diff options
Diffstat (limited to 'sys/kern/uipc_shm.c')
| -rw-r--r-- | sys/kern/uipc_shm.c | 860 |
1 files changed, 860 insertions, 0 deletions
diff --git a/sys/kern/uipc_shm.c b/sys/kern/uipc_shm.c new file mode 100644 index 0000000..7f75bdc --- /dev/null +++ b/sys/kern/uipc_shm.c @@ -0,0 +1,860 @@ +/*- + * Copyright (c) 2006, 2011 Robert N. M. Watson + * All rights reserved. + * + * 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. + */ + +/* + * Support for shared swap-backed anonymous memory objects via + * shm_open(2) and shm_unlink(2). While most of the implementation is + * here, vm_mmap.c contains mapping logic changes. + * + * TODO: + * + * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) + * and ipcrm(1) be expanded or should new tools to manage both POSIX + * kernel semaphores and POSIX shared memory be written? + * + * (2) Add support for this file type to fstat(1). + * + * (3) Resource limits? Does this need its own resource limits or are the + * existing limits in mmap(2) sufficient? + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_capsicum.h" + +#include <sys/param.h> +#include <sys/capability.h> +#include <sys/fcntl.h> +#include <sys/file.h> +#include <sys/filedesc.h> +#include <sys/fnv_hash.h> +#include <sys/kernel.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/mman.h> +#include <sys/mutex.h> +#include <sys/priv.h> +#include <sys/proc.h> +#include <sys/refcount.h> +#include <sys/resourcevar.h> +#include <sys/stat.h> +#include <sys/sysctl.h> +#include <sys/sysproto.h> +#include <sys/systm.h> +#include <sys/sx.h> +#include <sys/time.h> +#include <sys/vnode.h> + +#include <security/mac/mac_framework.h> + +#include <vm/vm.h> +#include <vm/vm_param.h> +#include <vm/pmap.h> +#include <vm/vm_extern.h> +#include <vm/vm_map.h> +#include <vm/vm_kern.h> +#include <vm/vm_object.h> +#include <vm/vm_page.h> +#include <vm/vm_pageout.h> +#include <vm/vm_pager.h> +#include <vm/swap_pager.h> + +struct shm_mapping { + char *sm_path; + Fnv32_t sm_fnv; + struct shmfd *sm_shmfd; + LIST_ENTRY(shm_mapping) sm_link; +}; + +static MALLOC_DEFINE(M_SHMFD, "shmfd", "shared memory file descriptor"); +static LIST_HEAD(, shm_mapping) *shm_dictionary; +static struct sx shm_dict_lock; +static struct mtx shm_timestamp_lock; +static u_long shm_hash; + +#define SHM_HASH(fnv) (&shm_dictionary[(fnv) & shm_hash]) + +static int shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags); +static struct shmfd *shm_alloc(struct ucred *ucred, mode_t mode); +static void shm_dict_init(void *arg); +static void shm_drop(struct shmfd *shmfd); +static struct shmfd *shm_hold(struct shmfd *shmfd); +static void shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd); +static struct shmfd *shm_lookup(char *path, Fnv32_t fnv); +static int shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred); +static int shm_dotruncate(struct shmfd *shmfd, off_t length); + +static fo_rdwr_t shm_read; +static fo_rdwr_t shm_write; +static fo_truncate_t shm_truncate; +static fo_ioctl_t shm_ioctl; +static fo_poll_t shm_poll; +static fo_kqfilter_t shm_kqfilter; +static fo_stat_t shm_stat; +static fo_close_t shm_close; +static fo_chmod_t shm_chmod; +static fo_chown_t shm_chown; + +/* File descriptor operations. */ +static struct fileops shm_ops = { + .fo_read = shm_read, + .fo_write = shm_write, + .fo_truncate = shm_truncate, + .fo_ioctl = shm_ioctl, + .fo_poll = shm_poll, + .fo_kqfilter = shm_kqfilter, + .fo_stat = shm_stat, + .fo_close = shm_close, + .fo_chmod = shm_chmod, + .fo_chown = shm_chown, + .fo_flags = DFLAG_PASSABLE +}; + +FEATURE(posix_shm, "POSIX shared memory"); + +static int +shm_read(struct file *fp, struct uio *uio, struct ucred *active_cred, + int flags, struct thread *td) +{ + + return (EOPNOTSUPP); +} + +static int +shm_write(struct file *fp, struct uio *uio, struct ucred *active_cred, + int flags, struct thread *td) +{ + + return (EOPNOTSUPP); +} + +static int +shm_truncate(struct file *fp, off_t length, struct ucred *active_cred, + struct thread *td) +{ + struct shmfd *shmfd; +#ifdef MAC + int error; +#endif + + shmfd = fp->f_data; +#ifdef MAC + error = mac_posixshm_check_truncate(active_cred, fp->f_cred, shmfd); + if (error) + return (error); +#endif + return (shm_dotruncate(shmfd, length)); +} + +static int +shm_ioctl(struct file *fp, u_long com, void *data, + struct ucred *active_cred, struct thread *td) +{ + + return (EOPNOTSUPP); +} + +static int +shm_poll(struct file *fp, int events, struct ucred *active_cred, + struct thread *td) +{ + + return (EOPNOTSUPP); +} + +static int +shm_kqfilter(struct file *fp, struct knote *kn) +{ + + return (EOPNOTSUPP); +} + +static int +shm_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, + struct thread *td) +{ + struct shmfd *shmfd; +#ifdef MAC + int error; +#endif + + shmfd = fp->f_data; + +#ifdef MAC + error = mac_posixshm_check_stat(active_cred, fp->f_cred, shmfd); + if (error) + return (error); +#endif + + /* + * Attempt to return sanish values for fstat() on a memory file + * descriptor. + */ + bzero(sb, sizeof(*sb)); + sb->st_blksize = PAGE_SIZE; + sb->st_size = shmfd->shm_size; + sb->st_blocks = (sb->st_size + sb->st_blksize - 1) / sb->st_blksize; + mtx_lock(&shm_timestamp_lock); + sb->st_atim = shmfd->shm_atime; + sb->st_ctim = shmfd->shm_ctime; + sb->st_mtim = shmfd->shm_mtime; + sb->st_birthtim = shmfd->shm_birthtime; + sb->st_mode = S_IFREG | shmfd->shm_mode; /* XXX */ + sb->st_uid = shmfd->shm_uid; + sb->st_gid = shmfd->shm_gid; + mtx_unlock(&shm_timestamp_lock); + + return (0); +} + +static int +shm_close(struct file *fp, struct thread *td) +{ + struct shmfd *shmfd; + + shmfd = fp->f_data; + fp->f_data = NULL; + shm_drop(shmfd); + + return (0); +} + +static int +shm_dotruncate(struct shmfd *shmfd, off_t length) +{ + vm_object_t object; + vm_page_t m, ma[1]; + vm_pindex_t idx, nobjsize; + vm_ooffset_t delta; + int base, rv; + + object = shmfd->shm_object; + VM_OBJECT_LOCK(object); + if (length == shmfd->shm_size) { + VM_OBJECT_UNLOCK(object); + return (0); + } + nobjsize = OFF_TO_IDX(length + PAGE_MASK); + + /* Are we shrinking? If so, trim the end. */ + if (length < shmfd->shm_size) { + /* + * Disallow any requests to shrink the size if this + * object is mapped into the kernel. + */ + if (shmfd->shm_kmappings > 0) { + VM_OBJECT_UNLOCK(object); + return (EBUSY); + } + + /* + * Zero the truncated part of the last page. + */ + base = length & PAGE_MASK; + if (base != 0) { + idx = OFF_TO_IDX(length); +retry: + m = vm_page_lookup(object, idx); + if (m != NULL) { + if ((m->oflags & VPO_BUSY) != 0 || + m->busy != 0) { + vm_page_sleep(m, "shmtrc"); + goto retry; + } + } else if (vm_pager_has_page(object, idx, NULL, NULL)) { + m = vm_page_alloc(object, idx, VM_ALLOC_NORMAL); + if (m == NULL) { + VM_OBJECT_UNLOCK(object); + VM_WAIT; + VM_OBJECT_LOCK(object); + goto retry; + } else if (m->valid != VM_PAGE_BITS_ALL) { + ma[0] = m; + rv = vm_pager_get_pages(object, ma, 1, + 0); + m = vm_page_lookup(object, idx); + } else + /* A cached page was reactivated. */ + rv = VM_PAGER_OK; + vm_page_lock(m); + if (rv == VM_PAGER_OK) { + vm_page_deactivate(m); + vm_page_unlock(m); + vm_page_wakeup(m); + } else { + vm_page_free(m); + vm_page_unlock(m); + VM_OBJECT_UNLOCK(object); + return (EIO); + } + } + if (m != NULL) { + pmap_zero_page_area(m, base, PAGE_SIZE - base); + KASSERT(m->valid == VM_PAGE_BITS_ALL, + ("shm_dotruncate: page %p is invalid", m)); + vm_page_dirty(m); + vm_pager_page_unswapped(m); + } + } + delta = ptoa(object->size - nobjsize); + + /* Toss in memory pages. */ + if (nobjsize < object->size) + vm_object_page_remove(object, nobjsize, object->size, + 0); + + /* Toss pages from swap. */ + if (object->type == OBJT_SWAP) + swap_pager_freespace(object, nobjsize, delta); + + /* Free the swap accounted for shm */ + swap_release_by_cred(delta, object->cred); + object->charge -= delta; + } else { + /* Attempt to reserve the swap */ + delta = ptoa(nobjsize - object->size); + if (!swap_reserve_by_cred(delta, object->cred)) { + VM_OBJECT_UNLOCK(object); + return (ENOMEM); + } + object->charge += delta; + } + shmfd->shm_size = length; + mtx_lock(&shm_timestamp_lock); + vfs_timestamp(&shmfd->shm_ctime); + shmfd->shm_mtime = shmfd->shm_ctime; + mtx_unlock(&shm_timestamp_lock); + object->size = nobjsize; + VM_OBJECT_UNLOCK(object); + return (0); +} + +/* + * shmfd object management including creation and reference counting + * routines. + */ +static struct shmfd * +shm_alloc(struct ucred *ucred, mode_t mode) +{ + struct shmfd *shmfd; + + shmfd = malloc(sizeof(*shmfd), M_SHMFD, M_WAITOK | M_ZERO); + shmfd->shm_size = 0; + shmfd->shm_uid = ucred->cr_uid; + shmfd->shm_gid = ucred->cr_gid; + shmfd->shm_mode = mode; + shmfd->shm_object = vm_pager_allocate(OBJT_DEFAULT, NULL, + shmfd->shm_size, VM_PROT_DEFAULT, 0, ucred); + KASSERT(shmfd->shm_object != NULL, ("shm_create: vm_pager_allocate")); + VM_OBJECT_LOCK(shmfd->shm_object); + vm_object_clear_flag(shmfd->shm_object, OBJ_ONEMAPPING); + vm_object_set_flag(shmfd->shm_object, OBJ_NOSPLIT); + VM_OBJECT_UNLOCK(shmfd->shm_object); + vfs_timestamp(&shmfd->shm_birthtime); + shmfd->shm_atime = shmfd->shm_mtime = shmfd->shm_ctime = + shmfd->shm_birthtime; + refcount_init(&shmfd->shm_refs, 1); +#ifdef MAC + mac_posixshm_init(shmfd); + mac_posixshm_create(ucred, shmfd); +#endif + + return (shmfd); +} + +static struct shmfd * +shm_hold(struct shmfd *shmfd) +{ + + refcount_acquire(&shmfd->shm_refs); + return (shmfd); +} + +static void +shm_drop(struct shmfd *shmfd) +{ + + if (refcount_release(&shmfd->shm_refs)) { +#ifdef MAC + mac_posixshm_destroy(shmfd); +#endif + vm_object_deallocate(shmfd->shm_object); + free(shmfd, M_SHMFD); + } +} + +/* + * Determine if the credentials have sufficient permissions for a + * specified combination of FREAD and FWRITE. + */ +static int +shm_access(struct shmfd *shmfd, struct ucred *ucred, int flags) +{ + accmode_t accmode; + int error; + + accmode = 0; + if (flags & FREAD) + accmode |= VREAD; + if (flags & FWRITE) + accmode |= VWRITE; + mtx_lock(&shm_timestamp_lock); + error = vaccess(VREG, shmfd->shm_mode, shmfd->shm_uid, shmfd->shm_gid, + accmode, ucred, NULL); + mtx_unlock(&shm_timestamp_lock); + return (error); +} + +/* + * Dictionary management. We maintain an in-kernel dictionary to map + * paths to shmfd objects. We use the FNV hash on the path to store + * the mappings in a hash table. + */ +static void +shm_dict_init(void *arg) +{ + + mtx_init(&shm_timestamp_lock, "shm timestamps", NULL, MTX_DEF); + sx_init(&shm_dict_lock, "shm dictionary"); + shm_dictionary = hashinit(1024, M_SHMFD, &shm_hash); +} +SYSINIT(shm_dict_init, SI_SUB_SYSV_SHM, SI_ORDER_ANY, shm_dict_init, NULL); + +static struct shmfd * +shm_lookup(char *path, Fnv32_t fnv) +{ + struct shm_mapping *map; + + LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { + if (map->sm_fnv != fnv) + continue; + if (strcmp(map->sm_path, path) == 0) + return (map->sm_shmfd); + } + + return (NULL); +} + +static void +shm_insert(char *path, Fnv32_t fnv, struct shmfd *shmfd) +{ + struct shm_mapping *map; + + map = malloc(sizeof(struct shm_mapping), M_SHMFD, M_WAITOK); + map->sm_path = path; + map->sm_fnv = fnv; + map->sm_shmfd = shm_hold(shmfd); + shmfd->shm_path = path; + LIST_INSERT_HEAD(SHM_HASH(fnv), map, sm_link); +} + +static int +shm_remove(char *path, Fnv32_t fnv, struct ucred *ucred) +{ + struct shm_mapping *map; + int error; + + LIST_FOREACH(map, SHM_HASH(fnv), sm_link) { + if (map->sm_fnv != fnv) + continue; + 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, 0); + 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); + + 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 +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_LOCK(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_UNLOCK(obj); + return (EINVAL); + } + + shmfd->shm_kmappings++; + vm_object_reference_locked(obj); + VM_OBJECT_UNLOCK(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_LOCK(obj); + shmfd->shm_kmappings--; + VM_OBJECT_UNLOCK(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_LOCK(obj); + KASSERT(shmfd->shm_kmappings > 0, ("shm_unmap: object not mapped")); + shmfd->shm_kmappings--; + VM_OBJECT_UNLOCK(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); +} |
