procfs_mem.c revision 54424
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: head/sys/fs/procfs/procfs_mem.c 54424 1999-12-11 10:21:34Z peter $ 41 */ 42 43/* 44 * This is a lightly hacked and merged version 45 * of sef's pread/pwrite functions 46 */ 47 48#include <sys/param.h> 49#include <sys/systm.h> 50#include <sys/proc.h> 51#include <sys/vnode.h> 52#include <miscfs/procfs/procfs.h> 53#include <vm/vm.h> 54#include <vm/vm_param.h> 55#include <sys/lock.h> 56#include <vm/pmap.h> 57#include <vm/vm_map.h> 58#include <vm/vm_kern.h> 59#include <vm/vm_object.h> 60#include <vm/vm_page.h> 61#include <sys/user.h> 62#include <sys/ptrace.h> 63 64static int procfs_rwmem __P((struct proc *curp, 65 struct proc *p, struct uio *uio)); 66 67static int 68procfs_rwmem(curp, p, uio) 69 struct proc *curp; 70 struct proc *p; 71 struct uio *uio; 72{ 73 int error; 74 int writing; 75 struct vmspace *vm; 76 vm_map_t map; 77 vm_object_t object = NULL; 78 vm_offset_t pageno = 0; /* page number */ 79 vm_prot_t reqprot; 80 vm_offset_t kva; 81 82 /* 83 * if the vmspace is in the midst of being deallocated or the 84 * process is exiting, don't try to grab anything. The page table 85 * usage in that process can be messed up. 86 */ 87 vm = p->p_vmspace; 88 if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1)) 89 return EFAULT; 90 ++vm->vm_refcnt; 91 /* 92 * The map we want... 93 */ 94 map = &vm->vm_map; 95 96 writing = uio->uio_rw == UIO_WRITE; 97 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ; 98 99 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 100 101 /* 102 * Only map in one page at a time. We don't have to, but it 103 * makes things easier. This way is trivial - right? 104 */ 105 do { 106 vm_map_t tmap; 107 vm_offset_t uva; 108 int page_offset; /* offset into page */ 109 vm_map_entry_t out_entry; 110 vm_prot_t out_prot; 111 boolean_t wired; 112 vm_pindex_t pindex; 113 u_int len; 114 vm_page_t m; 115 116 object = NULL; 117 118 uva = (vm_offset_t) uio->uio_offset; 119 120 /* 121 * Get the page number of this segment. 122 */ 123 pageno = trunc_page(uva); 124 page_offset = uva - pageno; 125 126 /* 127 * How many bytes to copy 128 */ 129 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 130 131 /* 132 * Fault the page on behalf of the process 133 */ 134 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL); 135 if (error) { 136 error = EFAULT; 137 break; 138 } 139 140 /* 141 * Now we need to get the page. out_entry, out_prot, wired, 142 * and single_use aren't used. One would think the vm code 143 * would be a *bit* nicer... We use tmap because 144 * vm_map_lookup() can change the map argument. 145 */ 146 tmap = map; 147 error = vm_map_lookup(&tmap, pageno, reqprot, 148 &out_entry, &object, &pindex, &out_prot, 149 &wired); 150 151 if (error) { 152 error = EFAULT; 153 154 /* 155 * Make sure that there is no residue in 'object' from 156 * an error return on vm_map_lookup. 157 */ 158 object = NULL; 159 160 break; 161 } 162 163 m = vm_page_lookup(object, pindex); 164 165 /* Allow fallback to backing objects if we are reading */ 166 167 while (m == NULL && !writing && object->backing_object) { 168 169 pindex += OFF_TO_IDX(object->backing_object_offset); 170 object = object->backing_object; 171 172 m = vm_page_lookup(object, pindex); 173 } 174 175 if (m == NULL) { 176 error = EFAULT; 177 178 /* 179 * Make sure that there is no residue in 'object' from 180 * an error return on vm_map_lookup. 181 */ 182 object = NULL; 183 184 vm_map_lookup_done(tmap, out_entry); 185 186 break; 187 } 188 189 /* 190 * Wire the page into memory 191 */ 192 vm_page_wire(m); 193 194 /* 195 * We're done with tmap now. 196 * But reference the object first, so that we won't loose 197 * it. 198 */ 199 vm_object_reference(object); 200 vm_map_lookup_done(tmap, out_entry); 201 202 pmap_kenter(kva, VM_PAGE_TO_PHYS(m)); 203 204 /* 205 * Now do the i/o move. 206 */ 207 error = uiomove((caddr_t)(kva + page_offset), len, uio); 208 209 pmap_kremove(kva); 210 211 /* 212 * release the page and the object 213 */ 214 vm_page_unwire(m, 1); 215 vm_object_deallocate(object); 216 217 object = NULL; 218 219 } while (error == 0 && uio->uio_resid > 0); 220 221 if (object) 222 vm_object_deallocate(object); 223 224 kmem_free(kernel_map, kva, PAGE_SIZE); 225 vmspace_free(vm); 226 return (error); 227} 228 229/* 230 * Copy data in and out of the target process. 231 * We do this by mapping the process's page into 232 * the kernel and then doing a uiomove direct 233 * from the kernel address space. 234 */ 235int 236procfs_domem(curp, p, pfs, uio) 237 struct proc *curp; 238 struct proc *p; 239 struct pfsnode *pfs; 240 struct uio *uio; 241{ 242 243 if (uio->uio_resid == 0) 244 return (0); 245 246 /* 247 * XXX 248 * We need to check for KMEM_GROUP because ps is sgid kmem; 249 * not allowing it here causes ps to not work properly. Arguably, 250 * this is a bug with what ps does. We only need to do this 251 * for Pmem nodes, and only if it's reading. This is still not 252 * good, as it may still be possible to grab illicit data if 253 * a process somehow gets to be KMEM_GROUP. Note that this also 254 * means that KMEM_GROUP can't change without editing procfs.h! 255 * All in all, quite yucky. 256 */ 257 258 if (p_trespass(curp, p) && 259 !(uio->uio_rw == UIO_READ && 260 procfs_kmemaccess(curp))) 261 return EPERM; 262 263 return (procfs_rwmem(curp, p, uio)); 264} 265 266/* 267 * Given process (p), find the vnode from which 268 * its text segment is being executed. 269 * 270 * It would be nice to grab this information from 271 * the VM system, however, there is no sure-fire 272 * way of doing that. Instead, fork(), exec() and 273 * wait() all maintain the p_textvp field in the 274 * process proc structure which contains a held 275 * reference to the exec'ed vnode. 276 * 277 * XXX - Currently, this is not not used, as the 278 * /proc/pid/file object exposes an information leak 279 * that shouldn't happen. Using a mount option would 280 * make it configurable on a per-system (or, at least, 281 * per-mount) basis; however, that's not really best. 282 * The best way to do it, I think, would be as an 283 * ioctl; this would restrict it to the uid running 284 * program, or root, which seems a reasonable compromise. 285 * However, the number of applications for this is 286 * minimal, if it can't be seen in the filesytem space, 287 * and doint it as an ioctl makes it somewhat less 288 * useful due to the, well, inelegance. 289 * 290 */ 291struct vnode * 292procfs_findtextvp(p) 293 struct proc *p; 294{ 295 296 return (p->p_textvp); 297} 298 299int procfs_kmemaccess(curp) 300 struct proc *curp; 301{ 302 int i; 303 struct ucred *cred; 304 305 cred = curp->p_ucred; 306 if (suser(curp)) 307 return 1; 308 309 /* XXX: Why isn't this done with file-perms ??? */ 310 for (i = 0; i < cred->cr_ngroups; i++) 311 if (cred->cr_groups[i] == KMEM_GROUP) 312 return 1; 313 314 return 0; 315} 316