Re: [PATCH v2 08/10] fs: port higher-level mapping helpers

Seth Forshee
2021-12-02T17:40:39Z

On Tue, Nov 30, 2021 at 01:10:30PM +0100, Christian Brauner wrote:
> From: Christian Brauner <christian.brauner@ubuntu.com>
>
> Enable the mapped_fs{g,u}id() helpers to support filesystems mounted
> with an idmapping. Apart from core mapping helpers that use
> mapped_fs{g,u}id() to initialize struct inode's i_{g,u}id fields xfs is
> the only place that uses these low-level helpers directly.
>
> The patch only extends the helpers to be able to take the filesystem
> idmapping into account. Since we don't actually yet pass the
> filesystem's idmapping in no functional changes happen. This will happen
> in a final patch.
>
> Link: https://lore.kernel.org/r/20211123114227.3124056-9-brauner@kernel.org (v1)
> Cc: Seth Forshee <sforshee@digitalocean.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> CC: linux-fsdevel@vger.kernel.org
> Reviewed-by: Amir Goldstein <amir73il@gmail.com>
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

Reviewed-by: Seth Forshee <sforshee@digitalocean.com>

> ---
> /* v2 */
> - Amir Goldstein <amir73il@gmail.com>:
> - Avoid using local variable and simply pass down initial idmapping
> directly.
> ---
> fs/xfs/xfs_inode.c | 8 ++++----
> fs/xfs/xfs_symlink.c | 4 ++--
> include/linux/fs.h | 8 ++++----
> include/linux/mnt_idmapping.h | 12 ++++++++----
> 4 files changed, 18 insertions(+), 14 deletions(-)
>
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index 64b9bf334806..5ca689459bed 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -988,8 +988,8 @@ xfs_create(
> /*
> * Make sure that we have allocated dquot(s) on disk.
> */
> - error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns),
> - mapped_fsgid(mnt_userns), prid,
> + error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns),
> + mapped_fsgid(mnt_userns, &init_user_ns), prid,
> XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> &udqp, &gdqp, &pdqp);
> if (error)
> @@ -1142,8 +1142,8 @@ xfs_create_tmpfile(
> /*
> * Make sure that we have allocated dquot(s) on disk.
> */
> - error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns),
> - mapped_fsgid(mnt_userns), prid,
> + error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns),
> + mapped_fsgid(mnt_userns, &init_user_ns), prid,
> XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> &udqp, &gdqp, &pdqp);
> if (error)
> diff --git a/fs/xfs/xfs_symlink.c b/fs/xfs/xfs_symlink.c
> index fc2c6a404647..a31d2e5d0321 100644
> --- a/fs/xfs/xfs_symlink.c
> +++ b/fs/xfs/xfs_symlink.c
> @@ -184,8 +184,8 @@ xfs_symlink(
> /*
> * Make sure that we have allocated dquot(s) on disk.
> */
> - error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns),
> - mapped_fsgid(mnt_userns), prid,
> + error = xfs_qm_vop_dqalloc(dp, mapped_fsuid(mnt_userns, &init_user_ns),
> + mapped_fsgid(mnt_userns, &init_user_ns), prid,
> XFS_QMOPT_QUOTALL | XFS_QMOPT_INHERIT,
> &udqp, &gdqp, &pdqp);
> if (error)
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 25de7f6ecd81..7c0499b63a02 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1664,7 +1664,7 @@ static inline kgid_t i_gid_into_mnt(struct user_namespace *mnt_userns,
> static inline void inode_fsuid_set(struct inode *inode,
> struct user_namespace *mnt_userns)
> {
> - inode->i_uid = mapped_fsuid(mnt_userns);
> + inode->i_uid = mapped_fsuid(mnt_userns, &init_user_ns);
> }
>
> /**
> @@ -1678,7 +1678,7 @@ static inline void inode_fsuid_set(struct inode *inode,
> static inline void inode_fsgid_set(struct inode *inode,
> struct user_namespace *mnt_userns)
> {
> - inode->i_gid = mapped_fsgid(mnt_userns);
> + inode->i_gid = mapped_fsgid(mnt_userns, &init_user_ns);
> }
>
> /**
> @@ -1699,10 +1699,10 @@ static inline bool fsuidgid_has_mapping(struct super_block *sb,
> kuid_t kuid;
> kgid_t kgid;
>
> - kuid = mapped_fsuid(mnt_userns);
> + kuid = mapped_fsuid(mnt_userns, &init_user_ns);
> if (!uid_valid(kuid))
> return false;
> - kgid = mapped_fsgid(mnt_userns);
> + kgid = mapped_fsgid(mnt_userns, &init_user_ns);
> if (!gid_valid(kgid))
> return false;
> return kuid_has_mapping(fs_userns, kuid) &&
> diff --git a/include/linux/mnt_idmapping.h b/include/linux/mnt_idmapping.h
> index c4b604a0c256..afd9bde6ba0d 100644
> --- a/include/linux/mnt_idmapping.h
> +++ b/include/linux/mnt_idmapping.h
> @@ -196,6 +196,7 @@ static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns,
> /**
> * mapped_fsuid - return caller's fsuid mapped up into a mnt_userns
> * @mnt_userns: the mount's idmapping
> + * @fs_userns: the filesystem's idmapping
> *
> * Use this helper to initialize a new vfs or filesystem object based on
> * the caller's fsuid. A common example is initializing the i_uid field of
> @@ -205,14 +206,16 @@ static inline kgid_t mapped_kgid_user(struct user_namespace *mnt_userns,
> *
> * Return: the caller's current fsuid mapped up according to @mnt_userns.
> */
> -static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns)
> +static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns,
> + struct user_namespace *fs_userns)
> {
> - return mapped_kuid_user(mnt_userns, &init_user_ns, current_fsuid());
> + return mapped_kuid_user(mnt_userns, fs_userns, current_fsuid());
> }
>
> /**
> * mapped_fsgid - return caller's fsgid mapped up into a mnt_userns
> * @mnt_userns: the mount's idmapping
> + * @fs_userns: the filesystem's idmapping
> *
> * Use this helper to initialize a new vfs or filesystem object based on
> * the caller's fsgid. A common example is initializing the i_gid field of
> @@ -222,9 +225,10 @@ static inline kuid_t mapped_fsuid(struct user_namespace *mnt_userns)
> *
> * Return: the caller's current fsgid mapped up according to @mnt_userns.
> */
> -static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns)
> +static inline kgid_t mapped_fsgid(struct user_namespace *mnt_userns,
> + struct user_namespace *fs_userns)
> {
> - return mapped_kgid_user(mnt_userns, &init_user_ns, current_fsgid());
> + return mapped_kgid_user(mnt_userns, fs_userns, current_fsgid());
> }
>
> #endif /* _LINUX_MNT_MAPPING_H */
> --
> 2.30.2
>