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1 | #include <linux/mm.h> | |
2 | #include <linux/slab.h> | |
3 | #include <linux/string.h> | |
4 | #include <linux/compiler.h> | |
5 | #include <linux/export.h> | |
6 | #include <linux/err.h> | |
7 | #include <linux/sched.h> | |
8 | #include <linux/security.h> | |
9 | #include <linux/swap.h> | |
10 | #include <linux/swapops.h> | |
11 | #include <linux/mman.h> | |
12 | #include <linux/hugetlb.h> | |
13 | #include <linux/vmalloc.h> | |
14 | ||
15 | #include <asm/uaccess.h> | |
16 | ||
17 | #include "internal.h" | |
18 | ||
19 | /** | |
20 | * kstrdup - allocate space for and copy an existing string | |
21 | * @s: the string to duplicate | |
22 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
23 | */ | |
24 | char *kstrdup(const char *s, gfp_t gfp) | |
25 | { | |
26 | size_t len; | |
27 | char *buf; | |
28 | ||
29 | if (!s) | |
30 | return NULL; | |
31 | ||
32 | len = strlen(s) + 1; | |
33 | buf = kmalloc_track_caller(len, gfp); | |
34 | if (buf) | |
35 | memcpy(buf, s, len); | |
36 | return buf; | |
37 | } | |
38 | EXPORT_SYMBOL(kstrdup); | |
39 | ||
40 | /** | |
41 | * kstrndup - allocate space for and copy an existing string | |
42 | * @s: the string to duplicate | |
43 | * @max: read at most @max chars from @s | |
44 | * @gfp: the GFP mask used in the kmalloc() call when allocating memory | |
45 | */ | |
46 | char *kstrndup(const char *s, size_t max, gfp_t gfp) | |
47 | { | |
48 | size_t len; | |
49 | char *buf; | |
50 | ||
51 | if (!s) | |
52 | return NULL; | |
53 | ||
54 | len = strnlen(s, max); | |
55 | buf = kmalloc_track_caller(len+1, gfp); | |
56 | if (buf) { | |
57 | memcpy(buf, s, len); | |
58 | buf[len] = '\0'; | |
59 | } | |
60 | return buf; | |
61 | } | |
62 | EXPORT_SYMBOL(kstrndup); | |
63 | ||
64 | /** | |
65 | * kmemdup - duplicate region of memory | |
66 | * | |
67 | * @src: memory region to duplicate | |
68 | * @len: memory region length | |
69 | * @gfp: GFP mask to use | |
70 | */ | |
71 | void *kmemdup(const void *src, size_t len, gfp_t gfp) | |
72 | { | |
73 | void *p; | |
74 | ||
75 | p = kmalloc_track_caller(len, gfp); | |
76 | if (p) | |
77 | memcpy(p, src, len); | |
78 | return p; | |
79 | } | |
80 | EXPORT_SYMBOL(kmemdup); | |
81 | ||
82 | /** | |
83 | * memdup_user - duplicate memory region from user space | |
84 | * | |
85 | * @src: source address in user space | |
86 | * @len: number of bytes to copy | |
87 | * | |
88 | * Returns an ERR_PTR() on failure. | |
89 | */ | |
90 | void *memdup_user(const void __user *src, size_t len) | |
91 | { | |
92 | void *p; | |
93 | ||
94 | /* | |
95 | * Always use GFP_KERNEL, since copy_from_user() can sleep and | |
96 | * cause pagefault, which makes it pointless to use GFP_NOFS | |
97 | * or GFP_ATOMIC. | |
98 | */ | |
99 | p = kmalloc_track_caller(len, GFP_KERNEL); | |
100 | if (!p) | |
101 | return ERR_PTR(-ENOMEM); | |
102 | ||
103 | if (copy_from_user(p, src, len)) { | |
104 | kfree(p); | |
105 | return ERR_PTR(-EFAULT); | |
106 | } | |
107 | ||
108 | return p; | |
109 | } | |
110 | EXPORT_SYMBOL(memdup_user); | |
111 | ||
112 | /* | |
113 | * strndup_user - duplicate an existing string from user space | |
114 | * @s: The string to duplicate | |
115 | * @n: Maximum number of bytes to copy, including the trailing NUL. | |
116 | */ | |
117 | char *strndup_user(const char __user *s, long n) | |
118 | { | |
119 | char *p; | |
120 | long length; | |
121 | ||
122 | length = strnlen_user(s, n); | |
123 | ||
124 | if (!length) | |
125 | return ERR_PTR(-EFAULT); | |
126 | ||
127 | if (length > n) | |
128 | return ERR_PTR(-EINVAL); | |
129 | ||
130 | p = memdup_user(s, length); | |
131 | ||
132 | if (IS_ERR(p)) | |
133 | return p; | |
134 | ||
135 | p[length - 1] = '\0'; | |
136 | ||
137 | return p; | |
138 | } | |
139 | EXPORT_SYMBOL(strndup_user); | |
140 | ||
141 | void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, | |
142 | struct vm_area_struct *prev, struct rb_node *rb_parent) | |
143 | { | |
144 | struct vm_area_struct *next; | |
145 | ||
146 | vma->vm_prev = prev; | |
147 | if (prev) { | |
148 | next = prev->vm_next; | |
149 | prev->vm_next = vma; | |
150 | } else { | |
151 | mm->mmap = vma; | |
152 | if (rb_parent) | |
153 | next = rb_entry(rb_parent, | |
154 | struct vm_area_struct, vm_rb); | |
155 | else | |
156 | next = NULL; | |
157 | } | |
158 | vma->vm_next = next; | |
159 | if (next) | |
160 | next->vm_prev = vma; | |
161 | } | |
162 | ||
163 | /* Check if the vma is being used as a stack by this task */ | |
164 | static int vm_is_stack_for_task(struct task_struct *t, | |
165 | struct vm_area_struct *vma) | |
166 | { | |
167 | return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(t)); | |
168 | } | |
169 | ||
170 | /* | |
171 | * Check if the vma is being used as a stack. | |
172 | * If is_group is non-zero, check in the entire thread group or else | |
173 | * just check in the current task. Returns the task_struct of the task | |
174 | * that the vma is stack for. Must be called under rcu_read_lock(). | |
175 | */ | |
176 | struct task_struct *task_of_stack(struct task_struct *task, | |
177 | struct vm_area_struct *vma, bool in_group) | |
178 | { | |
179 | if (vm_is_stack_for_task(task, vma)) | |
180 | return task; | |
181 | ||
182 | if (in_group) { | |
183 | struct task_struct *t; | |
184 | ||
185 | for_each_thread(task, t) { | |
186 | if (vm_is_stack_for_task(t, vma)) | |
187 | return t; | |
188 | } | |
189 | } | |
190 | ||
191 | return NULL; | |
192 | } | |
193 | ||
194 | #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT) | |
195 | void arch_pick_mmap_layout(struct mm_struct *mm) | |
196 | { | |
197 | mm->mmap_base = TASK_UNMAPPED_BASE; | |
198 | mm->get_unmapped_area = arch_get_unmapped_area; | |
199 | } | |
200 | #endif | |
201 | ||
202 | /* | |
203 | * Like get_user_pages_fast() except its IRQ-safe in that it won't fall | |
204 | * back to the regular GUP. | |
205 | * If the architecture not support this function, simply return with no | |
206 | * page pinned | |
207 | */ | |
208 | int __weak __get_user_pages_fast(unsigned long start, | |
209 | int nr_pages, int write, struct page **pages) | |
210 | { | |
211 | return 0; | |
212 | } | |
213 | EXPORT_SYMBOL_GPL(__get_user_pages_fast); | |
214 | ||
215 | /** | |
216 | * get_user_pages_fast() - pin user pages in memory | |
217 | * @start: starting user address | |
218 | * @nr_pages: number of pages from start to pin | |
219 | * @write: whether pages will be written to | |
220 | * @pages: array that receives pointers to the pages pinned. | |
221 | * Should be at least nr_pages long. | |
222 | * | |
223 | * Returns number of pages pinned. This may be fewer than the number | |
224 | * requested. If nr_pages is 0 or negative, returns 0. If no pages | |
225 | * were pinned, returns -errno. | |
226 | * | |
227 | * get_user_pages_fast provides equivalent functionality to get_user_pages, | |
228 | * operating on current and current->mm, with force=0 and vma=NULL. However | |
229 | * unlike get_user_pages, it must be called without mmap_sem held. | |
230 | * | |
231 | * get_user_pages_fast may take mmap_sem and page table locks, so no | |
232 | * assumptions can be made about lack of locking. get_user_pages_fast is to be | |
233 | * implemented in a way that is advantageous (vs get_user_pages()) when the | |
234 | * user memory area is already faulted in and present in ptes. However if the | |
235 | * pages have to be faulted in, it may turn out to be slightly slower so | |
236 | * callers need to carefully consider what to use. On many architectures, | |
237 | * get_user_pages_fast simply falls back to get_user_pages. | |
238 | */ | |
239 | int __weak get_user_pages_fast(unsigned long start, | |
240 | int nr_pages, int write, struct page **pages) | |
241 | { | |
242 | struct mm_struct *mm = current->mm; | |
243 | return get_user_pages_unlocked(current, mm, start, nr_pages, | |
244 | write, 0, pages); | |
245 | } | |
246 | EXPORT_SYMBOL_GPL(get_user_pages_fast); | |
247 | ||
248 | unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr, | |
249 | unsigned long len, unsigned long prot, | |
250 | unsigned long flag, unsigned long pgoff) | |
251 | { | |
252 | unsigned long ret; | |
253 | struct mm_struct *mm = current->mm; | |
254 | unsigned long populate; | |
255 | ||
256 | ret = security_mmap_file(file, prot, flag); | |
257 | if (!ret) { | |
258 | down_write(&mm->mmap_sem); | |
259 | ret = do_mmap_pgoff(file, addr, len, prot, flag, pgoff, | |
260 | &populate); | |
261 | up_write(&mm->mmap_sem); | |
262 | if (populate) | |
263 | mm_populate(ret, populate); | |
264 | } | |
265 | return ret; | |
266 | } | |
267 | ||
268 | unsigned long vm_mmap(struct file *file, unsigned long addr, | |
269 | unsigned long len, unsigned long prot, | |
270 | unsigned long flag, unsigned long offset) | |
271 | { | |
272 | if (unlikely(offset + PAGE_ALIGN(len) < offset)) | |
273 | return -EINVAL; | |
274 | if (unlikely(offset & ~PAGE_MASK)) | |
275 | return -EINVAL; | |
276 | ||
277 | return vm_mmap_pgoff(file, addr, len, prot, flag, offset >> PAGE_SHIFT); | |
278 | } | |
279 | EXPORT_SYMBOL(vm_mmap); | |
280 | ||
281 | void kvfree(const void *addr) | |
282 | { | |
283 | if (is_vmalloc_addr(addr)) | |
284 | vfree(addr); | |
285 | else | |
286 | kfree(addr); | |
287 | } | |
288 | EXPORT_SYMBOL(kvfree); | |
289 | ||
290 | struct address_space *page_mapping(struct page *page) | |
291 | { | |
292 | struct address_space *mapping = page->mapping; | |
293 | ||
294 | /* This happens if someone calls flush_dcache_page on slab page */ | |
295 | if (unlikely(PageSlab(page))) | |
296 | return NULL; | |
297 | ||
298 | if (unlikely(PageSwapCache(page))) { | |
299 | swp_entry_t entry; | |
300 | ||
301 | entry.val = page_private(page); | |
302 | mapping = swap_address_space(entry); | |
303 | } else if ((unsigned long)mapping & PAGE_MAPPING_ANON) | |
304 | mapping = NULL; | |
305 | return mapping; | |
306 | } | |
307 | ||
308 | int overcommit_ratio_handler(struct ctl_table *table, int write, | |
309 | void __user *buffer, size_t *lenp, | |
310 | loff_t *ppos) | |
311 | { | |
312 | int ret; | |
313 | ||
314 | ret = proc_dointvec(table, write, buffer, lenp, ppos); | |
315 | if (ret == 0 && write) | |
316 | sysctl_overcommit_kbytes = 0; | |
317 | return ret; | |
318 | } | |
319 | ||
320 | int overcommit_kbytes_handler(struct ctl_table *table, int write, | |
321 | void __user *buffer, size_t *lenp, | |
322 | loff_t *ppos) | |
323 | { | |
324 | int ret; | |
325 | ||
326 | ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos); | |
327 | if (ret == 0 && write) | |
328 | sysctl_overcommit_ratio = 0; | |
329 | return ret; | |
330 | } | |
331 | ||
332 | /* | |
333 | * Committed memory limit enforced when OVERCOMMIT_NEVER policy is used | |
334 | */ | |
335 | unsigned long vm_commit_limit(void) | |
336 | { | |
337 | unsigned long allowed; | |
338 | ||
339 | if (sysctl_overcommit_kbytes) | |
340 | allowed = sysctl_overcommit_kbytes >> (PAGE_SHIFT - 10); | |
341 | else | |
342 | allowed = ((totalram_pages - hugetlb_total_pages()) | |
343 | * sysctl_overcommit_ratio / 100); | |
344 | allowed += total_swap_pages; | |
345 | ||
346 | return allowed; | |
347 | } | |
348 | ||
349 | /** | |
350 | * get_cmdline() - copy the cmdline value to a buffer. | |
351 | * @task: the task whose cmdline value to copy. | |
352 | * @buffer: the buffer to copy to. | |
353 | * @buflen: the length of the buffer. Larger cmdline values are truncated | |
354 | * to this length. | |
355 | * Returns the size of the cmdline field copied. Note that the copy does | |
356 | * not guarantee an ending NULL byte. | |
357 | */ | |
358 | int get_cmdline(struct task_struct *task, char *buffer, int buflen) | |
359 | { | |
360 | int res = 0; | |
361 | unsigned int len; | |
362 | struct mm_struct *mm = get_task_mm(task); | |
363 | if (!mm) | |
364 | goto out; | |
365 | if (!mm->arg_end) | |
366 | goto out_mm; /* Shh! No looking before we're done */ | |
367 | ||
368 | len = mm->arg_end - mm->arg_start; | |
369 | ||
370 | if (len > buflen) | |
371 | len = buflen; | |
372 | ||
373 | res = access_process_vm(task, mm->arg_start, buffer, len, 0); | |
374 | ||
375 | /* | |
376 | * If the nul at the end of args has been overwritten, then | |
377 | * assume application is using setproctitle(3). | |
378 | */ | |
379 | if (res > 0 && buffer[res-1] != '\0' && len < buflen) { | |
380 | len = strnlen(buffer, res); | |
381 | if (len < res) { | |
382 | res = len; | |
383 | } else { | |
384 | len = mm->env_end - mm->env_start; | |
385 | if (len > buflen - res) | |
386 | len = buflen - res; | |
387 | res += access_process_vm(task, mm->env_start, | |
388 | buffer+res, len, 0); | |
389 | res = strnlen(buffer, res); | |
390 | } | |
391 | } | |
392 | out_mm: | |
393 | mmput(mm); | |
394 | out: | |
395 | return res; | |
396 | } |