sys/vfs/procfs/procfs_mem.c

   1 /*
   2  * Copyright (c) 1993 Jan-Simon Pendry
   3  * Copyright (c) 1993 Sean Eric Fagan
   4  * Copyright (c) 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Jan-Simon Pendry and Sean Eric Fagan.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. All advertising materials mentioning features or use of this software
  19  *    must display the following acknowledgement:
  20  *      This product includes software developed by the University of
  21  *      California, Berkeley and its contributors.
  22  * 4. Neither the name of the University nor the names of its contributors
  23  *    may be used to endorse or promote products derived from this software
  24  *    without specific prior written permission.
  25  *
  26  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  36  * SUCH DAMAGE.
  37  *
  38  *      @(#)procfs_mem.c        8.5 (Berkeley) 6/15/94
  39  *
  40  * $FreeBSD: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $
  41  * $DragonFly: src/sys/vfs/procfs/procfs_mem.c,v 1.16 2007/04/29 18:25:40 dillon Exp $
  42  */
  43
  44 /*
  45  * This is a lightly hacked and merged version
  46  * of sef's pread/pwrite functions
  47  */
  48
  49 #include <sys/param.h>
  50 #include <sys/systm.h>
  51 #include <sys/proc.h>
  52 #include <sys/vnode.h>
  53 #include <vfs/procfs/procfs.h>
  54 #include <vm/vm.h>
  55 #include <vm/vm_param.h>
  56 #include <sys/lock.h>
  57 #include <vm/pmap.h>
  58 #include <vm/vm_extern.h>
  59 #include <vm/vm_map.h>
  60 #include <vm/vm_kern.h>
  61 #include <vm/vm_object.h>
  62 #include <vm/vm_page.h>
  63 #include <sys/user.h>
  64 #include <sys/ptrace.h>
  65
  66 #include <sys/thread2.h>
  67 #include <sys/sysref2.h>
  68
  69 static int      procfs_rwmem (struct proc *curp,
  70                                   struct proc *p, struct uio *uio);
  71
  72 static int
  73 procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
  74 {
  75         int error;
  76         int writing;
  77         struct vmspace *vm;
  78         vm_map_t map;
  79         vm_offset_t pageno = 0;         /* page number */
  80         vm_prot_t reqprot;
  81         vm_offset_t kva;
  82
  83         /*
  84          * if the vmspace is in the midst of being allocated or deallocated,
  85          * or the process is exiting, don't try to grab anything.  The
  86          * page table usage in that process may be messed up.
  87          */
  88         vm = p->p_vmspace;
  89         sysref_get(&vm->vm_sysref);
  90         if ((p->p_flag & P_WEXIT) || sysref_isinactive(&vm->vm_sysref)) {
  91                 sysref_put(&vm->vm_sysref);
  92                 return EFAULT;
  93         }
  94
  95         /*
  96          * The map we want...
  97          */
  98         map = &vm->vm_map;
  99
 100         writing = uio->uio_rw == UIO_WRITE;
 101         reqprot = VM_PROT_READ;
 102         if (writing)
 103                 reqprot |= VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE;
 104
 105         kva = kmem_alloc_pageable(&kernel_map, PAGE_SIZE);
 106
 107         /*
 108          * Only map in one page at a time.  We don't have to, but it
 109          * makes things easier.  This way is trivial - right?
 110          */
 111         do {
 112                 vm_offset_t uva;
 113                 int page_offset;                /* offset into page */
 114                 u_int len;
 115                 vm_page_t m;
 116
 117                 uva = (vm_offset_t) uio->uio_offset;
 118
 119                 /*
 120                  * Get the page number of this segment.
 121                  */
 122                 pageno = trunc_page(uva);
 123                 page_offset = uva - pageno;
 124
 125                 /*
 126                  * How many bytes to copy
 127                  */
 128                 len = min(PAGE_SIZE - page_offset, uio->uio_resid);
 129
 130                 /*
 131                  * Fault the page on behalf of the process
 132                  */
 133                 m = vm_fault_page(map, pageno, reqprot,
 134                                   VM_FAULT_NORMAL, &error);
 135                 if (error) {
 136                         KKASSERT(m == NULL);
 137                         error = EFAULT;
 138                         break;
 139                 }
 140
 141                 /*
 142                  * Cleanup tmap then create a temporary KVA mapping and
 143                  * do the I/O.
 144                  */
 145                 pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
 146                 error = uiomove((caddr_t)(kva + page_offset), len, uio);
 147                 pmap_kremove(kva);
 148
 149                 /*
 150                  * release the page and we are done
 151                  */
 152                 crit_enter();
 153                 vm_page_unhold(m);
 154                 crit_exit();
 155         } while (error == 0 && uio->uio_resid > 0);
 156
 157         kmem_free(&kernel_map, kva, PAGE_SIZE);
 158         sysref_put(&vm->vm_sysref);
 159         return (error);
 160 }
 161
 162 /*
 163  * Copy data in and out of the target process.
 164  * We do this by mapping the process's page into
 165  * the kernel and then doing a uiomove direct
 166  * from the kernel address space.
 167  */
 168 int
 169 procfs_domem(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 170              struct uio *uio)
 171 {
 172         struct proc *p = lp->lwp_proc;
 173
 174         if (uio->uio_resid == 0)
 175                 return (0);
 176
 177         /* Can't trace a process that's currently exec'ing. */
 178         if ((p->p_flag & P_INEXEC) != 0)
 179                 return EAGAIN;
 180         if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred))
 181                 return EPERM;
 182
 183         return (procfs_rwmem(curp, p, uio));
 184 }
 185
 186 /*
 187  * Given process (p), find the vnode from which
 188  * its text segment is being executed.
 189  *
 190  * It would be nice to grab this information from
 191  * the VM system, however, there is no sure-fire
 192  * way of doing that.  Instead, fork(), exec() and
 193  * wait() all maintain the p_textvp field in the
 194  * process proc structure which contains a held
 195  * reference to the exec'ed vnode.
 196  *
 197  * XXX - Currently, this is not not used, as the
 198  * /proc/pid/file object exposes an information leak
 199  * that shouldn't happen.  Using a mount option would
 200  * make it configurable on a per-system (or, at least,
 201  * per-mount) basis; however, that's not really best.
 202  * The best way to do it, I think, would be as an
 203  * ioctl; this would restrict it to the uid running
 204  * program, or root, which seems a reasonable compromise.
 205  * However, the number of applications for this is
 206  * minimal, if it can't be seen in the filesytem space,
 207  * and doint it as an ioctl makes it somewhat less
 208  * useful due to the, well, inelegance.
 209  *
 210  */
 211 struct vnode *
 212 procfs_findtextvp(struct proc *p)
 213 {
 214         return (p->p_textvp);
 215 }