2021-01-21 15:23:28

by Christian Brauner

[permalink] [raw]
Subject: [PATCH v6 20/40] init: handle idmapped mounts

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.

Link: https://lore.kernel.org/r/[email protected]
Cc: Christoph Hellwig <[email protected]>
Cc: David Howells <[email protected]>
Cc: Al Viro <[email protected]>
Cc: [email protected]
Signed-off-by: Christian Brauner <[email protected]>
---
/* v2 */
patch introduced

/* v3 */
unchanged

/* v4 */
unchanged

/* v5 */
unchanged
base-commit: 7c53f6b671f4aba70ff15e1b05148b10d58c2837

/* v6 */
base-commit: 19c329f6808995b142b3966301f217c831e7cf31

- Christoph Hellwig <[email protected]>:
- Use new path_permission() helper.
---
fs/init.c | 20 +++++++++++---------
1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/fs/init.c b/fs/init.c
index e65452750fa5..5c36adaa9b44 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -157,8 +157,8 @@ 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;
}
@@ -167,6 +167,7 @@ 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);
@@ -181,14 +182,15 @@ 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:
@@ -207,8 +209,8 @@ 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;
}
@@ -231,8 +233,8 @@ 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


2021-01-22 18:38:03

by Christoph Hellwig

[permalink] [raw]
Subject: Re: [PATCH v6 20/40] init: handle idmapped mounts

Note that in the early init code the user namespace must be init_user_ns
by definition. But passing on the information from the file/path seem
ok just in case someone copy and pastes this code..

Reviewed-by: Christoph Hellwig <[email protected]>