From f0663000645c11336bbd097ee5d8186f23188c38 Mon Sep 17 00:00:00 2001 From: Olivier Brunel Date: Sat, 20 Oct 2018 19:39:56 +0200 Subject: [PATCH 2355/2944] umh: Add command line to user mode helpers to #29598827 commit 876dcf2f3aaa0f68d437b368b93a4c4b81521191 upstream. User mode helpers were spawned without a command line, and because an empty command line is used by many tools to identify processes as kernel threads, this could cause some issues. Notably during killing spree on shutdown, since such helper would then be skipped (i.e. not killed) which would result in the process remaining alive, and thus preventing unmouting of the rootfs (as experienced with the bpfilter umh). Fixes: 449325b52b7a ("umh: introduce fork_usermode_blob() helper") Signed-off-by: Olivier Brunel Signed-off-by: David S. Miller Signed-off-by: Tony Lu Acked-by: Dust Li --- include/linux/umh.h | 1 + kernel/umh.c | 16 ++++++++++++++-- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/include/linux/umh.h b/include/linux/umh.h index f665e59..0c08de3 100644 --- a/include/linux/umh.h +++ b/include/linux/umh.h @@ -44,6 +44,7 @@ struct subprocess_info *call_usermodehelper_setup_file(struct file *file, int (*init)(struct subprocess_info *info, struct cred *new), void (*cleanup)(struct subprocess_info *), void *data); struct umh_info { + const char *cmdline; struct file *pipe_to_umh; struct file *pipe_from_umh; struct list_head list; diff --git a/kernel/umh.c b/kernel/umh.c index 931ab8b..d937cba 100644 --- a/kernel/umh.c +++ b/kernel/umh.c @@ -409,11 +409,19 @@ struct subprocess_info *call_usermodehelper_setup_file(struct file *file, void (*cleanup)(struct subprocess_info *info), void *data) { struct subprocess_info *sub_info; + struct umh_info *info = data; + const char *cmdline = (info->cmdline) ? info->cmdline : "usermodehelper"; sub_info = kzalloc(sizeof(struct subprocess_info), GFP_KERNEL); if (!sub_info) return NULL; + sub_info->argv = argv_split(GFP_KERNEL, cmdline, NULL); + if (!sub_info->argv) { + kfree(sub_info); + return NULL; + } + INIT_WORK(&sub_info->work, call_usermodehelper_exec_work); sub_info->path = "none"; sub_info->file = file; @@ -462,10 +470,11 @@ static int umh_pipe_setup(struct subprocess_info *info, struct cred *new) return 0; } -static void umh_save_pid(struct subprocess_info *info) +static void umh_clean_and_save_pid(struct subprocess_info *info) { struct umh_info *umh_info = info->data; + argv_free(info->argv); umh_info->pid = info->pid; } @@ -475,6 +484,9 @@ static void umh_save_pid(struct subprocess_info *info) * @len: length of the blob * @info: information about usermode process (shouldn't be NULL) * + * If info->cmdline is set it will be used as command line for the + * user process, else "usermodehelper" is used. + * * Returns either negative error or zero which indicates success * in executing a blob of bytes as a usermode process. In such * case 'struct umh_info *info' is populated with two pipes @@ -504,7 +516,7 @@ int fork_usermode_blob(void *data, size_t len, struct umh_info *info) err = -ENOMEM; sub_info = call_usermodehelper_setup_file(file, umh_pipe_setup, - umh_save_pid, info); + umh_clean_and_save_pid, info); if (!sub_info) goto out; -- 1.8.3.1