[PATCH v5 28/42] init: handle idmapped mounts

Christian Brauner
2021-01-12T22:17:23Z

Enable the init helpers to handle idmapped mounts by passing down the
mount's user namespace. If the initial user namespace is passed nothing
changes so non-idmapped mounts will see identical behavior as before.

Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
/* v2 */
patch introduced

/* v3 */
unchanged

/* v4 */
unchanged

/* v5 */
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837
---
fs/init.c | 24 ++++++++++++++----------
1 file changed, 14 insertions(+), 10 deletions(-)

diff --git a/fs/init.c b/fs/init.c
index 06d8e52ce18e..1db2b392e4e6 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -49,7 +49,7 @@ int __init init_chdir(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
if (error)
return error;
- error = inode_permission(&init_user_ns, path.dentry->d_inode,
+ error = inode_permission(mnt_user_ns(path.mnt), path.dentry->d_inode,
MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &path);
@@ -65,7 +65,7 @@ int __init init_chroot(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
if (error)
return error;
- error = inode_permission(&init_user_ns, path.dentry->d_inode,
+ error = inode_permission(mnt_user_ns(path.mnt), path.dentry->d_inode,
MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
@@ -120,7 +120,7 @@ int __init init_eaccess(const char *filename)
error = kern_path(filename, LOOKUP_FOLLOW, &path);
if (error)
return error;
- error = inode_permission(&init_user_ns, d_inode(path.dentry),
+ error = inode_permission(mnt_user_ns(path.mnt), d_inode(path.dentry),
MAY_ACCESS);
path_put(&path);
return error;
@@ -160,8 +160,8 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
mode &= ~current_umask();
error = security_path_mknod(&path, dentry, mode, dev);
if (!error)
- error = vfs_mknod(&init_user_ns, path.dentry->d_inode, dentry,
- mode, new_decode_dev(dev));
+ error = vfs_mknod(mnt_user_ns(path.mnt), path.dentry->d_inode,
+ dentry, mode, new_decode_dev(dev));
done_path_create(&path, dentry);
return error;
}
@@ -170,6 +170,7 @@ int __init init_link(const char *oldname, const char *newname)
{
struct dentry *new_dentry;
struct path old_path, new_path;
+ struct user_namespace *mnt_userns;
int error;

error = kern_path(oldname, 0, &old_path);
@@ -184,14 +185,15 @@ int __init init_link(const char *oldname, const char *newname)
error = -EXDEV;
if (old_path.mnt != new_path.mnt)
goto out_dput;
- error = may_linkat(&init_user_ns, &old_path);
+ mnt_userns = mnt_user_ns(new_path.mnt);
+ error = may_linkat(mnt_userns, &old_path);
if (unlikely(error))
goto out_dput;
error = security_path_link(old_path.dentry, &new_path, new_dentry);
if (error)
goto out_dput;
- error = vfs_link(old_path.dentry, &init_user_ns,
- new_path.dentry->d_inode, new_dentry, NULL);
+ error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
+ new_dentry, NULL);
out_dput:
done_path_create(&new_path, new_dentry);
out:
@@ -210,7 +212,8 @@ int __init init_symlink(const char *oldname, const char *newname)
return PTR_ERR(dentry);
error = security_path_symlink(&path, dentry, oldname);
if (!error)
- error = vfs_symlink(&init_user_ns, path.dentry->d_inode, dentry, oldname);
+ error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode,
+ dentry, oldname);
done_path_create(&path, dentry);
return error;
}
@@ -233,7 +236,8 @@ int __init init_mkdir(const char *pathname, umode_t mode)
mode &= ~current_umask();
error = security_path_mkdir(&path, dentry, mode);
if (!error)
- error = vfs_mkdir(&init_user_ns, path.dentry->d_inode, dentry, mode);
+ error = vfs_mkdir(mnt_user_ns(path.mnt), path.dentry->d_inode,
+ dentry, mode);
done_path_create(&path, dentry);
return error;
}
--
2.30.0