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#include <linux/hugetlb.h>
22
23#include <asm/elf.h>
24#include <asm/ia32.h>
25
26/*
27 * Align a virtual address to avoid aliasing in the I$ on AMD F15h.
28 */
29static unsigned long get_align_mask(struct file *filp)
30{
31 if (filp && is_file_hugepages(file: filp))
32 return huge_page_mask_align(file: filp);
33 /* handle 32- and 64-bit case with a single conditional */
34 if (va_align.flags < 0 || !(va_align.flags & (2 - mmap_is_ia32())))
35 return 0;
36
37 if (!(current->flags & PF_RANDOMIZE))
38 return 0;
39
40 return va_align.mask;
41}
42
43/*
44 * To avoid aliasing in the I$ on AMD F15h, the bits defined by the
45 * va_align.bits, [12:upper_bit), are set to a random value instead of
46 * zeroing them. This random value is computed once per boot. This form
47 * of ASLR is known as "per-boot ASLR".
48 *
49 * To achieve this, the random value is added to the info.align_offset
50 * value before calling vm_unmapped_area() or ORed directly to the
51 * address.
52 */
53static unsigned long get_align_bits(void)
54{
55 return va_align.bits & get_align_mask(NULL);
56}
57
58static int __init control_va_addr_alignment(char *str)
59{
60 /* guard against enabling this on other CPU families */
61 if (va_align.flags < 0)
62 return 1;
63
64 if (*str == 0)
65 return 1;
66
67 if (!strcmp(str, "32"))
68 va_align.flags = ALIGN_VA_32;
69 else if (!strcmp(str, "64"))
70 va_align.flags = ALIGN_VA_64;
71 else if (!strcmp(str, "off"))
72 va_align.flags = 0;
73 else if (!strcmp(str, "on"))
74 va_align.flags = ALIGN_VA_32 | ALIGN_VA_64;
75 else
76 pr_warn("invalid option value: 'align_va_addr=%s'\n", str);
77
78 return 1;
79}
80__setup("align_va_addr=", control_va_addr_alignment);
81
82SYSCALL_DEFINE6(mmap, unsigned long, addr, unsigned long, len,
83 unsigned long, prot, unsigned long, flags,
84 unsigned long, fd, unsigned long, off)
85{
86 if (off & ~PAGE_MASK)
87 return -EINVAL;
88
89 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff: off >> PAGE_SHIFT);
90}
91
92static void find_start_end(unsigned long addr, unsigned long flags,
93 unsigned long *begin, unsigned long *end)
94{
95 if (!in_32bit_syscall() && (flags & MAP_32BIT)) {
96 /* This is usually used needed to map code in small
97 model, so it needs to be in the first 31bit. Limit
98 it to that. This means we need to move the
99 unmapped base down for this case. This can give
100 conflicts with the heap, but we assume that glibc
101 malloc knows how to fall back to mmap. Give it 1GB
102 of playground for now. -AK */
103 *begin = 0x40000000;
104 *end = 0x80000000;
105 if (current->flags & PF_RANDOMIZE) {
106 *begin = randomize_page(start: *begin, range: 0x02000000);
107 }
108 return;
109 }
110
111 *begin = get_mmap_base(is_legacy: 1);
112 if (in_32bit_syscall())
113 *end = task_size_32bit();
114 else
115 *end = task_size_64bit(full_addr_space: addr > DEFAULT_MAP_WINDOW);
116}
117
118static inline unsigned long stack_guard_placement(vm_flags_t vm_flags)
119{
120 if (vm_flags & VM_SHADOW_STACK)
121 return PAGE_SIZE;
122
123 return 0;
124}
125
126unsigned long
127arch_get_unmapped_area(struct file *filp, unsigned long addr, unsigned long len,
128 unsigned long pgoff, unsigned long flags, vm_flags_t vm_flags)
129{
130 struct mm_struct *mm = current->mm;
131 struct vm_area_struct *vma;
132 struct vm_unmapped_area_info info = {};
133 unsigned long begin, end;
134
135 if (flags & MAP_FIXED)
136 return addr;
137
138 find_start_end(addr, flags, begin: &begin, end: &end);
139
140 if (len > end)
141 return -ENOMEM;
142
143 if (addr) {
144 addr = PAGE_ALIGN(addr);
145 vma = find_vma(mm, addr);
146 if (end - len >= addr &&
147 (!vma || addr + len <= vm_start_gap(vma)))
148 return addr;
149 }
150
151 info.length = len;
152 info.low_limit = begin;
153 info.high_limit = end;
154 if (!(filp && is_file_hugepages(file: filp))) {
155 info.align_offset = pgoff << PAGE_SHIFT;
156 info.start_gap = stack_guard_placement(vm_flags);
157 }
158 if (filp) {
159 info.align_mask = get_align_mask(filp);
160 info.align_offset += get_align_bits();
161 }
162
163 return vm_unmapped_area(info: &info);
164}
165
166unsigned long
167arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr0,
168 unsigned long len, unsigned long pgoff,
169 unsigned long flags, vm_flags_t vm_flags)
170{
171 struct vm_area_struct *vma;
172 struct mm_struct *mm = current->mm;
173 unsigned long addr = addr0;
174 struct vm_unmapped_area_info info = {};
175
176 /* requested length too big for entire address space */
177 if (len > TASK_SIZE)
178 return -ENOMEM;
179
180 /* No address checking. See comment at mmap_address_hint_valid() */
181 if (flags & MAP_FIXED)
182 return addr;
183
184 /* for MAP_32BIT mappings we force the legacy mmap base */
185 if (!in_32bit_syscall() && (flags & MAP_32BIT))
186 goto bottomup;
187
188 /* requesting a specific address */
189 if (addr) {
190 addr &= PAGE_MASK;
191 if (!mmap_address_hint_valid(addr, len))
192 goto get_unmapped_area;
193
194 vma = find_vma(mm, addr);
195 if (!vma || addr + len <= vm_start_gap(vma))
196 return addr;
197 }
198get_unmapped_area:
199
200 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
201 info.length = len;
202 if (!in_32bit_syscall() && (flags & MAP_ABOVE4G))
203 info.low_limit = SZ_4G;
204 else
205 info.low_limit = PAGE_SIZE;
206
207 info.high_limit = get_mmap_base(is_legacy: 0);
208 if (!(filp && is_file_hugepages(file: filp))) {
209 info.start_gap = stack_guard_placement(vm_flags);
210 info.align_offset = pgoff << PAGE_SHIFT;
211 }
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 if (filp) {
224 info.align_mask = get_align_mask(filp);
225 info.align_offset += get_align_bits();
226 }
227 addr = vm_unmapped_area(info: &info);
228 if (!(addr & ~PAGE_MASK))
229 return addr;
230 VM_BUG_ON(addr != -ENOMEM);
231
232bottomup:
233 /*
234 * A failed mmap() very likely causes application failure,
235 * so fall back to the bottom-up function here. This scenario
236 * can happen with large stack limits and large mmap()
237 * allocations.
238 */
239 return arch_get_unmapped_area(filp, addr: addr0, len, pgoff, flags, vm_flags: 0);
240}
241