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b68cf25fe6
POSIX mqueue, compatibility ksem and POSIX shm create a file descriptor that has close-on-exec set. However, they do this incorrectly, leaving a window where a thread may fork and exec while the flag has not been set yet. The race is easily reproduced on a multicore system with one thread doing shm_open and close and another thread doing posix_spawnp and waitpid. Set UF_EXCLOSE via falloc()'s flags argument instead. This also simplifies the code. MFC after: 1 week
858 lines
21 KiB
C
858 lines
21 KiB
C
/*-
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* Copyright (c) 2006, 2011 Robert N. M. Watson
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Support for shared swap-backed anonymous memory objects via
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* shm_open(2) and shm_unlink(2). While most of the implementation is
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* here, vm_mmap.c contains mapping logic changes.
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*
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* TODO:
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*
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* (1) Need to export data to a userland tool via a sysctl. Should ipcs(1)
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* and ipcrm(1) be expanded or should new tools to manage both POSIX
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* kernel semaphores and POSIX shared memory be written?
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*
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* (2) Add support for this file type to fstat(1).
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*
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* (3) Resource limits? Does this need its own resource limits or are the
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* existing limits in mmap(2) sufficient?
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_capsicum.h"
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#include <sys/param.h>
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#include <sys/capability.h>
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#include <sys/fcntl.h>
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#include <sys/file.h>
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#include <sys/filedesc.h>
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#include <sys/fnv_hash.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/mman.h>
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#include <sys/mutex.h>
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#include <sys/priv.h>
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#include <sys/proc.h>
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#include <sys/refcount.h>
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#include <sys/resourcevar.h>
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#include <sys/rwlock.h>
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#include <sys/stat.h>
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#include <sys/sysctl.h>
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#include <sys/sysproto.h>
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#include <sys/systm.h>
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#include <sys/sx.h>
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#include <sys/time.h>
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#include <sys/vnode.h>
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#include <security/mac/mac_framework.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/pmap.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_map.h>
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#include <vm/vm_kern.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pageout.h>
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#include <vm/vm_pager.h>
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#include <vm/swap_pager.h>
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struct shm_mapping {
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char *sm_path;
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Fnv32_t sm_fnv;
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struct shmfd *sm_shmfd;
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LIST_ENTRY(shm_mapping) sm_link;
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};
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static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor");
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static LIST_HEAD(, shm_mapping) *shm_dictionary;
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static struct sx shm_dict_lock;
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static struct mtx shm_timestamp_lock;
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static u_long shm_hash;
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#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash])
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static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags);
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static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode);
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static void shm_dict_init(void *arg);
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static void shm_drop(struct shmfd *shmfd);
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static struct shmfd *shm_hold(struct shmfd *shmfd);
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static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd);
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static struct shmfd *shm_lookup(char *path, Fnv32_t fnv);
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static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred);
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static int shm_dotruncate(struct shmfd *shmfd, off_t length);
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static fo_rdwr_t shm_read;
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static fo_rdwr_t shm_write;
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static fo_truncate_t shm_truncate;
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static fo_ioctl_t shm_ioctl;
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static fo_poll_t shm_poll;
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static fo_kqfilter_t shm_kqfilter;
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static fo_stat_t shm_stat;
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static fo_close_t shm_close;
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static fo_chmod_t shm_chmod;
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static fo_chown_t shm_chown;
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/* File descriptor operations. */
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static struct fileops shm_ops = {
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.fo_read = shm_read,
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.fo_write = shm_write,
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.fo_truncate = shm_truncate,
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.fo_ioctl = shm_ioctl,
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.fo_poll = shm_poll,
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.fo_kqfilter = shm_kqfilter,
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.fo_stat = shm_stat,
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.fo_close = shm_close,
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.fo_chmod = shm_chmod,
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.fo_chown = shm_chown,
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.fo_flags = DFLAG_PASSABLE
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};
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FEATURE(posix_shm, "POSIX shared memory");
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static int
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shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred,
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int flags, struct thread *td)
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{
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return (EOPNOTSUPP);
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}
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static int
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shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred,
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int flags, struct thread *td)
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{
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return (EOPNOTSUPP);
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}
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static int
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shm_truncate(struct file *fp, off_t length, struct ucred *active_cred,
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struct thread *td)
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{
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struct shmfd *shmfd;
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#ifdef MAC
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int error;
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#endif
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shmfd = fp->f_data;
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#ifdef MAC
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error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd);
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if (error)
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return (error);
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#endif
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return (shm_dotruncate(shmfd, length));
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}
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static int
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shm_ioctl(struct file *fp, u_long com, void *data,
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struct ucred *active_cred, struct thread *td)
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{
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return (EOPNOTSUPP);
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}
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static int
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shm_poll(struct file *fp, int events, struct ucred *active_cred,
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struct thread *td)
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{
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return (EOPNOTSUPP);
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}
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static int
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shm_kqfilter(struct file *fp, struct knote *kn)
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{
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return (EOPNOTSUPP);
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}
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static int
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shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred,
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struct thread *td)
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{
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struct shmfd *shmfd;
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#ifdef MAC
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int error;
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#endif
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shmfd = fp->f_data;
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#ifdef MAC
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error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd);
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if (error)
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return (error);
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#endif
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/*
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* Attempt to return sanish values for fstat() on a memory file
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* descriptor.
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*/
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bzero(sb, sizeof(*sb));
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sb->st_blksize = PAGE_SIZE;
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sb->st_size = shmfd->shm_size;
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sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize;
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mtx_lock(&shm_timestamp_lock);
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sb->st_atim = shmfd->shm_atime;
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sb->st_ctim = shmfd->shm_ctime;
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sb->st_mtim = shmfd->shm_mtime;
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sb->st_birthtim = shmfd->shm_birthtime;
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sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */
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sb->st_uid = shmfd->shm_uid;
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sb->st_gid = shmfd->shm_gid;
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mtx_unlock(&shm_timestamp_lock);
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return (0);
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}
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static int
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shm_close(struct file *fp, struct thread *td)
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{
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struct shmfd *shmfd;
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shmfd = fp->f_data;
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fp->f_data = NULL;
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shm_drop(shmfd);
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return (0);
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}
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static int
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shm_dotruncate(struct shmfd *shmfd, off_t length)
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{
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vm_object_t object;
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vm_page_t m, ma[1];
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vm_pindex_t idx, nobjsize;
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vm_ooffset_t delta;
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int base, rv;
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object = shmfd->shm_object;
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VM_OBJECT_WLOCK(object);
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if (length == shmfd->shm_size) {
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VM_OBJECT_WUNLOCK(object);
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return (0);
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}
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nobjsize = OFF_TO_IDX(length + PAGE_MASK);
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/* Are we shrinking? If so, trim the end. */
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if (length < shmfd->shm_size) {
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/*
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* Disallow any requests to shrink the size if this
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* object is mapped into the kernel.
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*/
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if (shmfd->shm_kmappings > 0) {
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VM_OBJECT_WUNLOCK(object);
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return (EBUSY);
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}
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/*
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* Zero the truncated part of the last page.
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*/
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base = length & PAGE_MASK;
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if (base != 0) {
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idx = OFF_TO_IDX(length);
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retry:
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m = vm_page_lookup(object, idx);
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if (m != NULL) {
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if ((m->oflags & VPO_BUSY) != 0 ||
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m->busy != 0) {
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vm_page_sleep(m, "shmtrc");
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goto retry;
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}
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} else if (vm_pager_has_page(object, idx, NULL, NULL)) {
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m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL);
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if (m == NULL) {
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VM_OBJECT_WUNLOCK(object);
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VM_WAIT;
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VM_OBJECT_WLOCK(object);
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goto retry;
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} else if (m->valid != VM_PAGE_BITS_ALL) {
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ma[0] = m;
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rv = vm_pager_get_pages(object, ma, 1,
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0);
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m = vm_page_lookup(object, idx);
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} else
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/* A cached page was reactivated. */
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rv = VM_PAGER_OK;
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vm_page_lock(m);
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if (rv == VM_PAGER_OK) {
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vm_page_deactivate(m);
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vm_page_unlock(m);
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vm_page_wakeup(m);
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} else {
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vm_page_free(m);
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vm_page_unlock(m);
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VM_OBJECT_WUNLOCK(object);
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return (EIO);
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}
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}
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if (m != NULL) {
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pmap_zero_page_area(m, base, PAGE_SIZE - base);
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KASSERT(m->valid == VM_PAGE_BITS_ALL,
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("shm_dotruncate: page %p is invalid", m));
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vm_page_dirty(m);
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vm_pager_page_unswapped(m);
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}
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}
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delta = ptoa(object->size - nobjsize);
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/* Toss in memory pages. */
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if (nobjsize < object->size)
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vm_object_page_remove(object, nobjsize, object->size,
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0);
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/* Toss pages from swap. */
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if (object->type == OBJT_SWAP)
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swap_pager_freespace(object, nobjsize, delta);
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/* Free the swap accounted for shm */
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swap_release_by_cred(delta, object->cred);
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object->charge -= delta;
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} else {
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/* Attempt to reserve the swap */
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delta = ptoa(nobjsize - object->size);
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if (!swap_reserve_by_cred(delta, object->cred)) {
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VM_OBJECT_WUNLOCK(object);
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return (ENOMEM);
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}
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object->charge += delta;
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}
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shmfd->shm_size = length;
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mtx_lock(&shm_timestamp_lock);
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vfs_timestamp(&shmfd->shm_ctime);
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shmfd->shm_mtime = shmfd->shm_ctime;
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mtx_unlock(&shm_timestamp_lock);
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object->size = nobjsize;
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VM_OBJECT_WUNLOCK(object);
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return (0);
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}
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/*
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* shmfd object management including creation and reference counting
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* routines.
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*/
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static struct shmfd *
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shm_alloc(struct ucred *ucred, mode_t mode)
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{
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struct shmfd *shmfd;
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shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO);
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shmfd->shm_size = 0;
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shmfd->shm_uid = ucred->cr_uid;
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shmfd->shm_gid = ucred->cr_gid;
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shmfd->shm_mode = mode;
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shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL,
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shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred);
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KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
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VM_OBJECT_WLOCK(shmfd->shm_object);
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vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING);
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vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT);
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VM_OBJECT_WUNLOCK(shmfd->shm_object);
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vfs_timestamp(&shmfd->shm_birthtime);
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shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime =
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shmfd->shm_birthtime;
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refcount_init(&shmfd->shm_refs, 1);
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#ifdef MAC
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mac_posixshm_init(shmfd);
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mac_posixshm_create(ucred, shmfd);
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#endif
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return (shmfd);
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}
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static struct shmfd *
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shm_hold(struct shmfd *shmfd)
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{
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refcount_acquire(&shmfd->shm_refs);
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return (shmfd);
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}
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static void
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shm_drop(struct shmfd *shmfd)
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{
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if (refcount_release(&shmfd->shm_refs)) {
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#ifdef MAC
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mac_posixshm_destroy(shmfd);
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#endif
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vm_object_deallocate(shmfd->shm_object);
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free(shmfd, M_SHMFD);
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}
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}
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/*
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* Determine if the credentials have sufficient permissions for a
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* specified combination of FREAD and FWRITE.
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*/
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static int
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shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags)
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{
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accmode_t accmode;
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int error;
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accmode = 0;
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if (flags & FREAD)
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accmode |= VREAD;
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if (flags & FWRITE)
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accmode |= VWRITE;
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mtx_lock(&shm_timestamp_lock);
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error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
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accmode, ucred, NULL);
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mtx_unlock(&shm_timestamp_lock);
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return (error);
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}
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/*
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* Dictionary management. We maintain an in-kernel dictionary to map
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* paths to shmfd objects. We use the FNV hash on the path to store
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* the mappings in a hash table.
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*/
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static void
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shm_dict_init(void *arg)
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{
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mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF);
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sx_init(&shm_dict_lock, "shm dictionary");
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shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash);
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}
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SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL);
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static struct shmfd *
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shm_lookup(char *path, Fnv32_t fnv)
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{
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struct shm_mapping *map;
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LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
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if (map->sm_fnv != fnv)
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continue;
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if (strcmp(map->sm_path, path) == 0)
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return (map->sm_shmfd);
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}
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return (NULL);
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}
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static void
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shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd)
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{
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struct shm_mapping *map;
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map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK);
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map->sm_path = path;
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map->sm_fnv = fnv;
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map->sm_shmfd = shm_hold(shmfd);
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shmfd->shm_path = path;
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LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link);
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}
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static int
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shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred)
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{
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struct shm_mapping *map;
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int error;
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LIST_FOREACH(map, SHM_HASH(fnv), sm_link) {
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if (map->sm_fnv != fnv)
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continue;
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if (strcmp(map->sm_path, path) == 0) {
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
|
|
if (error)
|
|
return (error);
|
|
#endif
|
|
error = shm_access(map->sm_shmfd, ucred,
|
|
FREAD | FWRITE);
|
|
if (error)
|
|
return (error);
|
|
map->sm_shmfd->shm_path = NULL;
|
|
LIST_REMOVE(map, sm_link);
|
|
shm_drop(map->sm_shmfd);
|
|
free(map->sm_path, M_SHMFD);
|
|
free(map, M_SHMFD);
|
|
return (0);
|
|
}
|
|
}
|
|
|
|
return (ENOENT);
|
|
}
|
|
|
|
/* System calls. */
|
|
int
|
|
sys_shm_open(struct thread *td, struct shm_open_args *uap)
|
|
{
|
|
struct filedesc *fdp;
|
|
struct shmfd *shmfd;
|
|
struct file *fp;
|
|
char *path;
|
|
Fnv32_t fnv;
|
|
mode_t cmode;
|
|
int fd, error;
|
|
|
|
#ifdef CAPABILITY_MODE
|
|
/*
|
|
* shm_open(2) is only allowed for anonymous objects.
|
|
*/
|
|
if (IN_CAPABILITY_MODE(td) && (uap->path != SHM_ANON))
|
|
return (ECAPMODE);
|
|
#endif
|
|
|
|
if ((uap->flags & O_ACCMODE) != O_RDONLY &&
|
|
(uap->flags & O_ACCMODE) != O_RDWR)
|
|
return (EINVAL);
|
|
|
|
if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0)
|
|
return (EINVAL);
|
|
|
|
fdp = td->td_proc->p_fd;
|
|
cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
|
|
|
|
error = falloc(td, &fp, &fd, O_CLOEXEC);
|
|
if (error)
|
|
return (error);
|
|
|
|
/* A SHM_ANON path pointer creates an anonymous object. */
|
|
if (uap->path == SHM_ANON) {
|
|
/* A read-only anonymous object is pointless. */
|
|
if ((uap->flags & O_ACCMODE) == O_RDONLY) {
|
|
fdclose(fdp, fp, fd, td);
|
|
fdrop(fp, td);
|
|
return (EINVAL);
|
|
}
|
|
shmfd = shm_alloc(td->td_ucred, cmode);
|
|
} else {
|
|
path = malloc(MAXPATHLEN, M_SHMFD, M_WAITOK);
|
|
error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
|
|
|
|
/* Require paths to start with a '/' character. */
|
|
if (error == 0 && path[0] != '/')
|
|
error = EINVAL;
|
|
if (error) {
|
|
fdclose(fdp, fp, fd, td);
|
|
fdrop(fp, td);
|
|
free(path, M_SHMFD);
|
|
return (error);
|
|
}
|
|
|
|
fnv = fnv_32_str(path, FNV1_32_INIT);
|
|
sx_xlock(&shm_dict_lock);
|
|
shmfd = shm_lookup(path, fnv);
|
|
if (shmfd == NULL) {
|
|
/* Object does not yet exist, create it if requested. */
|
|
if (uap->flags & O_CREAT) {
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_create(td->td_ucred,
|
|
path);
|
|
if (error == 0) {
|
|
#endif
|
|
shmfd = shm_alloc(td->td_ucred, cmode);
|
|
shm_insert(path, fnv, shmfd);
|
|
#ifdef MAC
|
|
}
|
|
#endif
|
|
} else {
|
|
free(path, M_SHMFD);
|
|
error = ENOENT;
|
|
}
|
|
} else {
|
|
/*
|
|
* Object already exists, obtain a new
|
|
* reference if requested and permitted.
|
|
*/
|
|
free(path, M_SHMFD);
|
|
if ((uap->flags & (O_CREAT | O_EXCL)) ==
|
|
(O_CREAT | O_EXCL))
|
|
error = EEXIST;
|
|
else {
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_open(td->td_ucred,
|
|
shmfd, FFLAGS(uap->flags & O_ACCMODE));
|
|
if (error == 0)
|
|
#endif
|
|
error = shm_access(shmfd, td->td_ucred,
|
|
FFLAGS(uap->flags & O_ACCMODE));
|
|
}
|
|
|
|
/*
|
|
* Truncate the file back to zero length if
|
|
* O_TRUNC was specified and the object was
|
|
* opened with read/write.
|
|
*/
|
|
if (error == 0 &&
|
|
(uap->flags & (O_ACCMODE | O_TRUNC)) ==
|
|
(O_RDWR | O_TRUNC)) {
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_truncate(
|
|
td->td_ucred, fp->f_cred, shmfd);
|
|
if (error == 0)
|
|
#endif
|
|
shm_dotruncate(shmfd, 0);
|
|
}
|
|
if (error == 0)
|
|
shm_hold(shmfd);
|
|
}
|
|
sx_xunlock(&shm_dict_lock);
|
|
|
|
if (error) {
|
|
fdclose(fdp, fp, fd, td);
|
|
fdrop(fp, td);
|
|
return (error);
|
|
}
|
|
}
|
|
|
|
finit(fp, FFLAGS(uap->flags & O_ACCMODE), DTYPE_SHM, shmfd, &shm_ops);
|
|
|
|
td->td_retval[0] = fd;
|
|
fdrop(fp, td);
|
|
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
sys_shm_unlink(struct thread *td, struct shm_unlink_args *uap)
|
|
{
|
|
char *path;
|
|
Fnv32_t fnv;
|
|
int error;
|
|
|
|
path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK);
|
|
error = copyinstr(uap->path, path, MAXPATHLEN, NULL);
|
|
if (error) {
|
|
free(path, M_TEMP);
|
|
return (error);
|
|
}
|
|
|
|
fnv = fnv_32_str(path, FNV1_32_INIT);
|
|
sx_xlock(&shm_dict_lock);
|
|
error = shm_remove(path, fnv, td->td_ucred);
|
|
sx_xunlock(&shm_dict_lock);
|
|
free(path, M_TEMP);
|
|
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* mmap() helper to validate mmap() requests against shm object state
|
|
* and give mmap() the vm_object to use for the mapping.
|
|
*/
|
|
int
|
|
shm_mmap(struct shmfd *shmfd, vm_size_t objsize, vm_ooffset_t foff,
|
|
vm_object_t *obj)
|
|
{
|
|
|
|
/*
|
|
* XXXRW: This validation is probably insufficient, and subject to
|
|
* sign errors. It should be fixed.
|
|
*/
|
|
if (foff >= shmfd->shm_size ||
|
|
foff + objsize > round_page(shmfd->shm_size))
|
|
return (EINVAL);
|
|
|
|
mtx_lock(&shm_timestamp_lock);
|
|
vfs_timestamp(&shmfd->shm_atime);
|
|
mtx_unlock(&shm_timestamp_lock);
|
|
vm_object_reference(shmfd->shm_object);
|
|
*obj = shmfd->shm_object;
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
shm_chmod(struct file *fp, mode_t mode, struct ucred *active_cred,
|
|
struct thread *td)
|
|
{
|
|
struct shmfd *shmfd;
|
|
int error;
|
|
|
|
error = 0;
|
|
shmfd = fp->f_data;
|
|
mtx_lock(&shm_timestamp_lock);
|
|
/*
|
|
* SUSv4 says that x bits of permission need not be affected.
|
|
* Be consistent with our shm_open there.
|
|
*/
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_setmode(active_cred, shmfd, mode);
|
|
if (error != 0)
|
|
goto out;
|
|
#endif
|
|
error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid,
|
|
shmfd->shm_gid, VADMIN, active_cred, NULL);
|
|
if (error != 0)
|
|
goto out;
|
|
shmfd->shm_mode = mode & ACCESSPERMS;
|
|
out:
|
|
mtx_unlock(&shm_timestamp_lock);
|
|
return (error);
|
|
}
|
|
|
|
static int
|
|
shm_chown(struct file *fp, uid_t uid, gid_t gid, struct ucred *active_cred,
|
|
struct thread *td)
|
|
{
|
|
struct shmfd *shmfd;
|
|
int error;
|
|
|
|
error = 0;
|
|
shmfd = fp->f_data;
|
|
mtx_lock(&shm_timestamp_lock);
|
|
#ifdef MAC
|
|
error = mac_posixshm_check_setowner(active_cred, shmfd, uid, gid);
|
|
if (error != 0)
|
|
goto out;
|
|
#endif
|
|
if (uid == (uid_t)-1)
|
|
uid = shmfd->shm_uid;
|
|
if (gid == (gid_t)-1)
|
|
gid = shmfd->shm_gid;
|
|
if (((uid != shmfd->shm_uid && uid != active_cred->cr_uid) ||
|
|
(gid != shmfd->shm_gid && !groupmember(gid, active_cred))) &&
|
|
(error = priv_check_cred(active_cred, PRIV_VFS_CHOWN, 0)))
|
|
goto out;
|
|
shmfd->shm_uid = uid;
|
|
shmfd->shm_gid = gid;
|
|
out:
|
|
mtx_unlock(&shm_timestamp_lock);
|
|
return (error);
|
|
}
|
|
|
|
/*
|
|
* Helper routines to allow the backing object of a shared memory file
|
|
* descriptor to be mapped in the kernel.
|
|
*/
|
|
int
|
|
shm_map(struct file *fp, size_t size, off_t offset, void **memp)
|
|
{
|
|
struct shmfd *shmfd;
|
|
vm_offset_t kva, ofs;
|
|
vm_object_t obj;
|
|
int rv;
|
|
|
|
if (fp->f_type != DTYPE_SHM)
|
|
return (EINVAL);
|
|
shmfd = fp->f_data;
|
|
obj = shmfd->shm_object;
|
|
VM_OBJECT_WLOCK(obj);
|
|
/*
|
|
* XXXRW: This validation is probably insufficient, and subject to
|
|
* sign errors. It should be fixed.
|
|
*/
|
|
if (offset >= shmfd->shm_size ||
|
|
offset + size > round_page(shmfd->shm_size)) {
|
|
VM_OBJECT_WUNLOCK(obj);
|
|
return (EINVAL);
|
|
}
|
|
|
|
shmfd->shm_kmappings++;
|
|
vm_object_reference_locked(obj);
|
|
VM_OBJECT_WUNLOCK(obj);
|
|
|
|
/* Map the object into the kernel_map and wire it. */
|
|
kva = vm_map_min(kernel_map);
|
|
ofs = offset & PAGE_MASK;
|
|
offset = trunc_page(offset);
|
|
size = round_page(size + ofs);
|
|
rv = vm_map_find(kernel_map, obj, offset, &kva, size,
|
|
VMFS_ALIGNED_SPACE, VM_PROT_READ | VM_PROT_WRITE,
|
|
VM_PROT_READ | VM_PROT_WRITE, 0);
|
|
if (rv == KERN_SUCCESS) {
|
|
rv = vm_map_wire(kernel_map, kva, kva + size,
|
|
VM_MAP_WIRE_SYSTEM | VM_MAP_WIRE_NOHOLES);
|
|
if (rv == KERN_SUCCESS) {
|
|
*memp = (void *)(kva + ofs);
|
|
return (0);
|
|
}
|
|
vm_map_remove(kernel_map, kva, kva + size);
|
|
} else
|
|
vm_object_deallocate(obj);
|
|
|
|
/* On failure, drop our mapping reference. */
|
|
VM_OBJECT_WLOCK(obj);
|
|
shmfd->shm_kmappings--;
|
|
VM_OBJECT_WUNLOCK(obj);
|
|
|
|
return (vm_mmap_to_errno(rv));
|
|
}
|
|
|
|
/*
|
|
* We require the caller to unmap the entire entry. This allows us to
|
|
* safely decrement shm_kmappings when a mapping is removed.
|
|
*/
|
|
int
|
|
shm_unmap(struct file *fp, void *mem, size_t size)
|
|
{
|
|
struct shmfd *shmfd;
|
|
vm_map_entry_t entry;
|
|
vm_offset_t kva, ofs;
|
|
vm_object_t obj;
|
|
vm_pindex_t pindex;
|
|
vm_prot_t prot;
|
|
boolean_t wired;
|
|
vm_map_t map;
|
|
int rv;
|
|
|
|
if (fp->f_type != DTYPE_SHM)
|
|
return (EINVAL);
|
|
shmfd = fp->f_data;
|
|
kva = (vm_offset_t)mem;
|
|
ofs = kva & PAGE_MASK;
|
|
kva = trunc_page(kva);
|
|
size = round_page(size + ofs);
|
|
map = kernel_map;
|
|
rv = vm_map_lookup(&map, kva, VM_PROT_READ | VM_PROT_WRITE, &entry,
|
|
&obj, &pindex, &prot, &wired);
|
|
if (rv != KERN_SUCCESS)
|
|
return (EINVAL);
|
|
if (entry->start != kva || entry->end != kva + size) {
|
|
vm_map_lookup_done(map, entry);
|
|
return (EINVAL);
|
|
}
|
|
vm_map_lookup_done(map, entry);
|
|
if (obj != shmfd->shm_object)
|
|
return (EINVAL);
|
|
vm_map_remove(map, kva, kva + size);
|
|
VM_OBJECT_WLOCK(obj);
|
|
KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped"));
|
|
shmfd->shm_kmappings--;
|
|
VM_OBJECT_WUNLOCK(obj);
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
shm_path(struct shmfd *shmfd, char *path, size_t size)
|
|
{
|
|
|
|
if (shmfd->shm_path == NULL)
|
|
return;
|
|
sx_slock(&shm_dict_lock);
|
|
if (shmfd->shm_path != NULL)
|
|
strlcpy(path, shmfd->shm_path, size);
|
|
sx_sunlock(&shm_dict_lock);
|
|
}
|