summaryrefslogtreecommitdiffstats
path: root/linux-2.6-32bit-mmap-exec-randomization.patch
blob: f6079841dcc476f70c724656ba009948c421d044 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 735279e..0f9f005 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -756,6 +756,16 @@ unsigned long arch_align_stack(unsigned long sp)
 unsigned long arch_randomize_brk(struct mm_struct *mm)
 {
 	unsigned long range_end = mm->brk + 0x02000000;
-	return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
+	unsigned long bump = 0;
+#ifdef CONFIG_X86_32
+	/* in the case of NX emulation, shove the brk segment way out of the
+	   way of the exec randomization area, since it can collide with
+	   future allocations if not. */
+	if ( (mm->get_unmapped_exec_area == arch_get_unmapped_exec_area) &&
+	     (mm->brk < 0x08000000) ) {
+		bump = (TASK_SIZE/6);
+	}
+#endif
+	return bump + (randomize_range(mm->brk, range_end, 0) ? : mm->brk);
 }
 
diff --git a/arch/x86/mm/mmap.c b/arch/x86/mm/mmap.c
index 845df68..d437466 100644
--- a/arch/x86/mm/mmap.c
+++ b/arch/x86/mm/mmap.c
@@ -119,6 +119,12 @@ void arch_pick_mmap_layout(struct mm_struct *mm)
 	} else {
 		mm->mmap_base = mmap_base();
 		mm->get_unmapped_area = arch_get_unmapped_area_topdown;
+#ifdef CONFIG_X86_32
+		if (!(current->personality & READ_IMPLIES_EXEC)
+		    && !(__supported_pte_mask & _PAGE_NX)
+		    && mmap_is_ia32())
+			mm->get_unmapped_exec_area = arch_get_unmapped_exec_area;
+#endif
 		mm->unmap_area = arch_unmap_area_topdown;
 	}
 }
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 66e6d93..b80cde7 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -330,7 +330,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	if (compat)
 		addr = VDSO_HIGH_BASE;
 	else {
-		addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
+		addr = get_unmapped_area_prot(NULL, 0, PAGE_SIZE, 0, 0, 1);
 		if (IS_ERR_VALUE(addr)) {
 			ret = addr;
 			goto up_fail;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7d5c37f..92cb90d 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1389,7 +1389,13 @@ extern int install_special_mapping(struct mm_struct *mm,
 				   unsigned long addr, unsigned long len,
 				   unsigned long flags, struct page **pages);
 
-extern unsigned long get_unmapped_area(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
+extern unsigned long get_unmapped_area_prot(struct file *, unsigned long, unsigned long, unsigned long, unsigned long, int);
+
+static inline unsigned long get_unmapped_area(struct file *file, unsigned long addr,
+		unsigned long len, unsigned long pgoff, unsigned long flags)
+{
+	return get_unmapped_area_prot(file, addr, len, pgoff, flags, 0);
+}
 
 extern unsigned long mmap_region(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long flags,
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 26574c7..54a063d 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -294,6 +294,9 @@ struct mm_struct {
 	unsigned long (*get_unmapped_area) (struct file *filp,
 				unsigned long addr, unsigned long len,
 				unsigned long pgoff, unsigned long flags);
+       unsigned long (*get_unmapped_exec_area) (struct file *filp,
+				unsigned long addr, unsigned long len,
+				unsigned long pgoff, unsigned long flags);
 	void (*unmap_area) (struct mm_struct *mm, unsigned long addr);
 #endif
 	unsigned long mmap_base;		/* base of mmap area */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f45c0b2..7234f1d 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -391,6 +391,10 @@ extern void arch_pick_mmap_layout(struct mm_struct *mm);
 extern unsigned long
 arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
 		       unsigned long, unsigned long);
+
+extern unsigned long
+arch_get_unmapped_exec_area(struct file *, unsigned long, unsigned long,
+		       unsigned long, unsigned long);
 extern unsigned long
 arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
 			  unsigned long len, unsigned long pgoff,
diff --git a/mm/mmap.c b/mm/mmap.c
index e8dcfc7..4bb6ac9 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -31,6 +31,7 @@
 #include <linux/audit.h>
 #include <linux/khugepaged.h>
 #include <linux/uprobes.h>
+#include <linux/random.h>
 
 #include <asm/uaccess.h>
 #include <asm/cacheflush.h>
@@ -1013,7 +1014,8 @@ static unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
 	/* Obtain the address to map to. we verify (or select) it and ensure
 	 * that it represents a valid section of the address space.
 	 */
-	addr = get_unmapped_area(file, addr, len, pgoff, flags);
+	addr = get_unmapped_area_prot(file, addr, len, pgoff, flags,
+		prot & PROT_EXEC);
 	if (addr & ~PAGE_MASK)
 		return addr;
 
@@ -1603,8 +1605,8 @@ void arch_unmap_area_topdown(struct mm_struct *mm, unsigned long addr)
 }
 
 unsigned long
-get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
-		unsigned long pgoff, unsigned long flags)
+get_unmapped_area_prot(struct file *file, unsigned long addr, unsigned long len,
+		unsigned long pgoff, unsigned long flags, int exec)
 {
 	unsigned long (*get_area)(struct file *, unsigned long,
 				  unsigned long, unsigned long, unsigned long);
@@ -1617,7 +1619,11 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 	if (len > TASK_SIZE)
 		return -ENOMEM;
 
-	get_area = current->mm->get_unmapped_area;
+	if (exec && current->mm->get_unmapped_exec_area)
+		get_area = current->mm->get_unmapped_exec_area;
+	else
+		get_area = current->mm->get_unmapped_area;
+
 	if (file && file->f_op && file->f_op->get_unmapped_area)
 		get_area = file->f_op->get_unmapped_area;
 	addr = get_area(file, addr, len, pgoff, flags);
@@ -1631,8 +1637,83 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 
 	return arch_rebalance_pgtables(addr, len);
 }
+EXPORT_SYMBOL(get_unmapped_area_prot);
+
+static bool should_randomize(void)
+{
+	return (current->flags & PF_RANDOMIZE) &&
+		!(current->personality & ADDR_NO_RANDOMIZE);
+}
+
+#define SHLIB_BASE	0x00110000
+
+unsigned long
+arch_get_unmapped_exec_area(struct file *filp, unsigned long addr0,
+		unsigned long len0, unsigned long pgoff, unsigned long flags)
+{
+	unsigned long addr = addr0, len = len0;
+	struct mm_struct *mm = current->mm;
+	struct vm_area_struct *vma;
+	unsigned long tmp;
+
+	if (len > TASK_SIZE)
+		return -ENOMEM;
+
+	if (flags & MAP_FIXED)
+		return addr;
+
+	if (!addr)
+		addr = !should_randomize() ? SHLIB_BASE :
+			randomize_range(SHLIB_BASE, 0x01000000, len);
+
+	if (addr) {
+		addr = PAGE_ALIGN(addr);
+		vma = find_vma(mm, addr);
+		if (TASK_SIZE - len >= addr &&
+		    (!vma || addr + len <= vma->vm_start))
+			return addr;
+	}
+
+	addr = SHLIB_BASE;
+	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
+		/* At this point:  (!vma || addr < vma->vm_end). */
+		if (TASK_SIZE - len < addr)
+			return -ENOMEM;
+
+		if (!vma || addr + len <= vma->vm_start) {
+			/*
+			 * Must not let a PROT_EXEC mapping get into the
+			 * brk area:
+			 */
+			if (addr + len > mm->brk)
+				goto failed;
+
+			/*
+			 * Up until the brk area we randomize addresses
+			 * as much as possible:
+			 */
+			if (addr >= 0x01000000 && should_randomize()) {
+				tmp = randomize_range(0x01000000,
+					PAGE_ALIGN(max(mm->start_brk,
+					(unsigned long)0x08000000)), len);
+				vma = find_vma(mm, tmp);
+				if (TASK_SIZE - len >= tmp &&
+				    (!vma || tmp + len <= vma->vm_start))
+					return tmp;
+			}
+			/*
+			 * Ok, randomization didnt work out - return
+			 * the result of the linear search:
+			 */
+			return addr;
+		}
+		addr = vma->vm_end;
+	}
+
+failed:
+	return current->mm->get_unmapped_area(filp, addr0, len0, pgoff, flags);
+}
 
-EXPORT_SYMBOL(get_unmapped_area);
 
 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
 struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
diff --git a/mm/mremap.c b/mm/mremap.c
index db8d983..3a2d940 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -521,10 +521,10 @@ unsigned long do_mremap(unsigned long addr,
 		if (vma->vm_flags & VM_MAYSHARE)
 			map_flags |= MAP_SHARED;
 
-		new_addr = get_unmapped_area(vma->vm_file, 0, new_len,
+		new_addr = get_unmapped_area_prot(vma->vm_file, 0, new_len,
 					vma->vm_pgoff +
 					((addr - vma->vm_start) >> PAGE_SHIFT),
-					map_flags);
+					map_flags, vma->vm_flags & VM_EXEC);
 		if (new_addr & ~PAGE_MASK) {
 			ret = new_addr;
 			goto out;