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
Reported-by: Ondrej Valousek <ondrej.valousek@xxxxxxxxxxx>
Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2136452
Suggested-by: Andreas Gruenbacher <agruenba@xxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
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@xxxxxxxxxx
---
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)) {
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@xxxxxxxxxx>
