1 #include <linux/mm.h>
2 #include <linux/slab.h>
3 #include <linux/string.h>
4 #include <linux/module.h>
5 #include <linux/err.h>
6 #include <linux/sched.h>
7 #include <asm/uaccess.h>
8
9 /**
10 * kstrdup - allocate space for and copy an existing string
11 * @s: the string to duplicate
12 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
13 */
kstrdup(const char * s,gfp_t gfp)14 char *kstrdup(const char *s, gfp_t gfp)
15 {
16 size_t len;
17 char *buf;
18
19 if (!s)
20 return NULL;
21
22 len = strlen(s) + 1;
23 buf = kmalloc_track_caller(len, gfp);
24 if (buf)
25 memcpy(buf, s, len);
26 return buf;
27 }
28 EXPORT_SYMBOL(kstrdup);
29
30 /**
31 * kstrndup - allocate space for and copy an existing string
32 * @s: the string to duplicate
33 * @max: read at most @max chars from @s
34 * @gfp: the GFP mask used in the kmalloc() call when allocating memory
35 */
kstrndup(const char * s,size_t max,gfp_t gfp)36 char *kstrndup(const char *s, size_t max, gfp_t gfp)
37 {
38 size_t len;
39 char *buf;
40
41 if (!s)
42 return NULL;
43
44 len = strnlen(s, max);
45 buf = kmalloc_track_caller(len+1, gfp);
46 if (buf) {
47 memcpy(buf, s, len);
48 buf[len] = '\0';
49 }
50 return buf;
51 }
52 EXPORT_SYMBOL(kstrndup);
53
54 /**
55 * kmemdup - duplicate region of memory
56 *
57 * @src: memory region to duplicate
58 * @len: memory region length
59 * @gfp: GFP mask to use
60 */
kmemdup(const void * src,size_t len,gfp_t gfp)61 void *kmemdup(const void *src, size_t len, gfp_t gfp)
62 {
63 void *p;
64
65 p = kmalloc_track_caller(len, gfp);
66 if (p)
67 memcpy(p, src, len);
68 return p;
69 }
70 EXPORT_SYMBOL(kmemdup);
71
72 /**
73 * __krealloc - like krealloc() but don't free @p.
74 * @p: object to reallocate memory for.
75 * @new_size: how many bytes of memory are required.
76 * @flags: the type of memory to allocate.
77 *
78 * This function is like krealloc() except it never frees the originally
79 * allocated buffer. Use this if you don't want to free the buffer immediately
80 * like, for example, with RCU.
81 */
__krealloc(const void * p,size_t new_size,gfp_t flags)82 void *__krealloc(const void *p, size_t new_size, gfp_t flags)
83 {
84 void *ret;
85 size_t ks = 0;
86
87 if (unlikely(!new_size))
88 return ZERO_SIZE_PTR;
89
90 if (p)
91 ks = ksize(p);
92
93 if (ks >= new_size)
94 return (void *)p;
95
96 ret = kmalloc_track_caller(new_size, flags);
97 if (ret && p)
98 memcpy(ret, p, ks);
99
100 return ret;
101 }
102 EXPORT_SYMBOL(__krealloc);
103
104 /**
105 * krealloc - reallocate memory. The contents will remain unchanged.
106 * @p: object to reallocate memory for.
107 * @new_size: how many bytes of memory are required.
108 * @flags: the type of memory to allocate.
109 *
110 * The contents of the object pointed to are preserved up to the
111 * lesser of the new and old sizes. If @p is %NULL, krealloc()
112 * behaves exactly like kmalloc(). If @size is 0 and @p is not a
113 * %NULL pointer, the object pointed to is freed.
114 */
krealloc(const void * p,size_t new_size,gfp_t flags)115 void *krealloc(const void *p, size_t new_size, gfp_t flags)
116 {
117 void *ret;
118
119 if (unlikely(!new_size)) {
120 kfree(p);
121 return ZERO_SIZE_PTR;
122 }
123
124 ret = __krealloc(p, new_size, flags);
125 if (ret && p != ret)
126 kfree(p);
127
128 return ret;
129 }
130 EXPORT_SYMBOL(krealloc);
131
132 /**
133 * kzfree - like kfree but zero memory
134 * @p: object to free memory of
135 *
136 * The memory of the object @p points to is zeroed before freed.
137 * If @p is %NULL, kzfree() does nothing.
138 */
kzfree(const void * p)139 void kzfree(const void *p)
140 {
141 size_t ks;
142 void *mem = (void *)p;
143
144 if (unlikely(ZERO_OR_NULL_PTR(mem)))
145 return;
146 ks = ksize(mem);
147 memset(mem, 0, ks);
148 kfree(mem);
149 }
150 EXPORT_SYMBOL(kzfree);
151
152 /*
153 * strndup_user - duplicate an existing string from user space
154 * @s: The string to duplicate
155 * @n: Maximum number of bytes to copy, including the trailing NUL.
156 */
strndup_user(const char __user * s,long n)157 char *strndup_user(const char __user *s, long n)
158 {
159 char *p;
160 long length;
161
162 length = strnlen_user(s, n);
163
164 if (!length)
165 return ERR_PTR(-EFAULT);
166
167 if (length > n)
168 return ERR_PTR(-EINVAL);
169
170 p = kmalloc(length, GFP_KERNEL);
171
172 if (!p)
173 return ERR_PTR(-ENOMEM);
174
175 if (copy_from_user(p, s, length)) {
176 kfree(p);
177 return ERR_PTR(-EFAULT);
178 }
179
180 p[length - 1] = '\0';
181
182 return p;
183 }
184 EXPORT_SYMBOL(strndup_user);
185
186 #ifndef HAVE_ARCH_PICK_MMAP_LAYOUT
arch_pick_mmap_layout(struct mm_struct * mm)187 void arch_pick_mmap_layout(struct mm_struct *mm)
188 {
189 mm->mmap_base = TASK_UNMAPPED_BASE;
190 mm->get_unmapped_area = arch_get_unmapped_area;
191 mm->unmap_area = arch_unmap_area;
192 }
193 #endif
194
get_user_pages_fast(unsigned long start,int nr_pages,int write,struct page ** pages)195 int __attribute__((weak)) get_user_pages_fast(unsigned long start,
196 int nr_pages, int write, struct page **pages)
197 {
198 struct mm_struct *mm = current->mm;
199 int ret;
200
201 down_read(&mm->mmap_sem);
202 ret = get_user_pages(current, mm, start, nr_pages,
203 write, 0, pages, NULL);
204 up_read(&mm->mmap_sem);
205
206 return ret;
207 }
208 EXPORT_SYMBOL_GPL(get_user_pages_fast);
209