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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2007 Andi Kleen, SUSE Labs.
4 *
5 * This contains most of the x86 vDSO kernel-side code.
6 */
7#include <linux/mm.h>
8#include <linux/err.h>
9#include <linux/sched.h>
10#include <linux/sched/task_stack.h>
11#include <linux/slab.h>
12#include <linux/init.h>
13#include <linux/random.h>
14#include <linux/elf.h>
15#include <linux/cpu.h>
16#include <linux/ptrace.h>
17#include <linux/time_namespace.h>
18
19#include <asm/pvclock.h>
20#include <asm/vgtod.h>
21#include <asm/proto.h>
22#include <asm/vdso.h>
23#include <asm/vvar.h>
24#include <asm/tlb.h>
25#include <asm/page.h>
26#include <asm/desc.h>
27#include <asm/cpufeature.h>
28#include <clocksource/hyperv_timer.h>
29
30#undef _ASM_X86_VVAR_H
31#define EMIT_VVAR(name, offset) \
32 const size_t name ## _offset = offset;
33#include <asm/vvar.h>
34
35struct vdso_data *arch_get_vdso_data(void *vvar_page)
36{
37 return (struct vdso_data *)(vvar_page + _vdso_data_offset);
38}
39#undef EMIT_VVAR
40
41unsigned int vclocks_used __read_mostly;
42
43#if defined(CONFIG_X86_64)
44unsigned int __read_mostly vdso64_enabled = 1;
45#endif
46
47void __init init_vdso_image(const struct vdso_image *image)
48{
49 BUG_ON(image->size % PAGE_SIZE != 0);
50
51 apply_alternatives((struct alt_instr *)(image->data + image->alt),
52 (struct alt_instr *)(image->data + image->alt +
53 image->alt_len));
54}
55
56static const struct vm_special_mapping vvar_mapping;
57struct linux_binprm;
58
59static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
60 struct vm_area_struct *vma, struct vm_fault *vmf)
61{
62 const struct vdso_image *image = vma->vm_mm->context.vdso_image;
63
64 if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
65 return VM_FAULT_SIGBUS;
66
67 vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
68 get_page(vmf->page);
69 return 0;
70}
71
72static void vdso_fix_landing(const struct vdso_image *image,
73 struct vm_area_struct *new_vma)
74{
75#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
76 if (in_ia32_syscall() && image == &vdso_image_32) {
77 struct pt_regs *regs = current_pt_regs();
78 unsigned long vdso_land = image->sym_int80_landing_pad;
79 unsigned long old_land_addr = vdso_land +
80 (unsigned long)current->mm->context.vdso;
81
82 /* Fixing userspace landing - look at do_fast_syscall_32 */
83 if (regs->ip == old_land_addr)
84 regs->ip = new_vma->vm_start + vdso_land;
85 }
86#endif
87}
88
89static int vdso_mremap(const struct vm_special_mapping *sm,
90 struct vm_area_struct *new_vma)
91{
92 const struct vdso_image *image = current->mm->context.vdso_image;
93
94 vdso_fix_landing(image, new_vma);
95 current->mm->context.vdso = (void __user *)new_vma->vm_start;
96
97 return 0;
98}
99
100#ifdef CONFIG_TIME_NS
101/*
102 * The vvar page layout depends on whether a task belongs to the root or
103 * non-root time namespace. Whenever a task changes its namespace, the VVAR
104 * page tables are cleared and then they will re-faulted with a
105 * corresponding layout.
106 * See also the comment near timens_setup_vdso_data() for details.
107 */
108int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
109{
110 struct mm_struct *mm = task->mm;
111 struct vm_area_struct *vma;
112 VMA_ITERATOR(vmi, mm, 0);
113
114 mmap_read_lock(mm);
115 for_each_vma(vmi, vma) {
116 unsigned long size = vma->vm_end - vma->vm_start;
117
118 if (vma_is_special_mapping(vma, &vvar_mapping))
119 zap_page_range(vma, vma->vm_start, size);
120 }
121 mmap_read_unlock(mm);
122
123 return 0;
124}
125#endif
126
127static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
128 struct vm_area_struct *vma, struct vm_fault *vmf)
129{
130 const struct vdso_image *image = vma->vm_mm->context.vdso_image;
131 unsigned long pfn;
132 long sym_offset;
133
134 if (!image)
135 return VM_FAULT_SIGBUS;
136
137 sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
138 image->sym_vvar_start;
139
140 /*
141 * Sanity check: a symbol offset of zero means that the page
142 * does not exist for this vdso image, not that the page is at
143 * offset zero relative to the text mapping. This should be
144 * impossible here, because sym_offset should only be zero for
145 * the page past the end of the vvar mapping.
146 */
147 if (sym_offset == 0)
148 return VM_FAULT_SIGBUS;
149
150 if (sym_offset == image->sym_vvar_page) {
151 struct page *timens_page = find_timens_vvar_page(vma);
152
153 pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
154
155 /*
156 * If a task belongs to a time namespace then a namespace
157 * specific VVAR is mapped with the sym_vvar_page offset and
158 * the real VVAR page is mapped with the sym_timens_page
159 * offset.
160 * See also the comment near timens_setup_vdso_data().
161 */
162 if (timens_page) {
163 unsigned long addr;
164 vm_fault_t err;
165
166 /*
167 * Optimization: inside time namespace pre-fault
168 * VVAR page too. As on timens page there are only
169 * offsets for clocks on VVAR, it'll be faulted
170 * shortly by VDSO code.
171 */
172 addr = vmf->address + (image->sym_timens_page - sym_offset);
173 err = vmf_insert_pfn(vma, addr, pfn);
174 if (unlikely(err & VM_FAULT_ERROR))
175 return err;
176
177 pfn = page_to_pfn(timens_page);
178 }
179
180 return vmf_insert_pfn(vma, vmf->address, pfn);
181 } else if (sym_offset == image->sym_pvclock_page) {
182 struct pvclock_vsyscall_time_info *pvti =
183 pvclock_get_pvti_cpu0_va();
184 if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) {
185 return vmf_insert_pfn_prot(vma, vmf->address,
186 __pa(pvti) >> PAGE_SHIFT,
187 pgprot_decrypted(vma->vm_page_prot));
188 }
189 } else if (sym_offset == image->sym_hvclock_page) {
190 pfn = hv_get_tsc_pfn();
191
192 if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
193 return vmf_insert_pfn(vma, vmf->address, pfn);
194 } else if (sym_offset == image->sym_timens_page) {
195 struct page *timens_page = find_timens_vvar_page(vma);
196
197 if (!timens_page)
198 return VM_FAULT_SIGBUS;
199
200 pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
201 return vmf_insert_pfn(vma, vmf->address, pfn);
202 }
203
204 return VM_FAULT_SIGBUS;
205}
206
207static const struct vm_special_mapping vdso_mapping = {
208 .name = "[vdso]",
209 .fault = vdso_fault,
210 .mremap = vdso_mremap,
211};
212static const struct vm_special_mapping vvar_mapping = {
213 .name = "[vvar]",
214 .fault = vvar_fault,
215};
216
217/*
218 * Add vdso and vvar mappings to current process.
219 * @image - blob to map
220 * @addr - request a specific address (zero to map at free addr)
221 */
222static int map_vdso(const struct vdso_image *image, unsigned long addr)
223{
224 struct mm_struct *mm = current->mm;
225 struct vm_area_struct *vma;
226 unsigned long text_start;
227 int ret = 0;
228
229 if (mmap_write_lock_killable(mm))
230 return -EINTR;
231
232 addr = get_unmapped_area(NULL, addr,
233 image->size - image->sym_vvar_start, 0, 0);
234 if (IS_ERR_VALUE(addr)) {
235 ret = addr;
236 goto up_fail;
237 }
238
239 text_start = addr - image->sym_vvar_start;
240
241 /*
242 * MAYWRITE to allow gdb to COW and set breakpoints
243 */
244 vma = _install_special_mapping(mm,
245 text_start,
246 image->size,
247 VM_READ|VM_EXEC|
248 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
249 &vdso_mapping);
250
251 if (IS_ERR(vma)) {
252 ret = PTR_ERR(vma);
253 goto up_fail;
254 }
255
256 vma = _install_special_mapping(mm,
257 addr,
258 -image->sym_vvar_start,
259 VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
260 VM_PFNMAP,
261 &vvar_mapping);
262
263 if (IS_ERR(vma)) {
264 ret = PTR_ERR(vma);
265 do_munmap(mm, text_start, image->size, NULL);
266 } else {
267 current->mm->context.vdso = (void __user *)text_start;
268 current->mm->context.vdso_image = image;
269 }
270
271up_fail:
272 mmap_write_unlock(mm);
273 return ret;
274}
275
276#ifdef CONFIG_X86_64
277/*
278 * Put the vdso above the (randomized) stack with another randomized
279 * offset. This way there is no hole in the middle of address space.
280 * To save memory make sure it is still in the same PTE as the stack
281 * top. This doesn't give that many random bits.
282 *
283 * Note that this algorithm is imperfect: the distribution of the vdso
284 * start address within a PMD is biased toward the end.
285 *
286 * Only used for the 64-bit and x32 vdsos.
287 */
288static unsigned long vdso_addr(unsigned long start, unsigned len)
289{
290 unsigned long addr, end;
291 unsigned offset;
292
293 /*
294 * Round up the start address. It can start out unaligned as a result
295 * of stack start randomization.
296 */
297 start = PAGE_ALIGN(start);
298
299 /* Round the lowest possible end address up to a PMD boundary. */
300 end = (start + len + PMD_SIZE - 1) & PMD_MASK;
301 if (end >= TASK_SIZE_MAX)
302 end = TASK_SIZE_MAX;
303 end -= len;
304
305 if (end > start) {
306 offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
307 addr = start + (offset << PAGE_SHIFT);
308 } else {
309 addr = start;
310 }
311
312 /*
313 * Forcibly align the final address in case we have a hardware
314 * issue that requires alignment for performance reasons.
315 */
316 addr = align_vdso_addr(addr);
317
318 return addr;
319}
320
321static int map_vdso_randomized(const struct vdso_image *image)
322{
323 unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
324
325 return map_vdso(image, addr);
326}
327#endif
328
329int map_vdso_once(const struct vdso_image *image, unsigned long addr)
330{
331 struct mm_struct *mm = current->mm;
332 struct vm_area_struct *vma;
333 VMA_ITERATOR(vmi, mm, 0);
334
335 mmap_write_lock(mm);
336 /*
337 * Check if we have already mapped vdso blob - fail to prevent
338 * abusing from userspace install_special_mapping, which may
339 * not do accounting and rlimit right.
340 * We could search vma near context.vdso, but it's a slowpath,
341 * so let's explicitly check all VMAs to be completely sure.
342 */
343 for_each_vma(vmi, vma) {
344 if (vma_is_special_mapping(vma, &vdso_mapping) ||
345 vma_is_special_mapping(vma, &vvar_mapping)) {
346 mmap_write_unlock(mm);
347 return -EEXIST;
348 }
349 }
350 mmap_write_unlock(mm);
351
352 return map_vdso(image, addr);
353}
354
355#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
356static int load_vdso32(void)
357{
358 if (vdso32_enabled != 1) /* Other values all mean "disabled" */
359 return 0;
360
361 return map_vdso(&vdso_image_32, 0);
362}
363#endif
364
365#ifdef CONFIG_X86_64
366int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
367{
368 if (!vdso64_enabled)
369 return 0;
370
371 return map_vdso_randomized(&vdso_image_64);
372}
373
374#ifdef CONFIG_COMPAT
375int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
376 int uses_interp, bool x32)
377{
378#ifdef CONFIG_X86_X32_ABI
379 if (x32) {
380 if (!vdso64_enabled)
381 return 0;
382 return map_vdso_randomized(&vdso_image_x32);
383 }
384#endif
385#ifdef CONFIG_IA32_EMULATION
386 return load_vdso32();
387#else
388 return 0;
389#endif
390}
391#endif
392#else
393int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
394{
395 return load_vdso32();
396}
397#endif
398
399bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
400{
401#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
402 const struct vdso_image *image = current->mm->context.vdso_image;
403 unsigned long vdso = (unsigned long) current->mm->context.vdso;
404
405 if (in_ia32_syscall() && image == &vdso_image_32) {
406 if (regs->ip == vdso + image->sym_vdso32_sigreturn_landing_pad ||
407 regs->ip == vdso + image->sym_vdso32_rt_sigreturn_landing_pad)
408 return true;
409 }
410#endif
411 return false;
412}
413
414#ifdef CONFIG_X86_64
415static __init int vdso_setup(char *s)
416{
417 vdso64_enabled = simple_strtoul(s, NULL, 0);
418 return 1;
419}
420__setup("vdso=", vdso_setup);
421
422static int __init init_vdso(void)
423{
424 BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32);
425
426 init_vdso_image(&vdso_image_64);
427
428#ifdef CONFIG_X86_X32_ABI
429 init_vdso_image(&vdso_image_x32);
430#endif
431
432 return 0;
433}
434subsys_initcall(init_vdso);
435#endif /* CONFIG_X86_64 */
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2007 Andi Kleen, SUSE Labs.
4 *
5 * This contains most of the x86 vDSO kernel-side code.
6 */
7#include <linux/mm.h>
8#include <linux/err.h>
9#include <linux/sched.h>
10#include <linux/sched/task_stack.h>
11#include <linux/slab.h>
12#include <linux/init.h>
13#include <linux/random.h>
14#include <linux/elf.h>
15#include <linux/cpu.h>
16#include <linux/ptrace.h>
17#include <linux/time_namespace.h>
18
19#include <asm/pvclock.h>
20#include <asm/vgtod.h>
21#include <asm/proto.h>
22#include <asm/vdso.h>
23#include <asm/vvar.h>
24#include <asm/tlb.h>
25#include <asm/page.h>
26#include <asm/desc.h>
27#include <asm/cpufeature.h>
28#include <clocksource/hyperv_timer.h>
29
30#undef _ASM_X86_VVAR_H
31#define EMIT_VVAR(name, offset) \
32 const size_t name ## _offset = offset;
33#include <asm/vvar.h>
34
35struct vdso_data *arch_get_vdso_data(void *vvar_page)
36{
37 return (struct vdso_data *)(vvar_page + _vdso_data_offset);
38}
39#undef EMIT_VVAR
40
41unsigned int vclocks_used __read_mostly;
42
43#if defined(CONFIG_X86_64)
44unsigned int __read_mostly vdso64_enabled = 1;
45#endif
46
47int __init init_vdso_image(const struct vdso_image *image)
48{
49 BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32);
50 BUG_ON(image->size % PAGE_SIZE != 0);
51
52 apply_alternatives((struct alt_instr *)(image->data + image->alt),
53 (struct alt_instr *)(image->data + image->alt +
54 image->alt_len));
55
56 return 0;
57}
58
59static const struct vm_special_mapping vvar_mapping;
60struct linux_binprm;
61
62static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
63 struct vm_area_struct *vma, struct vm_fault *vmf)
64{
65 const struct vdso_image *image = vma->vm_mm->context.vdso_image;
66
67 if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size)
68 return VM_FAULT_SIGBUS;
69
70 vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT));
71 get_page(vmf->page);
72 return 0;
73}
74
75static void vdso_fix_landing(const struct vdso_image *image,
76 struct vm_area_struct *new_vma)
77{
78#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
79 if (in_ia32_syscall() && image == &vdso_image_32) {
80 struct pt_regs *regs = current_pt_regs();
81 unsigned long vdso_land = image->sym_int80_landing_pad;
82 unsigned long old_land_addr = vdso_land +
83 (unsigned long)current->mm->context.vdso;
84
85 /* Fixing userspace landing - look at do_fast_syscall_32 */
86 if (regs->ip == old_land_addr)
87 regs->ip = new_vma->vm_start + vdso_land;
88 }
89#endif
90}
91
92static int vdso_mremap(const struct vm_special_mapping *sm,
93 struct vm_area_struct *new_vma)
94{
95 const struct vdso_image *image = current->mm->context.vdso_image;
96
97 vdso_fix_landing(image, new_vma);
98 current->mm->context.vdso = (void __user *)new_vma->vm_start;
99
100 return 0;
101}
102
103#ifdef CONFIG_TIME_NS
104/*
105 * The vvar page layout depends on whether a task belongs to the root or
106 * non-root time namespace. Whenever a task changes its namespace, the VVAR
107 * page tables are cleared and then they will re-faulted with a
108 * corresponding layout.
109 * See also the comment near timens_setup_vdso_data() for details.
110 */
111int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
112{
113 struct mm_struct *mm = task->mm;
114 struct vm_area_struct *vma;
115 VMA_ITERATOR(vmi, mm, 0);
116
117 mmap_read_lock(mm);
118 for_each_vma(vmi, vma) {
119 if (vma_is_special_mapping(vma, &vvar_mapping))
120 zap_vma_pages(vma);
121 }
122 mmap_read_unlock(mm);
123
124 return 0;
125}
126#endif
127
128static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
129 struct vm_area_struct *vma, struct vm_fault *vmf)
130{
131 const struct vdso_image *image = vma->vm_mm->context.vdso_image;
132 unsigned long pfn;
133 long sym_offset;
134
135 if (!image)
136 return VM_FAULT_SIGBUS;
137
138 sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) +
139 image->sym_vvar_start;
140
141 /*
142 * Sanity check: a symbol offset of zero means that the page
143 * does not exist for this vdso image, not that the page is at
144 * offset zero relative to the text mapping. This should be
145 * impossible here, because sym_offset should only be zero for
146 * the page past the end of the vvar mapping.
147 */
148 if (sym_offset == 0)
149 return VM_FAULT_SIGBUS;
150
151 if (sym_offset == image->sym_vvar_page) {
152 struct page *timens_page = find_timens_vvar_page(vma);
153
154 pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
155
156 /*
157 * If a task belongs to a time namespace then a namespace
158 * specific VVAR is mapped with the sym_vvar_page offset and
159 * the real VVAR page is mapped with the sym_timens_page
160 * offset.
161 * See also the comment near timens_setup_vdso_data().
162 */
163 if (timens_page) {
164 unsigned long addr;
165 vm_fault_t err;
166
167 /*
168 * Optimization: inside time namespace pre-fault
169 * VVAR page too. As on timens page there are only
170 * offsets for clocks on VVAR, it'll be faulted
171 * shortly by VDSO code.
172 */
173 addr = vmf->address + (image->sym_timens_page - sym_offset);
174 err = vmf_insert_pfn(vma, addr, pfn);
175 if (unlikely(err & VM_FAULT_ERROR))
176 return err;
177
178 pfn = page_to_pfn(timens_page);
179 }
180
181 return vmf_insert_pfn(vma, vmf->address, pfn);
182 } else if (sym_offset == image->sym_pvclock_page) {
183 struct pvclock_vsyscall_time_info *pvti =
184 pvclock_get_pvti_cpu0_va();
185 if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) {
186 return vmf_insert_pfn_prot(vma, vmf->address,
187 __pa(pvti) >> PAGE_SHIFT,
188 pgprot_decrypted(vma->vm_page_prot));
189 }
190 } else if (sym_offset == image->sym_hvclock_page) {
191 pfn = hv_get_tsc_pfn();
192
193 if (pfn && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK))
194 return vmf_insert_pfn(vma, vmf->address, pfn);
195 } else if (sym_offset == image->sym_timens_page) {
196 struct page *timens_page = find_timens_vvar_page(vma);
197
198 if (!timens_page)
199 return VM_FAULT_SIGBUS;
200
201 pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
202 return vmf_insert_pfn(vma, vmf->address, pfn);
203 }
204
205 return VM_FAULT_SIGBUS;
206}
207
208static const struct vm_special_mapping vdso_mapping = {
209 .name = "[vdso]",
210 .fault = vdso_fault,
211 .mremap = vdso_mremap,
212};
213static const struct vm_special_mapping vvar_mapping = {
214 .name = "[vvar]",
215 .fault = vvar_fault,
216};
217
218/*
219 * Add vdso and vvar mappings to current process.
220 * @image - blob to map
221 * @addr - request a specific address (zero to map at free addr)
222 */
223static int map_vdso(const struct vdso_image *image, unsigned long addr)
224{
225 struct mm_struct *mm = current->mm;
226 struct vm_area_struct *vma;
227 unsigned long text_start;
228 int ret = 0;
229
230 if (mmap_write_lock_killable(mm))
231 return -EINTR;
232
233 addr = get_unmapped_area(NULL, addr,
234 image->size - image->sym_vvar_start, 0, 0);
235 if (IS_ERR_VALUE(addr)) {
236 ret = addr;
237 goto up_fail;
238 }
239
240 text_start = addr - image->sym_vvar_start;
241
242 /*
243 * MAYWRITE to allow gdb to COW and set breakpoints
244 */
245 vma = _install_special_mapping(mm,
246 text_start,
247 image->size,
248 VM_READ|VM_EXEC|
249 VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
250 &vdso_mapping);
251
252 if (IS_ERR(vma)) {
253 ret = PTR_ERR(vma);
254 goto up_fail;
255 }
256
257 vma = _install_special_mapping(mm,
258 addr,
259 -image->sym_vvar_start,
260 VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP|
261 VM_PFNMAP,
262 &vvar_mapping);
263
264 if (IS_ERR(vma)) {
265 ret = PTR_ERR(vma);
266 do_munmap(mm, text_start, image->size, NULL);
267 } else {
268 current->mm->context.vdso = (void __user *)text_start;
269 current->mm->context.vdso_image = image;
270 }
271
272up_fail:
273 mmap_write_unlock(mm);
274 return ret;
275}
276
277#ifdef CONFIG_X86_64
278/*
279 * Put the vdso above the (randomized) stack with another randomized
280 * offset. This way there is no hole in the middle of address space.
281 * To save memory make sure it is still in the same PTE as the stack
282 * top. This doesn't give that many random bits.
283 *
284 * Note that this algorithm is imperfect: the distribution of the vdso
285 * start address within a PMD is biased toward the end.
286 *
287 * Only used for the 64-bit and x32 vdsos.
288 */
289static unsigned long vdso_addr(unsigned long start, unsigned len)
290{
291 unsigned long addr, end;
292 unsigned offset;
293
294 /*
295 * Round up the start address. It can start out unaligned as a result
296 * of stack start randomization.
297 */
298 start = PAGE_ALIGN(start);
299
300 /* Round the lowest possible end address up to a PMD boundary. */
301 end = (start + len + PMD_SIZE - 1) & PMD_MASK;
302 if (end >= DEFAULT_MAP_WINDOW)
303 end = DEFAULT_MAP_WINDOW;
304 end -= len;
305
306 if (end > start) {
307 offset = get_random_u32_below(((end - start) >> PAGE_SHIFT) + 1);
308 addr = start + (offset << PAGE_SHIFT);
309 } else {
310 addr = start;
311 }
312
313 /*
314 * Forcibly align the final address in case we have a hardware
315 * issue that requires alignment for performance reasons.
316 */
317 addr = align_vdso_addr(addr);
318
319 return addr;
320}
321
322static int map_vdso_randomized(const struct vdso_image *image)
323{
324 unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start);
325
326 return map_vdso(image, addr);
327}
328#endif
329
330int map_vdso_once(const struct vdso_image *image, unsigned long addr)
331{
332 struct mm_struct *mm = current->mm;
333 struct vm_area_struct *vma;
334 VMA_ITERATOR(vmi, mm, 0);
335
336 mmap_write_lock(mm);
337 /*
338 * Check if we have already mapped vdso blob - fail to prevent
339 * abusing from userspace install_special_mapping, which may
340 * not do accounting and rlimit right.
341 * We could search vma near context.vdso, but it's a slowpath,
342 * so let's explicitly check all VMAs to be completely sure.
343 */
344 for_each_vma(vmi, vma) {
345 if (vma_is_special_mapping(vma, &vdso_mapping) ||
346 vma_is_special_mapping(vma, &vvar_mapping)) {
347 mmap_write_unlock(mm);
348 return -EEXIST;
349 }
350 }
351 mmap_write_unlock(mm);
352
353 return map_vdso(image, addr);
354}
355
356#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
357static int load_vdso32(void)
358{
359 if (vdso32_enabled != 1) /* Other values all mean "disabled" */
360 return 0;
361
362 return map_vdso(&vdso_image_32, 0);
363}
364#endif
365
366#ifdef CONFIG_X86_64
367int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
368{
369 if (!vdso64_enabled)
370 return 0;
371
372 return map_vdso_randomized(&vdso_image_64);
373}
374
375#ifdef CONFIG_COMPAT
376int compat_arch_setup_additional_pages(struct linux_binprm *bprm,
377 int uses_interp, bool x32)
378{
379#ifdef CONFIG_X86_X32_ABI
380 if (x32) {
381 if (!vdso64_enabled)
382 return 0;
383 return map_vdso_randomized(&vdso_image_x32);
384 }
385#endif
386#ifdef CONFIG_IA32_EMULATION
387 return load_vdso32();
388#else
389 return 0;
390#endif
391}
392#endif
393#else
394int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
395{
396 return load_vdso32();
397}
398#endif
399
400bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs)
401{
402#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION)
403 const struct vdso_image *image = current->mm->context.vdso_image;
404 unsigned long vdso = (unsigned long) current->mm->context.vdso;
405
406 if (in_ia32_syscall() && image == &vdso_image_32) {
407 if (regs->ip == vdso + image->sym_vdso32_sigreturn_landing_pad ||
408 regs->ip == vdso + image->sym_vdso32_rt_sigreturn_landing_pad)
409 return true;
410 }
411#endif
412 return false;
413}
414
415#ifdef CONFIG_X86_64
416static __init int vdso_setup(char *s)
417{
418 vdso64_enabled = simple_strtoul(s, NULL, 0);
419 return 1;
420}
421__setup("vdso=", vdso_setup);
422#endif /* CONFIG_X86_64 */