1
2#include <linux/fs.h>
3#include <linux/fs_struct.h>
4#include <linux/kernel_read_file.h>
5#include <linux/security.h>
6#include <linux/vmalloc.h>
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35int kernel_read_file(struct file *file, loff_t offset, void **buf,
36 size_t buf_size, size_t *file_size,
37 enum kernel_read_file_id id)
38{
39 loff_t i_size, pos;
40 size_t copied;
41 void *allocated = NULL;
42 bool whole_file;
43 int ret;
44
45 if (offset != 0 && (!*buf || !file_size))
46 return -EINVAL;
47
48 if (!S_ISREG(file_inode(file)->i_mode))
49 return -EINVAL;
50
51 ret = deny_write_access(file);
52 if (ret)
53 return ret;
54
55 i_size = i_size_read(file_inode(file));
56 if (i_size <= 0) {
57 ret = -EINVAL;
58 goto out;
59 }
60
61 if (i_size > INT_MAX) {
62 ret = -EFBIG;
63 goto out;
64 }
65
66 if (!file_size && offset == 0 && i_size > buf_size) {
67 ret = -EFBIG;
68 goto out;
69 }
70
71 whole_file = (offset == 0 && i_size <= buf_size);
72 ret = security_kernel_read_file(file, id, whole_file);
73 if (ret)
74 goto out;
75
76 if (file_size)
77 *file_size = i_size;
78
79 if (!*buf)
80 *buf = allocated = vmalloc(i_size);
81 if (!*buf) {
82 ret = -ENOMEM;
83 goto out;
84 }
85
86 pos = offset;
87 copied = 0;
88 while (copied < buf_size) {
89 ssize_t bytes;
90 size_t wanted = min_t(size_t, buf_size - copied,
91 i_size - pos);
92
93 bytes = kernel_read(file, *buf + copied, wanted, &pos);
94 if (bytes < 0) {
95 ret = bytes;
96 goto out_free;
97 }
98
99 if (bytes == 0)
100 break;
101 copied += bytes;
102 }
103
104 if (whole_file) {
105 if (pos != i_size) {
106 ret = -EIO;
107 goto out_free;
108 }
109
110 ret = security_kernel_post_read_file(file, *buf, i_size, id);
111 }
112
113out_free:
114 if (ret < 0) {
115 if (allocated) {
116 vfree(*buf);
117 *buf = NULL;
118 }
119 }
120
121out:
122 allow_write_access(file);
123 return ret == 0 ? copied : ret;
124}
125EXPORT_SYMBOL_GPL(kernel_read_file);
126
127int kernel_read_file_from_path(const char *path, loff_t offset, void **buf,
128 size_t buf_size, size_t *file_size,
129 enum kernel_read_file_id id)
130{
131 struct file *file;
132 int ret;
133
134 if (!path || !*path)
135 return -EINVAL;
136
137 file = filp_open(path, O_RDONLY, 0);
138 if (IS_ERR(file))
139 return PTR_ERR(file);
140
141 ret = kernel_read_file(file, offset, buf, buf_size, file_size, id);
142 fput(file);
143 return ret;
144}
145EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
146
147int kernel_read_file_from_path_initns(const char *path, loff_t offset,
148 void **buf, size_t buf_size,
149 size_t *file_size,
150 enum kernel_read_file_id id)
151{
152 struct file *file;
153 struct path root;
154 int ret;
155
156 if (!path || !*path)
157 return -EINVAL;
158
159 task_lock(&init_task);
160 get_fs_root(init_task.fs, &root);
161 task_unlock(&init_task);
162
163 file = file_open_root(&root, path, O_RDONLY, 0);
164 path_put(&root);
165 if (IS_ERR(file))
166 return PTR_ERR(file);
167
168 ret = kernel_read_file(file, offset, buf, buf_size, file_size, id);
169 fput(file);
170 return ret;
171}
172EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
173
174int kernel_read_file_from_fd(int fd, loff_t offset, void **buf,
175 size_t buf_size, size_t *file_size,
176 enum kernel_read_file_id id)
177{
178 struct fd f = fdget(fd);
179 int ret = -EBADF;
180
181 if (!f.file)
182 goto out;
183
184 ret = kernel_read_file(f.file, offset, buf, buf_size, file_size, id);
185out:
186 fdput(f);
187 return ret;
188}
189EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
190