92 lines
2.2 KiB
C
92 lines
2.2 KiB
C
#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/pid_namespace.h>
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#include "internal.h"
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/*
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* /proc/self:
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*/
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static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
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int buflen)
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{
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struct pid_namespace *ns = dentry->d_sb->s_fs_info;
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pid_t tgid = task_tgid_nr_ns(current, ns);
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char tmp[PROC_NUMBUF];
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if (!tgid)
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return -ENOENT;
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sprintf(tmp, "%d", tgid);
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return readlink_copy(buffer, buflen, tmp);
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}
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static const char *proc_self_get_link(struct dentry *dentry,
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struct inode *inode,
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struct delayed_call *done)
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{
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struct pid_namespace *ns = inode->i_sb->s_fs_info;
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pid_t tgid = task_tgid_nr_ns(current, ns);
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char *name;
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/*
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* Not currently supported. Once we can inherit all of struct pid,
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* we can allow this.
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*/
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if (current->flags & PF_KTHREAD)
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return ERR_PTR(-EOPNOTSUPP);
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if (!tgid)
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return ERR_PTR(-ENOENT);
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/* 11 for max length of signed int in decimal + NULL term */
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name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
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if (unlikely(!name))
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return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
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sprintf(name, "%d", tgid);
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set_delayed_call(done, kfree_link, name);
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return name;
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}
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static const struct inode_operations proc_self_inode_operations = {
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.readlink = proc_self_readlink,
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.get_link = proc_self_get_link,
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};
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static unsigned self_inum;
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int proc_setup_self(struct super_block *s)
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{
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struct inode *root_inode = d_inode(s->s_root);
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struct pid_namespace *ns = s->s_fs_info;
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struct dentry *self;
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inode_lock(root_inode);
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self = d_alloc_name(s->s_root, "self");
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if (self) {
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struct inode *inode = new_inode(s);
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if (inode) {
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inode->i_ino = self_inum;
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inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
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inode->i_mode = S_IFLNK | S_IRWXUGO;
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inode->i_uid = GLOBAL_ROOT_UID;
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inode->i_gid = GLOBAL_ROOT_GID;
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inode->i_op = &proc_self_inode_operations;
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d_add(self, inode);
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} else {
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dput(self);
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self = ERR_PTR(-ENOMEM);
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}
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} else {
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self = ERR_PTR(-ENOMEM);
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}
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inode_unlock(root_inode);
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if (IS_ERR(self)) {
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pr_err("proc_fill_super: can't allocate /proc/self\n");
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return PTR_ERR(self);
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}
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ns->proc_self = self;
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return 0;
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}
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void __init proc_self_init(void)
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{
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proc_alloc_inum(&self_inum);
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}
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