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
|
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/fs.h>
#include <linux/fs_struct.h>
#include <linux/kernel_read_file.h>
#include <linux/security.h>
#include <linux/vmalloc.h>
/**
* kernel_read_file() - read file contents into a kernel buffer
*
* @file file to read from
* @buf pointer to a "void *" buffer for reading into (if
* *@buf is NULL, a buffer will be allocated, and
* @buf_size will be ignored)
* @buf_size size of buf, if already allocated. If @buf not
* allocated, this is the largest size to allocate.
* @id the kernel_read_file_id identifying the type of
* file contents being read (for LSMs to examine)
*
* Returns number of bytes read (no single read will be bigger
* than INT_MAX), or negative on error.
*
*/
int kernel_read_file(struct file *file, void **buf,
size_t buf_size, enum kernel_read_file_id id)
{
loff_t i_size, pos;
ssize_t bytes = 0;
void *allocated = NULL;
int ret;
if (!S_ISREG(file_inode(file)->i_mode))
return -EINVAL;
ret = deny_write_access(file);
if (ret)
return ret;
ret = security_kernel_read_file(file, id);
if (ret)
goto out;
i_size = i_size_read(file_inode(file));
if (i_size <= 0) {
ret = -EINVAL;
goto out;
}
if (i_size > INT_MAX || i_size > buf_size) {
ret = -EFBIG;
goto out;
}
if (!*buf)
*buf = allocated = vmalloc(i_size);
if (!*buf) {
ret = -ENOMEM;
goto out;
}
pos = 0;
while (pos < i_size) {
bytes = kernel_read(file, *buf + pos, i_size - pos, &pos);
if (bytes < 0) {
ret = bytes;
goto out_free;
}
if (bytes == 0)
break;
}
if (pos != i_size) {
ret = -EIO;
goto out_free;
}
ret = security_kernel_post_read_file(file, *buf, i_size, id);
out_free:
if (ret < 0) {
if (allocated) {
vfree(*buf);
*buf = NULL;
}
}
out:
allow_write_access(file);
return ret == 0 ? pos : ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file);
int kernel_read_file_from_path(const char *path, void **buf,
size_t buf_size, enum kernel_read_file_id id)
{
struct file *file;
int ret;
if (!path || !*path)
return -EINVAL;
file = filp_open(path, O_RDONLY, 0);
if (IS_ERR(file))
return PTR_ERR(file);
ret = kernel_read_file(file, buf, buf_size, id);
fput(file);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path);
int kernel_read_file_from_path_initns(const char *path, void **buf,
size_t buf_size,
enum kernel_read_file_id id)
{
struct file *file;
struct path root;
int ret;
if (!path || !*path)
return -EINVAL;
task_lock(&init_task);
get_fs_root(init_task.fs, &root);
task_unlock(&init_task);
file = file_open_root(root.dentry, root.mnt, path, O_RDONLY, 0);
path_put(&root);
if (IS_ERR(file))
return PTR_ERR(file);
ret = kernel_read_file(file, buf, buf_size, id);
fput(file);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_path_initns);
int kernel_read_file_from_fd(int fd, void **buf, size_t buf_size,
enum kernel_read_file_id id)
{
struct fd f = fdget(fd);
int ret = -EBADF;
if (!f.file)
goto out;
ret = kernel_read_file(f.file, buf, buf_size, id);
out:
fdput(f);
return ret;
}
EXPORT_SYMBOL_GPL(kernel_read_file_from_fd);
|
