Messages in this thread Patch in this message | | | Subject | Re: [PATCH] fs/ceph/super: add mount options "snapdir{mode,uid,gid}" | From | Xiubo Li <> | Date | Sun, 9 Oct 2022 14:23:22 +0800 |
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Hi Max,
Sorry for late and just back from a long vocation.
On 27/09/2022 20:08, Max Kellermann wrote: > By default, the ".snap" directory inherits the parent's permissions > and ownership, which allows all users to create new cephfs snapshots > in arbitrary directories they have write access on. > > In some environments, giving everybody this capability is not > desirable, but there is currently no way to disallow only some users > to create snapshots. It is only possible to revoke the permission to > the whole client (i.e. all users on the computer which mounts the > cephfs). > > This patch allows overriding the permissions and ownership of all > virtual ".snap" directories in a cephfs mount, which allows > restricting (read and write) access to snapshots. > > For example, the mount options: > > snapdirmode=0751,snapdiruid=0,snapdirgid=4 > > ... allows only user "root" to create or delete snapshots, and group > "adm" (gid=4) is allowed to get a list of snapshots. All others are > allowed to read the contents of existing snapshots (if they know the > name).
I don't think this is a good place to implement this in client side. Should this be a feature in cephx.
With this for the same directories in different mounts will behave differently. Isn't that odd ?
-- Xiubo
> Signed-off-by: Max Kellermann <max.kellermann@ionos.com> > --- > fs/ceph/inode.c | 7 ++++--- > fs/ceph/super.c | 33 +++++++++++++++++++++++++++++++++ > fs/ceph/super.h | 4 ++++ > 3 files changed, 41 insertions(+), 3 deletions(-) > > diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c > index 56c53ab3618e..0e9388af2821 100644 > --- a/fs/ceph/inode.c > +++ b/fs/ceph/inode.c > @@ -80,6 +80,7 @@ struct inode *ceph_get_snapdir(struct inode *parent) > }; > struct inode *inode = ceph_get_inode(parent->i_sb, vino); > struct ceph_inode_info *ci = ceph_inode(inode); > + struct ceph_mount_options *const fsopt = ceph_inode_to_client(parent)->mount_options; > > if (IS_ERR(inode)) > return inode; > @@ -96,9 +97,9 @@ struct inode *ceph_get_snapdir(struct inode *parent) > goto err; > } > > - inode->i_mode = parent->i_mode; > - inode->i_uid = parent->i_uid; > - inode->i_gid = parent->i_gid; > + inode->i_mode = fsopt->snapdir_mode == (umode_t)-1 ? parent->i_mode : fsopt->snapdir_mode; > + inode->i_uid = uid_eq(fsopt->snapdir_uid, INVALID_UID) ? parent->i_uid : fsopt->snapdir_uid; > + inode->i_gid = gid_eq(fsopt->snapdir_gid, INVALID_GID) ? parent->i_gid : fsopt->snapdir_gid; > inode->i_mtime = parent->i_mtime; > inode->i_ctime = parent->i_ctime; > inode->i_atime = parent->i_atime; > diff --git a/fs/ceph/super.c b/fs/ceph/super.c > index 40140805bdcf..5e5713946f7b 100644 > --- a/fs/ceph/super.c > +++ b/fs/ceph/super.c > @@ -143,6 +143,9 @@ enum { > Opt_readdir_max_entries, > Opt_readdir_max_bytes, > Opt_congestion_kb, > + Opt_snapdirmode, > + Opt_snapdiruid, > + Opt_snapdirgid, > /* int args above */ > Opt_snapdirname, > Opt_mds_namespace, > @@ -200,6 +203,9 @@ static const struct fs_parameter_spec ceph_mount_parameters[] = { > fsparam_flag_no ("require_active_mds", Opt_require_active_mds), > fsparam_u32 ("rsize", Opt_rsize), > fsparam_string ("snapdirname", Opt_snapdirname), > + fsparam_u32oct ("snapdirmode", Opt_snapdirmode), > + fsparam_u32 ("snapdiruid", Opt_snapdiruid), > + fsparam_u32 ("snapdirgid", Opt_snapdirgid), > fsparam_string ("source", Opt_source), > fsparam_string ("mon_addr", Opt_mon_addr), > fsparam_u32 ("wsize", Opt_wsize), > @@ -414,6 +420,22 @@ static int ceph_parse_mount_param(struct fs_context *fc, > fsopt->snapdir_name = param->string; > param->string = NULL; > break; > + case Opt_snapdirmode: > + fsopt->snapdir_mode = result.uint_32; > + if (fsopt->snapdir_mode & ~0777) > + return invalfc(fc, "Invalid snapdirmode"); > + fsopt->snapdir_mode |= S_IFDIR; > + break; > + case Opt_snapdiruid: > + fsopt->snapdir_uid = make_kuid(current_user_ns(), result.uint_32); > + if (!uid_valid(fsopt->snapdir_uid)) > + return invalfc(fc, "Invalid snapdiruid"); > + break; > + case Opt_snapdirgid: > + fsopt->snapdir_gid = make_kgid(current_user_ns(), result.uint_32); > + if (!gid_valid(fsopt->snapdir_gid)) > + return invalfc(fc, "Invalid snapdirgid"); > + break; > case Opt_mds_namespace: > if (!namespace_equals(fsopt, param->string, strlen(param->string))) > return invalfc(fc, "Mismatching mds_namespace"); > @@ -734,6 +756,14 @@ static int ceph_show_options(struct seq_file *m, struct dentry *root) > seq_printf(m, ",readdir_max_bytes=%u", fsopt->max_readdir_bytes); > if (strcmp(fsopt->snapdir_name, CEPH_SNAPDIRNAME_DEFAULT)) > seq_show_option(m, "snapdirname", fsopt->snapdir_name); > + if (fsopt->snapdir_mode != (umode_t)-1) > + seq_printf(m, ",snapdirmode=%o", fsopt->snapdir_mode); > + if (!uid_eq(fsopt->snapdir_uid, INVALID_UID)) > + seq_printf(m, ",snapdiruid=%o", > + from_kuid_munged(&init_user_ns, fsopt->snapdir_uid)); > + if (!gid_eq(fsopt->snapdir_gid, INVALID_GID)) > + seq_printf(m, ",snapdirgid=%o", > + from_kgid_munged(&init_user_ns, fsopt->snapdir_gid)); > > return 0; > } > @@ -1335,6 +1365,9 @@ static int ceph_init_fs_context(struct fs_context *fc) > fsopt->wsize = CEPH_MAX_WRITE_SIZE; > fsopt->rsize = CEPH_MAX_READ_SIZE; > fsopt->rasize = CEPH_RASIZE_DEFAULT; > + fsopt->snapdir_mode = (umode_t)-1; > + fsopt->snapdir_uid = INVALID_UID; > + fsopt->snapdir_gid = INVALID_GID; > fsopt->snapdir_name = kstrdup(CEPH_SNAPDIRNAME_DEFAULT, GFP_KERNEL); > if (!fsopt->snapdir_name) > goto nomem; > diff --git a/fs/ceph/super.h b/fs/ceph/super.h > index d44a366b2f1b..3c930816078d 100644 > --- a/fs/ceph/super.h > +++ b/fs/ceph/super.h > @@ -85,6 +85,10 @@ struct ceph_mount_options { > unsigned int max_readdir; /* max readdir result (entries) */ > unsigned int max_readdir_bytes; /* max readdir result (bytes) */ > > + umode_t snapdir_mode; > + kuid_t snapdir_uid; > + kgid_t snapdir_gid; > + > bool new_dev_syntax; > > /*
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