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#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/pid_namespace.h>
#include "internal.h"
/*
* /proc/thread_self:
*/
static int proc_thread_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);
pid_t pid = task_pid_nr_ns(current, ns);
char tmp[PROC_NUMBUF + 6 + PROC_NUMBUF];
if (!pid)
return -ENOENT;
sprintf(tmp, "%d/task/%d", tgid, pid);
return readlink_copy(buffer, buflen, tmp);
}
static const char *proc_thread_self_get_link(struct dentry *dentry,
struct inode *inode, void **cookie)
{
struct pid_namespace *ns = inode->i_sb->s_fs_info;
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(PROC_NUMBUF + 6 + PROC_NUMBUF,
dentry ? GFP_KERNEL : GFP_ATOMIC);
if (unlikely(!name))
return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
sprintf(name, "%d/task/%d", tgid, pid);
return *cookie = name;
}
static const struct inode_operations proc_thread_self_inode_operations = {
.readlink = proc_thread_self_readlink,
.get_link = proc_thread_self_get_link,
.put_link = kfree_put_link,
};
static unsigned thread_self_inum;
int proc_setup_thread_self(struct super_block *s)
{
struct inode *root_inode = d_inode(s->s_root);
struct pid_namespace *ns = s->s_fs_info;
struct dentry *thread_self;
mutex_lock(&root_inode->i_mutex);
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->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);
}
mutex_unlock(&root_inode->i_mutex);
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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