[PATCH v2 01/15] umh: Capture the pid in umh_pipe_setup

From: Eric W. Biederman
Date: Mon Jun 29 2020 - 16:01:17 EST



The pid in struct subprocess_info is only used by umh_clean_and_save_pid to
write the pid into umh_info.

Instead always capture the pid on struct umh_info in umh_pipe_setup, removing
code that is specific to user mode drivers from the common user path of
user mode helpers.

Link: https://lkml.kernel.org/r/87h7uygf9i.fsf_-_@xxxxxxxxxxxxxxxxxxxxx
Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
---
include/linux/umh.h | 1 -
kernel/umh.c | 5 ++---
2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/include/linux/umh.h b/include/linux/umh.h
index 0c08de356d0d..aae16a0ebd0f 100644
--- a/include/linux/umh.h
+++ b/include/linux/umh.h
@@ -25,7 +25,6 @@ struct subprocess_info {
struct file *file;
int wait;
int retval;
- pid_t pid;
int (*init)(struct subprocess_info *info, struct cred *new);
void (*cleanup)(struct subprocess_info *info);
void *data;
diff --git a/kernel/umh.c b/kernel/umh.c
index 79f139a7ca03..c2a582b3a2bf 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -102,7 +102,6 @@ static int call_usermodehelper_exec_async(void *data)

commit_creds(new);

- sub_info->pid = task_pid_nr(current);
if (sub_info->file) {
retval = do_execve_file(sub_info->file,
sub_info->argv, sub_info->envp);
@@ -468,6 +467,7 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new)

umh_info->pipe_to_umh = to_umh[1];
umh_info->pipe_from_umh = from_umh[0];
+ umh_info->pid = task_pid_nr(current);
return 0;
}

@@ -476,13 +476,12 @@ static void umh_clean_and_save_pid(struct subprocess_info *info)
struct umh_info *umh_info = info->data;

/* cleanup if umh_pipe_setup() was successful but exec failed */
- if (info->pid && info->retval) {
+ if (info->retval) {
fput(umh_info->pipe_to_umh);
fput(umh_info->pipe_from_umh);
}

argv_free(info->argv);
- umh_info->pid = info->pid;
}

/**
--
2.25.0