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From:   "Eric W. Biederman" <ebiederm@xmission.com>
To:     linux-kernel@vger.kernel.org
Cc:     David Miller <davem@davemloft.net>,
        Greg Kroah-Hartman <greg@kroah.com>,
        Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Alexei Starovoitov <ast@kernel.org>,
        Al Viro <viro@zeniv.linux.org.uk>, bpf <bpf@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        Gary Lin <GLin@suse.com>, Bruno Meneguele <bmeneg@redhat.com>,
        LSM List <linux-security-module@vger.kernel.org>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Luis Chamberlain <mcgrof@kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date:   Thu,  2 Jul 2020 11:41:25 -0500
Message-Id: <20200702164140.4468-1-ebiederm@xmission.com>
In-Reply-To: <87y2o1swee.fsf_-_@x220.int.ebiederm.org>
References: <87y2o1swee.fsf_-_@x220.int.ebiederm.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Subject: [PATCH v3 01/16] umh: Capture the pid in umh_pipe_setup
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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.

v1: https://lkml.kernel.org/r/87h7uygf9i.fsf_-_@x220.int.ebiederm.org
v2: https://lkml.kernel.org/r/875zb97iix.fsf_-_@x220.int.ebiederm.org
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
 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