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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/self:
*/
static const char *proc_self_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
struct pid_namespace *ns = proc_pid_ns(inode->i_sb);
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name;
if (!tgid)
return ERR_PTR(-ENOENT);
/* max length of unsigned int in decimal + NULL term */
name = kmalloc(10 + 1, dentry ? GFP_KERNEL : GFP_ATOMIC);
if (unlikely(!name))
return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
sprintf(name, "%u", tgid);
set_delayed_call(done, kfree_link, name);
return name;
}
static const struct inode_operations proc_self_inode_operations = {
.get_link = proc_self_get_link,
};
static unsigned self_inum __ro_after_init;
int proc_setup_self(struct super_block *s)
{
struct inode *root_inode = d_inode(s->s_root);
struct proc_fs_info *fs_info = proc_sb_info(s);
struct dentry *self;
int ret = -ENOMEM;
inode_lock(root_inode);
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);
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);
ret = 0;
} else {
dput(self);
}
}
inode_unlock(root_inode);
if (ret)
pr_err("proc_fill_super: can't allocate /proc/self\n");
else
fs_info->proc_self = self;
return ret;
}
void __init proc_self_init(void)
{
proc_alloc_inum(&self_inum);
}
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