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: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $ 41 * $DragonFly: src/sys/vfs/procfs/procfs_mem.c,v 1.10 2004/06/07 16:26:51 dillon Exp $ 42 */ 43 44 /* 45 * This is a lightly hacked and merged version 46 * of sef's pread/pwrite functions 47 */ 48 49 #include <sys/param.h> 50 #include <sys/systm.h> 51 #include <sys/proc.h> 52 #include <sys/vnode.h> 53 #include <vfs/procfs/procfs.h> 54 #include <vm/vm.h> 55 #include <vm/vm_param.h> 56 #include <sys/lock.h> 57 #include <vm/pmap.h> 58 #include <vm/vm_extern.h> 59 #include <vm/vm_map.h> 60 #include <vm/vm_kern.h> 61 #include <vm/vm_object.h> 62 #include <vm/vm_page.h> 63 #include <sys/user.h> 64 #include <sys/ptrace.h> 65 66 static int procfs_rwmem (struct proc *curp, 67 struct proc *p, struct uio *uio); 68 69 static int 70 procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio) 71 { 72 int error; 73 int writing; 74 struct vmspace *vm; 75 vm_map_t map; 76 vm_offset_t pageno = 0; /* page number */ 77 vm_prot_t reqprot; 78 vm_offset_t kva; 79 80 /* 81 * if the vmspace is in the midst of being deallocated or the 82 * process is exiting, don't try to grab anything. The page table 83 * usage in that process can be messed up. 84 */ 85 vm = p->p_vmspace; 86 if ((p->p_flag & P_WEXIT) || (vm->vm_refcnt < 1)) 87 return EFAULT; 88 ++vm->vm_refcnt; 89 /* 90 * The map we want... 91 */ 92 map = &vm->vm_map; 93 94 writing = uio->uio_rw == UIO_WRITE; 95 reqprot = writing ? (VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE) : VM_PROT_READ; 96 97 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE); 98 99 /* 100 * Only map in one page at a time. We don't have to, but it 101 * makes things easier. This way is trivial - right? 102 */ 103 do { 104 vm_map_t tmap; 105 vm_offset_t uva; 106 int page_offset; /* offset into page */ 107 vm_map_entry_t out_entry; 108 vm_prot_t out_prot; 109 boolean_t wired; 110 vm_pindex_t pindex; 111 vm_object_t object; 112 vm_object_t nobject; 113 u_int len; 114 vm_page_t m; 115 int s; 116 117 uva = (vm_offset_t) uio->uio_offset; 118 119 /* 120 * Get the page number of this segment. 121 */ 122 pageno = trunc_page(uva); 123 page_offset = uva - pageno; 124 125 /* 126 * How many bytes to copy 127 */ 128 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 129 130 /* 131 * Fault the page on behalf of the process 132 */ 133 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL); 134 if (error) { 135 error = EFAULT; 136 break; 137 } 138 139 /* 140 * Now we need to get the page. out_entry, out_prot, wired, 141 * and single_use aren't used. One would think the vm code 142 * would be a *bit* nicer... We use tmap because 143 * vm_map_lookup() can change the map argument. 144 */ 145 tmap = map; 146 error = vm_map_lookup(&tmap, pageno, reqprot, 147 &out_entry, &object, &pindex, &out_prot, 148 &wired); 149 150 if (error) { 151 error = EFAULT; 152 break; 153 } 154 155 /* 156 * spl protection is required to avoid interrupt freeing 157 * races, reference the object to avoid it being ripped 158 * out from under us if we block. 159 */ 160 s = splvm(); 161 vm_object_reference(object); 162 again: 163 m = vm_page_lookup(object, pindex); 164 165 /* 166 * Allow fallback to backing objects if we are reading 167 */ 168 while (m == NULL && !writing && object->backing_object) { 169 pindex += OFF_TO_IDX(object->backing_object_offset); 170 nobject = object->backing_object; 171 vm_object_reference(nobject); 172 vm_object_deallocate(object); 173 object = nobject; 174 m = vm_page_lookup(object, pindex); 175 } 176 177 /* 178 * Wait for any I/O's to complete, then hold the page 179 * so we can release the spl. 180 */ 181 if (m) { 182 if (vm_page_sleep_busy(m, FALSE, "rwmem")) 183 goto again; 184 vm_page_hold(m); 185 } 186 splx(s); 187 188 /* 189 * We no longer need the object. If we do not have a page 190 * then cleanup. 191 */ 192 vm_object_deallocate(object); 193 if (m == NULL) { 194 vm_map_lookup_done(tmap, out_entry, 0); 195 error = EFAULT; 196 break; 197 } 198 199 /* 200 * Cleanup tmap then create a temporary KVA mapping and 201 * do the I/O. 202 */ 203 vm_map_lookup_done(tmap, out_entry, 0); 204 pmap_kenter(kva, VM_PAGE_TO_PHYS(m)); 205 error = uiomove((caddr_t)(kva + page_offset), len, uio); 206 pmap_kremove(kva); 207 208 /* 209 * release the page and we are done 210 */ 211 s = splbio(); 212 vm_page_unhold(m); 213 splx(s); 214 } while (error == 0 && uio->uio_resid > 0); 215 216 kmem_free(kernel_map, kva, PAGE_SIZE); 217 vmspace_free(vm); 218 return (error); 219 } 220 221 /* 222 * Copy data in and out of the target process. 223 * We do this by mapping the process's page into 224 * the kernel and then doing a uiomove direct 225 * from the kernel address space. 226 */ 227 int 228 procfs_domem(struct proc *curp, struct proc *p, struct pfsnode *pfs, 229 struct uio *uio) 230 { 231 if (uio->uio_resid == 0) 232 return (0); 233 234 /* Can't trace a process that's currently exec'ing. */ 235 if ((p->p_flag & P_INEXEC) != 0) 236 return EAGAIN; 237 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred)) 238 return EPERM; 239 240 return (procfs_rwmem(curp, p, uio)); 241 } 242 243 /* 244 * Given process (p), find the vnode from which 245 * its text segment is being executed. 246 * 247 * It would be nice to grab this information from 248 * the VM system, however, there is no sure-fire 249 * way of doing that. Instead, fork(), exec() and 250 * wait() all maintain the p_textvp field in the 251 * process proc structure which contains a held 252 * reference to the exec'ed vnode. 253 * 254 * XXX - Currently, this is not not used, as the 255 * /proc/pid/file object exposes an information leak 256 * that shouldn't happen. Using a mount option would 257 * make it configurable on a per-system (or, at least, 258 * per-mount) basis; however, that's not really best. 259 * The best way to do it, I think, would be as an 260 * ioctl; this would restrict it to the uid running 261 * program, or root, which seems a reasonable compromise. 262 * However, the number of applications for this is 263 * minimal, if it can't be seen in the filesytem space, 264 * and doint it as an ioctl makes it somewhat less 265 * useful due to the, well, inelegance. 266 * 267 */ 268 struct vnode * 269 procfs_findtextvp(struct proc *p) 270 { 271 return (p->p_textvp); 272 } 273