1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/compat.h>
3 #include <linux/errno.h>
4 #include <linux/sched.h>
5 #include <linux/sched/mm.h>
6 #include <linux/syscalls.h>
7 #include <linux/mm.h>
8 #include <linux/fs.h>
9 #include <linux/smp.h>
10 #include <linux/sem.h>
11 #include <linux/msg.h>
12 #include <linux/shm.h>
13 #include <linux/stat.h>
14 #include <linux/mman.h>
15 #include <linux/file.h>
16 #include <linux/utsname.h>
17 #include <linux/personality.h>
18 #include <linux/random.h>
19 #include <linux/uaccess.h>
20 #include <linux/elf.h>
21
22 #include <asm/elf.h>
23 #include <asm/ia32.h>
24 #include <asm/syscalls.h>
25 #include <asm/mpx.h>
26
27 /*
28 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
29 */
get_align_mask(void)30 static unsigned long get_align_mask(void)
31 {
32 /* handle 32- and 64-bit case with a single conditional */
33 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
34 return 0;
35
36 if (!(current->flags & PF_RANDOMIZE))
37 return 0;
38
39 return va_align.mask;
40 }
41
42 /*
43 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
44 * va_align.bits, [12:upper_bit), are set to a random value instead of
45 * zeroing them. This random value is computed once per boot. This form
46 * of ASLR is known as "per-boot ASLR".
47 *
48 * To achieve this, the random value is added to the info.align_offset
49 * value before calling vm_unmapped_area() or ORed directly to the
50 * address.
51 */
get_align_bits(void)52 static unsigned long get_align_bits(void)
53 {
54 return va_align.bits & get_align_mask();
55 }
56
align_vdso_addr(unsigned long addr)57 unsigned long align_vdso_addr(unsigned long addr)
58 {
59 unsigned long align_mask = get_align_mask();
60 addr = (addr + align_mask) & ~align_mask;
61 return addr | get_align_bits();
62 }
63
control_va_addr_alignment(char * str)64 static int __init control_va_addr_alignment(char *str)
65 {
66 /* guard against enabling this on other CPU families */
67 if (va_align.flags < 0)
68 return 1;
69
70 if (*str == 0)
71 return 1;
72
73 if (!strcmp(str, "32"))
74 va_align.flags = ALIGN_VA_32;
75 else if (!strcmp(str, "64"))
76 va_align.flags = ALIGN_VA_64;
77 else if (!strcmp(str, "off"))
78 va_align.flags = 0;
79 else if (!strcmp(str, "on"))
80 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
81 else
82 pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
83
84 return 1;
85 }
86 __setup("align_va_addr=", control_va_addr_alignment);
87
SYSCALL_DEFINE6(mmap,unsigned long,addr,unsigned long,len,unsigned long,prot,unsigned long,flags,unsigned long,fd,unsigned long,off)88 SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
89 unsigned long, prot, unsigned long, flags,
90 unsigned long, fd, unsigned long, off)
91 {
92 long error;
93 error = -EINVAL;
94 if (off & ~PAGE_MASK)
95 goto out;
96
97 error = ksys_mmap_pgoff(addr, len, prot, flags, fd, off >> PAGE_SHIFT);
98 out:
99 return error;
100 }
101
find_start_end(unsigned long addr,unsigned long flags,unsigned long * begin,unsigned long * end)102 static void find_start_end(unsigned long addr, unsigned long flags,
103 unsigned long *begin, unsigned long *end)
104 {
105 if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
106 /* This is usually used needed to map code in small
107 model, so it needs to be in the first 31bit. Limit
108 it to that. This means we need to move the
109 unmapped base down for this case. This can give
110 conflicts with the heap, but we assume that glibc
111 malloc knows how to fall back to mmap. Give it 1GB
112 of playground for now. -AK */
113 *begin = 0x40000000;
114 *end = 0x80000000;
115 if (current->flags & PF_RANDOMIZE) {
116 *begin = randomize_page(*begin, 0x02000000);
117 }
118 return;
119 }
120
121 *begin = get_mmap_base(1);
122 if (in_32bit_syscall())
123 *end = task_size_32bit();
124 else
125 *end = task_size_64bit(addr > DEFAULT_MAP_WINDOW);
126 }
127
128 unsigned long
arch_get_unmapped_area(struct file * filp,unsigned long addr,unsigned long len,unsigned long pgoff,unsigned long flags)129 arch_get_unmapped_area(struct file *filp, unsigned long addr,
130 unsigned long len, unsigned long pgoff, unsigned long flags)
131 {
132 struct mm_struct *mm = current->mm;
133 struct vm_area_struct *vma;
134 struct vm_unmapped_area_info info;
135 unsigned long begin, end;
136
137 addr = mpx_unmapped_area_check(addr, len, flags);
138 if (IS_ERR_VALUE(addr))
139 return addr;
140
141 if (flags & MAP_FIXED)
142 return addr;
143
144 find_start_end(addr, flags, &begin, &end);
145
146 if (len > end)
147 return -ENOMEM;
148
149 if (addr) {
150 addr = PAGE_ALIGN(addr);
151 vma = find_vma(mm, addr);
152 if (end - len >= addr &&
153 (!vma || addr + len <= vm_start_gap(vma)))
154 return addr;
155 }
156
157 info.flags = 0;
158 info.length = len;
159 info.low_limit = begin;
160 info.high_limit = end;
161 info.align_mask = 0;
162 info.align_offset = pgoff << PAGE_SHIFT;
163 if (filp) {
164 info.align_mask = get_align_mask();
165 info.align_offset += get_align_bits();
166 }
167 return vm_unmapped_area(&info);
168 }
169
170 unsigned long
arch_get_unmapped_area_topdown(struct file * filp,const unsigned long addr0,const unsigned long len,const unsigned long pgoff,const unsigned long flags)171 arch_get_unmapped_area_topdown(struct file *filp, const unsigned long addr0,
172 const unsigned long len, const unsigned long pgoff,
173 const unsigned long flags)
174 {
175 struct vm_area_struct *vma;
176 struct mm_struct *mm = current->mm;
177 unsigned long addr = addr0;
178 struct vm_unmapped_area_info info;
179
180 addr = mpx_unmapped_area_check(addr, len, flags);
181 if (IS_ERR_VALUE(addr))
182 return addr;
183
184 /* requested length too big for entire address space */
185 if (len > TASK_SIZE)
186 return -ENOMEM;
187
188 /* No address checking. See comment at mmap_address_hint_valid() */
189 if (flags & MAP_FIXED)
190 return addr;
191
192 /* for MAP_32BIT mappings we force the legacy mmap base */
193 if (!in_32bit_syscall() && (flags & MAP_32BIT))
194 goto bottomup;
195
196 /* requesting a specific address */
197 if (addr) {
198 addr &= PAGE_MASK;
199 if (!mmap_address_hint_valid(addr, len))
200 goto get_unmapped_area;
201
202 vma = find_vma(mm, addr);
203 if (!vma || addr + len <= vm_start_gap(vma))
204 return addr;
205 }
206 get_unmapped_area:
207
208 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
209 info.length = len;
210 info.low_limit = PAGE_SIZE;
211 info.high_limit = get_mmap_base(0);
212
213 /*
214 * If hint address is above DEFAULT_MAP_WINDOW, look for unmapped area
215 * in the full address space.
216 *
217 * !in_32bit_syscall() check to avoid high addresses for x32
218 * (and make it no op on native i386).
219 */
220 if (addr > DEFAULT_MAP_WINDOW && !in_32bit_syscall())
221 info.high_limit += TASK_SIZE_MAX - DEFAULT_MAP_WINDOW;
222
223 info.align_mask = 0;
224 info.align_offset = pgoff << PAGE_SHIFT;
225 if (filp) {
226 info.align_mask = get_align_mask();
227 info.align_offset += get_align_bits();
228 }
229 addr = vm_unmapped_area(&info);
230 if (!(addr & ~PAGE_MASK))
231 return addr;
232 VM_BUG_ON(addr != -ENOMEM);
233
234 bottomup:
235 /*
236 * A failed mmap() very likely causes application failure,
237 * so fall back to the bottom-up function here. This scenario
238 * can happen with large stack limits and large mmap()
239 * allocations.
240 */
241 return arch_get_unmapped_area(filp, addr0, len, pgoff, flags);
242 }
243