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Subject[PATCH v4 1/3] Make call_usermodehelper_exec possible to set namespaces
Date
Current call_usermodehelper_work() can not set namespaces for
the executed program.

This patch add above function for call_usermodehelper_work().
The init_intermediate is introduced for init works which should
be done before fork(). So that we get a method to set namespaces
for children. The cleanup_intermediate is introduced for cleaning
up what we have done in init_intermediate, like switching back
the namespace.

This function is helpful for coredump to run pipe_program in
specific container environment.

Signed-off-by: Cao Shufeng <caosf.fnst@cn.fujitsu.com>
Co-author-by: Zhao Lei <zhaolei@cn.fujitsu.com>
---
fs/coredump.c | 3 ++-
include/linux/kmod.h | 4 ++++
init/do_mounts_initrd.c | 3 ++-
kernel/kmod.c | 43 +++++++++++++++++++++++++++++++++++--------
lib/kobject_uevent.c | 3 ++-
security/keys/request_key.c | 4 ++--
6 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/fs/coredump.c b/fs/coredump.c
index 281b768..52f2ed6 100644
--- a/fs/coredump.c
+++ b/fs/coredump.c
@@ -641,7 +641,8 @@ void do_coredump(const siginfo_t *siginfo)
retval = -ENOMEM;
sub_info = call_usermodehelper_setup(helper_argv[0],
helper_argv, NULL, GFP_KERNEL,
- umh_pipe_setup, NULL, &cprm);
+ NULL, NULL, umh_pipe_setup,
+ NULL, &cprm);
if (sub_info)
retval = call_usermodehelper_exec(sub_info,
UMH_WAIT_EXEC);
diff --git a/include/linux/kmod.h b/include/linux/kmod.h
index fcfd2bf..994e429 100644
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -61,6 +61,8 @@ struct subprocess_info {
char **envp;
int wait;
int retval;
+ void (*init_intermediate)(struct subprocess_info *info);
+ void (*cleanup_intermediate)(struct subprocess_info *info);
int (*init)(struct subprocess_info *info, struct cred *new);
void (*cleanup)(struct subprocess_info *info);
void *data;
@@ -71,6 +73,8 @@ call_usermodehelper(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,
+ void (*init_intermediate)(struct subprocess_info *info),
+ void (*cleanup_intermediate)(struct subprocess_info *info),
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *), void *data);

diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c
index a1000ca..59d11c9 100644
--- a/init/do_mounts_initrd.c
+++ b/init/do_mounts_initrd.c
@@ -72,7 +72,8 @@ static void __init handle_initrd(void)
current->flags |= PF_FREEZER_SKIP;

info = call_usermodehelper_setup("/linuxrc", argv, envp_init,
- GFP_KERNEL, init_linuxrc, NULL, NULL);
+ GFP_KERNEL, NULL, NULL, init_linuxrc,
+ NULL, NULL);
if (!info)
return;
call_usermodehelper_exec(info, UMH_WAIT_PROC);
diff --git a/kernel/kmod.c b/kernel/kmod.c
index 0277d12..42f5a74 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -91,7 +91,8 @@ static int call_modprobe(char *module_name, int wait)
argv[4] = NULL;

info = call_usermodehelper_setup(modprobe_path, argv, envp, GFP_KERNEL,
- NULL, free_modprobe_argv, NULL);
+ NULL, NULL, NULL, free_modprobe_argv,
+ NULL);
if (!info)
goto free_module_name;

@@ -301,6 +302,9 @@ static void call_usermodehelper_exec_sync(struct subprocess_info *sub_info)
/* Restore default kernel sig handler */
kernel_sigaction(SIGCHLD, SIG_IGN);

+ if(sub_info->cleanup_intermediate) {
+ sub_info->cleanup_intermediate(sub_info);
+ }
umh_complete(sub_info);
}

@@ -322,6 +326,9 @@ static void call_usermodehelper_exec_work(struct work_struct *work)
{
struct subprocess_info *sub_info =
container_of(work, struct subprocess_info, work);
+ if(sub_info->init_intermediate) {
+ sub_info->init_intermediate(sub_info);
+ }

if (sub_info->wait & UMH_WAIT_PROC) {
call_usermodehelper_exec_sync(sub_info);
@@ -334,6 +341,11 @@ static void call_usermodehelper_exec_work(struct work_struct *work)
*/
pid = kernel_thread(call_usermodehelper_exec_async, sub_info,
CLONE_PARENT | SIGCHLD);
+
+ if(sub_info->cleanup_intermediate) {
+ sub_info->cleanup_intermediate(sub_info);
+ }
+
if (pid < 0) {
sub_info->retval = pid;
umh_complete(sub_info);
@@ -499,25 +511,38 @@ static void helper_unlock(void)
* @argv: arg vector for process
* @envp: environment for process
* @gfp_mask: gfp mask for memory allocation
- * @cleanup: a cleanup function
+ * @init_intermediate: init function which is called in parent task
+ * @cleanup_intermediate: clean function which is called in parent task
* @init: an init function
+ * @cleanup: a cleanup function
* @data: arbitrary context sensitive data
*
* Returns either %NULL on allocation failure, or a subprocess_info
* structure. This should be passed to call_usermodehelper_exec to
* exec the process and free the structure.
*
- * The init function is used to customize the helper process prior to
- * exec. A non-zero return code causes the process to error out, exit,
- * and return the failure to the calling process
+ * The init_intermediate is called in the parent task of user mode
+ * helper. It's designed for init works which must be done in
+ * parent task, like switching the pid_ns_for_children.
+ *
+ * The cleanup_intermediate is used when we want to cleanup what
+ * we have done in init_intermediate, it is also called in parent
+ * task.
+ *
+ * The init function is called after fork. It is used to customize the
+ * helper process prior to exec. A non-zero return code causes the
+ * process to error out, exit, and return the failure to the
+ * calling process.
*
- * The cleanup function is just before ethe subprocess_info is about to
+ * The cleanup function is just before the subprocess_info is about to
* be freed. This can be used for freeing the argv and envp. The
* 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,
char **envp, gfp_t gfp_mask,
+ void (*init_intermediate)(struct subprocess_info *info),
+ void (*cleanup_intermediate)(struct subprocess_info *info),
int (*init)(struct subprocess_info *info, struct cred *new),
void (*cleanup)(struct subprocess_info *info),
void *data)
@@ -532,8 +557,10 @@ struct subprocess_info *call_usermodehelper_setup(char *path, char **argv,
sub_info->argv = argv;
sub_info->envp = envp;

- sub_info->cleanup = cleanup;
+ sub_info->init_intermediate = init_intermediate;
+ sub_info->cleanup_intermediate = cleanup_intermediate;
sub_info->init = init;
+ sub_info->cleanup = cleanup;
sub_info->data = data;
out:
return sub_info;
@@ -619,7 +646,7 @@ int call_usermodehelper(char *path, char **argv, char **envp, int wait)
gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL;

info = call_usermodehelper_setup(path, argv, envp, gfp_mask,
- NULL, NULL, NULL);
+ NULL, NULL, NULL, NULL, NULL);
if (info == NULL)
return -ENOMEM;

diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index f6c2c1e..7a7c57a 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -345,7 +345,8 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action,
retval = -ENOMEM;
info = call_usermodehelper_setup(env->argv[0], env->argv,
env->envp, GFP_KERNEL,
- NULL, cleanup_uevent_env, env);
+ NULL, NULL, NULL,
+ cleanup_uevent_env, env);
if (info) {
retval = call_usermodehelper_exec(info, UMH_NO_WAIT);
env = NULL; /* freed by cleanup_uevent_env */
diff --git a/security/keys/request_key.c b/security/keys/request_key.c
index 43affcf..51dfb38 100644
--- a/security/keys/request_key.c
+++ b/security/keys/request_key.c
@@ -78,8 +78,8 @@ static int call_usermodehelper_keys(char *path, char **argv, char **envp,
struct subprocess_info *info;

info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
- umh_keys_init, umh_keys_cleanup,
- session_keyring);
+ NULL, NULL, umh_keys_init,
+ umh_keys_cleanup, session_keyring);
if (!info)
return -ENOMEM;

--
2.7.4


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