[PATCH] knfsd: nfsd4: acls: avoid unnecessary denies
We're inserting deny's between some ACEs in order to enforce posix draft acl semantics which prevent permissions from accumulating across entries in an acl. That's fine, but we're doing that by inserting a deny after *every* allow, which is overkill. We shouldn't be adding them in places where they actually make no difference. Also replaced some helper functions for creating acl entries; I prefer just assigning directly to the struct fields--it takes a few more lines, but the field names provide some documentation that I think makes the result easier understand. Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by: Neil Brown <neilb@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
J. Bruce Fields
Linus Torvalds
Родитель
f43daf6787
Коммит
bec50c47aa
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@ -89,12 +89,19 @@ mask_from_posix(unsigned short perm, unsigned int flags)
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}
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static u32
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deny_mask(u32 allow_mask, unsigned int flags)
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deny_mask_from_posix(unsigned short perm, u32 flags)
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{
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u32 ret = ~allow_mask & ~NFS4_MASK_UNSUPP;
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if (!(flags & NFS4_ACL_DIR))
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ret &= ~NFS4_ACE_DELETE_CHILD;
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return ret;
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u32 mask = 0;
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if (perm & ACL_READ)
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mask |= NFS4_READ_MODE;
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if (perm & ACL_WRITE)
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mask |= NFS4_WRITE_MODE;
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if ((perm & ACL_WRITE) && (flags & NFS4_ACL_DIR))
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mask |= NFS4_ACE_DELETE_CHILD;
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if (perm & ACL_EXECUTE)
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mask |= NFS4_EXECUTE_MODE;
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return mask;
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}
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/* XXX: modify functions to return NFS errors; they're only ever
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@ -164,14 +171,51 @@ nfs4_acl_posix_to_nfsv4(struct posix_acl *pacl, struct posix_acl *dpacl,
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return acl;
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}
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struct posix_acl_summary {
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unsigned short owner;
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unsigned short users;
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unsigned short group;
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unsigned short groups;
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unsigned short other;
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unsigned short mask;
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};
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static void
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nfs4_acl_add_pair(struct nfs4_acl *acl, int eflag, u32 mask, int whotype,
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uid_t owner, unsigned int flags)
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summarize_posix_acl(struct posix_acl *acl, struct posix_acl_summary *pas)
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{
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE,
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eflag, mask, whotype, owner);
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_DENIED_ACE_TYPE,
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eflag, deny_mask(mask, flags), whotype, owner);
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struct posix_acl_entry *pa, *pe;
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pas->users = 0;
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pas->groups = 0;
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pas->mask = 07;
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pe = acl->a_entries + acl->a_count;
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FOREACH_ACL_ENTRY(pa, acl, pe) {
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switch (pa->e_tag) {
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case ACL_USER_OBJ:
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pas->owner = pa->e_perm;
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break;
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case ACL_GROUP_OBJ:
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pas->group = pa->e_perm;
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break;
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case ACL_USER:
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pas->users |= pa->e_perm;
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break;
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case ACL_GROUP:
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pas->groups |= pa->e_perm;
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break;
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case ACL_OTHER:
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pas->other = pa->e_perm;
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break;
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case ACL_MASK:
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pas->mask = pa->e_perm;
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break;
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}
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}
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/* We'll only care about effective permissions: */
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pas->users &= pas->mask;
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pas->group &= pas->mask;
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pas->groups &= pas->mask;
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}
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/* We assume the acl has been verified with posix_acl_valid. */
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@ -179,30 +223,63 @@ static void
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_posix_to_nfsv4_one(struct posix_acl *pacl, struct nfs4_acl *acl,
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unsigned int flags)
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{
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struct posix_acl_entry *pa, *pe, *group_owner_entry;
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u32 mask;
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unsigned short mask_mask;
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struct posix_acl_entry *pa, *group_owner_entry;
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struct nfs4_ace *ace;
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struct posix_acl_summary pas;
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unsigned short deny;
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int eflag = ((flags & NFS4_ACL_TYPE_DEFAULT) ?
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NFS4_INHERITANCE_FLAGS : 0);
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BUG_ON(pacl->a_count < 3);
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pe = pacl->a_entries + pacl->a_count;
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pa = pe - 2; /* if mask entry exists, it's second from the last. */
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if (pa->e_tag == ACL_MASK)
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mask_mask = pa->e_perm;
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else
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mask_mask = S_IRWXO;
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summarize_posix_acl(pacl, &pas);
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pa = pacl->a_entries;
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BUG_ON(pa->e_tag != ACL_USER_OBJ);
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mask = mask_from_posix(pa->e_perm, flags | NFS4_ACL_OWNER);
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nfs4_acl_add_pair(acl, eflag, mask, NFS4_ACL_WHO_OWNER, 0, flags);
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ace = acl->aces + acl->naces;
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/* We could deny everything not granted by the owner: */
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deny = ~pas.owner;
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/*
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* but it is equivalent (and simpler) to deny only what is not
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* granted by later entries:
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*/
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deny &= pas.users | pas.group | pas.groups | pas.other;
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if (deny) {
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ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = deny_mask_from_posix(deny, flags);
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ace->whotype = NFS4_ACL_WHO_OWNER;
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ace++;
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acl->naces++;
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}
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ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = mask_from_posix(pa->e_perm, flags | NFS4_ACL_OWNER);
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ace->whotype = NFS4_ACL_WHO_OWNER;
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ace++;
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acl->naces++;
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pa++;
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while (pa->e_tag == ACL_USER) {
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mask = mask_from_posix(pa->e_perm & mask_mask, flags);
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nfs4_acl_add_pair(acl, eflag, mask,
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NFS4_ACL_WHO_NAMED, pa->e_id, flags);
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deny = ~(pa->e_perm & pas.mask);
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deny &= pas.groups | pas.group | pas.other;
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if (deny) {
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ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = deny_mask_from_posix(deny, flags);
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ace->whotype = NFS4_ACL_WHO_NAMED;
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ace->who = pa->e_id;
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ace++;
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acl->naces++;
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}
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ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = mask_from_posix(pa->e_perm & pas.mask,
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flags);
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ace->whotype = NFS4_ACL_WHO_NAMED;
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ace->who = pa->e_id;
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ace++;
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acl->naces++;
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pa++;
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}
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@ -212,41 +289,64 @@ _posix_to_nfsv4_one(struct posix_acl *pacl, struct nfs4_acl *acl,
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/* allow ACEs */
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group_owner_entry = pa;
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mask = mask_from_posix(pa->e_perm & mask_mask, flags);
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE,
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NFS4_ACE_IDENTIFIER_GROUP | eflag, mask,
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NFS4_ACL_WHO_GROUP, 0);
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ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = mask_from_posix(pas.group, flags);
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ace->whotype = NFS4_ACL_WHO_GROUP;
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ace++;
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acl->naces++;
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pa++;
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while (pa->e_tag == ACL_GROUP) {
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mask = mask_from_posix(pa->e_perm & mask_mask, flags);
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE,
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NFS4_ACE_IDENTIFIER_GROUP | eflag, mask,
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NFS4_ACL_WHO_NAMED, pa->e_id);
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ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
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ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
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ace->access_mask = mask_from_posix(pa->e_perm & pas.mask,
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flags);
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ace->whotype = NFS4_ACL_WHO_NAMED;
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ace->who = pa->e_id;
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ace++;
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acl->naces++;
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pa++;
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}
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/* deny ACEs */
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pa = group_owner_entry;
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mask = mask_from_posix(pa->e_perm, flags);
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_DENIED_ACE_TYPE,
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NFS4_ACE_IDENTIFIER_GROUP | eflag,
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deny_mask(mask, flags), NFS4_ACL_WHO_GROUP, 0);
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deny = ~pas.group & pas.other;
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if (deny) {
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ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
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ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
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ace->access_mask = deny_mask_from_posix(deny, flags);
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ace->whotype = NFS4_ACL_WHO_GROUP;
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ace++;
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acl->naces++;
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}
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pa++;
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while (pa->e_tag == ACL_GROUP) {
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mask = mask_from_posix(pa->e_perm, flags);
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nfs4_acl_add_ace(acl, NFS4_ACE_ACCESS_DENIED_ACE_TYPE,
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NFS4_ACE_IDENTIFIER_GROUP | eflag,
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deny_mask(mask, flags), NFS4_ACL_WHO_NAMED, pa->e_id);
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deny = ~(pa->e_perm & pas.mask);
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deny &= pas.other;
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if (deny) {
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ace->type = NFS4_ACE_ACCESS_DENIED_ACE_TYPE;
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ace->flag = eflag | NFS4_ACE_IDENTIFIER_GROUP;
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ace->access_mask = mask_from_posix(deny, flags);
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ace->whotype = NFS4_ACL_WHO_NAMED;
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ace->who = pa->e_id;
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ace++;
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acl->naces++;
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}
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pa++;
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}
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if (pa->e_tag == ACL_MASK)
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pa++;
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BUG_ON(pa->e_tag != ACL_OTHER);
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mask = mask_from_posix(pa->e_perm, flags);
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nfs4_acl_add_pair(acl, eflag, mask, NFS4_ACL_WHO_EVERYONE, 0, flags);
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ace->type = NFS4_ACE_ACCESS_ALLOWED_ACE_TYPE;
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ace->flag = eflag;
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ace->access_mask = mask_from_posix(pa->e_perm, flags);
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ace->whotype = NFS4_ACL_WHO_EVERYONE;
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acl->naces++;
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}
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static void
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