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@xxxxxxxxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
---
include/linux/fs.h | 1 +
include/linux/ima.h | 6 ----
include/linux/lsm_hooks.h | 7 ----
include/linux/security.h | 5 ---
kernel/module.c | 68 +++++----------------------------------
security/integrity/ima/ima_main.c | 35 ++++++++------------
security/security.c | 12 -------
7 files changed, 22 insertions(+), 112 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9c85dea..fb08b66 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2578,6 +2578,7 @@ extern int do_pipe_flags(int *, int);
enum kernel_read_file_id {
READING_FIRMWARE = 1,
+ READING_MODULE,
READING_MAX_ID
};
diff --git a/include/linux/ima.h b/include/linux/ima.h
index 6adcaea..e6516cb 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -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;
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index d32b7bd..cdee11c 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -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;
diff --git a/include/linux/security.h b/include/linux/security.h
index 071fb74..157f0cb 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -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)
{
diff --git a/kernel/module.c b/kernel/module.c
index 8358f46..9554109 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -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);
}
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 80c24aa..f6039f5 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -316,28 +316,6 @@ 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
* @read_id: caller identifier
@@ -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);
}
diff --git a/security/security.c b/security/security.c
index 1728fe2..3573c82 100644
--- a/security/security.c
+++ b/security/security.c
@@ -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;
@@ -1703,8 +1693,6 @@ 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 =
--
2.1.0
--
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