freebsd-dev/sys/miscfs/procfs/procfs_mem.c
1999-12-20 18:26:58 +00:00

317 lines
8.1 KiB
C

/*
* Copyright (c) 1993 Jan-Simon Pendry
* Copyright (c) 1993 Sean Eric Fagan
* Copyright (c) 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Jan-Simon Pendry and Sean Eric Fagan.
*
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*
* @(#)procfs_mem.c 8.5 (Berkeley) 6/15/94
*
* $FreeBSD$
*/
/*
* This is a lightly hacked and merged version
* of sef's pread/pwrite functions
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <miscfs/procfs/procfs.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <sys/lock.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 <sys/user.h>
#include <sys/ptrace.h>
static int procfs_rwmem __P((struct proc *curp,
struct proc *p, struct uio *uio));
static int
procfs_rwmem(curp, p, uio)
struct proc *curp;
struct proc *p;
struct uio *uio;
{
int error;
int writing;
struct vmspace *vm;
vm_map_t map;
vm_object_t object = NULL;
vm_offset_t pageno = 0; /* page number */
vm_prot_t reqprot;
vm_offset_t kva;
/*
* if the vmspace is in the midst of being deallocated or the
* process is exiting, don't try to grab anything. The page table
* usage in that process can be messed up.
*/
vm = p->p_vmspace;
if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1))
return EFAULT;
++vm->vm_refcnt;
/*
* The map we want...
*/
map = &vm->vm_map;
writing = uio->uio_rw == UIO_WRITE;
reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ;
kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE);
/*
* Only map in one page at a time. We don't have to, but it
* makes things easier. This way is trivial - right?
*/
do {
vm_map_t tmap;
vm_offset_t uva;
int page_offset; /* offset into page */
vm_map_entry_t out_entry;
vm_prot_t out_prot;
boolean_t wired;
vm_pindex_t pindex;
u_int len;
vm_page_t m;
object = NULL;
uva = (vm_offset_t) uio->uio_offset;
/*
* Get the page number of this segment.
*/
pageno = trunc_page(uva);
page_offset = uva - pageno;
/*
* How many bytes to copy
*/
len = min(PAGE_SIZE - page_offset, uio->uio_resid);
/*
* Fault the page on behalf of the process
*/
error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL);
if (error) {
error = EFAULT;
break;
}
/*
* Now we need to get the page. out_entry, out_prot, wired,
* and single_use aren't used. One would think the vm code
* would be a *bit* nicer... We use tmap because
* vm_map_lookup() can change the map argument.
*/
tmap = map;
error = vm_map_lookup(&tmap, pageno, reqprot,
&out_entry, &object, &pindex, &out_prot,
&wired);
if (error) {
error = EFAULT;
/*
* Make sure that there is no residue in 'object' from
* an error return on vm_map_lookup.
*/
object = NULL;
break;
}
m = vm_page_lookup(object, pindex);
/* Allow fallback to backing objects if we are reading */
while (m == NULL && !writing && object->backing_object) {
pindex += OFF_TO_IDX(object->backing_object_offset);
object = object->backing_object;
m = vm_page_lookup(object, pindex);
}
if (m == NULL) {
error = EFAULT;
/*
* Make sure that there is no residue in 'object' from
* an error return on vm_map_lookup.
*/
object = NULL;
vm_map_lookup_done(tmap, out_entry);
break;
}
/*
* Wire the page into memory
*/
vm_page_wire(m);
/*
* We're done with tmap now.
* But reference the object first, so that we won't loose
* it.
*/
vm_object_reference(object);
vm_map_lookup_done(tmap, out_entry);
pmap_kenter(kva, VM_PAGE_TO_PHYS(m));
/*
* Now do the i/o move.
*/
error = uiomove((caddr_t)(kva + page_offset), len, uio);
pmap_kremove(kva);
/*
* release the page and the object
*/
vm_page_unwire(m, 1);
vm_object_deallocate(object);
object = NULL;
} while (error == 0 && uio->uio_resid > 0);
if (object)
vm_object_deallocate(object);
kmem_free(kernel_map, kva, PAGE_SIZE);
vmspace_free(vm);
return (error);
}
/*
* Copy data in and out of the target process.
* We do this by mapping the process's page into
* the kernel and then doing a uiomove direct
* from the kernel address space.
*/
int
procfs_domem(curp, p, pfs, uio)
struct proc *curp;
struct proc *p;
struct pfsnode *pfs;
struct uio *uio;
{
if (uio->uio_resid == 0)
return (0);
/*
* XXX
* We need to check for KMEM_GROUP because ps is sgid kmem;
* not allowing it here causes ps to not work properly. Arguably,
* this is a bug with what ps does. We only need to do this
* for Pmem nodes, and only if it's reading. This is still not
* good, as it may still be possible to grab illicit data if
* a process somehow gets to be KMEM_GROUP. Note that this also
* means that KMEM_GROUP can't change without editing procfs.h!
* All in all, quite yucky.
*/
if (p_trespass(curp, p) &&
!(uio->uio_rw == UIO_READ &&
procfs_kmemaccess(curp)))
return EPERM;
return (procfs_rwmem(curp, p, uio));
}
/*
* Given process (p), find the vnode from which
* its text segment is being executed.
*
* It would be nice to grab this information from
* the VM system, however, there is no sure-fire
* way of doing that. Instead, fork(), exec() and
* wait() all maintain the p_textvp field in the
* process proc structure which contains a held
* reference to the exec'ed vnode.
*
* XXX - Currently, this is not not used, as the
* /proc/pid/file object exposes an information leak
* that shouldn't happen. Using a mount option would
* make it configurable on a per-system (or, at least,
* per-mount) basis; however, that's not really best.
* The best way to do it, I think, would be as an
* ioctl; this would restrict it to the uid running
* program, or root, which seems a reasonable compromise.
* However, the number of applications for this is
* minimal, if it can't be seen in the filesytem space,
* and doint it as an ioctl makes it somewhat less
* useful due to the, well, inelegance.
*
*/
struct vnode *
procfs_findtextvp(p)
struct proc *p;
{
return (p->p_textvp);
}
int procfs_kmemaccess(curp)
struct proc *curp;
{
int i;
struct ucred *cred;
cred = curp->p_ucred;
if (suser(curp))
return 1;
/* XXX: Why isn't this done with file-perms ??? */
for (i = 0; i < cred->cr_ngroups; i++)
if (cred->cr_groups[i] == KMEM_GROUP)
return 1;
return 0;
}