Messages in this thread Patch in this message | | | Subject | [RFC PATCH 5 2/7] kmod - teach usermodehelper to use service workqueues | From | Ian Kent <> | Date | Tue, 31 Mar 2015 11:14:50 +0800 |
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The call_usermodehelper() function executes all binaries in the global "init" root context. This doesn't allow a binary to be run within a namespace environment such as a container. To do this the namespace environment of the contaner must be available to provide the required execution environment.
This can be done by creating a service thread, identified by issuing a token identifier, used when executing the helper with a function that takes the token as a parameter.
Signed-off-by: Ian Kent <ikent@redhat.com> Cc: Benjamin Coddington <bcodding@redhat.com> Cc: Al Viro <viro@ZenIV.linux.org.uk> Cc: J. Bruce Fields <bfields@fieldses.org> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <trond.myklebust@primarydata.com> Cc: Oleg Nesterov <onestero@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Jeff Layton <jeff.layton@primarydata.com> --- include/linux/kmod.h | 5 +++++ kernel/kmod.c | 38 +++++++++++++++++++++++++++++++------- 2 files changed, 36 insertions(+), 7 deletions(-)
diff --git a/include/linux/kmod.h b/include/linux/kmod.h index fa46722..9a9fcb3 100644 --- a/include/linux/kmod.h +++ b/include/linux/kmod.h @@ -56,6 +56,7 @@ struct file; struct subprocess_info { struct work_struct work; struct completion *complete; + int wq_token; char *path; char **argv; char **envp; @@ -72,6 +73,10 @@ extern void umh_wq_put_token(int token); extern int call_usermodehelper(char *path, char **argv, char **envp, int wait); +extern int +call_usermodehelper_service(char *path, char **argv, + char **envp, int token, int wait); + extern struct subprocess_info * call_usermodehelper_setup(char *path, char **argv, char **envp, gfp_t gfp_mask, int (*init)(struct subprocess_info *info, struct cred *new), diff --git a/kernel/kmod.c b/kernel/kmod.c index 55d20ce..47c5ff5 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -712,6 +712,7 @@ EXPORT_SYMBOL(call_usermodehelper_setup); */ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) { + static struct workqueue_struct *wq; DECLARE_COMPLETION_ONSTACK(done); int retval = 0; @@ -720,7 +721,8 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) return -EINVAL; } helper_lock(); - if (!khelper_wq || usermodehelper_disabled) { + wq = umh_find_wq(sub_info->wq_token, wait); + if (!wq || usermodehelper_disabled) { retval = -EBUSY; goto out; } @@ -732,7 +734,7 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info, int wait) sub_info->complete = (wait == UMH_NO_WAIT) ? NULL : &done; sub_info->wait = wait; - queue_work(khelper_wq, &sub_info->work); + queue_work(wq, &sub_info->work); if (wait == UMH_NO_WAIT) /* task has freed sub_info */ goto unlock; @@ -759,19 +761,21 @@ unlock: EXPORT_SYMBOL(call_usermodehelper_exec); /** - * call_usermodehelper() - prepare and start a usermode application + * call_usermodehelper_service() - start a usermode application within + * a service environment. * @path: path to usermode executable * @argv: arg vector for process * @envp: environment for process + * @token: token corresponding to a service environment obtained by a + * call to umh_wq_get_token(). * @wait: wait for the application to finish and return status. * when UMH_NO_WAIT don't wait at all, but you get no useful error back * when the program couldn't be exec'ed. This makes it safe to call * from interrupt context. - * - * This function is the equivalent to use call_usermodehelper_setup() and - * call_usermodehelper_exec(). */ -int call_usermodehelper(char *path, char **argv, char **envp, int wait) +int call_usermodehelper_service(char *path, + char **argv, char **envp, + int token, int wait) { struct subprocess_info *info; gfp_t gfp_mask = (wait == UMH_NO_WAIT) ? GFP_ATOMIC : GFP_KERNEL; @@ -780,9 +784,29 @@ int call_usermodehelper(char *path, char **argv, char **envp, int wait) NULL, NULL, NULL); if (info == NULL) return -ENOMEM; + info->wq_token = token; return call_usermodehelper_exec(info, wait); } +EXPORT_SYMBOL(call_usermodehelper_service); + +/** + * call_usermodehelper() - prepare and start a usermode application + * @path: path to usermode executable + * @argv: arg vector for process + * @envp: environment for process + * @wait: wait for the application to finish and return status. + * when UMH_NO_WAIT don't wait at all, but you get no useful error back + * when the program couldn't be exec'ed. This makes it safe to call + * from interrupt context. + * + * This function is the equivalent to using call_usermodehelper_setup() and + * call_usermodehelper_exec(). + */ +int call_usermodehelper(char *path, char **argv, char **envp, int wait) +{ + return call_usermodehelper_service(path, argv, envp, 0, wait); +} EXPORT_SYMBOL(call_usermodehelper); static int proc_cap_handler(struct ctl_table *table, int write,
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