| Message ID | 20230128014159.1741728-1-development@efficientek.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | hostfs: handle idmapped mounts | expand |
Hi, On Fri, 27 Jan 2023 19:41:59 -0600 Glenn Washburn <development@efficientek.com> wrote: > Let hostfs handle idmapped mounts. This allows to have the same hostfs > mount appear in multiple locations with different id mappings. This patch is based off of linux-next in the Richard's UML repo[1]. However, I've noticed that this patch needs some modifications to be applied against the tip[2]. So I'm wondering which branch in what repo is best to base patches from? Glenn [1] git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml.git [2] git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
On Mon, Feb 27, 2023 at 10:33:36AM -0600, Glenn Washburn wrote: > Hi, > > On Fri, 27 Jan 2023 19:41:59 -0600 > Glenn Washburn <development@efficientek.com> wrote: > > > Let hostfs handle idmapped mounts. This allows to have the same hostfs > > mount appear in multiple locations with different id mappings. > > This patch is based off of linux-next in the Richard's UML repo[1]. > However, I've noticed that this patch needs some modifications to be > applied against the tip[2]. So I'm wondering which branch in what repo > is best to base patches from? Hey Glenn, Linus merged my pull request that introduces a dedicated new type for idmapped mounts into the vfs: struct mnt_idmap. So any branch you base this on should contain that work. Let me know if you need help with the conversion. Christian
On Tue, 28 Feb 2023 10:01:42 +0100 Christian Brauner <brauner@kernel.org> wrote: > On Mon, Feb 27, 2023 at 10:33:36AM -0600, Glenn Washburn wrote: > > Hi, > > > > On Fri, 27 Jan 2023 19:41:59 -0600 > > Glenn Washburn <development@efficientek.com> wrote: > > > > > Let hostfs handle idmapped mounts. This allows to have the same > > > hostfs mount appear in multiple locations with different id > > > mappings. > > > > This patch is based off of linux-next in the Richard's UML repo[1]. > > However, I've noticed that this patch needs some modifications to be > > applied against the tip[2]. So I'm wondering which branch in what > > repo is best to base patches from? > > Hey Glenn, > > Linus merged my pull request that introduces a dedicated new type for > idmapped mounts into the vfs: struct mnt_idmap. So any branch you base > this on should contain that work. Let me know if you need help with > the conversion. Hi Christian, I was about to ask for help yesterday when I was trying to figure it out, but I think I got it working. However, you probably will have suggestions for improvement. I'll send an updated version soon, and make sure you're explicitly included. Glenn
diff --git a/fs/hostfs/hostfs_kern.c b/fs/hostfs/hostfs_kern.c index cc1bc6f93a01..876b73e05ac1 100644 --- a/fs/hostfs/hostfs_kern.c +++ b/fs/hostfs/hostfs_kern.c @@ -786,7 +786,7 @@ static int hostfs_permission(struct user_namespace *mnt_userns, err = access_file(name, r, w, x); __putname(name); if (!err) - err = generic_permission(&init_user_ns, ino, desired); + err = generic_permission(mnt_userns, ino, desired); return err; } @@ -800,7 +800,7 @@ static int hostfs_setattr(struct user_namespace *mnt_userns, int fd = HOSTFS_I(inode)->fd; - err = setattr_prepare(&init_user_ns, dentry, attr); + err = setattr_prepare(mnt_userns, dentry, attr); if (err) return err; @@ -814,11 +814,11 @@ static int hostfs_setattr(struct user_namespace *mnt_userns, } if (attr->ia_valid & ATTR_UID) { attrs.ia_valid |= HOSTFS_ATTR_UID; - attrs.ia_uid = from_kuid(&init_user_ns, attr->ia_uid); + attrs.ia_uid = from_kuid(mnt_userns, attr->ia_uid); } if (attr->ia_valid & ATTR_GID) { attrs.ia_valid |= HOSTFS_ATTR_GID; - attrs.ia_gid = from_kgid(&init_user_ns, attr->ia_gid); + attrs.ia_gid = from_kgid(mnt_userns, attr->ia_gid); } if (attr->ia_valid & ATTR_SIZE) { attrs.ia_valid |= HOSTFS_ATTR_SIZE; @@ -857,7 +857,7 @@ static int hostfs_setattr(struct user_namespace *mnt_userns, attr->ia_size != i_size_read(inode)) truncate_setsize(inode, attr->ia_size); - setattr_copy(&init_user_ns, inode, attr); + setattr_copy(mnt_userns, inode, attr); mark_inode_dirty(inode); return 0; } @@ -991,7 +991,7 @@ static struct file_system_type hostfs_type = { .name = "hostfs", .mount = hostfs_read_sb, .kill_sb = hostfs_kill_sb, - .fs_flags = 0, + .fs_flags = FS_ALLOW_IDMAP, }; MODULE_ALIAS_FS("hostfs");
Let hostfs handle idmapped mounts. This allows to have the same hostfs mount appear in multiple locations with different id mappings. root@(none):/media# id uid=0(root) gid=0(root) groups=0(root) root@(none):/media# mkdir mnt idmapped root@(none):/media# mount -thostfs -o/home/user hostfs mnt root@(none):/media# touch mnt/aaa root@(none):/media# mount-idmapped --map-mount u:`id -u user`:0:1 --map-mount g:`id -g user`:0:1 /media/mnt /media/idmapped root@(none):/media# ls -l mnt/aaa idmapped/aaa -rw-r--r-- 1 root root 0 Jan 28 01:23 idmapped/aaa -rw-r--r-- 1 user user 0 Jan 28 01:23 mnt/aaa root@(none):/media# touch idmapped/bbb root@(none):/media# ls -l mnt/bbb idmapped/bbb -rw-r--r-- 1 root root 0 Jan 28 01:26 idmapped/bbb -rw-r--r-- 1 user user 0 Jan 28 01:26 mnt/bbb Signed-off-by: Glenn Washburn <development@efficientek.com> --- fs/hostfs/hostfs_kern.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)