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// SPDX-License-Identifier: GPL-2.0
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/pid_namespace.h>
#include "internal.h"
/*
* /proc/thread_self:
*/
static const char *proc_thread_self_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
struct pid_namespace *ns = proc_pid_ns(inode);
pid_t tgid = task_tgid_nr_ns(current, ns);
pid_t pid = task_pid_nr_ns(current, ns);
char *name;
if (!pid)
return ERR_PTR(-ENOENT);
name = kmalloc(10 + 6 + 10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
if (unlikely(!name))
return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
sprintf(name, "%u/task/%u", tgid, pid);
set_delayed_call(done, kfree_link, name);
return name;
}
static const struct inode_operations proc_thread_self_inode_operations = {
.get_link = proc_thread_self_get_link,
};
static unsigned thread_self_inum __ro_after_init;
int proc_setup_thread_self(struct super_block *s)
{
struct inode *root_inode = d_inode(s->s_root);
struct pid_namespace *ns = proc_pid_ns(root_inode);
struct dentry *thread_self;
inode_lock(root_inode);
thread_self = d_alloc_name(s->s_root, "thread-self");
if (thread_self) {
struct inode *inode = new_inode_pseudo(s);
if (inode) {
inode->i_ino = thread_self_inum;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
inode->i_op = &proc_thread_self_inode_operations;
d_add(thread_self, inode);
} else {
dput(thread_self);
thread_self = ERR_PTR(-ENOMEM);
}
} else {
thread_self = ERR_PTR(-ENOMEM);
}
inode_unlock(root_inode);
if (IS_ERR(thread_self)) {
pr_err("proc_fill_super: can't allocate /proc/thread_self\n");
return PTR_ERR(thread_self);
}
ns->proc_thread_self = thread_self;
return 0;
}
void __init proc_thread_self_init(void)
{
proc_alloc_inum(&thread_self_inum);
}
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