sys/kern/kern_fp.c

   1 /*
   2  * Copyright (c) 2003,2004 The DragonFly Project.  All rights reserved.
   3  *
   4  * This code is derived from software contributed to The DragonFly Project
   5  * by Matthew Dillon <dillon@backplane.com>
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions
   9  * are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in
  15  *    the documentation and/or other materials provided with the
  16  *    distribution.
  17  * 3. Neither the name of The DragonFly Project nor the names of its
  18  *    contributors may be used to endorse or promote products derived
  19  *    from this software without specific, prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
  25  * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  26  * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
  27  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  28  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  29  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  30  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
  31  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $DragonFly: src/sys/kern/kern_fp.c,v 1.20 2007/01/12 06:06:57 dillon Exp $
  35  */
  36
  37 /*
  38  * Direct file pointer API functions for in-kernel operations on files.  These
  39  * functions provide a open/read/write/close like interface within the kernel
  40  * for operating on files that are not necessarily associated with processes
  41  * and which do not (typically) have descriptors.
  42  *
  43  * FUTURE: file handle conversion routines to support checkpointing,
  44  * and additional file operations (ioctl, fcntl).
  45  */
  46
  47 #include <sys/param.h>
  48 #include <sys/kernel.h>
  49 #include <sys/systm.h>
  50 #include <sys/malloc.h>
  51 #include <sys/sysproto.h>
  52 #include <sys/conf.h>
  53 #include <sys/filedesc.h>
  54 #include <sys/sysctl.h>
  55 #include <sys/vnode.h>
  56 #include <sys/proc.h>
  57 #include <sys/nlookup.h>
  58 #include <sys/file.h>
  59 #include <sys/stat.h>
  60 #include <sys/filio.h>
  61 #include <sys/fcntl.h>
  62 #include <sys/unistd.h>
  63 #include <sys/resourcevar.h>
  64 #include <sys/event.h>
  65 #include <sys/mman.h>
  66
  67 #include <vm/vm.h>
  68 #include <vm/vm_param.h>
  69 #include <sys/lock.h>
  70 #include <vm/pmap.h>
  71 #include <vm/vm_map.h>
  72 #include <vm/vm_object.h>
  73 #include <vm/vm_page.h>
  74 #include <vm/vm_pager.h>
  75 #include <vm/vm_pageout.h>
  76 #include <vm/vm_extern.h>
  77 #include <vm/vm_page.h>
  78 #include <vm/vm_kern.h>
  79
  80 #include <sys/file2.h>
  81 #include <machine/limits.h>
  82
  83 typedef struct file *file_t;
  84
  85 /*
  86  * fp_open:
  87  *
  88  *      Open a file as specified.  Use O_* flags for flags.
  89  *
  90  *      NOTE! O_ROOTCRED not quite working yet, vn_open() asserts that the
  91  *      cred must match the process's cred. XXX
  92  *
  93  *      NOTE! when fp_open() is called from a pure thread, root creds are
  94  *      used.
  95  */
  96 int
  97 fp_open(const char *path, int flags, int mode, file_t *fpp)
  98 {
  99     struct nlookupdata nd;
 100     struct thread *td;
 101     struct file *fp;
 102     int error;
 103
 104     if ((error = falloc(NULL, fpp, NULL)) != 0)
 105         return (error);
 106     fp = *fpp;
 107     td = curthread;
 108     if (td->td_proc) {
 109         if ((flags & O_ROOTCRED) == 0)
 110             fsetcred(fp, td->td_proc->p_ucred);
 111     }
 112     error = nlookup_init(&nd, path, UIO_SYSSPACE, NLC_LOCKVP);
 113     flags = FFLAGS(flags);
 114     if (error == 0)
 115         error = vn_open(&nd, fp, flags, mode);
 116     nlookup_done(&nd);
 117     if (error) {
 118         fdrop(fp);
 119         *fpp = NULL;
 120     }
 121     return(error);
 122 }
 123
 124
 125 /*
 126  * fp_vpopen(): convert a vnode to a file pointer, call VOP_OPEN() on the
 127  * the vnode.  The vnode must be refd and locked.
 128  *
 129  * On success the vnode's ref is inherited by the file pointer and the caller
 130  * should not vrele() it, and the vnode is unlocked.
 131  *
 132  * On failure the vnode remains locked and refd and the caller is responsible
 133  * for vput()ing it.
 134  */
 135 int
 136 fp_vpopen(struct vnode *vp, int flags, file_t *fpp)
 137 {
 138     struct thread *td;
 139     struct file *fp;
 140     int vmode;
 141     int error;
 142
 143     td = curthread;
 144
 145     /*
 146      * Vnode checks (from vn_open())
 147      */
 148     if (vp->v_type == VLNK) {
 149         error = EMLINK;
 150         goto bad2;
 151     }
 152     if (vp->v_type == VSOCK) {
 153         error = EOPNOTSUPP;
 154         goto bad2;
 155     }
 156     flags = FFLAGS(flags);
 157     vmode = 0;
 158     if (flags & (FWRITE | O_TRUNC)) {
 159         if (vp->v_type == VDIR) {
 160             error = EISDIR;
 161             goto bad2;
 162         }
 163         error = vn_writechk(vp, NULL);
 164         if (error)
 165             goto bad2;
 166         vmode |= VWRITE;
 167     }
 168     if (flags & FREAD)
 169         vmode |= VREAD;
 170     if (vmode) {
 171         error = VOP_ACCESS(vp, vmode, td->td_proc->p_ucred);
 172         if (error)
 173             goto bad2;
 174     }
 175
 176     /*
 177      * File pointer setup
 178      */
 179     if ((error = falloc(NULL, fpp, NULL)) != 0)
 180         goto bad2;
 181     fp = *fpp;
 182     if ((flags & O_ROOTCRED) == 0 && td->td_proc)
 183         fsetcred(fp, td->td_proc->p_ucred);
 184
 185     error = VOP_OPEN(vp, flags, td->td_proc->p_ucred, fp);
 186     if (error)
 187         goto bad1;
 188
 189     vput(vp);
 190     return (0);
 191 bad1:
 192     fp->f_ops = &badfileops;    /* open failed, don't close */
 193     fp->f_data = NULL;
 194     fdrop(fp);
 195     /* leave the vnode intact, but fall through and unlock it anyway */
 196 bad2:
 197     *fpp = NULL;
 198     return (error);
 199 }
 200
 201 /*
 202  * fp_*read() is meant to operate like the normal descriptor based syscalls
 203  * would.  Note that if 'buf' points to user memory a UIO_USERSPACE
 204  * transfer will be used.
 205  */
 206 int
 207 fp_pread(file_t fp, void *buf, size_t nbytes, off_t offset, ssize_t *res,
 208          enum uio_seg seg)
 209 {
 210     struct uio auio;
 211     struct iovec aiov;
 212     size_t count;
 213     int error;
 214
 215     if (res)
 216         *res = 0;
 217     if (nbytes > INT_MAX)
 218         return (EINVAL);
 219     bzero(&auio, sizeof(auio));
 220     aiov.iov_base = (caddr_t)buf;
 221     aiov.iov_len = nbytes;
 222     auio.uio_iov = &aiov;
 223     auio.uio_iovcnt = 1;
 224     auio.uio_offset = offset;
 225     auio.uio_resid = nbytes;
 226     auio.uio_rw = UIO_READ;
 227     auio.uio_segflg = seg;
 228     auio.uio_td = curthread;
 229
 230     count = nbytes;
 231     error = fo_read(fp, &auio, fp->f_cred, O_FOFFSET);
 232     if (error) {
 233         if (auio.uio_resid != nbytes && (error == ERESTART || error == EINTR ||
 234             error == EWOULDBLOCK)
 235         ) {
 236             error = 0;
 237         }
 238     }
 239     count -= auio.uio_resid;
 240     if (res)
 241         *res = count;
 242     return(error);
 243 }
 244
 245 int
 246 fp_read(file_t fp, void *buf, size_t nbytes, ssize_t *res, int all,
 247         enum uio_seg seg)
 248 {
 249     struct uio auio;
 250     struct iovec aiov;
 251     int error;
 252     int lastresid;
 253
 254     if (res)
 255         *res = 0;
 256     if (nbytes > INT_MAX)
 257         return (EINVAL);
 258     bzero(&auio, sizeof(auio));
 259     aiov.iov_base = (caddr_t)buf;
 260     aiov.iov_len = nbytes;
 261     auio.uio_iov = &aiov;
 262     auio.uio_iovcnt = 1;
 263     auio.uio_offset = 0;
 264     auio.uio_resid = nbytes;
 265     auio.uio_rw = UIO_READ;
 266     auio.uio_segflg = seg;
 267     auio.uio_td = curthread;
 268
 269     /*
 270      * If all is false call fo_read() once.
 271      * If all is true we attempt to read the entire request.  We have to
 272      * break out of the loop if an unrecoverable error or EOF occurs.
 273      */
 274     do {
 275         lastresid = auio.uio_resid;
 276         error = fo_read(fp, &auio, fp->f_cred, 0);
 277     } while (all && auio.uio_resid &&
 278              ((error == 0 && auio.uio_resid != lastresid) ||
 279              error == ERESTART || error == EINTR));
 280     if (all && error == 0 && auio.uio_resid)
 281         error = ESPIPE;
 282
 283     /*
 284      * If an error occured but some data was read, silently forget the
 285      * error.  However, if this is a non-blocking descriptor and 'all'
 286      * was specified, return an error even if some data was read (this
 287      * is considered a bug in the caller for using an illegal combination
 288      * of 'all' and a non-blocking descriptor).
 289      */
 290     if (error) {
 291         if (auio.uio_resid != nbytes) {
 292             if (error == ERESTART || error == EINTR)
 293                 error = 0;
 294             if (error == EWOULDBLOCK && all == 0)
 295                 error = 0;
 296         }
 297     }
 298     if (res)
 299         *res = nbytes - auio.uio_resid;
 300     return(error);
 301 }
 302
 303 int
 304 fp_pwrite(file_t fp, void *buf, size_t nbytes, off_t offset, ssize_t *res,
 305           enum uio_seg seg)
 306 {
 307     struct uio auio;
 308     struct iovec aiov;
 309     size_t count;
 310     int error;
 311
 312     if (res)
 313         *res = 0;
 314     if (nbytes > INT_MAX)
 315         return (EINVAL);
 316     bzero(&auio, sizeof(auio));
 317     aiov.iov_base = (caddr_t)buf;
 318     aiov.iov_len = nbytes;
 319     auio.uio_iov = &aiov;
 320     auio.uio_iovcnt = 1;
 321     auio.uio_offset = offset;
 322     auio.uio_resid = nbytes;
 323     auio.uio_rw = UIO_WRITE;
 324     auio.uio_segflg = seg;
 325     auio.uio_td = curthread;
 326
 327     count = nbytes;
 328     error = fo_write(fp, &auio, fp->f_cred, O_FOFFSET);
 329     if (error) {
 330         if (auio.uio_resid != nbytes && (error == ERESTART || error == EINTR ||
 331             error == EWOULDBLOCK)
 332         ) {
 333             error = 0;
 334         }
 335     }
 336     count -= auio.uio_resid;
 337     if (res)
 338         *res = count;
 339     return(error);
 340 }
 341
 342
 343 int
 344 fp_write(file_t fp, void *buf, size_t nbytes, ssize_t *res, enum uio_seg seg)
 345 {
 346     struct uio auio;
 347     struct iovec aiov;
 348     size_t count;
 349     int error;
 350
 351     if (res)
 352         *res = 0;
 353     if (nbytes > INT_MAX)
 354         return (EINVAL);
 355     bzero(&auio, sizeof(auio));
 356     aiov.iov_base = (caddr_t)buf;
 357     aiov.iov_len = nbytes;
 358     auio.uio_iov = &aiov;
 359     auio.uio_iovcnt = 1;
 360     auio.uio_offset = 0;
 361     auio.uio_resid = nbytes;
 362     auio.uio_rw = UIO_WRITE;
 363     auio.uio_segflg = seg;
 364     auio.uio_td = curthread;
 365
 366     count = nbytes;
 367     error = fo_write(fp, &auio, fp->f_cred, 0);
 368     if (error) {
 369         if (auio.uio_resid != nbytes && (error == ERESTART || error == EINTR ||
 370             error == EWOULDBLOCK)
 371         ) {
 372             error = 0;
 373         }
 374     }
 375     count -= auio.uio_resid;
 376     if (res)
 377         *res = count;
 378     return(error);
 379 }
 380
 381 int
 382 fp_stat(file_t fp, struct stat *ub)
 383 {
 384     int error;
 385
 386     error = fo_stat(fp, ub, fp->f_cred);
 387     return(error);
 388 }
 389
 390 /*
 391  * non-anonymous, non-stack descriptor mappings only!
 392  *
 393  * This routine mostly snarfed from vm/vm_mmap.c
 394  */
 395 int
 396 fp_mmap(void *addr_arg, size_t size, int prot, int flags, struct file *fp,
 397     off_t pos, void **resp)
 398 {
 399     struct thread *td = curthread;
 400     struct proc *p = td->td_proc;
 401     vm_size_t pageoff;
 402     vm_prot_t maxprot;
 403     vm_offset_t addr;
 404     void *handle;
 405     int error;
 406     vm_object_t obj;
 407     struct vmspace *vms = p->p_vmspace;
 408     struct vnode *vp;
 409     int disablexworkaround;
 410
 411     prot &= VM_PROT_ALL;
 412
 413     if ((ssize_t)size < 0 || (flags & MAP_ANON))
 414         return(EINVAL);
 415
 416     pageoff = (pos & PAGE_MASK);
 417     pos -= pageoff;
 418
 419     /* Adjust size for rounding (on both ends). */
 420     size += pageoff;                            /* low end... */
 421     size = (vm_size_t)round_page(size);         /* hi end */
 422     addr = (vm_offset_t)addr_arg;
 423
 424     /*
 425      * Check for illegal addresses.  Watch out for address wrap... Note
 426      * that VM_*_ADDRESS are not constants due to casts (argh).
 427      */
 428     if (flags & MAP_FIXED) {
 429         /*
 430          * The specified address must have the same remainder
 431          * as the file offset taken modulo PAGE_SIZE, so it
 432          * should be aligned after adjustment by pageoff.
 433          */
 434         addr -= pageoff;
 435         if (addr & PAGE_MASK)
 436             return (EINVAL);
 437         /* Address range must be all in user VM space. */
 438         if (VM_MAX_USER_ADDRESS > 0 && addr + size > VM_MAX_USER_ADDRESS)
 439             return (EINVAL);
 440         if (VM_MIN_USER_ADDRESS > 0 && addr < VM_MIN_USER_ADDRESS)
 441             return (EINVAL);
 442         if (addr + size < addr)
 443             return (EINVAL);
 444     } else if (addr == 0 ||
 445         (addr >= round_page((vm_offset_t)vms->vm_taddr) &&
 446          addr < round_page((vm_offset_t)vms->vm_daddr + maxdsiz))
 447     ) {
 448         /*
 449          * XXX for non-fixed mappings where no hint is provided or
 450          * the hint would fall in the potential heap space,
 451          * place it after the end of the largest possible heap.
 452          *
 453          * There should really be a pmap call to determine a reasonable
 454          * location.
 455          */
 456         addr = round_page((vm_offset_t)vms->vm_daddr + maxdsiz);
 457     }
 458
 459     /*
 460      * Mapping file, get fp for validation. Obtain vnode and make
 461      * sure it is of appropriate type.
 462      */
 463     if (fp->f_type != DTYPE_VNODE)
 464         return (EINVAL);
 465
 466     /*
 467      * POSIX shared-memory objects are defined to have
 468      * kernel persistence, and are not defined to support
 469      * read(2)/write(2) -- or even open(2).  Thus, we can
 470      * use MAP_ASYNC to trade on-disk coherence for speed.
 471      * The shm_open(3) library routine turns on the FPOSIXSHM
 472      * flag to request this behavior.
 473      */
 474     if (fp->f_flag & FPOSIXSHM)
 475         flags |= MAP_NOSYNC;
 476     vp = (struct vnode *) fp->f_data;
 477     if (vp->v_type != VREG && vp->v_type != VCHR)
 478         return (EINVAL);
 479
 480     /*
 481      * Get the proper underlying object
 482      */
 483     if (vp->v_type == VREG) {
 484         if ((obj = vp->v_object) == NULL)
 485             return (EINVAL);
 486         KKASSERT(vp == (struct vnode *)obj->handle);
 487     }
 488
 489     /*
 490      * XXX hack to handle use of /dev/zero to map anon memory (ala
 491      * SunOS).
 492      */
 493     if (vp->v_type == VCHR && iszerodev(vp->v_rdev)) {
 494         handle = NULL;
 495         maxprot = VM_PROT_ALL;
 496         flags |= MAP_ANON;
 497         pos = 0;
 498     } else {
 499         /*
 500          * cdevs does not provide private mappings of any kind.
 501          */
 502         /*
 503          * However, for XIG X server to continue to work,
 504          * we should allow the superuser to do it anyway.
 505          * We only allow it at securelevel < 1.
 506          * (Because the XIG X server writes directly to video
 507          * memory via /dev/mem, it should never work at any
 508          * other securelevel.
 509          * XXX this will have to go
 510          */
 511         if (securelevel >= 1)
 512             disablexworkaround = 1;
 513         else
 514             disablexworkaround = suser(td);
 515         if (vp->v_type == VCHR && disablexworkaround &&
 516             (flags & (MAP_PRIVATE|MAP_COPY))) {
 517                 error = EINVAL;
 518                 goto done;
 519         }
 520         /*
 521          * Ensure that file and memory protections are
 522          * compatible.  Note that we only worry about
 523          * writability if mapping is shared; in this case,
 524          * current and max prot are dictated by the open file.
 525          * XXX use the vnode instead?  Problem is: what
 526          * credentials do we use for determination? What if
 527          * proc does a setuid?
 528          */
 529         maxprot = VM_PROT_EXECUTE;      /* ??? */
 530         if (fp->f_flag & FREAD) {
 531             maxprot |= VM_PROT_READ;
 532         } else if (prot & PROT_READ) {
 533             error = EACCES;
 534             goto done;
 535         }
 536         /*
 537          * If we are sharing potential changes (either via
 538          * MAP_SHARED or via the implicit sharing of character
 539          * device mappings), and we are trying to get write
 540          * permission although we opened it without asking
 541          * for it, bail out.  Check for superuser, only if
 542          * we're at securelevel < 1, to allow the XIG X server
 543          * to continue to work.
 544          */
 545
 546         if ((flags & MAP_SHARED) != 0 ||
 547             (vp->v_type == VCHR && disablexworkaround)
 548         ) {
 549             if ((fp->f_flag & FWRITE) != 0) {
 550                 struct vattr va;
 551                 if ((error = VOP_GETATTR(vp, &va))) {
 552                     goto done;
 553                 }
 554                 if ((va.va_flags & (IMMUTABLE|APPEND)) == 0) {
 555                     maxprot |= VM_PROT_WRITE;
 556                 } else if (prot & PROT_WRITE) {
 557                     error = EPERM;
 558                     goto done;
 559                 }
 560             } else if ((prot & PROT_WRITE) != 0) {
 561                 error = EACCES;
 562                 goto done;
 563             }
 564         } else {
 565             maxprot |= VM_PROT_WRITE;
 566         }
 567         handle = (void *)vp;
 568     }
 569     error = vm_mmap(&vms->vm_map, &addr, size, prot,
 570                     maxprot, flags, handle, pos);
 571     if (error == 0 && addr_arg)
 572         *resp = (void *)addr;
 573 done:
 574     return (error);
 575 }
 576
 577 int
 578 fp_close(file_t fp)
 579 {
 580     return(fdrop(fp));
 581 }
 582
 583 int
 584 fp_shutdown(file_t fp, int how)
 585 {
 586     return(fo_shutdown(fp, how));
 587 }
 588