proc: proper pidns handling for /proc/self

ebiederm · Linus Torvalds · commit 488e5bc4560d · 2008-02-08T09:22:24.000-08:00
Currently if you access a /proc that is not mounted with your processes
current pid namespace /proc/self will point at a completely random task.

This patch fixes /proc/self to point to the current process if it is
available in the particular mount of /proc or to return -ENOENT if the
current process is not visible.

Signed-off-by: Eric W. Biederman &lt;ebiederm@xmission.com&gt;
Cc: Pavel Emelyanov &lt;xemul@openvz.org&gt;
Cc: Alexey Dobriyan &lt;adobriyan@gmail.com&gt;
Cc: Oleg Nesterov &lt;oleg@tv-sign.ru&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
diff --git a/fs/proc/base.c b/fs/proc/base.c
@@ -2101,15 +2101,23 @@ static const struct file_operations proc_coredump_filter_operations = {
 static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
 			      int buflen)
 {
+	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+	pid_t tgid = task_tgid_nr_ns(current, ns);
 	char tmp[PROC_NUMBUF];
-	sprintf(tmp, "%d", task_tgid_vnr(current));
+	if (!tgid)
+		return -ENOENT;
+	sprintf(tmp, "%d", tgid);
 	return vfs_readlink(dentry,buffer,buflen,tmp);
 }
 
 static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
+	struct pid_namespace *ns = dentry->d_sb->s_fs_info;
+	pid_t tgid = task_tgid_nr_ns(current, ns);
 	char tmp[PROC_NUMBUF];
-	sprintf(tmp, "%d", task_tgid_vnr(current));
+	if (!tgid)
+		return ERR_PTR(-ENOENT);
+	sprintf(tmp, "%d", task_tgid_nr_ns(current, ns));
 	return ERR_PTR(vfs_follow_link(nd,tmp));
 }
 

Original file line number	Diff line number	Diff line change
`@@ -2101,15 +2101,23 @@ static const struct file_operations proc_coredump_filter_operations = {`
`2101`	`2101`	`static int proc_self_readlink(struct dentry dentry, char __user buffer,`
`2102`	`2102`	`int buflen)`
`2103`	`2103`	`{`
	`2104`	`+ struct pid_namespace *ns = dentry->d_sb->s_fs_info;`
	`2105`	`+ pid_t tgid = task_tgid_nr_ns(current, ns);`
`2104`	`2106`	`char tmp[PROC_NUMBUF];`
`2105`		`- sprintf(tmp, "%d", task_tgid_vnr(current));`
	`2107`	`+ if (!tgid)`
	`2108`	`+ return -ENOENT;`
	`2109`	`+ sprintf(tmp, "%d", tgid);`
`2106`	`2110`	`return vfs_readlink(dentry,buffer,buflen,tmp);`
`2107`	`2111`	`}`
`2108`	`2112`
`2109`	`2113`	`static void proc_self_follow_link(struct dentry dentry, struct nameidata *nd)`
`2110`	`2114`	`{`
	`2115`	`+ struct pid_namespace *ns = dentry->d_sb->s_fs_info;`
	`2116`	`+ pid_t tgid = task_tgid_nr_ns(current, ns);`
`2111`	`2117`	`char tmp[PROC_NUMBUF];`
`2112`		`- sprintf(tmp, "%d", task_tgid_vnr(current));`
	`2118`	`+ if (!tgid)`
	`2119`	`+ return ERR_PTR(-ENOENT);`
	`2120`	`+ sprintf(tmp, "%d", task_tgid_nr_ns(current, ns));`
`2113`	`2121`	`return ERR_PTR(vfs_follow_link(nd,tmp));`
`2114`	`2122`	`}`
`2115`	`2123`