From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/fs/nsfs.c | 82 ++++++++++++++++++++++++++--------------
1 files changed, 53 insertions(+), 29 deletions(-)
diff --git a/kernel/fs/nsfs.c b/kernel/fs/nsfs.c
index 30d150a..800c1d0 100644
--- a/kernel/fs/nsfs.c
+++ b/kernel/fs/nsfs.c
@@ -1,7 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
#include <linux/file.h>
#include <linux/fs.h>
+#include <linux/proc_fs.h>
#include <linux/proc_ns.h>
#include <linux/magic.h>
#include <linux/ktime.h>
@@ -9,6 +11,8 @@
#include <linux/user_namespace.h>
#include <linux/nsfs.h>
#include <linux/uaccess.h>
+
+#include "internal.h"
static struct vfsmount *nsfs_mnt;
@@ -51,7 +55,7 @@
ns->ops->put(ns);
}
-static void *__ns_get_path(struct path *path, struct ns_common *ns)
+static int __ns_get_path(struct path *path, struct ns_common *ns)
{
struct vfsmount *mnt = nsfs_mnt;
struct dentry *dentry;
@@ -70,13 +74,13 @@
got_it:
path->mnt = mntget(mnt);
path->dentry = dentry;
- return NULL;
+ return 0;
slow:
rcu_read_unlock();
inode = new_inode_pseudo(mnt->mnt_sb);
if (!inode) {
ns->ops->put(ns);
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
}
inode->i_ino = ns->inum;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
@@ -88,7 +92,7 @@
dentry = d_alloc_anon(mnt->mnt_sb);
if (!dentry) {
iput(inode);
- return ERR_PTR(-ENOMEM);
+ return -ENOMEM;
}
d_instantiate(dentry, inode);
dentry->d_fsdata = (void *)ns->ops;
@@ -97,25 +101,23 @@
d_delete(dentry); /* make sure ->d_prune() does nothing */
dput(dentry);
cpu_relax();
- return ERR_PTR(-EAGAIN);
+ return -EAGAIN;
}
goto got_it;
}
-void *ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
+int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
void *private_data)
{
- struct ns_common *ns;
- void *ret;
+ int ret;
-again:
- ns = ns_get_cb(private_data);
- if (!ns)
- return ERR_PTR(-ENOENT);
+ do {
+ struct ns_common *ns = ns_get_cb(private_data);
+ if (!ns)
+ return -ENOENT;
+ ret = __ns_get_path(path, ns);
+ } while (ret == -EAGAIN);
- ret = __ns_get_path(path, ns);
- if (IS_ERR(ret) && PTR_ERR(ret) == -EAGAIN)
- goto again;
return ret;
}
@@ -131,7 +133,7 @@
return args->ns_ops->get(args->task);
}
-void *ns_get_path(struct path *path, struct task_struct *task,
+int ns_get_path(struct path *path, struct task_struct *task,
const struct proc_ns_operations *ns_ops)
{
struct ns_get_path_task_args args = {
@@ -147,14 +149,14 @@
{
struct path path = {};
struct file *f;
- void *err;
+ int err;
int fd;
fd = get_unused_fd_flags(O_CLOEXEC);
if (fd < 0)
return fd;
- while (1) {
+ do {
struct ns_common *relative;
relative = get_ns(ns);
@@ -164,13 +166,11 @@
}
err = __ns_get_path(&path, relative);
- if (IS_ERR(err) && PTR_ERR(err) == -EAGAIN)
- continue;
- break;
- }
- if (IS_ERR(err)) {
+ } while (err == -EAGAIN);
+
+ if (err) {
put_unused_fd(fd);
- return PTR_ERR(err);
+ return err;
}
f = dentry_open(&path, O_RDONLY, current_cred());
@@ -229,6 +229,11 @@
return res;
}
+bool proc_ns_file(const struct file *file)
+{
+ return file->f_op == &ns_file_operations;
+}
+
struct file *proc_ns_fget(int fd)
{
struct file *file;
@@ -247,6 +252,20 @@
return ERR_PTR(-EINVAL);
}
+/**
+ * ns_match() - Returns true if current namespace matches dev/ino provided.
+ * @ns_common: current ns
+ * @dev: dev_t from nsfs that will be matched against current nsfs
+ * @ino: ino_t from nsfs that will be matched against current nsfs
+ *
+ * Return: true if dev and ino matches the current nsfs.
+ */
+bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
+{
+ return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
+}
+
+
static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
@@ -261,15 +280,20 @@
.evict_inode = nsfs_evict,
.show_path = nsfs_show_path,
};
-static struct dentry *nsfs_mount(struct file_system_type *fs_type,
- int flags, const char *dev_name, void *data)
+
+static int nsfs_init_fs_context(struct fs_context *fc)
{
- return mount_pseudo(fs_type, "nsfs:", &nsfs_ops,
- &ns_dentry_operations, NSFS_MAGIC);
+ struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
+ if (!ctx)
+ return -ENOMEM;
+ ctx->ops = &nsfs_ops;
+ ctx->dops = &ns_dentry_operations;
+ return 0;
}
+
static struct file_system_type nsfs = {
.name = "nsfs",
- .mount = nsfs_mount,
+ .init_fs_context = nsfs_init_fs_context,
.kill_sb = kill_anon_super,
};
--
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