[PATCH] Create call_usermodehelper_pipe()

A new member in the ever growing family of call_usermode* functions is born. The new call_usermodehelper_pipe() function allows to pipe data to the stdin of the called user mode progam and behaves otherwise like the normal call_usermodehelp() (except that it always waits for the child to finish) Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>

[PATCH] Create call_usermodehelper_pipe()
A new member in the ever growing family of call_usermode* functions is born. The new call_usermodehelper_pipe() function allows to pipe data to the stdin of the called user mode progam and behaves otherwise like the normal call_usermodehelp() (except that it always waits for the child to finish) Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Andi Kleen · Linus Torvalds
1 parent d6cbd281d1
Showing 2 changed files with 58 additions and 1 deletions Side-by-side Diff
include/linux/kmod.h
kernel/kmod.c
@@ -47,5 +47,9 @@
  
 extern void usermodehelper_init(void);
  
+struct file;
+extern int call_usermodehelper_pipe(char *path, char *argv[], char *envp[],
+				    struct file **filp);
+
 #endif /* __LINUX_KMOD_H__ */
@@ -122,6 +122,7 @@
 	struct key *ring;
 	int wait;
 	int retval;
+	struct file *stdin;
 };
  
 /*
  
@@ -145,12 +146,26 @@
  
 	key_put(old_session);
  
+	/* Install input pipe when needed */
+	if (sub_info->stdin) {
+		struct files_struct *f = current->files;
+		struct fdtable *fdt;
+		/* no races because files should be private here */
+		sys_close(0);
+		fd_install(0, sub_info->stdin);
+		spin_lock(&f->file_lock);
+		fdt = files_fdtable(f);
+		FD_SET(0, fdt->open_fds);
+		FD_CLR(0, fdt->close_on_exec);
+		spin_unlock(&f->file_lock);
+	}
+
 	/* We can run anywhere, unlike our parent keventd(). */
 	set_cpus_allowed(current, CPU_MASK_ALL);
  
 	retval = -EPERM;
 	if (current->fs->root)
-		retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
+		retval = execve(sub_info->path, sub_info->argv, sub_info->envp);
  
 	/* Exec failed? */
 	sub_info->retval = retval;
@@ -267,6 +282,44 @@
 	return sub_info.retval;
 }
 EXPORT_SYMBOL(call_usermodehelper_keys);
+
+int call_usermodehelper_pipe(char *path, char **argv, char **envp,
+			     struct file **filp)
+{
+	DECLARE_COMPLETION(done);
+	struct subprocess_info sub_info = {
+		.complete	= &done,
+		.path		= path,
+		.argv		= argv,
+		.envp		= envp,
+		.retval		= 0,
+	};
+	struct file *f;
+	DECLARE_WORK(work, __call_usermodehelper, &sub_info);
+
+	if (!khelper_wq)
+		return -EBUSY;
+
+	if (path[0] == '\0')
+		return 0;
+
+	f = create_write_pipe();
+	if (!f)
+		return -ENOMEM;
+	*filp = f;
+
+	f = create_read_pipe(f);
+	if (!f) {
+		free_write_pipe(*filp);
+		return -ENOMEM;
+	}
+	sub_info.stdin = f;
+
+	queue_work(khelper_wq, &work);
+	wait_for_completion(&done);
+	return sub_info.retval;
+}
+EXPORT_SYMBOL(call_usermodehelper_pipe);
  
 void __init usermodehelper_init(void)
 {
...	...	@@ -47,5 +47,9 @@
47	47
48	48	extern void usermodehelper_init(void);
49	49
	50	+struct file;
	51	+extern int call_usermodehelper_pipe(char path, char argv[], char *envp[],
	52	+ struct file **filp);
	53	+
50	54	#endif /* __LINUX_KMOD_H__ */
...	...	@@ -122,6 +122,7 @@
122	122	struct key *ring;
123	123	int wait;
124	124	int retval;
	125	+ struct file *stdin;
125	126	};
126	127
127	128	/*
128	129
...	...	@@ -145,12 +146,26 @@
145	146
146	147	key_put(old_session);
147	148
	149	+ /* Install input pipe when needed */
	150	+ if (sub_info->stdin) {
	151	+ struct files_struct *f = current->files;
	152	+ struct fdtable *fdt;
	153	+ /* no races because files should be private here */
	154	+ sys_close(0);
	155	+ fd_install(0, sub_info->stdin);
	156	+ spin_lock(&f->file_lock);
	157	+ fdt = files_fdtable(f);
	158	+ FD_SET(0, fdt->open_fds);
	159	+ FD_CLR(0, fdt->close_on_exec);
	160	+ spin_unlock(&f->file_lock);
	161	+ }
	162	+
148	163	/* We can run anywhere, unlike our parent keventd(). */
149	164	set_cpus_allowed(current, CPU_MASK_ALL);
150	165
151	166	retval = -EPERM;
152	167	if (current->fs->root)
153		- retval = execve(sub_info->path, sub_info->argv,sub_info->envp);
	168	+ retval = execve(sub_info->path, sub_info->argv, sub_info->envp);
154	169
155	170	/* Exec failed? */
156	171	sub_info->retval = retval;
...	...	@@ -267,6 +282,44 @@
267	282	return sub_info.retval;
268	283	}
269	284	EXPORT_SYMBOL(call_usermodehelper_keys);
	285	+
	286	+int call_usermodehelper_pipe(char path, char argv, char *envp,
	287	+ struct file **filp)
	288	+{
	289	+ DECLARE_COMPLETION(done);
	290	+ struct subprocess_info sub_info = {
	291	+ .complete = &done,
	292	+ .path = path,
	293	+ .argv = argv,
	294	+ .envp = envp,
	295	+ .retval = 0,
	296	+ };
	297	+ struct file *f;
	298	+ DECLARE_WORK(work, __call_usermodehelper, &sub_info);
	299	+
	300	+ if (!khelper_wq)
	301	+ return -EBUSY;
	302	+
	303	+ if (path[0] == '\0')
	304	+ return 0;
	305	+
	306	+ f = create_write_pipe();
	307	+ if (!f)
	308	+ return -ENOMEM;
	309	+ *filp = f;
	310	+
	311	+ f = create_read_pipe(f);
	312	+ if (!f) {
	313	+ free_write_pipe(*filp);
	314	+ return -ENOMEM;
	315	+ }
	316	+ sub_info.stdin = f;
	317	+
	318	+ queue_work(khelper_wq, &work);
	319	+ wait_for_completion(&done);
	320	+ return sub_info.retval;
	321	+}
	322	+EXPORT_SYMBOL(call_usermodehelper_pipe);
270	323
271	324	void __init usermodehelper_init(void)
272	325	{