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