Return-Path: Received: from mail-wi0-f177.google.com ([209.85.212.177]:36041 "EHLO mail-wi0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754743AbbDXLFT (ORCPT ); Fri, 24 Apr 2015 07:05:19 -0400 From: Andreas Gruenbacher To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-nfs@vger.kernel.org Subject: [RFC v3 20/45] richacl: Automatic Inheritance Date: Fri, 24 Apr 2015 13:04:17 +0200 Message-Id: <28e2cd75064ff56bad897b6f69356f4fb15b8128.1429868795.git.agruenba@redhat.com> In-Reply-To: References: In-Reply-To: References: Sender: linux-nfs-owner@vger.kernel.org List-ID: Automatic Inheritance (AI) allows changes to the acl of a directory to recursively propagate down to files and directories in the directory. To implement this, the kernel keeps track of which permissions have been inherited, and makes sure that permission propagation is turned off when the file permission bits of a file are changed (upon create or chmod). The actual permission propagation is implemented in user space. Automatic Inheritance works as follows: - When the ACL4_AUTO_INHERIT flag in the acl of a file is not set, the file is not affected by AI. - When the ACL4_AUTO_INHERIT flag in the acl of a directory is set and a file or subdirectory is created in that directory, files created in the directory will have the ACL4_AUTO_INHERIT flag set, and all inherited aces will have the ACE4_INHERITED_ACE flag set. This allows user space to distinguish between aces which have been inherited and aces which have been explicitly added. - When the ACL4_PROTECTED acl flag in the acl of a file is set, AI will not modify the acl of the file. This does not affect propagation of permissions from the file to its children (if the file is a directory). Linux does not have a way of creating files without setting the file permission bits, so all files created inside a directory with ACL4_AUTO_INHERIT set will also have the ACL4_PROTECTED flag set. This effectively disables Automatic Inheritance. Protocols which support creating files without specifying permissions can explicitly clear the ACL4_PROTECTED flag after creating a file and reset the file masks to "undo" applying the create mode; see richacl_compute_max_masks(). This is a workaround; a mechanism that would allow a process to indicate to the kernel to ignore the create mode when there are inherited permissions would fix this problem. Signed-off-by: Andreas Gruenbacher --- fs/richacl_base.c | 10 +++++++++- fs/richacl_inode.c | 7 ++++++- include/linux/richacl.h | 25 +++++++++++++++++++++++-- 3 files changed, 38 insertions(+), 4 deletions(-) diff --git a/fs/richacl_base.c b/fs/richacl_base.c index 54cb482..572f1b8 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -352,7 +352,8 @@ richacl_chmod(struct richacl *acl, mode_t mode) if (acl->a_owner_mask == owner_mask && acl->a_group_mask == group_mask && acl->a_other_mask == other_mask && - (acl->a_flags & RICHACL_MASKED)) + (acl->a_flags & RICHACL_MASKED) && + (!richacl_is_auto_inherit(acl) || richacl_is_protected(acl))) return acl; clone = richacl_clone(acl, GFP_KERNEL); @@ -364,6 +365,8 @@ richacl_chmod(struct richacl *acl, mode_t mode) clone->a_owner_mask = owner_mask; clone->a_group_mask = group_mask; clone->a_other_mask = other_mask; + if (richacl_is_auto_inherit(clone)) + clone->a_flags |= RICHACL_PROTECTED; return clone; } @@ -434,6 +437,11 @@ richacl_inherit(const struct richacl *dir_acl, int isdir) ace++; } } + if (richacl_is_auto_inherit(dir_acl)) { + acl->a_flags = RICHACL_AUTO_INHERIT; + richacl_for_each_entry(ace, acl) + ace->e_flags |= RICHACE_INHERITED_ACE; + } return acl; } diff --git a/fs/richacl_inode.c b/fs/richacl_inode.c index 1a5b868..dfbb15a 100644 --- a/fs/richacl_inode.c +++ b/fs/richacl_inode.c @@ -223,9 +223,14 @@ richacl_inherit_inode(const struct richacl *dir_acl, struct inode *inode) acl = richacl_inherit(dir_acl, S_ISDIR(inode->i_mode)); if (acl) { + /* + * We need to set RICHACL_PROTECTED because we are + * doing an implicit chmod + */ + if (richacl_is_auto_inherit(acl)) + acl->a_flags |= RICHACL_PROTECTED; richacl_compute_max_masks(acl); - /* * Ensure that the acl will not grant any permissions beyond * the create mode. diff --git a/include/linux/richacl.h b/include/linux/richacl.h index 8a92b89..bcc2b64 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -53,9 +53,15 @@ struct richacl { _ace--) /* a_flag values */ +#define RICHACL_AUTO_INHERIT 0x01 +#define RICHACL_PROTECTED 0x02 +#define RICHACL_DEFAULTED 0x04 #define RICHACL_MASKED 0x80 -#define RICHACL_VALID_FLAGS ( \ +#define RICHACL_VALID_FLAGS ( \ + RICHACL_AUTO_INHERIT | \ + RICHACL_PROTECTED | \ + RICHACL_DEFAULTED | \ RICHACL_MASKED) /* e_type values */ @@ -68,6 +74,7 @@ struct richacl { #define RICHACE_NO_PROPAGATE_INHERIT_ACE 0x0004 #define RICHACE_INHERIT_ONLY_ACE 0x0008 #define RICHACE_IDENTIFIER_GROUP 0x0040 +#define RICHACE_INHERITED_ACE 0x0080 #define RICHACE_SPECIAL_WHO 0x4000 #define RICHACE_VALID_FLAGS ( \ @@ -76,6 +83,7 @@ struct richacl { RICHACE_NO_PROPAGATE_INHERIT_ACE | \ RICHACE_INHERIT_ONLY_ACE | \ RICHACE_IDENTIFIER_GROUP | \ + RICHACE_INHERITED_ACE | \ RICHACE_SPECIAL_WHO) /* e_mask bitflags */ @@ -187,6 +195,18 @@ extern void set_cached_richacl(struct inode *, struct richacl *); extern void forget_cached_richacl(struct inode *); extern struct richacl *get_richacl(struct inode *); +static inline int +richacl_is_auto_inherit(const struct richacl *acl) +{ + return acl->a_flags & RICHACL_AUTO_INHERIT; +} + +static inline int +richacl_is_protected(const struct richacl *acl) +{ + return acl->a_flags & RICHACL_PROTECTED; +} + /** * richace_is_owner - check if @ace is an OWNER@ entry */ @@ -257,7 +277,8 @@ richace_clear_inheritance_flags(struct richace *ace) ace->e_flags &= ~(RICHACE_FILE_INHERIT_ACE | RICHACE_DIRECTORY_INHERIT_ACE | RICHACE_NO_PROPAGATE_INHERIT_ACE | - RICHACE_INHERIT_ONLY_ACE); + RICHACE_INHERIT_ONLY_ACE | + RICHACE_INHERITED_ACE); } /** -- 2.1.0