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. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)procfs_mem.c 8.5 (Berkeley) 6/15/94
35 *
36 * $FreeBSD: src/sys/miscfs/procfs/procfs_mem.c,v 1.46.2.3 2002/01/22 17:22:59 nectar Exp $
37 */
38
39 /*
40 * This is a lightly hacked and merged version
41 * of sef's pread/pwrite functions
42 */
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/uio.h>
47 #include <sys/proc.h>
48 #include <sys/caps.h>
49 #include <sys/vnode.h>
50 #include <vfs/procfs/procfs.h>
51 #include <vm/vm.h>
52 #include <vm/vm_param.h>
53 #include <sys/lock.h>
54 #include <vm/pmap.h>
55 #include <vm/vm_extern.h>
56 #include <vm/vm_map.h>
57 #include <vm/vm_kern.h>
58 #include <vm/vm_object.h>
59 #include <vm/vm_page.h>
60 #include <sys/ptrace.h>
61
62 static int procfs_rwmem (struct proc *curp,
63 struct proc *p, struct uio *uio);
64
65 /*
66 * p->p_token is held on entry.
67 */
68 static int
procfs_rwmem(struct proc * curp,struct proc * p,struct uio * uio)69 procfs_rwmem(struct proc *curp, struct proc *p, struct uio *uio)
70 {
71 int error;
72 int writing;
73 struct vmspace *vm;
74 vm_map_t map;
75 vm_offset_t pageno = 0; /* page number */
76 vm_prot_t reqprot;
77 vm_offset_t kva;
78
79 /*
80 * if the vmspace is in the midst of being allocated or deallocated,
81 * or the process is exiting, don't try to grab anything. The
82 * page table usage in that process may be messed up.
83 */
84 vm = p->p_vmspace;
85 if (p->p_stat == SIDL || p->p_stat == SZOMB)
86 return EFAULT;
87 if ((p->p_flags & (P_WEXIT | P_INEXEC)) || vmspace_getrefs(vm) < 0)
88 return EFAULT;
89
90 /*
91 * The map we want...
92 */
93 vmspace_hold(vm);
94 map = &vm->vm_map;
95
96 writing = (uio->uio_rw == UIO_WRITE);
97 reqprot = VM_PROT_READ;
98 if (writing)
99 reqprot |= VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE;
100
101 kva = kmem_alloc_pageable(kernel_map, PAGE_SIZE, VM_SUBSYS_PROC);
102
103 /*
104 * Only map in one page at a time. We don't have to, but it
105 * makes things easier. This way is trivial - right?
106 */
107 do {
108 vm_offset_t uva;
109 vm_offset_t page_offset; /* offset into page */
110 size_t len;
111 vm_page_t m;
112 int busy;
113
114 uva = (vm_offset_t) uio->uio_offset;
115
116 /*
117 * Get the page number of this segment.
118 */
119 pageno = trunc_page(uva);
120 page_offset = uva - pageno;
121
122 /*
123 * How many bytes to copy
124 */
125 len = szmin(PAGE_SIZE - page_offset, uio->uio_resid);
126
127 /*
128 * Fault the page on behalf of the process
129 *
130 * XXX busied page on write fault can deadlock against our
131 * uiomove.
132 */
133 m = vm_fault_page(map, pageno, reqprot,
134 VM_FAULT_NORMAL,
135 &error, &busy);
136 if (error) {
137 KKASSERT(m == NULL);
138 error = EFAULT;
139 break;
140 }
141
142 /*
143 * Cleanup pmap then create a temporary KVA mapping and
144 * do the I/O. We can switch between cpus so don't bother
145 * synchronizing across all cores.
146 */
147 pmap_kenter_quick(kva, VM_PAGE_TO_PHYS(m));
148 error = uiomove((caddr_t)(kva + page_offset), len, uio);
149 pmap_kremove_quick(kva);
150
151 /*
152 * Release the page and we are done
153 */
154 if (busy)
155 vm_page_wakeup(m);
156 else
157 vm_page_unhold(m);
158 } while (error == 0 && uio->uio_resid > 0);
159
160 vmspace_drop(vm);
161 kmem_free(kernel_map, kva, PAGE_SIZE);
162
163 return (error);
164 }
165
166 /*
167 * Copy data in and out of the target process.
168 * We do this by mapping the process's page into
169 * the kernel and then doing a uiomove direct
170 * from the kernel address space.
171 *
172 * lp->lwp_proc->p_token is held on entry.
173 */
174 int
procfs_domem(struct proc * curp,struct lwp * lp,struct pfsnode * pfs,struct uio * uio)175 procfs_domem(struct proc *curp, struct lwp *lp, struct pfsnode *pfs,
176 struct uio *uio)
177 {
178 struct proc *p = lp->lwp_proc;
179 int error;
180
181 if (uio->uio_resid == 0)
182 return (0);
183
184 if ((p->p_flags & P_INEXEC) != 0) {
185 /*
186 * Can't trace a process that's currently exec'ing.
187 */
188 error = EAGAIN;
189 } else if (!CHECKIO(curp, p) || p_trespass(curp->p_ucred, p->p_ucred)) {
190 /*
191 * Can't trace processes outside our jail
192 */
193 error = EPERM;
194 } else {
195 error = procfs_rwmem(curp, p, uio);
196 }
197 return(error);
198 }
199
200 /*
201 * Given process (p), find the vnode from which
202 * its text segment is being executed.
203 *
204 * It would be nice to grab this information from
205 * the VM system, however, there is no sure-fire
206 * way of doing that. Instead, fork(), exec() and
207 * wait() all maintain the p_textvp field in the
208 * process proc structure which contains a held
209 * reference to the exec'ed vnode.
210 *
211 * XXX - Currently, this is not not used, as the
212 * /proc/pid/file object exposes an information leak
213 * that shouldn't happen. Using a mount option would
214 * make it configurable on a per-system (or, at least,
215 * per-mount) basis; however, that's not really best.
216 * The best way to do it, I think, would be as an
217 * ioctl; this would restrict it to the uid running
218 * program, or root, which seems a reasonable compromise.
219 * However, the number of applications for this is
220 * minimal, if it can't be seen in the filesytem space,
221 * and doint it as an ioctl makes it somewhat less
222 * useful due to the, well, inelegance.
223 *
224 */
225 struct vnode *
procfs_findtextvp(struct proc * p)226 procfs_findtextvp(struct proc *p)
227 {
228 return (p->p_textvp);
229 }
230