1 /*-
2 * Copyright (c) 2004 Tim J. Robbins
3 * Copyright (c) 2002 Doug Rabson
4 * Copyright (c) 2000 Marcel Moolenaar
5 * Copyright (c) 1994-1995 Søren Schmidt
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer
13 * in this position and unchanged.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of the author may not be used to endorse or promote products
18 * derived from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
21 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
22 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
23 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
24 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
25 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
26 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
27 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
28 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
29 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 *
31 * $FreeBSD: releng/11.1/sys/compat/linux/linux_mmap.c 315556 2017-03-19 15:32:12Z trasz $
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: releng/11.1/sys/compat/linux/linux_mmap.c 315556 2017-03-19 15:32:12Z trasz $");
36
37 #include <sys/capsicum.h>
38 #include <sys/file.h>
39 #include <sys/imgact.h>
40 #include <sys/ktr.h>
41 #include <sys/mman.h>
42 #include <sys/proc.h>
43 #include <sys/resourcevar.h>
44 #include <sys/syscallsubr.h>
45 #include <sys/sysent.h>
46 #include <sys/sysproto.h>
47
48 #include <vm/pmap.h>
49 #include <vm/vm_extern.h>
50 #include <vm/vm_map.h>
51
52 #include <compat/linux/linux_emul.h>
53 #include <compat/linux/linux_mmap.h>
54 #include <compat/linux/linux_persona.h>
55 #include <compat/linux/linux_util.h>
56
57
58 #define STACK_SIZE (2 * 1024 * 1024)
59 #define GUARD_SIZE (4 * PAGE_SIZE)
60
61 #if defined(__amd64__)
62 static void linux_fixup_prot(struct thread *td, int *prot);
63 #endif
64
65
66 int
67 linux_mmap_common(struct thread *td, uintptr_t addr, size_t len, int prot,
68 int flags, int fd, off_t pos)
69 {
70 struct proc *p = td->td_proc;
71 struct vmspace *vms = td->td_proc->p_vmspace;
72 int bsd_flags, error;
73 struct file *fp;
74
75 cap_rights_t rights;
76 LINUX_CTR6(mmap2, "0x%lx, %ld, %ld, 0x%08lx, %ld, 0x%lx",
77 addr, len, prot, flags, fd, pos);
78
79 error = 0;
80 bsd_flags = 0;
81 fp = NULL;
82
83 /*
84 * Linux mmap(2):
85 * You must specify exactly one of MAP_SHARED and MAP_PRIVATE
86 */
87 if (!((flags & LINUX_MAP_SHARED) ^ (flags & LINUX_MAP_PRIVATE)))
88 return (EINVAL);
89
90 if (flags & LINUX_MAP_SHARED)
91 bsd_flags |= MAP_SHARED;
92 if (flags & LINUX_MAP_PRIVATE)
93 bsd_flags |= MAP_PRIVATE;
94 if (flags & LINUX_MAP_FIXED)
95 bsd_flags |= MAP_FIXED;
96 if (flags & LINUX_MAP_ANON) {
97 /* Enforce pos to be on page boundary, then ignore. */
98 if ((pos & PAGE_MASK) != 0)
99 return (EINVAL);
100 pos = 0;
101 bsd_flags |= MAP_ANON;
102 } else
103 bsd_flags |= MAP_NOSYNC;
104 if (flags & LINUX_MAP_GROWSDOWN)
105 bsd_flags |= MAP_STACK;
106
107 /*
108 * PROT_READ, PROT_WRITE, or PROT_EXEC implies PROT_READ and PROT_EXEC
109 * on Linux/i386 if the binary requires executable stack.
110 * We do this only for IA32 emulation as on native i386 this is does not
111 * make sense without PAE.
112 *
113 * XXX. Linux checks that the file system is not mounted with noexec.
114 */
115 #if defined(__amd64__)
116 linux_fixup_prot(td, &prot);
117 #endif
118
119 /* Linux does not check file descriptor when MAP_ANONYMOUS is set. */
120 fd = (bsd_flags & MAP_ANON) ? -1 : fd;
121 if (fd != -1) {
122 /*
123 * Linux follows Solaris mmap(2) description:
124 * The file descriptor fildes is opened with
125 * read permission, regardless of the
126 * protection options specified.
127 */
128
129 error = fget(td, fd, cap_rights_init(&rights, CAP_MMAP), &fp);
130 if (error != 0)
131 return (error);
132 if (fp->f_type != DTYPE_VNODE) {
133 fdrop(fp, td);
134 return (EINVAL);
135 }
136
137 /* Linux mmap() just fails for O_WRONLY files */
138 if (!(fp->f_flag & FREAD)) {
139 fdrop(fp, td);
140 return (EACCES);
141 }
142
143 fdrop(fp, td);
144 }
145
146 if (flags & LINUX_MAP_GROWSDOWN) {
147 /*
148 * The Linux MAP_GROWSDOWN option does not limit auto
149 * growth of the region. Linux mmap with this option
150 * takes as addr the initial BOS, and as len, the initial
151 * region size. It can then grow down from addr without
152 * limit. However, Linux threads has an implicit internal
153 * limit to stack size of STACK_SIZE. Its just not
154 * enforced explicitly in Linux. But, here we impose
155 * a limit of (STACK_SIZE - GUARD_SIZE) on the stack
156 * region, since we can do this with our mmap.
157 *
158 * Our mmap with MAP_STACK takes addr as the maximum
159 * downsize limit on BOS, and as len the max size of
160 * the region. It then maps the top SGROWSIZ bytes,
161 * and auto grows the region down, up to the limit
162 * in addr.
163 *
164 * If we don't use the MAP_STACK option, the effect
165 * of this code is to allocate a stack region of a
166 * fixed size of (STACK_SIZE - GUARD_SIZE).
167 */
168
169 if ((caddr_t)addr + len > vms->vm_maxsaddr) {
170 /*
171 * Some Linux apps will attempt to mmap
172 * thread stacks near the top of their
173 * address space. If their TOS is greater
174 * than vm_maxsaddr, vm_map_growstack()
175 * will confuse the thread stack with the
176 * process stack and deliver a SEGV if they
177 * attempt to grow the thread stack past their
178 * current stacksize rlimit. To avoid this,
179 * adjust vm_maxsaddr upwards to reflect
180 * the current stacksize rlimit rather
181 * than the maximum possible stacksize.
182 * It would be better to adjust the
183 * mmap'ed region, but some apps do not check
184 * mmap's return value.
185 */
186 PROC_LOCK(p);
187 vms->vm_maxsaddr = (char *)p->p_sysent->sv_usrstack -
188 lim_cur_proc(p, RLIMIT_STACK);
189 PROC_UNLOCK(p);
190 }
191
192 /*
193 * This gives us our maximum stack size and a new BOS.
194 * If we're using VM_STACK, then mmap will just map
195 * the top SGROWSIZ bytes, and let the stack grow down
196 * to the limit at BOS. If we're not using VM_STACK
197 * we map the full stack, since we don't have a way
198 * to autogrow it.
199 */
200 if (len <= STACK_SIZE - GUARD_SIZE) {
201 addr = addr - (STACK_SIZE - GUARD_SIZE - len);
202 len = STACK_SIZE - GUARD_SIZE;
203 }
204 }
205
206 /*
207 * FreeBSD is free to ignore the address hint if MAP_FIXED wasn't
208 * passed. However, some Linux applications, like the ART runtime,
209 * depend on the hint. If the MAP_FIXED wasn't passed, but the
210 * address is not zero, try with MAP_FIXED and MAP_EXCL first,
211 * and fall back to the normal behaviour if that fails.
212 */
213 if (addr != 0 && (bsd_flags & MAP_FIXED) == 0 &&
214 (bsd_flags & MAP_EXCL) == 0) {
215 error = kern_mmap(td, addr, len, prot,
216 bsd_flags | MAP_FIXED | MAP_EXCL, fd, pos);
217 if (error == 0)
218 goto out;
219 }
220
221 error = kern_mmap(td, addr, len, prot, bsd_flags, fd, pos);
222 out:
223 LINUX_CTR2(mmap2, "return: %d (%p)", error, td->td_retval[0]);
224
225 return (error);
226 }
227
228 int
229 linux_mprotect_common(struct thread *td, uintptr_t addr, size_t len, int prot)
230 {
231
232 #if defined(__amd64__)
233 linux_fixup_prot(td, &prot);
234 #endif
235 return (kern_mprotect(td, addr, len, prot));
236 }
237
238 #if defined(__amd64__)
239 static void
240 linux_fixup_prot(struct thread *td, int *prot)
241 {
242 struct linux_pemuldata *pem;
243
244 if (SV_PROC_FLAG(td->td_proc, SV_ILP32) && *prot & PROT_READ) {
245 pem = pem_find(td->td_proc);
246 if (pem->persona & LINUX_READ_IMPLIES_EXEC)
247 *prot |= PROT_EXEC;
248 }
249
250 }
251 #endif
Cache object: cf420e1d2f76d0e82b4efe06e7465fd8
|