From 2f221d6f7b881d95de1f356a3097d755ab1e47d4 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 21 Jan 2021 14:19:26 +0100 Subject: attr: handle idmapped mounts When file attributes are changed most filesystems rely on the setattr_prepare(), setattr_copy(), and notify_change() helpers for initialization and permission checking. Let them handle idmapped mounts. If the inode is accessed through an idmapped mount map it into the mount's user namespace. Afterwards the checks are identical to non-idmapped mounts. If the initial user namespace is passed nothing changes so non-idmapped mounts will see identical behavior as before. Helpers that perform checks on the ia_uid and ia_gid fields in struct iattr assume that ia_uid and ia_gid are intended values and have already been mapped correctly at the userspace-kernelspace boundary as we already do today. 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/20210121131959.646623-8-christian.brauner@ubuntu.com Cc: Christoph Hellwig Cc: David Howells Cc: Al Viro Cc: linux-fsdevel@vger.kernel.org Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner --- fs/overlayfs/copy_up.c | 8 ++++---- fs/overlayfs/dir.c | 2 +- fs/overlayfs/inode.c | 4 ++-- fs/overlayfs/super.c | 2 +- 4 files changed, 8 insertions(+), 8 deletions(-) (limited to 'fs/overlayfs') diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index e5b616c93e11..3e9957ae19fa 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -235,7 +235,7 @@ static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat) .ia_size = stat->size, }; - return notify_change(upperdentry, &attr, NULL); + return notify_change(&init_user_ns, upperdentry, &attr, NULL); } static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) @@ -247,7 +247,7 @@ static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat) .ia_mtime = stat->mtime, }; - return notify_change(upperdentry, &attr, NULL); + return notify_change(&init_user_ns, upperdentry, &attr, NULL); } int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) @@ -259,7 +259,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) .ia_valid = ATTR_MODE, .ia_mode = stat->mode, }; - err = notify_change(upperdentry, &attr, NULL); + err = notify_change(&init_user_ns, upperdentry, &attr, NULL); } if (!err) { struct iattr attr = { @@ -267,7 +267,7 @@ int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat) .ia_uid = stat->uid, .ia_gid = stat->gid, }; - err = notify_change(upperdentry, &attr, NULL); + err = notify_change(&init_user_ns, upperdentry, &attr, NULL); } if (!err) ovl_set_timestamps(upperdentry, stat); diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c index 98a23353b19a..29840820a46c 100644 --- a/fs/overlayfs/dir.c +++ b/fs/overlayfs/dir.c @@ -508,7 +508,7 @@ static int ovl_create_over_whiteout(struct dentry *dentry, struct inode *inode, .ia_mode = cattr->mode, }; inode_lock(newdentry->d_inode); - err = notify_change(newdentry, &attr, NULL); + err = notify_change(&init_user_ns, newdentry, &attr, NULL); inode_unlock(newdentry->d_inode); if (err) goto out_cleanup; diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index c101ebbb7a77..5aa66881dbd7 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -21,7 +21,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) struct dentry *upperdentry; const struct cred *old_cred; - err = setattr_prepare(dentry, attr); + err = setattr_prepare(&init_user_ns, dentry, attr); if (err) return err; @@ -79,7 +79,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr) inode_lock(upperdentry->d_inode); old_cred = ovl_override_creds(dentry->d_sb); - err = notify_change(upperdentry, attr, NULL); + err = notify_change(&init_user_ns, upperdentry, attr, NULL); revert_creds(old_cred); if (!err) ovl_copyattr(upperdentry->d_inode, dentry->d_inode); diff --git a/fs/overlayfs/super.c b/fs/overlayfs/super.c index 3e925deaa19a..39b2e9aa0e5b 100644 --- a/fs/overlayfs/super.c +++ b/fs/overlayfs/super.c @@ -804,7 +804,7 @@ retry: /* Clear any inherited mode bits */ inode_lock(work->d_inode); - err = notify_change(work, &attr, NULL); + err = notify_change(&init_user_ns, work, &attr, NULL); inode_unlock(work->d_inode); if (err) goto out_dput; -- cgit v1.2.3