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[RFC v6 27/40] richacl: Create richacl from mode values

From Andreas Gruenbacher <andreas.gruenbacher@gmail.com>
Newsgroups linux.kernel
Subject [RFC v6 27/40] richacl: Create richacl from mode values
Date 2015-08-04 14:10 +0200
Message-ID <pTJcG-1D3-97@gated-at.bofh.it> (permalink)
References <pTJ2V-1c2-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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A file can have "no acl" in the sense that only the file mode permission
bits determine access.  In that case, the getxattr system call fails with
errno == ENODATA (No such attribute).

Over the NFSv4 protocol, a file always has an acl, and we convert the file
mode permission bits into an equivalent acl with richacl_from_mode.  Such
"trivial" acls can be converted back to a file mode with
richacl_equiv_mode.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
---
 fs/richacl_compat.c     | 88 +++++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/richacl.h |  1 +
 2 files changed, 89 insertions(+)

diff --git a/fs/richacl_compat.c b/fs/richacl_compat.c
index e552c95..50839a1 100644
--- a/fs/richacl_compat.c
+++ b/fs/richacl_compat.c
@@ -839,3 +839,91 @@ richacl_apply_masks(struct richacl **acl, kuid_t owner)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(richacl_apply_masks);
+
+/**
+ * richacl_from_mode  -  create an acl which corresponds to @mode
+ *
+ * The resulting acl doesn't have the RICHACL_MASKED flag set.
+ *
+ * @mode:	file mode including the file type
+ */
+struct richacl *
+richacl_from_mode(mode_t mode)
+{
+	unsigned int owner_mask = richacl_mode_to_mask(mode >> 6);
+	unsigned int group_mask = richacl_mode_to_mask(mode >> 3);
+	unsigned int other_mask = richacl_mode_to_mask(mode);
+	unsigned int denied;
+	unsigned int entries = 0;
+	struct richacl *acl;
+	struct richace *ace;
+
+	/* RICHACE_DELETE_CHILD is meaningless for non-directories. */
+	if (!S_ISDIR(mode)) {
+		owner_mask &= ~RICHACE_DELETE_CHILD;
+		group_mask &= ~RICHACE_DELETE_CHILD;
+		other_mask &= ~RICHACE_DELETE_CHILD;
+	}
+
+	denied = ~owner_mask & (group_mask | other_mask);
+	if (denied)
+		entries++;  /* owner@ deny entry needed */
+	if (owner_mask & ~(group_mask & other_mask))
+		entries++;  /* owner@ allow entry needed */
+	denied = ~group_mask & other_mask;
+	if (denied)
+		entries++;  /* group@ deny entry needed */
+	if (group_mask & ~other_mask)
+		entries++;  /* group@ allow entry needed */
+	if (other_mask)
+		entries++;  /* everyone@ allow entry needed */
+
+	acl = richacl_alloc(entries, GFP_KERNEL);
+	if (!acl)
+		return NULL;
+	acl->a_owner_mask = owner_mask;
+	acl->a_group_mask = group_mask;
+	acl->a_other_mask = other_mask;
+	ace = acl->a_entries;
+
+	denied = ~owner_mask & (group_mask | other_mask);
+	if (denied) {
+		ace->e_type = RICHACE_ACCESS_DENIED_ACE_TYPE;
+		ace->e_flags = RICHACE_SPECIAL_WHO;
+		ace->e_mask = denied;
+		ace->e_id.special = RICHACE_OWNER_SPECIAL_ID;
+		ace++;
+	}
+	if (owner_mask & ~(group_mask & other_mask)) {
+		ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE;
+		ace->e_flags = RICHACE_SPECIAL_WHO;
+		ace->e_mask = owner_mask;
+		ace->e_id.special = RICHACE_OWNER_SPECIAL_ID;
+		ace++;
+	}
+	denied = ~group_mask & other_mask;
+	if (denied) {
+		ace->e_type = RICHACE_ACCESS_DENIED_ACE_TYPE;
+		ace->e_flags = RICHACE_SPECIAL_WHO;
+		ace->e_mask = denied;
+		ace->e_id.special = RICHACE_GROUP_SPECIAL_ID;
+		ace++;
+	}
+	if (group_mask & ~other_mask) {
+		ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE;
+		ace->e_flags = RICHACE_SPECIAL_WHO;
+		ace->e_mask = group_mask;
+		ace->e_id.special = RICHACE_GROUP_SPECIAL_ID;
+		ace++;
+	}
+	if (other_mask) {
+		ace->e_type = RICHACE_ACCESS_ALLOWED_ACE_TYPE;
+		ace->e_flags = RICHACE_SPECIAL_WHO;
+		ace->e_mask = other_mask;
+		ace->e_id.special = RICHACE_EVERYONE_SPECIAL_ID;
+		ace++;
+	}
+
+	return acl;
+}
+EXPORT_SYMBOL_GPL(richacl_from_mode);
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index 8723ec9..fce5d84 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -340,5 +340,6 @@ extern struct richacl *richacl_create(struct inode *, struct inode *);
 
 /* richacl_compat.c */
 extern int richacl_apply_masks(struct richacl **, kuid_t);
+extern struct richacl *richacl_from_mode(mode_t);
 
 #endif /* __RICHACL_H */
-- 
2.5.0

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Thread

[RFC v6 00/40] Richacls Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:00 +0200
  [RFC v6 25/40] richacl: Isolate the owner and group classes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:00 +0200
  [RFC v6 33/40] richacl: Add support for unmapped identifiers Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:00 +0200
  [RFC v6 39/40] nfs: Add richacl support Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:00 +0200
  [RFC v6 29/40] nfsd: Use richacls as internal acl representation Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:00 +0200
  [RFC v6 23/40] richacl: Set the owner permissions to the owner mask Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 21/40] richacl: Move everyone@ aces down the acl Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 31/40] nfsd: Add support for the v4.1 dacl attribute Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 14/40] richacl: Create-time inheritance Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 19/40] ext4: Add richacl feature flag Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 28/40] nfsd: Keep list of acls to dispose of in compoundargs Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 26/40] richacl: Apply the file masks to a richacl Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 20/40] richacl: acl editing helper functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 15/40] richacl: Automatic Inheritance Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 22/40] richacl: Propagate everyone@ permissions to other aces Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 24/40] richacl: Set the other permissions to the other mask Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 18/40] ext4: Add richacl support Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 11/40] vfs: Cache base_acl objects in inodes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 12/40] vfs: Cache richacl in struct inode Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 17/40] vfs: Add richacl permission checking Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 27/40] richacl: Create richacl from mode values Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:10 +0200
  [RFC v6 01/40] vfs: Add IS_ACL() and IS_RICHACL() tests Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200
  [RFC v6 07/40] richacl: Permission mapping functions Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200
  [RFC v6 05/40] vfs: Add permission flags for setting file attributes Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200
  [RFC v6 04/40] vfs: Make the inode passed to inode_change_ok non-const Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200
  [RFC v6 02/40] vfs: Add MAY_CREATE_FILE and MAY_CREATE_DIR permission flags Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200
  [RFC v6 09/40] richacl: Update the file masks in chmod() Andreas Gruenbacher <andreas.gruenbacher@gmail.com> - 2015-08-04 14:20 +0200

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