/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * Copyright (c) 2013, OmniTI Computer Consulting, Inc. All rights reserved.
 * Copyright 2021 OmniOS Community Edition (OmniOSce) Association.
 */
/*
 * Portions of this source code were derived from Berkeley 4.3 BSD
 * under license from the Regents of the University of California.
 */

#include <sys/param.h>
#include <sys/isa_defs.h>
#include <sys/types.h>
#include <sys/sysmacros.h>
#include <sys/user.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/vnode.h>
#include <sys/vfs.h>
#include <sys/file.h>
#include <sys/mode.h>
#include <sys/uio.h>
#include <sys/debug.h>
#include <c2/audit.h>

/*
 * Common code for openat().  Check permissions, allocate an open
 * file structure, and call the device open routine (if any).
 */

static int
copen(int startfd, char *fname, int filemode, int createmode)
{
        struct pathname pn;
        vnode_t *vp, *sdvp;
        file_t *fp, *startfp;
        enum vtype type;
        int error;
        int fd, dupfd;
        vnode_t *startvp;
        proc_t *p = curproc;
        uio_seg_t seg = UIO_USERSPACE;
        char *open_filename = fname;
        uint32_t auditing = AU_AUDITING();
        char startchar;

        if (filemode & (FSEARCH|FEXEC)) {
                /*
                 * Must be one or the other and neither FREAD nor FWRITE
                 * Must not be any of FAPPEND FCREAT FTRUNC FXATTR FXATTRDIROPEN
                 * XXX: Should these just be silently ignored?
                 */
                if ((filemode & (FREAD|FWRITE)) ||
                    (filemode & (FSEARCH|FEXEC)) == (FSEARCH|FEXEC) ||
                    (filemode & (FAPPEND|FCREAT|FTRUNC|FXATTR|FXATTRDIROPEN)))
                        return (set_errno(EINVAL));
        }

        if (startfd == AT_FDCWD) {
                /*
                 * Regular open()
                 */
                startvp = NULL;
        } else {
                /*
                 * We're here via openat()
                 */
                if (copyin(fname, &startchar, sizeof (char)))
                        return (set_errno(EFAULT));

                /*
                 * if startchar is / then startfd is ignored
                 */
                if (startchar == '/')
                        startvp = NULL;
                else {
                        if ((startfp = getf(startfd)) == NULL)
                                return (set_errno(EBADF));
                        startvp = startfp->f_vnode;
                        VN_HOLD(startvp);
                        releasef(startfd);
                }
        }

        /*
         * Handle __openattrdirat() requests
         */
        if (filemode & FXATTRDIROPEN) {
                if (auditing && startvp != NULL)
                        audit_setfsat_path(1);
                error = lookupnameat(fname, seg, FOLLOW, NULLVPP, &vp, startvp);
                if (startvp != NULL)
                        VN_RELE(startvp);
                if (error != 0)
                        return (set_errno(error));

                startvp = vp;
        }

        /*
         * Do we need to go into extended attribute space?
         */
        if (filemode & FXATTR) {
                if (startfd == AT_FDCWD) {
                        if (copyin(fname, &startchar, sizeof (char)))
                                return (set_errno(EFAULT));

                        /*
                         * If startchar == '/' then no extended attributes
                         * are looked up.
                         */
                        if (startchar == '/') {
                                startvp = NULL;
                        } else {
                                mutex_enter(&p->p_lock);
                                startvp = PTOU(p)->u_cdir;
                                VN_HOLD(startvp);
                                mutex_exit(&p->p_lock);
                        }
                }

                /*
                 * Make sure we have a valid extended attribute request.
                 * We must either have a real fd or AT_FDCWD and a relative
                 * pathname.
                 */
                if (startvp == NULL) {
                        goto noxattr;
                }
        }

        if (filemode & (FXATTR|FXATTRDIROPEN)) {
                vattr_t vattr;

                if (error = pn_get(fname, UIO_USERSPACE, &pn)) {
                        goto out;
                }

                /*
                 * In order to access hidden attribute directory the
                 * user must be able to stat() the file
                 */
                vattr.va_mask = AT_ALL;
                if (error = VOP_GETATTR(startvp, &vattr, 0, CRED(), NULL)) {
                        pn_free(&pn);
                        goto out;
                }

                if ((startvp->v_vfsp->vfs_flag & VFS_XATTR) != 0 ||
                    vfs_has_feature(startvp->v_vfsp, VFSFT_SYSATTR_VIEWS)) {
                        error = VOP_LOOKUP(startvp, "", &sdvp, &pn,
                            (filemode & FXATTRDIROPEN) ? LOOKUP_XATTR :
                            LOOKUP_XATTR|CREATE_XATTR_DIR, rootvp, CRED(),
                            NULL, NULL, NULL);
                } else {
                        error = EINVAL;
                }

                /*
                 * For __openattrdirat() use "." as filename to open
                 * as part of vn_openat()
                 */
                if (error == 0 && (filemode & FXATTRDIROPEN)) {
                        open_filename = ".";
                        seg = UIO_SYSSPACE;
                }

                pn_free(&pn);
                if (error != 0)
                        goto out;

                VN_RELE(startvp);
                startvp = sdvp;
        }

noxattr:
        if ((filemode & (FREAD|FWRITE|FSEARCH|FEXEC|FXATTRDIROPEN)) != 0) {
                if ((filemode & (FNONBLOCK|FNDELAY)) == (FNONBLOCK|FNDELAY))
                        filemode &= ~FNDELAY;
                error = falloc((vnode_t *)NULL, filemode, &fp, &fd);
                if (error == 0) {
                        if (auditing && startvp != NULL)
                                audit_setfsat_path(1);
                        /*
                         * Last arg is a don't-care term if
                         * !(filemode & FCREAT).
                         */
                        error = vn_openat(open_filename, seg, filemode,
                            (int)(createmode & MODEMASK),
                            &vp, CRCREAT, PTOU(curproc)->u_cmask,
                            startvp, fd);

                        if (startvp != NULL)
                                VN_RELE(startvp);
                        if (error == 0) {
                                if ((vp->v_flag & VDUP) == 0) {
                                        fp->f_vnode = vp;
                                        mutex_exit(&fp->f_tlock);
                                        /*
                                         * We must now fill in the slot
                                         * falloc reserved.
                                         */
                                        setf(fd, fp);
                                        if ((filemode & FCLOEXEC) != 0) {
                                                f_setfd_or(fd, FD_CLOEXEC);
                                        }

                                        if ((filemode & FCLOFORK) != 0) {
                                                f_setfd_or(fd, FD_CLOFORK);
                                        }
                                        return (fd);
                                } else {
                                        /*
                                         * Special handling for /dev/fd.
                                         * Give up the file pointer
                                         * and dup the indicated file descriptor
                                         * (in v_rdev). This is ugly, but I've
                                         * seen worse.
                                         */
                                        unfalloc(fp);
                                        dupfd = getminor(vp->v_rdev);
                                        type = vp->v_type;
                                        mutex_enter(&vp->v_lock);
                                        vp->v_flag &= ~VDUP;
                                        mutex_exit(&vp->v_lock);
                                        VN_RELE(vp);
                                        if (type != VCHR)
                                                return (set_errno(EINVAL));
                                        if ((fp = getf(dupfd)) == NULL) {
                                                setf(fd, NULL);
                                                return (set_errno(EBADF));
                                        }
                                        mutex_enter(&fp->f_tlock);
                                        fp->f_count++;
                                        mutex_exit(&fp->f_tlock);
                                        setf(fd, fp);
                                        if ((filemode & FCLOEXEC) != 0) {
                                                f_setfd_or(fd, FD_CLOEXEC);
                                        }

                                        if ((filemode & FCLOFORK) != 0) {
                                                f_setfd_or(fd, FD_CLOFORK);
                                        }
                                        releasef(dupfd);
                                }
                                return (fd);
                        } else {
                                setf(fd, NULL);
                                unfalloc(fp);
                                return (set_errno(error));
                        }
                }
        } else {
                error = EINVAL;
        }
out:
        if (startvp != NULL)
                VN_RELE(startvp);
        return (set_errno(error));
}

#define OPENMODE32(fmode)       (((fmode) & (FSEARCH | FEXEC))? \
                                    (fmode) : (fmode) - FOPEN)
#define OPENMODE64(fmode)       (OPENMODE32(fmode) | FOFFMAX)
#ifdef _LP64
#define OPENMODE(fmode)         OPENMODE64(fmode)
#else
#define OPENMODE(fmode)         OPENMODE32(fmode)
#endif

/*
 * Open a file.
 */
int
openat(int fd, char *path, int fmode, int cmode)
{
        return (copen(fd, path, OPENMODE(fmode), cmode));
}

int
open(char *path, int fmode, int cmode)
{
        return (openat(AT_FDCWD, path, fmode, cmode));
}

#if defined(_ILP32) || defined(_SYSCALL32_IMPL)
/*
 * Open for large files in 32-bit environment. Sets the FOFFMAX flag.
 */
int
openat64(int fd, char *path, int fmode, int cmode)
{
        return (copen(fd, path, OPENMODE64(fmode), cmode));
}

int
open64(char *path, int fmode, int cmode)
{
        return (openat64(AT_FDCWD, path, fmode, cmode));
}

#endif  /* _ILP32 || _SYSCALL32_IMPL */

#ifdef _SYSCALL32_IMPL
/*
 * Open for 32-bit compatibility on 64-bit kernel
 */
int
openat32(int fd, char *path, int fmode, int cmode)
{
        return (copen(fd, path, OPENMODE32(fmode), cmode));
}

int
open32(char *path, int fmode, int cmode)
{
        return (openat32(AT_FDCWD, path, fmode, cmode));
}

#endif  /* _SYSCALL32_IMPL */