bcf11e8d00
and used in a large number of files, but also because an increasing number of incorrect uses of MAC calls were sneaking in due to copy-and-paste of MAC-aware code without the associated opt_mac.h include. Discussed with: pjd
630 lines
16 KiB
C
630 lines
16 KiB
C
/*-
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* Copyright (c) 2006 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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* (2) 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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* (3) Add support for this file type to fstat(1).
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*
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* (4) 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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* (5) Partial page truncation. vnode_pager_setsize() will zero any parts
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* of a partially mapped page as a result of ftruncate(2)/truncate(2).
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* We can do the same (with the same pmap evil), but do we need to
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* worry about the bits on disk if the page is swapped out or will the
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* swapper zero the parts of a page that are invalid if the page is
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* swapped back in for us?
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*
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* (6) Add MAC support in mac_biba(4) and mac_mls(4).
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*
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* (7) Add a MAC check_create() hook for creating new named objects.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.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/proc.h>
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#include <sys/refcount.h>
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#include <sys/resourcevar.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_map.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_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 void 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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/* 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_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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shm_dotruncate(shmfd, length);
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return (0);
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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_mode = S_IFREG | shmfd->shm_mode; /* XXX */
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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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sb->st_atimespec = shmfd->shm_atime;
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sb->st_ctimespec = shmfd->shm_ctime;
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sb->st_mtimespec = shmfd->shm_mtime;
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sb->st_birthtimespec = shmfd->shm_birthtime;
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sb->st_uid = shmfd->shm_uid;
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sb->st_gid = shmfd->shm_gid;
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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 void
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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;
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vm_pindex_t nobjsize;
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object = shmfd->shm_object;
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VM_OBJECT_LOCK(object);
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if (length == shmfd->shm_size) {
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VM_OBJECT_UNLOCK(object);
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return;
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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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/* 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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FALSE);
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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,
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object->size - nobjsize);
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/*
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* If the last page is partially mapped, then zero out
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* the garbage at the end of the page. See comments
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* in vnode_pager_setsize() for more details.
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*
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* XXXJHB: This handles in memory pages, but what about
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* a page swapped out to disk?
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*/
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if ((length & PAGE_MASK) &&
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(m = vm_page_lookup(object, OFF_TO_IDX(length))) != NULL &&
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m->valid != 0) {
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int base = (int)length & PAGE_MASK;
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int size = PAGE_SIZE - base;
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pmap_zero_page_area(m, base, size);
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/*
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* Update the valid bits to reflect the blocks that
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* have been zeroed. Some of these valid bits may
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* have already been set.
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*/
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vm_page_set_valid(m, base, size);
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/*
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* Round "base" to the next block boundary so that the
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* dirty bit for a partially zeroed block is not
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* cleared.
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*/
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base = roundup2(base, DEV_BSIZE);
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vm_page_lock_queues();
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vm_page_clear_dirty(m, base, PAGE_SIZE - base);
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vm_page_unlock_queues();
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} else if ((length & PAGE_MASK) &&
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__predict_false(object->cache != NULL)) {
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vm_page_cache_free(object, OFF_TO_IDX(length),
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nobjsize);
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}
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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_UNLOCK(object);
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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);
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KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate"));
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VM_OBJECT_LOCK(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_UNLOCK(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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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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return (vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid,
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accmode, ucred, NULL));
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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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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) {
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#ifdef MAC
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error = mac_posixshm_check_unlink(ucred, map->sm_shmfd);
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if (error)
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return (error);
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#endif
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error = shm_access(map->sm_shmfd, ucred,
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FREAD | FWRITE);
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if (error)
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return (error);
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LIST_REMOVE(map, sm_link);
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shm_drop(map->sm_shmfd);
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free(map->sm_path, M_SHMFD);
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free(map, M_SHMFD);
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return (0);
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}
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}
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return (ENOENT);
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}
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/* System calls. */
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int
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shm_open(struct thread *td, struct shm_open_args *uap)
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{
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struct filedesc *fdp;
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struct shmfd *shmfd;
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struct file *fp;
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char *path;
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Fnv32_t fnv;
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mode_t cmode;
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int fd, error;
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if ((uap->flags & O_ACCMODE) != O_RDONLY &&
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(uap->flags & O_ACCMODE) != O_RDWR)
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return (EINVAL);
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if ((uap->flags & ~(O_ACCMODE | O_CREAT | O_EXCL | O_TRUNC)) != 0)
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return (EINVAL);
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fdp = td->td_proc->p_fd;
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cmode = (uap->mode & ~fdp->fd_cmask) & ACCESSPERMS;
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error = falloc(td, &fp, &fd);
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if (error)
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return (error);
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/* A SHM_ANON path pointer creates an anonymous object. */
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if (uap->path == SHM_ANON) {
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/* A read-only anonymous object is pointless. */
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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) {
|
|
shmfd = shm_alloc(td->td_ucred, cmode);
|
|
shm_insert(path, fnv, shmfd);
|
|
} 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);
|
|
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);
|
|
|
|
FILEDESC_XLOCK(fdp);
|
|
if (fdp->fd_ofiles[fd] == fp)
|
|
fdp->fd_ofileflags[fd] |= UF_EXCLOSE;
|
|
FILEDESC_XUNLOCK(fdp);
|
|
td->td_retval[0] = fd;
|
|
fdrop(fp, td);
|
|
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
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);
|
|
}
|