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144 lines
4.7 KiB
144 lines
4.7 KiB
From: Andreas Gruenbacher <agruen@suse.de>
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Date: Fri, 11 Jun 2010 16:12:52 +0530
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Subject: [PATCH 12/16] richacl: Automatic Inheritance
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Patch-mainline: not yet
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Automatic Inheritance (AI) allows changes to the acl of a directory to
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recursively propagate down to files and directories in the directory.
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To implement this, the kernel keeps track of which permissions have been
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inherited, and makes sure that permission propagation is turned off when
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the file permission bits of a file are changed (upon create or chmod).
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The actual permission propagation is implemented in user space.
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AI works as follows:
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- When the ACL4_AUTO_INHERIT flag in the acl of a file is cleared, the
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file is not affected by AI.
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- When the ACL4_AUTO_INHERIT flag in the acl of a directory is set and
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a file or subdirectory is created in that directory, files created in
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the directory will have the ACL4_AUTO_INHERIT flag set, and all
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inherited aces will have the ACE4_INHERITED_ACE flag set. This
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allows user space to distinguish between aces which have been
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inherited, and aces which have been explicitly added.
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- When the ACL4_PROTECTED acl flag in the acl of a file is set, AI will
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not modify the acl of the file. This does not affect propagation of
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permissions from the file to its children (if the file is a
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directory).
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Linux does not have a way of creating files without setting the file
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permission bits, so all files created inside a directory with
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ACL4_AUTO_INHERIT set will also have the ACL4_PROTECTED flag set. This
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effectively disables AI.
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Protocols which support creating files without specifying permissions
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can explicitly clear the ACL4_PROTECTED flag after creating a file (and
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reset the file masks to "undo" applying the create mode; see
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richacl_compute_max_masks()). This is a workaround; a per-create or
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per-process flag indicating to ignore the create mode when AI is in
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effect would fix this problem.
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Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
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Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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---
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fs/richacl_base.c | 15 ++++++++++++++-
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include/linux/richacl.h | 25 ++++++++++++++++++++++++-
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2 files changed, 38 insertions(+), 2 deletions(-)
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--- a/fs/richacl_base.c
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+++ b/fs/richacl_base.c
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@@ -352,7 +352,8 @@ richacl_chmod(struct richacl *acl, mode_
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if (acl->a_owner_mask == owner_mask &&
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acl->a_group_mask == group_mask &&
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- acl->a_other_mask == other_mask)
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+ acl->a_other_mask == other_mask &&
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+ (!richacl_is_auto_inherit(acl) || richacl_is_protected(acl)))
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return acl;
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clone = richacl_clone(acl);
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@@ -363,6 +364,8 @@ richacl_chmod(struct richacl *acl, mode_
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clone->a_owner_mask = owner_mask;
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clone->a_group_mask = group_mask;
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clone->a_other_mask = other_mask;
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+ if (richacl_is_auto_inherit(clone))
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+ clone->a_flags |= ACL4_PROTECTED;
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return clone;
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}
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@@ -539,6 +542,16 @@ richacl_inherit(const struct richacl *di
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acl->a_other_mask &= richacl_mode_to_mask(inode->i_mode);
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mask = ~S_IRWXUGO | richacl_masks_to_mode(acl);
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+ if (richacl_is_auto_inherit(dir_acl)) {
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+ /*
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+ * We need to set ACL4_PROTECTED because we are
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+ * doing an implicit chmod
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+ */
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+ acl->a_flags = ACL4_AUTO_INHERIT | ACL4_PROTECTED;
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+ richacl_for_each_entry(ace, acl)
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+ ace->e_flags |= ACE4_INHERITED_ACE;
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+ }
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+
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mask:
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inode->i_mode &= mask;
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return acl;
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--- a/include/linux/richacl.h
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+++ b/include/linux/richacl.h
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@@ -47,6 +47,15 @@ struct richacl {
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_ace != _acl->a_entries - 1; \
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_ace--)
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+/* a_flags values */
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+#define ACL4_AUTO_INHERIT 0x01
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+#define ACL4_PROTECTED 0x02
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+/*#define ACL4_DEFAULTED 0x04*/
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+
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+#define ACL4_VALID_FLAGS ( \
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+ ACL4_AUTO_INHERIT | \
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+ ACL4_PROTECTED)
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+
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/* e_type values */
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#define ACE4_ACCESS_ALLOWED_ACE_TYPE 0x0000
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#define ACE4_ACCESS_DENIED_ACE_TYPE 0x0001
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@@ -61,6 +70,7 @@ struct richacl {
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/*#define ACE4_SUCCESSFUL_ACCESS_ACE_FLAG 0x0010*/
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/*#define ACE4_FAILED_ACCESS_ACE_FLAG 0x0020*/
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#define ACE4_IDENTIFIER_GROUP 0x0040
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+#define ACE4_INHERITED_ACE 0x0080
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/* in-memory representation only */
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#define ACE4_SPECIAL_WHO 0x4000
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@@ -69,7 +79,8 @@ struct richacl {
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ACE4_DIRECTORY_INHERIT_ACE | \
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ACE4_NO_PROPAGATE_INHERIT_ACE | \
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ACE4_INHERIT_ONLY_ACE | \
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- ACE4_IDENTIFIER_GROUP)
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+ ACE4_IDENTIFIER_GROUP | \
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+ ACE4_INHERITED_ACE)
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/* e_mask bitflags */
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#define ACE4_READ_DATA 0x00000001
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@@ -162,6 +173,18 @@ richacl_put(struct richacl *acl)
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kfree(acl);
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}
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+static inline int
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+richacl_is_auto_inherit(const struct richacl *acl)
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+{
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+ return acl->a_flags & ACL4_AUTO_INHERIT;
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+}
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+
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+static inline int
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+richacl_is_protected(const struct richacl *acl)
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+{
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+ return acl->a_flags & ACL4_PROTECTED;
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+}
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+
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/*
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* Special e_who identifiers: we use these pointer values in comparisons
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* instead of doing a strcmp.
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