path: root/kernel/umh.c
diff options
authorOlivier Brunel <jjk@jjacky.com>2018-10-20 19:39:56 +0200
committerDavid S. Miller <davem@davemloft.net>2018-10-22 19:37:36 -0700
commit876dcf2f3aaa0f68d437b368b93a4c4b81521191 (patch)
tree839b76ae222a0ecd942d4af9a6099336b366d549 /kernel/umh.c
parentc94f026fb742b2d3199422751dbc4f6fc0e753d8 (diff)
umh: Add command line to user mode helpers
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 <jjk@jjacky.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/umh.c')
1 files changed, 14 insertions, 2 deletions
diff --git a/kernel/umh.c b/kernel/umh.c
index c449858946af..0baa672e023c 100644
--- a/kernel/umh.c
+++ b/kernel/umh.c
@@ -405,11 +405,19 @@ 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;
@@ -458,10 +466,11 @@ 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;
@@ -471,6 +480,9 @@ 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
@@ -500,7 +512,7 @@ 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;

Privacy Policy