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 * $FreeBSD$ 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/lock.h> 51 #include <sys/mutex.h> 52 #include <sys/proc.h> 53 #include <sys/ptrace.h> 54 #include <sys/user.h> 55 #include <sys/vnode.h> 56 57 #include <fs/procfs/procfs.h> 58 59 #include <vm/vm.h> 60 #include <vm/vm_param.h> 61 #include <vm/pmap.h> 62 #include <vm/vm_extern.h> 63 #include <vm/vm_map.h> 64 #include <vm/vm_kern.h> 65 #include <vm/vm_object.h> 66 #include <vm/vm_page.h> 67 68 static int procfs_rwmem __P((struct proc *curp, 69 struct proc *p, struct uio *uio)); 70 71 static int 72 procfs_rwmem(curp, p, uio) 73 struct proc *curp; 74 struct proc *p; 75 struct uio *uio; 76 { 77 int error; 78 int writing; 79 struct vmspace *vm; 80 vm_map_t map; 81 vm_object_t object = NULL; 82 vm_offset_t pageno = 0; /* page number */ 83 vm_prot_t reqprot; 84 vm_offset_t kva; 85 86 /* 87 * if the vmspace is in the midst of being deallocated or the 88 * process is exiting, don't try to grab anything. The page table 89 * usage in that process can be messed up. 90 */ 91 vm = p->p_vmspace; 92 if ((p->p_flag & P_WEXIT)) 93 return EFAULT; 94 95 mtx_lock(&vm_mtx); 96 if (vm->vm_refcnt < 1) { 97 mtx_unlock(&vm_mtx); 98 return EFAULT; 99 } 100 ++vm->vm_refcnt; 101 /* 102 * The map we want... 103 */ 104 map = &vm->vm_map; 105 106 writing = uio->uio_rw == UIO_WRITE; 107 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ; 108 109 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 110 111 /* 112 * Only map in one page at a time. We don't have to, but it 113 * makes things easier. This way is trivial - right? 114 */ 115 do { 116 vm_map_t tmap; 117 vm_offset_t uva; 118 int page_offset; /* offset into page */ 119 vm_map_entry_t out_entry; 120 vm_prot_t out_prot; 121 boolean_t wired; 122 vm_pindex_t pindex; 123 u_int len; 124 vm_page_t m; 125 126 object = NULL; 127 128 uva = (vm_offset_t) uio->uio_offset; 129 130 /* 131 * Get the page number of this segment. 132 */ 133 pageno = trunc_page(uva); 134 page_offset = uva - pageno; 135 136 /* 137 * How many bytes to copy 138 */ 139 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 140 141 /* 142 * Fault the page on behalf of the process 143 */ 144 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL); 145 if (error) { 146 error = EFAULT; 147 break; 148 } 149 150 /* 151 * Now we need to get the page. out_entry, out_prot, wired, 152 * and single_use aren't used. One would think the vm code 153 * would be a *bit* nicer... We use tmap because 154 * vm_map_lookup() can change the map argument. 155 */ 156 tmap = map; 157 error = vm_map_lookup(&tmap, pageno, reqprot, 158 &out_entry, &object, &pindex, &out_prot, 159 &wired); 160 161 if (error) { 162 error = EFAULT; 163 164 /* 165 * Make sure that there is no residue in 'object' from 166 * an error return on vm_map_lookup. 167 */ 168 object = NULL; 169 170 break; 171 } 172 173 m = vm_page_lookup(object, pindex); 174 175 /* Allow fallback to backing objects if we are reading */ 176 177 while (m == NULL && !writing && object->backing_object) { 178 179 pindex += OFF_TO_IDX(object->backing_object_offset); 180 object = object->backing_object; 181 182 m = vm_page_lookup(object, pindex); 183 } 184 185 if (m == NULL) { 186 error = EFAULT; 187 188 /* 189 * Make sure that there is no residue in 'object' from 190 * an error return on vm_map_lookup. 191 */ 192 object = NULL; 193 194 vm_map_lookup_done(tmap, out_entry); 195 196 break; 197 } 198 199 /* 200 * Wire the page into memory 201 */ 202 vm_page_wire(m); 203 204 /* 205 * We're done with tmap now. 206 * But reference the object first, so that we won't loose 207 * it. 208 */ 209 vm_object_reference(object); 210 vm_map_lookup_done(tmap, out_entry); 211 212 pmap_kenter(kva, VM_PAGE_TO_PHYS(m)); 213 214 /* 215 * Now do the i/o move. 216 */ 217 mtx_unlock(&vm_mtx); 218 error = uiomove((caddr_t)(kva + page_offset), len, uio); 219 mtx_lock(&vm_mtx); 220 221 pmap_kremove(kva); 222 223 /* 224 * release the page and the object 225 */ 226 vm_page_unwire(m, 1); 227 vm_object_deallocate(object); 228 229 object = NULL; 230 231 } while (error == 0 && uio->uio_resid > 0); 232 233 if (object) 234 vm_object_deallocate(object); 235 236 kmem_free(kernel_map, kva, PAGE_SIZE); 237 vmspace_free(vm); 238 mtx_unlock(&vm_mtx); 239 return (error); 240 } 241 242 /* 243 * Copy data in and out of the target process. 244 * We do this by mapping the process's page into 245 * the kernel and then doing a uiomove direct 246 * from the kernel address space. 247 */ 248 int 249 procfs_domem(curp, p, pfs, uio) 250 struct proc *curp; 251 struct proc *p; 252 struct pfsnode *pfs; 253 struct uio *uio; 254 { 255 256 if (uio->uio_resid == 0) 257 return (0); 258 259 /* 260 * XXX 261 * We need to check for KMEM_GROUP because ps is sgid kmem; 262 * not allowing it here causes ps to not work properly. Arguably, 263 * this is a bug with what ps does. We only need to do this 264 * for Pmem nodes, and only if it's reading. This is still not 265 * good, as it may still be possible to grab illicit data if 266 * a process somehow gets to be KMEM_GROUP. Note that this also 267 * means that KMEM_GROUP can't change without editing procfs.h! 268 * All in all, quite yucky. 269 */ 270 271 if (p_can(curp, p, P_CAN_DEBUG, NULL) && 272 !(uio->uio_rw == UIO_READ && 273 procfs_kmemaccess(curp))) 274 return EPERM; 275 276 return (procfs_rwmem(curp, p, uio)); 277 } 278 279 /* 280 * Given process (p), find the vnode from which 281 * its text segment is being executed. 282 * 283 * It would be nice to grab this information from 284 * the VM system, however, there is no sure-fire 285 * way of doing that. Instead, fork(), exec() and 286 * wait() all maintain the p_textvp field in the 287 * process proc structure which contains a held 288 * reference to the exec'ed vnode. 289 * 290 * XXX - Currently, this is not not used, as the 291 * /proc/pid/file object exposes an information leak 292 * that shouldn't happen. Using a mount option would 293 * make it configurable on a per-system (or, at least, 294 * per-mount) basis; however, that's not really best. 295 * The best way to do it, I think, would be as an 296 * ioctl; this would restrict it to the uid running 297 * program, or root, which seems a reasonable compromise. 298 * However, the number of applications for this is 299 * minimal, if it can't be seen in the filesytem space, 300 * and doint it as an ioctl makes it somewhat less 301 * useful due to the, well, inelegance. 302 * 303 */ 304 struct vnode * 305 procfs_findtextvp(p) 306 struct proc *p; 307 { 308 309 return (p->p_textvp); 310 } 311 312 int procfs_kmemaccess(curp) 313 struct proc *curp; 314 { 315 int i; 316 struct ucred *cred; 317 318 cred = curp->p_ucred; 319 if (suser(curp)) 320 return 1; 321 322 /* XXX: Why isn't this done with file-perms ??? */ 323 for (i = 0; i < cred->cr_ngroups; i++) 324 if (cred->cr_groups[i] == KMEM_GROUP) 325 return 1; 326 327 return 0; 328 } 329