> On Jul 19, 2023, at 1:49 PM, Jeff Layton <jlayton@xxxxxxxxxx> wrote: > > A well-formed NFSv4 ACL will always contain OWNER@/GROUP@/EVERYONE@ > ACEs, but there is no requirement for inheritable entries for those > entities. POSIX ACLs must always have owner/group/other entries, even for a > default ACL. > > nfsd builds the default ACL from inheritable ACEs, but the current code > just leaves any unspecified ACEs zeroed out. The result is that adding a > default user or group ACE to an inode can leave it with unwanted deny > entries. > > For instance, a newly created directory with no acl will look something > like this: > > # NFSv4 translation by server > A::OWNER@:rwaDxtTcCy > A::GROUP@:rxtcy > A::EVERYONE@:rxtcy > > # POSIX ACL of underlying file > user::rwx > group::r-x > other::r-x > > ...if I then add new v4 ACE: > > nfs4_setfacl -a A:fd:1000:rwx /mnt/local/test > > ...I end up with a result like this today: > > user::rwx > user:1000:rwx > group::r-x > mask::rwx > other::r-x > default:user::--- > default:user:1000:rwx > default:group::--- > default:mask::rwx > default:other::--- > > A::OWNER@:rwaDxtTcCy > A::1000:rwaDxtcy > A::GROUP@:rxtcy > A::EVERYONE@:rxtcy > D:fdi:OWNER@:rwaDx > A:fdi:OWNER@:tTcCy > A:fdi:1000:rwaDxtcy > A:fdi:GROUP@:tcy > A:fdi:EVERYONE@:tcy > > ...which is not at all expected. Adding a single inheritable allow ACE > should not result in everyone else losing access. > > The setfacl command solves a silimar issue by copying owner/group/other > entries from the effective ACL when none of them are set: > > "If a Default ACL entry is created, and the Default ACL contains no > owner, owning group, or others entry, a copy of the ACL owner, > owning group, or others entry is added to the Default ACL. > > Having nfsd do the same provides a more sane result (with no deny ACEs > in the resulting set): > > user::rwx > user:1000:rwx > group::r-x > mask::rwx > other::r-x > default:user::rwx > default:user:1000:rwx > default:group::r-x > default:mask::rwx > default:other::r-x > > A::OWNER@:rwaDxtTcCy > A::1000:rwaDxtcy > A::GROUP@:rxtcy > A::EVERYONE@:rxtcy > A:fdi:OWNER@:rwaDxtTcCy > A:fdi:1000:rwaDxtcy > A:fdi:GROUP@:rxtcy > A:fdi:EVERYONE@:rxtcy > > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2136452 > Reported-by: Ondrej Valousek <ondrej.valousek@xxxxxxxxxxx> > Suggested-by: Andreas Gruenbacher <agruen@xxxxxxxxxx> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx> As you pointed out in the bug report, there is not much testing infrastructure for NFSv4 ACLs. It will be hard to tell in advance if this change results in a behavior regression. On the other hand, I'm not sure we have a large cohort of NFSv4 ACL users on Linux. I can certainly apply this to nfsd-next at least for a few weeks to see if anyone yelps. > --- > fs/nfsd/nfs4acl.c | 32 +++++++++++++++++++++++++++++--- > 1 file changed, 29 insertions(+), 3 deletions(-) > > diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c > index 518203821790..64e45551d1b6 100644 > --- a/fs/nfsd/nfs4acl.c > +++ b/fs/nfsd/nfs4acl.c > @@ -441,7 +441,8 @@ struct posix_ace_state_array { > * calculated so far: */ > > struct posix_acl_state { > - int empty; > + bool empty; > + unsigned char valid; > struct posix_ace_state owner; > struct posix_ace_state group; > struct posix_ace_state other; > @@ -457,7 +458,7 @@ init_state(struct posix_acl_state *state, int cnt) > int alloc; > > memset(state, 0, sizeof(struct posix_acl_state)); > - state->empty = 1; > + state->empty = true; > /* > * In the worst case, each individual acl could be for a distinct > * named user or group, but we don't know which, so we allocate > @@ -624,7 +625,7 @@ static void process_one_v4_ace(struct posix_acl_state *state, > u32 mask = ace->access_mask; > int i; > > - state->empty = 0; > + state->empty = false; > > switch (ace2type(ace)) { > case ACL_USER_OBJ: > @@ -633,6 +634,7 @@ static void process_one_v4_ace(struct posix_acl_state *state, > } else { > deny_bits(&state->owner, mask); > } > + state->valid |= ACL_USER_OBJ; > break; > case ACL_USER: > i = find_uid(state, ace->who_uid); > @@ -655,6 +657,7 @@ static void process_one_v4_ace(struct posix_acl_state *state, > deny_bits_array(state->users, mask); > deny_bits_array(state->groups, mask); > } > + state->valid |= ACL_GROUP_OBJ; > break; > case ACL_GROUP: > i = find_gid(state, ace->who_gid); > @@ -686,6 +689,7 @@ static void process_one_v4_ace(struct posix_acl_state *state, > deny_bits_array(state->users, mask); > deny_bits_array(state->groups, mask); > } > + state->valid |= ACL_OTHER; > } > } > > @@ -726,6 +730,28 @@ static int nfs4_acl_nfsv4_to_posix(struct nfs4_acl *acl, > if (!(ace->flag & NFS4_ACE_INHERIT_ONLY_ACE)) > process_one_v4_ace(&effective_acl_state, ace); > } > + > + /* > + * At this point, the default ACL may have zeroed-out entries for owner, > + * group and other. That usually results in a non-sensical resulting ACL > + * that denies all access except to any ACE that was explicitly added. > + * > + * The setfacl command solves a similar problem with this logic: > + * > + * "If a Default ACL entry is created, and the Default ACL contains > + * no owner, owning group, or others entry, a copy of the ACL > + * owner, owning group, or others entry is added to the Default ACL." > + * > + * If none of the requisite ACEs were set, and some explicit user or group > + * ACEs were, copy the requisite entries from the effective set. > + */ > + if (!default_acl_state.valid && > + (default_acl_state.users->n || default_acl_state.groups->n)) { > + default_acl_state.owner = effective_acl_state.owner; > + default_acl_state.group = effective_acl_state.group; > + default_acl_state.other = effective_acl_state.other; > + } > + > *pacl = posix_state_to_acl(&effective_acl_state, flags); > if (IS_ERR(*pacl)) { > ret = PTR_ERR(*pacl); > > --- > base-commit: 9d985ab8ed33176c3c0380b7de589ea2ae51a48d > change-id: 20230719-nfsd-acl-5ab61537e4e6 > > Best regards, > -- > Jeff Layton <jlayton@xxxxxxxxxx> > -- Chuck Lever
