1 /* $NetBSD: procfs_mem.c,v 1.17 1998/02/05 08:00:14 mrg Exp $ */ 2 3 /* 4 * Copyright (c) 1993 Jan-Simon Pendry 5 * Copyright (c) 1993 Sean Eric Fagan 6 * Copyright (c) 1993 7 * The Regents of the University of California. All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * Jan-Simon Pendry and Sean Eric Fagan. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * @(#)procfs_mem.c 8.5 (Berkeley) 6/15/94 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/time.h> 51 #include <sys/kernel.h> 52 #include <sys/proc.h> 53 #include <sys/vnode.h> 54 #include <miscfs/procfs/procfs.h> 55 #include <vm/vm.h> 56 #include <vm/vm_kern.h> 57 #include <vm/vm_page.h> 58 59 #if defined(UVM) 60 #include <uvm/uvm_extern.h> 61 #endif 62 63 #define ISSET(t, f) ((t) & (f)) 64 65 #if !defined(UVM) 66 static int procfs_rwmem __P((struct proc *, struct uio *)); 67 68 static int 69 procfs_rwmem(p, uio) 70 struct proc *p; 71 struct uio *uio; 72 { 73 int error; 74 int writing; 75 76 writing = uio->uio_rw == UIO_WRITE; 77 78 /* 79 * Only map in one page at a time. We don't have to, but it 80 * makes things easier. This way is trivial - right? 81 */ 82 do { 83 vm_map_t map, tmap; 84 vm_object_t object; 85 vm_offset_t kva; 86 vm_offset_t uva; 87 int page_offset; /* offset into page */ 88 vm_offset_t pageno; /* page number */ 89 vm_map_entry_t out_entry; 90 vm_prot_t out_prot; 91 vm_page_t m; 92 boolean_t wired, single_use; 93 vm_offset_t off; 94 u_int len; 95 int fix_prot; 96 97 uva = (vm_offset_t) uio->uio_offset; 98 if (uva > VM_MAXUSER_ADDRESS) { 99 error = 0; 100 break; 101 } 102 103 /* 104 * Get the page number of this segment. 105 */ 106 pageno = trunc_page(uva); 107 page_offset = uva - pageno; 108 109 /* 110 * How many bytes to copy 111 */ 112 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 113 114 /* 115 * The map we want... 116 */ 117 map = &p->p_vmspace->vm_map; 118 119 /* 120 * Check the permissions for the area we're interested 121 * in. 122 */ 123 fix_prot = 0; 124 if (writing) 125 fix_prot = !vm_map_check_protection(map, pageno, 126 pageno + PAGE_SIZE, VM_PROT_WRITE); 127 128 if (fix_prot) { 129 /* 130 * If the page is not writable, we make it so. 131 * XXX It is possible that a page may *not* be 132 * read/executable, if a process changes that! 133 * We will assume, for now, that a page is either 134 * VM_PROT_ALL, or VM_PROT_READ|VM_PROT_EXECUTE. 135 */ 136 error = vm_map_protect(map, pageno, 137 pageno + PAGE_SIZE, VM_PROT_ALL, 0); 138 if (error) 139 break; 140 } 141 142 /* 143 * Now we need to get the page. out_entry, out_prot, wired, 144 * and single_use aren't used. One would think the vm code 145 * would be a *bit* nicer... We use tmap because 146 * vm_map_lookup() can change the map argument. 147 */ 148 tmap = map; 149 error = vm_map_lookup(&tmap, pageno, 150 writing ? VM_PROT_WRITE : VM_PROT_READ, 151 &out_entry, &object, &off, &out_prot, 152 &wired, &single_use); 153 /* 154 * We're done with tmap now. 155 */ 156 if (!error) 157 vm_map_lookup_done(tmap, out_entry); 158 159 /* 160 * Fault the page in... 161 */ 162 if (!error && writing && object->shadow) { 163 m = vm_page_lookup(object, off); 164 if (m == 0 || (m->flags & PG_COPYONWRITE)) 165 error = vm_fault(map, pageno, 166 VM_PROT_WRITE, FALSE); 167 } 168 169 /* Find space in kernel_map for the page we're interested in */ 170 if (!error) { 171 kva = VM_MIN_KERNEL_ADDRESS; 172 error = vm_map_find(kernel_map, object, off, &kva, 173 PAGE_SIZE, 1); 174 } 175 176 if (!error) { 177 /* 178 * Neither vm_map_lookup() nor vm_map_find() appear 179 * to add a reference count to the object, so we do 180 * that here and now. 181 */ 182 vm_object_reference(object); 183 184 /* 185 * Mark the page we just found as pageable. 186 */ 187 error = vm_map_pageable(kernel_map, kva, 188 kva + PAGE_SIZE, 0); 189 190 /* 191 * Now do the i/o move. 192 */ 193 if (!error) 194 error = uiomove((caddr_t) (kva + page_offset), 195 len, uio); 196 197 vm_map_remove(kernel_map, kva, kva + PAGE_SIZE); 198 } 199 if (fix_prot) 200 vm_map_protect(map, pageno, pageno + PAGE_SIZE, 201 VM_PROT_READ|VM_PROT_EXECUTE, 0); 202 } while (error == 0 && uio->uio_resid > 0); 203 204 return (error); 205 } 206 #endif 207 208 /* 209 * Copy data in and out of the target process. 210 * We do this by mapping the process's page into 211 * the kernel and then doing a uiomove direct 212 * from the kernel address space. 213 */ 214 int 215 procfs_domem(curp, p, pfs, uio) 216 struct proc *curp; /* tracer */ 217 struct proc *p; /* traced */ 218 struct pfsnode *pfs; 219 struct uio *uio; 220 { 221 int error; 222 223 if (uio->uio_resid == 0) 224 return (0); 225 226 if ((error = procfs_checkioperm(curp, p)) != 0) 227 return (error); 228 229 #if defined(UVM) 230 /* XXXCDC: how should locking work here? */ 231 if ((p->p_flag & P_WEXIT) || (p->p_vmspace->vm_refcnt < 1)) 232 return(EFAULT); 233 PHOLD(p); 234 p->p_vmspace->vm_refcnt++; /* XXX */ 235 error = uvm_io(&p->p_vmspace->vm_map, uio); 236 PRELE(p); 237 uvmspace_free(p->p_vmspace); 238 #else 239 PHOLD(p); 240 error = procfs_rwmem(p, uio); 241 PRELE(p); 242 #endif 243 return (error); 244 } 245 246 /* 247 * Given process (p), find the vnode from which 248 * it's text segment is being executed. 249 * 250 * It would be nice to grab this information from 251 * the VM system, however, there is no sure-fire 252 * way of doing that. Instead, fork(), exec() and 253 * wait() all maintain the p_textvp field in the 254 * process proc structure which contains a held 255 * reference to the exec'ed vnode. 256 */ 257 struct vnode * 258 procfs_findtextvp(p) 259 struct proc *p; 260 { 261 262 return (p->p_textvp); 263 } 264 265 /* 266 * Ensure that a process has permission to perform I/O on another. 267 * Arguments: 268 * p The process wishing to do the I/O (the tracer). 269 * t The process who's memory/registers will be read/written. 270 */ 271 int 272 procfs_checkioperm(p, t) 273 struct proc *p, *t; 274 { 275 int error; 276 277 /* 278 * You cannot attach to a processes mem/regs if: 279 * 280 * (1) it's not owned by you, or is set-id on exec 281 * (unless you're root), or... 282 */ 283 if ((t->p_cred->p_ruid != p->p_cred->p_ruid || 284 ISSET(t->p_flag, P_SUGID)) && 285 (error = suser(p->p_ucred, &p->p_acflag)) != 0) 286 return (error); 287 288 /* 289 * (2) ...it's init, which controls the security level 290 * of the entire system, and the system was not 291 * compiled with permanetly insecure mode turned on. 292 */ 293 if (t == initproc && securelevel > -1) 294 return (EPERM); 295 296 return (0); 297 } 298 299 #ifdef probably_never 300 /* 301 * Given process (p), find the vnode from which 302 * it's text segment is being mapped. 303 * 304 * (This is here, rather than in procfs_subr in order 305 * to keep all the VM related code in one place.) 306 */ 307 struct vnode * 308 procfs_findtextvp(p) 309 struct proc *p; 310 { 311 int error; 312 vm_object_t object; 313 vm_offset_t pageno; /* page number */ 314 315 /* find a vnode pager for the user address space */ 316 317 for (pageno = VM_MIN_ADDRESS; 318 pageno < VM_MAXUSER_ADDRESS; 319 pageno += PAGE_SIZE) { 320 vm_map_t map; 321 vm_map_entry_t out_entry; 322 vm_prot_t out_prot; 323 boolean_t wired, single_use; 324 vm_offset_t off; 325 326 map = &p->p_vmspace->vm_map; 327 error = vm_map_lookup(&map, pageno, 328 VM_PROT_READ, 329 &out_entry, &object, &off, &out_prot, 330 &wired, &single_use); 331 332 if (!error) { 333 vm_pager_t pager; 334 335 printf("procfs: found vm object\n"); 336 vm_map_lookup_done(map, out_entry); 337 printf("procfs: vm object = %p\n", object); 338 339 /* 340 * At this point, assuming no errors, object 341 * is the VM object mapping UVA (pageno). 342 * Ensure it has a vnode pager, then grab 343 * the vnode from that pager's handle. 344 */ 345 346 pager = object->pager; 347 printf("procfs: pager = %p\n", pager); 348 if (pager) 349 printf("procfs: found pager, type = %d\n", 350 pager->pg_type); 351 if (pager && pager->pg_type == PG_VNODE) { 352 struct vnode *vp; 353 354 vp = (struct vnode *) pager->pg_handle; 355 printf("procfs: vp = %p\n", vp); 356 return (vp); 357 } 358 } 359 } 360 361 printf("procfs: text object not found\n"); 362 return (0); 363 } 364 #endif /* probably_never */ 365