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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [patch 03/44] usermodehelper: split setup from execution
Rather than having hundreds of variations of call_usermodehelper for
various pieces of usermode state which could be set up, split the
info allocation and initialization from the actual process execution.
This means the general pattern becomes:
info = call_usermodehelper_setup(path, argv, envp); /* basic state */
call_usermodehelper_<SET EXTRA STATE>(info, stuff...); /* extra state */
call_usermodehelper_exec(info, wait); /* run process and free info */
This patch introduces wrappers for all the existing calling styles for
call_usermodehelper_*, but folds their implementations into one.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Bj?rn Steinbrink <B.Steinbrink@xxxxxx>
Cc: Randy Dunlap <randy.dunlap@xxxxxxxxxx>
---
include/linux/kmod.h | 44 +++++++++-
kernel/kmod.c | 207 ++++++++++++++++++++++++++++++++++----------------
2 files changed, 184 insertions(+), 67 deletions(-)
===================================================================
--- a/include/linux/kmod.h
+++ b/include/linux/kmod.h
@@ -36,13 +36,51 @@ static inline int request_module(const c
#define try_then_request_module(x, mod...) ((x) ?: (request_module(mod), (x)))
struct key;
-extern int call_usermodehelper_keys(char *path, char *argv[], char *envp[],
- struct key *session_keyring, int wait);
+struct file;
+struct subprocess_info;
+
+/* Allocate a subprocess_info structure */
+struct subprocess_info *call_usermodehelper_setup(char *path,
+ char **argv, char **envp);
+
+/* Set various pieces of state into the subprocess_info structure */
+void call_usermodehelper_setkeys(struct subprocess_info *info,
+ struct key *session_keyring);
+int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
+ struct file **filp);
+void call_usermodehelper_setcleanup(struct subprocess_info *info,
+ void (*cleanup)(char **argv, char **envp));
+
+/* Actually execute the sub-process */
+int call_usermodehelper_exec(struct subprocess_info *info, int wait);
+
+/* Free the subprocess_info. This is only needed if you're not going
+ to call call_usermodehelper_exec */
+void call_usermodehelper_freeinfo(struct subprocess_info *info);
static inline int
call_usermodehelper(char *path, char **argv, char **envp, int wait)
{
- return call_usermodehelper_keys(path, argv, envp, NULL, wait);
+ struct subprocess_info *info;
+
+ info = call_usermodehelper_setup(path, argv, envp);
+ if (info == NULL)
+ return -ENOMEM;
+ return call_usermodehelper_exec(info, wait);
+}
+
+static inline int
+call_usermodehelper_keys(char *path, char **argv, char **envp,
+ struct key *session_keyring, int wait)
+{
+ struct subprocess_info *info;
+
+ info = call_usermodehelper_setup(path, argv, envp);
+ if (info == NULL)
+ return -ENOMEM;
+
+ call_usermodehelper_setkeys(info, session_keyring);
+ return call_usermodehelper_exec(info, wait);
}
extern void usermodehelper_init(void);
===================================================================
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -123,6 +123,7 @@ struct subprocess_info {
int wait;
int retval;
struct file *stdin;
+ void (*cleanup)(char **argv, char **envp);
};
/*
@@ -176,6 +177,14 @@ static int ____call_usermodehelper(void
do_exit(0);
}
+void call_usermodehelper_freeinfo(struct subprocess_info *info)
+{
+ if (info->cleanup)
+ (*info->cleanup)(info->argv, info->envp);
+ kfree(info);
+}
+EXPORT_SYMBOL(call_usermodehelper_freeinfo);
+
/* Keventd can't block, but this (a child) can. */
static int wait_for_helper(void *data)
{
@@ -218,7 +227,7 @@ static int wait_for_helper(void *data)
}
if (sub_info->wait < 0)
- kfree(sub_info);
+ call_usermodehelper_freeinfo(sub_info);
else
complete(sub_info->complete);
return 0;
@@ -253,11 +262,94 @@ static void __call_usermodehelper(struct
}
/**
- * call_usermodehelper_keys - start a usermode application
- * @path: pathname for the application
- * @argv: null-terminated argument list
- * @envp: null-terminated environment list
- * @session_keyring: session keyring for process (NULL for an empty keyring)
+ * call_usermodehelper_setup - prepare to call a usermode helper
+ * @path - path to usermode executable
+ * @argv - arg vector for process
+ * @envp - environment for process
+ *
+ * Returns either NULL on allocation failure, or a subprocess_info
+ * structure. This should be passed to call_usermodehelper_exec to
+ * exec the process and free the structure.
+ */
+struct subprocess_info *call_usermodehelper_setup(char *path,
+ char **argv, char **envp)
+{
+ struct subprocess_info *sub_info;
+ sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
+ if (!sub_info)
+ goto out;
+
+ INIT_WORK(&sub_info->work, __call_usermodehelper);
+ sub_info->path = path;
+ sub_info->argv = argv;
+ sub_info->envp = envp;
+
+ out:
+ return sub_info;
+}
+EXPORT_SYMBOL(call_usermodehelper_setup);
+
+/**
+ * call_usermodehelper_setkeys - set the session keys for usermode helper
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @session_keyring: the session keyring for the process
+ */
+void call_usermodehelper_setkeys(struct subprocess_info *info,
+ struct key *session_keyring)
+{
+ info->ring = session_keyring;
+}
+EXPORT_SYMBOL(call_usermodehelper_setkeys);
+
+/**
+ * call_usermodehelper_setcleanup - set a cleanup function
+ * @info: a subprocess_info returned by call_usermodehelper_setup
+ * @cleanup: a cleanup function
+ *
+ * The cleanup function is just befor ethe subprocess_info is about to
+ * be freed. This can be used for freeing the argv and envp. The
+ * Function must be runnable in either a process context or the
+ * context in which call_usermodehelper_exec is called.
+ */
+void call_usermodehelper_setcleanup(struct subprocess_info *info,
+ void (*cleanup)(char **argv, char **envp))
+{
+ info->cleanup = cleanup;
+}
+EXPORT_SYMBOL(call_usermodehelper_setcleanup);
+
+/**
+ * call_usermodehelper_stdinpipe - set up a pipe to be used for stdin
+ * @sub_info: a subprocess_info returned by call_usermodehelper_setup
+ * @filp: set to the write-end of a pipe
+ *
+ * This constructs a pipe, and sets the read end to be the stdin of the
+ * subprocess, and returns the write-end in *@filp.
+ */
+int call_usermodehelper_stdinpipe(struct subprocess_info *sub_info,
+ struct file **filp)
+{
+ struct file *f;
+
+ f = create_write_pipe();
+ if (IS_ERR(f))
+ return PTR_ERR(f);
+ *filp = f;
+
+ f = create_read_pipe(f);
+ if (IS_ERR(f)) {
+ free_write_pipe(*filp);
+ return PTR_ERR(f);
+ }
+ sub_info->stdin = f;
+
+ return 0;
+}
+EXPORT_SYMBOL(call_usermodehelper_stdinpipe);
+
+/**
+ * call_usermodehelper_exec - start a usermode application
+ * @sub_info: information about the subprocessa
* @wait: wait for the application to finish and return status.
* when -1 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
@@ -266,33 +358,24 @@ static void __call_usermodehelper(struct
* Runs a user-space application. The application is started
* asynchronously if wait is not set, and runs as a child of keventd.
* (ie. it runs with full root capabilities).
- *
- * Must be called from process context. Returns a negative error code
- * if program was not execed successfully, or 0.
- */
-int call_usermodehelper_keys(char *path, char **argv, char **envp,
- struct key *session_keyring, int wait)
+ */
+int call_usermodehelper_exec(struct subprocess_info *sub_info,
+ int wait)
{
DECLARE_COMPLETION_ONSTACK(done);
- struct subprocess_info *sub_info;
int retval;
- if (!khelper_wq)
- return -EBUSY;
-
- if (path[0] == '\0')
- return 0;
-
- sub_info = kzalloc(sizeof(struct subprocess_info), GFP_ATOMIC);
- if (!sub_info)
- return -ENOMEM;
-
- INIT_WORK(&sub_info->work, __call_usermodehelper);
+ if (sub_info->path[0] == '\0') {
+ retval = 0;
+ goto out;
+ }
+
+ if (!khelper_wq) {
+ retval = -EBUSY;
+ goto out;
+ }
+
sub_info->complete = &done;
- sub_info->path = path;
- sub_info->argv = argv;
- sub_info->envp = envp;
- sub_info->ring = session_keyring;
sub_info->wait = wait;
queue_work(khelper_wq, &sub_info->work);
@@ -300,47 +383,43 @@ int call_usermodehelper_keys(char *path,
return 0;
wait_for_completion(&done);
retval = sub_info->retval;
- kfree(sub_info);
+
+ out:
+ call_usermodehelper_freeinfo(sub_info);
return retval;
}
-EXPORT_SYMBOL(call_usermodehelper_keys);
-
+EXPORT_SYMBOL(call_usermodehelper_exec);
+
+/**
+ * call_usermodehelper_pipe - call a usermode helper process with a pipe stdin
+ * @path: path to usermode executable
+ * @argv: arg vector for process
+ * @envp: environment for process
+ * @filp: set to the write-end of a pipe
+ *
+ * This is a simple wrapper which executes a usermode-helper function
+ * with a pipe as stdin. It is implemented entirely in terms of
+ * lower-level call_usermodehelper_* functions.
+ */
int call_usermodehelper_pipe(char *path, char **argv, char **envp,
struct file **filp)
{
- DECLARE_COMPLETION(done);
- struct subprocess_info sub_info = {
- .work = __WORK_INITIALIZER(sub_info.work,
- __call_usermodehelper),
- .complete = &done,
- .path = path,
- .argv = argv,
- .envp = envp,
- .retval = 0,
- };
- struct file *f;
-
- if (!khelper_wq)
- return -EBUSY;
-
- if (path[0] == '\0')
- return 0;
-
- f = create_write_pipe();
- if (IS_ERR(f))
- return PTR_ERR(f);
- *filp = f;
-
- f = create_read_pipe(f);
- if (IS_ERR(f)) {
- free_write_pipe(*filp);
- return PTR_ERR(f);
- }
- sub_info.stdin = f;
-
- queue_work(khelper_wq, &sub_info.work);
- wait_for_completion(&done);
- return sub_info.retval;
+ struct subprocess_info *sub_info;
+ int ret;
+
+ sub_info = call_usermodehelper_setup(path, argv, envp);
+ if (sub_info == NULL)
+ return -ENOMEM;
+
+ ret = call_usermodehelper_stdinpipe(sub_info, filp);
+ if (ret < 0)
+ goto out;
+
+ return call_usermodehelper_exec(sub_info, 1);
+
+ out:
+ call_usermodehelper_freeinfo(sub_info);
+ return ret;
}
EXPORT_SYMBOL(call_usermodehelper_pipe);
--
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