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module: replace copy_module_from_fd with kernel version 

Replace copy_module_from_fd() with kernel_read_file_from_fd().

Although none of the upstreamed LSMs define a kernel_module_from_file
hook, IMA is called, based on policy, to prevent unsigned kernel modules
from being loaded by the original kernel module syscall and to
measure/appraise signed kernel modules.

The security function security_kernel_module_from_file() was called prior
to reading a kernel module.  Preventing unsigned kernel modules from being
loaded by the original kernel module syscall remains on the pre-read
kernel_read_file() security hook.  Instead of reading the kernel module
twice, once for measuring/appraising and again for loading the kernel
module, the signature validation is moved to the kernel_post_read_file()
security hook.

This patch removes the security_kernel_module_from_file() hook and security
call.

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Mimi Zohar 2015-12-30 07:35:30 -05:00
parent b844f0ecbc
commit a1db742094
7 changed files with 22 additions and 112 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/fs.h
View File

@ -2578,6 +2578,7 @@ extern int do_pipe_flags(int *, int);
enum kernel_read_file_id {
READING_FIRMWARE = 1,
READING_MODULE,
READING_MAX_ID
};

6
include/linux/ima.h
View File

@ -18,7 +18,6 @@ extern int ima_bprm_check(struct linux_binprm *bprm);
extern int ima_file_check(struct file *file, int mask, int opened);
extern void ima_file_free(struct file *file);
extern int ima_file_mmap(struct file *file, unsigned long prot);
extern int ima_module_check(struct file *file);
extern int ima_read_file(struct file *file, enum kernel_read_file_id id);
extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
enum kernel_read_file_id id);
@ -44,11 +43,6 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot)
return 0;
}
static inline int ima_module_check(struct file *file)
{
return 0;
}
static inline int ima_read_file(struct file *file, enum kernel_read_file_id id)
{
return 0;

7
include/linux/lsm_hooks.h
View File

@ -546,12 +546,6 @@
* userspace to load a kernel module with the given name.
* @kmod_name name of the module requested by the kernel
* Return 0 if successful.
* @kernel_module_from_file:
* Load a kernel module from userspace.
* @file contains the file structure pointing to the file containing
* the kernel module to load. If the module is being loaded from a blob,
* this argument will be NULL.
* Return 0 if permission is granted.
* @kernel_read_file:
* Read a file specified by userspace.
* @file contains the file structure pointing to the file being read
@ -1725,7 +1719,6 @@ struct security_hook_heads {
struct list_head kernel_read_file;
struct list_head kernel_post_read_file;
struct list_head kernel_module_request;
struct list_head kernel_module_from_file;
struct list_head task_fix_setuid;
struct list_head task_setpgid;
struct list_head task_getpgid;

5
include/linux/security.h
View File

@ -859,11 +859,6 @@ static inline int security_kernel_module_request(char *kmod_name)
return 0;
}
static inline int security_kernel_module_from_file(struct file *file)
{
return 0;
}
static inline int security_kernel_read_file(struct file *file,
enum kernel_read_file_id id)
{

68
kernel/module.c
View File

@ -2654,7 +2654,7 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
if (info->len < sizeof(*(info->hdr)))
return -ENOEXEC;
err = security_kernel_module_from_file(NULL);
err = security_kernel_read_file(NULL, READING_MODULE);
if (err)
return err;
@ -2672,63 +2672,6 @@ static int copy_module_from_user(const void __user *umod, unsigned long len,
return 0;
}
/* Sets info->hdr and info->len. */
static int copy_module_from_fd(int fd, struct load_info *info)
{
struct fd f = fdget(fd);
int err;
struct kstat stat;
loff_t pos;
ssize_t bytes = 0;
if (!f.file)
return -ENOEXEC;
err = security_kernel_module_from_file(f.file);
if (err)
goto out;
err = vfs_getattr(&f.file->f_path, &stat);
if (err)
goto out;
if (stat.size > INT_MAX) {
err = -EFBIG;
goto out;
}
/* Don't hand 0 to vmalloc, it whines. */
if (stat.size == 0) {
err = -EINVAL;
goto out;
}
info->hdr = vmalloc(stat.size);
if (!info->hdr) {
err = -ENOMEM;
goto out;
}
pos = 0;
while (pos < stat.size) {
bytes = kernel_read(f.file, pos, (char *)(info->hdr) + pos,
stat.size - pos);
if (bytes < 0) {
vfree(info->hdr);
err = bytes;
goto out;
}
if (bytes == 0)
break;
pos += bytes;
}
info->len = pos;
out:
fdput(f);
return err;
}
static void free_copy(struct load_info *info)
{
vfree(info->hdr);
@ -3589,8 +3532,10 @@ SYSCALL_DEFINE3(init_module, void __user *, umod,
SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
{
int err;
struct load_info info = { };
loff_t size;
void *hdr;
int err;
err = may_init_module();
if (err)
@ -3602,9 +3547,12 @@ SYSCALL_DEFINE3(finit_module, int, fd, const char __user *, uargs, int, flags)
|MODULE_INIT_IGNORE_VERMAGIC))
return -EINVAL;
err = copy_module_from_fd(fd, &info);
err = kernel_read_file_from_fd(fd, &hdr, &size, INT_MAX,
READING_MODULE);
if (err)
return err;
info.hdr = hdr;
info.len = size;
return load_module(&info, uargs, flags);
}

35
security/integrity/ima/ima_main.c
View File

@ -315,28 +315,6 @@ int ima_file_check(struct file *file, int mask, int opened)
}
EXPORT_SYMBOL_GPL(ima_file_check);
/**
* ima_module_check - based on policy, collect/store/appraise measurement.
* @file: pointer to the file to be measured/appraised
*
* Measure/appraise kernel modules based on policy.
*
* On success return 0. On integrity appraisal error, assuming the file
* is in policy and IMA-appraisal is in enforcing mode, return -EACCES.
*/
int ima_module_check(struct file *file)
{
if (!file) {
#ifndef CONFIG_MODULE_SIG_FORCE
if ((ima_appraise & IMA_APPRAISE_MODULES) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES; /* INTEGRITY_UNKNOWN */
#endif
return 0; /* We rely on module signature checking */
}
return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0);
}
/**
* ima_read_file - pre-measure/appraise hook decision based on policy
* @file: pointer to the file to be measured/appraised/audit
@ -350,6 +328,14 @@ int ima_module_check(struct file *file)
*/
int ima_read_file(struct file *file, enum kernel_read_file_id read_id)
{
if (!file && read_id == READING_MODULE) {
#ifndef CONFIG_MODULE_SIG_FORCE
if ((ima_appraise & IMA_APPRAISE_MODULES) &&
(ima_appraise & IMA_APPRAISE_ENFORCE))
return -EACCES; /* INTEGRITY_UNKNOWN */
#endif
return 0; /* We rely on module signature checking */
}
return 0;
}
@ -378,6 +364,9 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
return 0;
}
if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
return 0;
if (!file || !buf || size == 0) { /* should never happen */
if (ima_appraise & IMA_APPRAISE_ENFORCE)
return -EACCES;
@ -386,6 +375,8 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
if (read_id == READING_FIRMWARE)
func = FIRMWARE_CHECK;
else if (read_id == READING_MODULE)
func = MODULE_CHECK;
return process_measurement(file, buf, size, MAY_READ, func, 0);
}

12
security/security.c
View File

@ -889,16 +889,6 @@ int security_kernel_module_request(char *kmod_name)
return call_int_hook(kernel_module_request, 0, kmod_name);
}
int security_kernel_module_from_file(struct file *file)
{
int ret;
ret = call_int_hook(kernel_module_from_file, 0, file);
if (ret)
return ret;
return ima_module_check(file);
}
int security_kernel_read_file(struct file *file, enum kernel_read_file_id id)
{
int ret;
@ -1705,8 +1695,6 @@ struct security_hook_heads security_hook_heads = {
LIST_HEAD_INIT(security_hook_heads.kernel_create_files_as),
.kernel_module_request =
LIST_HEAD_INIT(security_hook_heads.kernel_module_request),
.kernel_module_from_file =
LIST_HEAD_INIT(security_hook_heads.kernel_module_from_file),
.kernel_read_file =
LIST_HEAD_INIT(security_hook_heads.kernel_read_file),
.kernel_post_read_file =