namespaces.c 4.1 KB
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#include <linux/proc_fs.h>
#include <linux/nsproxy.h>
#include <linux/ptrace.h>
#include <linux/namei.h>
#include <linux/file.h>
#include <linux/utsname.h>
#include <net/net_namespace.h>
#include <linux/ipc_namespace.h>
#include <linux/pid_namespace.h>
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#include <linux/user_namespace.h>
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#include "internal.h"


static const struct proc_ns_operations *ns_entries[] = {
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#ifdef CONFIG_NET_NS
	&netns_operations,
#endif
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#ifdef CONFIG_UTS_NS
	&utsns_operations,
#endif
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#ifdef CONFIG_IPC_NS
	&ipcns_operations,
#endif
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#ifdef CONFIG_PID_NS
	&pidns_operations,
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#endif
#ifdef CONFIG_USER_NS
	&userns_operations,
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#endif
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	&mntns_operations,
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#ifdef CONFIG_CGROUPS
	&cgroupns_operations,
#endif
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};

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static const char *proc_ns_get_link(struct dentry *dentry,
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				    struct inode *inode,
				    struct delayed_call *done)
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{
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	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
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	struct task_struct *task;
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	struct path ns_path;
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	void *error = ERR_PTR(-EACCES);

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	if (!dentry)
		return ERR_PTR(-ECHILD);

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	task = get_proc_task(inode);
	if (!task)
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		return error;
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	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
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		error = ns_get_path(&ns_path, task, ns_ops);
		if (!error)
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			nd_jump_link(&ns_path);
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	}
	put_task_struct(task);
	return error;
}

static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int buflen)
{
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	struct inode *inode = d_inode(dentry);
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	const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns_ops;
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	struct task_struct *task;
	char name[50];
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	int res = -EACCES;
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	task = get_proc_task(inode);
	if (!task)
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		return res;
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	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {
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		res = ns_get_name(name, sizeof(name), task, ns_ops);
		if (res >= 0)
			res = readlink_copy(buffer, buflen, name);
	}
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	put_task_struct(task);
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	return res;
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}

static const struct inode_operations proc_ns_link_inode_operations = {
	.readlink	= proc_ns_readlink,
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	.get_link	= proc_ns_get_link,
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	.setattr	= proc_setattr,
};

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static int proc_ns_instantiate(struct inode *dir,
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	struct dentry *dentry, struct task_struct *task, const void *ptr)
{
	const struct proc_ns_operations *ns_ops = ptr;
	struct inode *inode;
	struct proc_inode *ei;

	inode = proc_pid_make_inode(dir->i_sb, task);
	if (!inode)
		goto out;

	ei = PROC_I(inode);
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	inode->i_mode = S_IFLNK|S_IRWXUGO;
	inode->i_op = &proc_ns_link_inode_operations;
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	ei->ns_ops = ns_ops;
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	d_set_d_op(dentry, &pid_dentry_operations);
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	d_add(dentry, inode);
	/* Close the race of the process dying before we return the dentry */
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	if (pid_revalidate(dentry, 0))
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		return 0;
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out:
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	return -ENOENT;
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}

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static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)
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{
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	struct task_struct *task = get_proc_task(file_inode(file));
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	const struct proc_ns_operations **entry, **last;

	if (!task)
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		return -ENOENT;
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	if (!dir_emit_dots(file, ctx))
		goto out;
	if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
		goto out;
	entry = ns_entries + (ctx->pos - 2);
	last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
	while (entry <= last) {
		const struct proc_ns_operations *ops = *entry;
		if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
				     proc_ns_instantiate, task, ops))
			break;
		ctx->pos++;
		entry++;
	}
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out:
	put_task_struct(task);
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	return 0;
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}

const struct file_operations proc_ns_dir_operations = {
	.read		= generic_read_dir,
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	.iterate	= proc_ns_dir_readdir,
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};

static struct dentry *proc_ns_dir_lookup(struct inode *dir,
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				struct dentry *dentry, unsigned int flags)
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{
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	int error;
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	struct task_struct *task = get_proc_task(dir);
	const struct proc_ns_operations **entry, **last;
	unsigned int len = dentry->d_name.len;

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	error = -ENOENT;
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	if (!task)
		goto out_no_task;

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	last = &ns_entries[ARRAY_SIZE(ns_entries)];
	for (entry = ns_entries; entry < last; entry++) {
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		if (strlen((*entry)->name) != len)
			continue;
		if (!memcmp(dentry->d_name.name, (*entry)->name, len))
			break;
	}
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	if (entry == last)
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		goto out;

	error = proc_ns_instantiate(dir, dentry, task, *entry);
out:
	put_task_struct(task);
out_no_task:
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	return ERR_PTR(error);
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}

const struct inode_operations proc_ns_dir_inode_operations = {
	.lookup		= proc_ns_dir_lookup,
	.getattr	= pid_getattr,
	.setattr	= proc_setattr,
};