[PATCH 1/4] kmod: make usermodehelper path a const string

Greg KH
2016-12-14T18:50:20Z

This is in preparation for making it so that usermode helper programs
can't be changed, if desired, by userspace. We will tackle the mess of
cleaning up the write-ability of argv and env later, that's going to
take more work, for much less gain...

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/kmod.h | 7 ++++---
kernel/kmod.c | 4 ++--
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index fcfd2bf14d3f..c4e441e00db5 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -56,7 +56,7 @@ struct file;
struct subprocess_info {
struct work_struct work;
struct completion *complete;
- char *path;
+ const char *path;
char **argv;
char **envp;
int wait;
@@ -67,10 +67,11 @@ struct subprocess_info {
};

extern int
-call_usermodehelper(char *path, char **argv, char **envp, int wait);
+call_usermodehelper(const char *path, char **argv, char **envp, int wait);

extern struct subprocess_info *
-call_usermodehelper_setup(char *path, char **argv, char **envp, gfp_t gfp_mask,
+call_usermodehelper_setup(const char *path, char **argv, char **envp,
+ gfp_t gfp_mask,
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *), void *data);

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 0277d1216f80..0c216b76afca 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -516,7 +516,7 @@ static void helper_unlock(void)
* Function must be runnable in either a process context or the
* context in which call_usermodehelper_exec is called.
*/
-struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
+struct subprocess_info *call_usermodehelper_setup(const char *path, char **argv,
char **envp, gfp_t gfp_mask,
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *info),
@@ -613,7 +613,7 @@ EXPORT_SYMBOL(call_usermodehelper_exec);
* This function is the equivalent to use call_usermodehelper_setup() and
* call_usermodehelper_exec().
*/
-int call_usermodehelper(char *path, char **argv, char **envp, int wait)
+int call_usermodehelper(const char *path, char **argv, char **envp, int wait)
{
struct subprocess_info *info;
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;
--
2.10.2