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-rw-r--r--kernel/fs/proc/self.c84
1 files changed, 84 insertions, 0 deletions
diff --git a/kernel/fs/proc/self.c b/kernel/fs/proc/self.c
new file mode 100644
index 000000000..6195b4a7c
--- /dev/null
+++ b/kernel/fs/proc/self.c
@@ -0,0 +1,84 @@
+#include <linux/sched.h>
+#include <linux/namei.h>
+#include <linux/slab.h>
+#include <linux/pid_namespace.h>
+#include "internal.h"
+
+/*
+ * /proc/self:
+ */
+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];
+ if (!tgid)
+ return -ENOENT;
+ sprintf(tmp, "%d", tgid);
+ return readlink_copy(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 *name = ERR_PTR(-ENOENT);
+ if (tgid) {
+ /* 11 for max length of signed int in decimal + NULL term */
+ name = kmalloc(12, GFP_KERNEL);
+ if (!name)
+ name = ERR_PTR(-ENOMEM);
+ else
+ sprintf(name, "%d", tgid);
+ }
+ nd_set_link(nd, name);
+ return NULL;
+}
+
+static const struct inode_operations proc_self_inode_operations = {
+ .readlink = proc_self_readlink,
+ .follow_link = proc_self_follow_link,
+ .put_link = kfree_put_link,
+};
+
+static unsigned self_inum;
+
+int proc_setup_self(struct super_block *s)
+{
+ struct inode *root_inode = d_inode(s->s_root);
+ struct pid_namespace *ns = s->s_fs_info;
+ struct dentry *self;
+
+ mutex_lock(&root_inode->i_mutex);
+ self = d_alloc_name(s->s_root, "self");
+ if (self) {
+ struct inode *inode = new_inode_pseudo(s);
+ if (inode) {
+ inode->i_ino = self_inum;
+ inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+ inode->i_mode = S_IFLNK | S_IRWXUGO;
+ inode->i_uid = GLOBAL_ROOT_UID;
+ inode->i_gid = GLOBAL_ROOT_GID;
+ inode->i_op = &proc_self_inode_operations;
+ d_add(self, inode);
+ } else {
+ dput(self);
+ self = ERR_PTR(-ENOMEM);
+ }
+ } else {
+ self = ERR_PTR(-ENOMEM);
+ }
+ mutex_unlock(&root_inode->i_mutex);
+ if (IS_ERR(self)) {
+ pr_err("proc_fill_super: can't allocate /proc/self\n");
+ return PTR_ERR(self);
+ }
+ ns->proc_self = self;
+ return 0;
+}
+
+void __init proc_self_init(void)
+{
+ proc_alloc_inum(&self_inum);
+}