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 (arg->val < 0 || arg->val > seminfo.semvmx) { error = ERANGE; goto done2; } semakptr->u.sem_base[semnum].semval = arg->val; SEMUNDO_LOCK(); semundo_clear(semidx, semnum); SEMUNDO_UNLOCK(); wakeup(semakptr); break; case SETALL: /* * See comment on GETALL for why 'count' shouldn't change * and why we require a userland buffer. */ count = semakptr->u.sem_nsems; mtx_unlock(sema_mtxp); array = malloc(sizeof(*array) * count, M_TEMP, M_WAITOK); error = copyin(arg->array, array, count * sizeof(*array)); mtx_lock(sema_mtxp); if (error) break; if ((error = semvalid(semid, semakptr)) != 0) goto done2; KASSERT(count == semakptr->u.sem_nsems, ("nsems changed")); 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(semidx, -1); SEMUNDO_UNLOCK(); wakeup(semakptr); break; default: error = EINVAL; break; } done2: mtx_unlock(sema_mtxp); if (cmd == IPC_RMID) mtx_unlock(&sem_mtx); if (array != NULL) free(array, M_TEMP); return(error); } #ifndef _SYS_SYSPROTO_H_ struct semget_args { key_t key; int nsems; int semflg; }; #endif int semget(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 (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC)) return (ENOSYS); mtx_lock(&sem_mtx); 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; } #ifdef MAC error = mac_sysvsem_check_semget(cred, &sema[semid]); if (error != 0) goto done2; #endif 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)); mtx_lock(&sema_mtx[semid]); KASSERT((sema[semid].u.sem_perm.mode & SEM_ALLOC) == 0, ("Lost semaphore %d", 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); #ifdef MAC mac_sysvsem_create(cred, &sema[semid]); #endif mtx_unlock(&sema_mtx[semid]); DPRINTF(("sembase = %p, next = %p\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(&sem_mtx); return (error); } #ifndef _SYS_SYSPROTO_H_ struct semop_args { int semid; struct sembuf *sops; size_t nsops; }; #endif int semop(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; unsigned short seq; #ifdef SEM_DEBUG sops = NULL; #endif DPRINTF(("call to semop(%d, %p, %u)\n", semid, sops, nsops)); if (!prison_allow(td->td_ucred, PR_ALLOW_SYSVIPC)) 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(%p, %p, %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; } seq = semakptr->u.sem_perm.seq; if (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; } #ifdef MAC error = mac_sysvsem_check_semop(td->td_ucred, semakptr, j); if (error != 0) goto done2; #endif /* * 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=%p, sem_base=%p, " "semptr=%p, 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 */ seq = semakptr->u.sem_perm.seq; if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 || seq != IPCID_TO_SEQ(uap->semid)) { error = EIDRM; goto done2; } /* * Renew the semaphore's pointer after wakeup since * during msleep sem_base may have been modified and semptr * is not valid any more */ semptr = &semakptr->u.sem_base[sopptr->sem_num]; /* * 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, seq, 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, seq, 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(void *arg, struct proc *p) { struct sem_undo *suptr; struct semid_kernel *semakptr; struct mtx *sema_mtxp; int semid, semnum, adjval, ix; unsigned short seq; /* * Go through the chain of undo vectors looking for one * associated with this process. */ SEMUNDO_LOCK(); LIST_FOREACH(suptr, &semu_list, un_next) { if (suptr->un_proc == p) break; } if (suptr == NULL) { SEMUNDO_UNLOCK(); return; } LIST_REMOVE(suptr, un_next); DPRINTF(("proc @%p 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) { SEMUNDO_UNLOCK(); for (ix = 0; ix < suptr->un_cnt; ix++) { semid = suptr->un_ent[ix].un_id; semnum = suptr->un_ent[ix].un_num; adjval = suptr->un_ent[ix].un_adjval; seq = suptr->un_ent[ix].un_seq; semakptr = &sema[semid]; sema_mtxp = &sema_mtx[semid]; mtx_lock(sema_mtxp); if ((semakptr->u.sem_perm.mode & SEM_ALLOC) == 0 || (semakptr->u.sem_perm.seq != seq)) { mtx_unlock(sema_mtxp); continue; } if (semnum >= semakptr->u.sem_nsems) panic("semexit - semnum out of range"); DPRINTF(( "semexit: %p 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 && semakptr->u.sem_base[semnum].semval < -adjval) semakptr->u.sem_base[semnum].semval = 0; else semakptr->u.sem_base[semnum].semval += adjval; wakeup(semakptr); DPRINTF(("semexit: back from wakeup\n")); mtx_unlock(sema_mtxp); } SEMUNDO_LOCK(); } /* * Deallocate the undo vector. */ DPRINTF(("removing vector\n")); suptr->un_proc = NULL; suptr->un_cnt = 0; LIST_INSERT_HEAD(&semu_free_list, suptr, un_next); SEMUNDO_UNLOCK(); } static int sysctl_sema(SYSCTL_HANDLER_ARGS) { return (SYSCTL_OUT(req, sema, sizeof(struct semid_kernel) * seminfo.semmni)); }