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. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  *      @(#)procfs_mem.c        8.5 (Berkeley) 6/15/94
  35  *
  36  * $FreeBSD: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $
  37  * $DragonFly: src/sys/vfs/procfs/procfs_mem.c,v 1.16 2007/04/29 18:25:40 dillon Exp $
  38  */
  39
  40 /*
  41  * This is a lightly hacked and merged version
  42  * of sef's pread/pwrite functions
  43  */
  44
  45 #include <sys/param.h>
  46 #include <sys/systm.h>
  47 #include <sys/proc.h>
  48 #include <sys/priv.h>
  49 #include <sys/vnode.h>
  50 #include <vfs/procfs/procfs.h>
  51 #include <vm/vm.h>
  52 #include <vm/vm_param.h>
  53 #include <sys/lock.h>
  54 #include <vm/pmap.h>
  55 #include <vm/vm_extern.h>
  56 #include <vm/vm_map.h>
  57 #include <vm/vm_kern.h>
  58 #include <vm/vm_object.h>
  59 #include <vm/vm_page.h>
  60 #include <sys/user.h>
  61 #include <sys/ptrace.h>
  62
  63 #include <machine/vmm.h>
  64
  65 #include <sys/thread2.h>
  66 #include <sys/sysref2.h>
  67
  68 static int      procfs_rwmem (struct proc *curp,
  69                                   struct proc *p, struct uio *uio);
  70
  71 /*
  72  * p->p_token is held on entry.
  73  */
  74 static int
  75 procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
  76 {
  77         int error;
  78         int writing;
  79         struct vmspace *vm;
  80         vm_map_t map;
  81         vm_offset_t pageno = 0;         /* page number */
  82         vm_prot_t reqprot;
  83         vm_offset_t kva;
  84
  85         /*
  86          * if the vmspace is in the midst of being allocated or deallocated,
  87          * or the process is exiting, don't try to grab anything.  The
  88          * page table usage in that process may be messed up.
  89          */
  90         vm = p->p_vmspace;
  91         if (p->p_stat == SIDL || p->p_stat == SZOMB)
  92                 return EFAULT;
  93         if ((p->p_flags & (P_WEXIT | P_INEXEC)) || vmspace_getrefs(vm) < 0)
  94                 return EFAULT;
  95
  96         /*
  97          * The map we want...
  98          */
  99         vmspace_hold(vm);
 100         map = &vm->vm_map;
 101
 102         writing = (uio->uio_rw == UIO_WRITE);
 103         reqprot = VM_PROT_READ;
 104         if (writing)
 105                 reqprot |= VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE;
 106
 107         kva = kmem_alloc_pageable(&kernel_map, PAGE_SIZE, VM_SUBSYS_PROC);
 108
 109         /*
 110          * Only map in one page at a time.  We don't have to, but it
 111          * makes things easier.  This way is trivial - right?
 112          */
 113         do {
 114                 vm_offset_t uva;
 115                 vm_offset_t page_offset;        /* offset into page */
 116                 size_t len;
 117                 vm_page_t m;
 118
 119                 uva = (vm_offset_t) uio->uio_offset;
 120
 121                 /*
 122                  * Get the page number of this segment.
 123                  */
 124                 pageno = trunc_page(uva);
 125                 page_offset = uva - pageno;
 126
 127                 /*
 128                  * If the target process is running in VMM mode
 129                  * translate the address into a GPA (Guest Physical
 130                  * Address) via the EPT before doing the lookup.
 131                  */
 132                 if (p->p_vmm) {
 133                         register_t gpa;
 134                         vmm_vm_get_gpa(p, &gpa, (register_t) pageno);
 135                         pageno = (vm_offset_t)gpa;
 136                 }
 137
 138                 /*
 139                  * How many bytes to copy
 140                  */
 141                 len = szmin(PAGE_SIZE - page_offset, uio->uio_resid);
 142
 143                 /*
 144                  * Fault the page on behalf of the process
 145                  */
 146                 m = vm_fault_page(map, pageno, reqprot,
 147                                   VM_FAULT_NORMAL, &error);
 148                 if (error) {
 149                         KKASSERT(m == NULL);
 150                         error = EFAULT;
 151                         break;
 152                 }
 153
 154                 /*
 155                  * Cleanup tmap then create a temporary KVA mapping and
 156                  * do the I/O.  We can switch between cpus so don't bother
 157                  * synchronizing across all cores.
 158                  */
 159                 pmap_kenter_quick(kva, VM_PAGE_TO_PHYS(m));
 160                 error = uiomove((caddr_t)(kva + page_offset), len, uio);
 161                 pmap_kremove_quick(kva);
 162
 163                 /*
 164                  * release the page and we are done
 165                  */
 166                 vm_page_unhold(m);
 167         } while (error == 0 && uio->uio_resid > 0);
 168
 169         vmspace_drop(vm);
 170         kmem_free(&kernel_map, kva, PAGE_SIZE);
 171
 172         return (error);
 173 }
 174
 175 /*
 176  * Copy data in and out of the target process.
 177  * We do this by mapping the process's page into
 178  * the kernel and then doing a uiomove direct
 179  * from the kernel address space.
 180  *
 181  * lp->lwp_proc->p_token is held on entry.
 182  */
 183 int
 184 procfs_domem(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
 185              struct uio *uio)
 186 {
 187         struct proc *p = lp->lwp_proc;
 188         int error;
 189
 190         if (uio->uio_resid == 0)
 191                 return (0);
 192
 193         if ((p->p_flags & P_INEXEC) != 0) {
 194                 /*
 195                  * Can't trace a process that's currently exec'ing.
 196                  */
 197                 error = EAGAIN;
 198         } else if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred)) {
 199                 /*
 200                  * Can't trace processes outside our jail
 201                  */
 202                 error = EPERM;
 203         } else {
 204                 error = procfs_rwmem(curp, p, uio);
 205         }
 206         return(error);
 207 }
 208
 209 /*
 210  * Given process (p), find the vnode from which
 211  * its text segment is being executed.
 212  *
 213  * It would be nice to grab this information from
 214  * the VM system, however, there is no sure-fire
 215  * way of doing that.  Instead, fork(), exec() and
 216  * wait() all maintain the p_textvp field in the
 217  * process proc structure which contains a held
 218  * reference to the exec'ed vnode.
 219  *
 220  * XXX - Currently, this is not not used, as the
 221  * /proc/pid/file object exposes an information leak
 222  * that shouldn't happen.  Using a mount option would
 223  * make it configurable on a per-system (or, at least,
 224  * per-mount) basis; however, that's not really best.
 225  * The best way to do it, I think, would be as an
 226  * ioctl; this would restrict it to the uid running
 227  * program, or root, which seems a reasonable compromise.
 228  * However, the number of applications for this is
 229  * minimal, if it can't be seen in the filesytem space,
 230  * and doint it as an ioctl makes it somewhat less
 231  * useful due to the, well, inelegance.
 232  *
 233  */
 234 struct vnode *
 235 procfs_findtextvp(struct proc *p)
 236 {
 237         return (p->p_textvp);
 238 }