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 1.9 2004/05/13 17:40:19 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 u_int len; 113 vm_page_t m; 114 int s; 115 116 uva = (vm_offset_t) uio->uio_offset; 117 118 /* 119 * Get the page number of this segment. 120 */ 121 pageno = trunc_page(uva); 122 page_offset = uva - pageno; 123 124 /* 125 * How many bytes to copy 126 */ 127 len = min(PAGE_SIZE - page_offset, uio->uio_resid); 128 129 /* 130 * Fault the page on behalf of the process 131 */ 132 error = vm_fault(map, pageno, reqprot, VM_FAULT_NORMAL); 133 if (error) { 134 error = EFAULT; 135 break; 136 } 137 138 /* 139 * Now we need to get the page. out_entry, out_prot, wired, 140 * and single_use aren't used. One would think the vm code 141 * would be a *bit* nicer... We use tmap because 142 * vm_map_lookup() can change the map argument. 143 */ 144 tmap = map; 145 error = vm_map_lookup(&tmap, pageno, reqprot, 146 &out_entry, &object, &pindex, &out_prot, 147 &wired); 148 149 if (error) { 150 error = EFAULT; 151 break; 152 } 153 154 /* 155 * spl protection is required to avoid interrupt freeing 156 * races, reference the object to avoid it being ripped 157 * out from under us if we block. 158 */ 159 s = splvm(); 160 vm_object_reference(object); 161 again: 162 m = vm_page_lookup(object, pindex); 163 164 /* 165 * Allow fallback to backing objects if we are reading 166 */ 167 while (m == NULL && !writing && object->backing_object) { 168 pindex += OFF_TO_IDX(object->backing_object_offset); 169 object = object->backing_object; 170 m = vm_page_lookup(object, pindex); 171 } 172 173 /* 174 * Wait for any I/O's to complete, then hold the page 175 * so we can release the spl. 176 */ 177 if (m) { 178 if (vm_page_sleep_busy(m, FALSE, "rwmem")) 179 goto again; 180 vm_page_hold(m); 181 } 182 splx(s); 183 184 /* 185 * We no longer need the object. If we do not have a page 186 * then cleanup. 187 */ 188 vm_object_deallocate(object); 189 if (m == NULL) { 190 vm_map_lookup_done(tmap, out_entry, 0); 191 error = EFAULT; 192 break; 193 } 194 195 /* 196 * Cleanup tmap then create a temporary KVA mapping and 197 * do the I/O. 198 */ 199 vm_map_lookup_done(tmap, out_entry, 0); 200 pmap_kenter(kva, VM_PAGE_TO_PHYS(m)); 201 error = uiomove((caddr_t)(kva + page_offset), len, uio); 202 pmap_kremove(kva); 203 204 /* 205 * release the page and we are done 206 */ 207 s = splbio(); 208 vm_page_unhold(m); 209 splx(s); 210 } while (error == 0 && uio->uio_resid > 0); 211 212 kmem_free(kernel_map, kva, PAGE_SIZE); 213 vmspace_free(vm); 214 return (error); 215 } 216 217 /* 218 * Copy data in and out of the target process. 219 * We do this by mapping the process's page into 220 * the kernel and then doing a uiomove direct 221 * from the kernel address space. 222 */ 223 int 224 procfs_domem(struct proc *curp, struct proc *p, struct pfsnode *pfs, 225 struct uio *uio) 226 { 227 if (uio->uio_resid == 0) 228 return (0); 229 230 /* Can't trace a process that's currently exec'ing. */ 231 if ((p->p_flag & P_INEXEC) != 0) 232 return EAGAIN; 233 if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred)) 234 return EPERM; 235 236 return (procfs_rwmem(curp, p, uio)); 237 } 238 239 /* 240 * Given process (p), find the vnode from which 241 * its text segment is being executed. 242 * 243 * It would be nice to grab this information from 244 * the VM system, however, there is no sure-fire 245 * way of doing that. Instead, fork(), exec() and 246 * wait() all maintain the p_textvp field in the 247 * process proc structure which contains a held 248 * reference to the exec'ed vnode. 249 * 250 * XXX - Currently, this is not not used, as the 251 * /proc/pid/file object exposes an information leak 252 * that shouldn't happen. Using a mount option would 253 * make it configurable on a per-system (or, at least, 254 * per-mount) basis; however, that's not really best. 255 * The best way to do it, I think, would be as an 256 * ioctl; this would restrict it to the uid running 257 * program, or root, which seems a reasonable compromise. 258 * However, the number of applications for this is 259 * minimal, if it can't be seen in the filesytem space, 260 * and doint it as an ioctl makes it somewhat less 261 * useful due to the, well, inelegance. 262 * 263 */ 264 struct vnode * 265 procfs_findtextvp(struct proc *p) 266 { 267 return (p->p_textvp); 268 } 269