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Message-ID: <8903ae45c4802af9a56590460d2e1180b0f041f9.camel@kernel.org>
Date: Mon, 24 Jul 2023 09:54:22 -0400
From: Jeff Layton <jlayton@...nel.org>
To: Chuck Lever <chuck.lever@...cle.com>
Cc: Neil Brown <neilb@...e.de>, Olga Kornievskaia <kolga@...app.com>,
Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
Andreas Gruenbacher <agruenba@...hat.com>,
linux-nfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org,
Ondrej Valousek <ondrej.valousek@...semi.com>
Subject: Re: [PATCH v2] nfsd: inherit required unset default acls from
effective set
On Mon, 2023-07-24 at 09:44 -0400, Chuck Lever wrote:
> On Mon, Jul 24, 2023 at 08:13:05AM -0400, Jeff Layton wrote:
> > A well-formed NFSv4 ACL will always contain OWNER@...OUP@...ERYONE@
> > 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
> >
> > Reported-by: Ondrej Valousek <ondrej.valousek@...semi.com>
> > Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2136452
> > Suggested-by: Andreas Gruenbacher <agruenba@...hat.com>
> > Signed-off-by: Jeff Layton <jlayton@...nel.org>
> > ---
> > Changes in v2:
> > - always set missing ACEs whenever default ACL has any ACEs that are
> > explicitly set. This better conforms to how setfacl works.
> > - drop now-unneeded "empty" boolean
> > - Link to v1: https://lore.kernel.org/r/20230719-nfsd-acl-v1-1-eb0faf3d2917@kernel.org
> > ---
> > fs/nfsd/nfs4acl.c | 32 ++++++++++++++++++++++++++++----
> > 1 file changed, 28 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4acl.c b/fs/nfsd/nfs4acl.c
> > index 518203821790..b931d4383517 100644
> > --- a/fs/nfsd/nfs4acl.c
> > +++ b/fs/nfsd/nfs4acl.c
> > @@ -441,7 +441,7 @@ struct posix_ace_state_array {
> > * calculated so far: */
> >
> > struct posix_acl_state {
> > - int empty;
> > + unsigned char valid;
> > struct posix_ace_state owner;
> > struct posix_ace_state group;
> > struct posix_ace_state other;
> > @@ -457,7 +457,6 @@ init_state(struct posix_acl_state *state, int cnt)
> > int alloc;
> >
> > memset(state, 0, sizeof(struct posix_acl_state));
> > - state->empty = 1;
> > /*
> > * 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
> > @@ -500,7 +499,7 @@ posix_state_to_acl(struct posix_acl_state *state, unsigned int flags)
> > * and effective cases: when there are no inheritable ACEs,
> > * calls ->set_acl with a NULL ACL structure.
> > */
> > - if (state->empty && (flags & NFS4_ACL_TYPE_DEFAULT))
> > + if (!state->valid && (flags & NFS4_ACL_TYPE_DEFAULT))
> > return NULL;
> >
> > /*
> > @@ -622,9 +621,10 @@ static void process_one_v4_ace(struct posix_acl_state *state,
> > struct nfs4_ace *ace)
> > {
> > u32 mask = ace->access_mask;
> > + short type = ace2type(ace);
> > int i;
> >
> > - state->empty = 0;
> > + state->valid |= type;
> >
> > switch (ace2type(ace)) {
>
> Mechanical issue: the patch adds @type, but uses it just once.
> The switch here also wants the value of ace2type(ace).
>
>
Doh! I had that fixed in one version of the patch, but had to rework the
branch and lost that delta. I can respin, or if you just want to fix
that in place, then that would be fine too.
> > case ACL_USER_OBJ:
> > @@ -726,6 +726,30 @@ 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."
> > + *
> > + * Copy any missing ACEs from the effective set, if any ACEs were
> > + * explicitly set.
> > + */
> > + if (default_acl_state.valid) {
> > + if (!(default_acl_state.valid & ACL_USER_OBJ))
> > + default_acl_state.owner = effective_acl_state.owner;
> > + if (!(default_acl_state.valid & ACL_GROUP_OBJ))
> > + default_acl_state.group = effective_acl_state.group;
> > + if (!(default_acl_state.valid & ACL_OTHER))
> > + 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: 7bfb36a2ee1d329a501ba4781db4145dc951c798
> > change-id: 20230719-nfsd-acl-5ab61537e4e6
> >
> > Best regards,
> > --
> > Jeff Layton <jlayton@...nel.org>
> >
>
--
Jeff Layton <jlayton@...nel.org>
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