| Message ID | 1445008706-15115-17-git-send-email-agruenba@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, Oct 16, 2015 at 8:17 AM, Andreas Gruenbacher <agruenba@redhat.com> wrote: > Automatic Inheritance (AI) allows changes to the acl of a directory to > propagate down to children. > > This is mostly implemented in user space: when a process changes the > permissions of a directory and Automatic Inheritance is enabled for that > directory, the process must propagate those changes to all children, > recursively. > > The kernel enables this by keeping track of which permissions have been > inherited at create time. In addition, it makes sure that permission > propagation is turned off when the permissions are set explicitly (for > example, upon create or chmod). > > Automatic Inheritance works as follows: > > - When the RICHACL_AUTO_INHERIT flag in the acl of a file or directory > is not set, the file or directory is not affected by AI. > > - When the RICHACL_AUTO_INHERIT flag in the acl of a directory is set > and a file or subdirectory is created in that directory, the > inherited acl will have the RICHACL_AUTO_INHERIT flag set, and all > inherited aces will have the RICHACE_INHERITED_ACE flag set. This > allows user space to distinguish between aces which have been > inherited and aces which have been explicitly added. What if the file or subdirectory that's created in that directory is a hard link? --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Oct 16, 2015 at 6:00 PM, Andy Lutomirski <luto@amacapital.net> wrote: > On Fri, Oct 16, 2015 at 8:17 AM, Andreas Gruenbacher > <agruenba@redhat.com> wrote: >> Automatic Inheritance works as follows: >> >> - When the RICHACL_AUTO_INHERIT flag in the acl of a file or directory >> is not set, the file or directory is not affected by AI. >> >> - When the RICHACL_AUTO_INHERIT flag in the acl of a directory is set >> and a file or subdirectory is created in that directory, the >> inherited acl will have the RICHACL_AUTO_INHERIT flag set, and all >> inherited aces will have the RICHACE_INHERITED_ACE flag set. This >> allows user space to distinguish between aces which have been >> inherited and aces which have been explicitly added. > > What if the file or subdirectory that's created in that directory is a > hard link? Directories cannot have hard links. When a file is hard linked into multiple directories with different inheritable permissions, the permissions set last will "win". This isn't particularly pretty, but it's the way this has worked on that other operating system with significant marked share for the last fifteen years. Thanks, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/richacl_base.c b/fs/richacl_base.c index cb5081e..3a97a82 100644 --- a/fs/richacl_base.c +++ b/fs/richacl_base.c @@ -366,7 +366,8 @@ __richacl_chmod(struct richacl *acl, umode_t mode) acl->a_group_mask == group_mask && acl->a_other_mask == other_mask && (acl->a_flags & RICHACL_MASKED) && - (acl->a_flags & RICHACL_WRITE_THROUGH)) + (acl->a_flags & RICHACL_WRITE_THROUGH) && + (!richacl_is_auto_inherit(acl) || richacl_is_protected(acl))) return acl; clone = richacl_clone(acl, GFP_KERNEL); @@ -378,6 +379,8 @@ __richacl_chmod(struct richacl *acl, umode_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; } @@ -551,6 +554,11 @@ 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 4f3a1b7..b88a2f1 100644 --- a/fs/richacl_inode.c +++ b/fs/richacl_inode.c @@ -277,6 +277,13 @@ richacl_inherit_inode(const struct richacl *dir_acl, umode_t *mode_p) richacl_put(acl); acl = NULL; } else { + /* + * 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 diff --git a/include/linux/richacl.h b/include/linux/richacl.h index d7e10aa..67843a6 100644 --- a/include/linux/richacl.h +++ b/include/linux/richacl.h @@ -41,6 +41,9 @@ struct richacl { }; #define RICHACL_VALID_FLAGS ( \ + RICHACL_AUTO_INHERIT | \ + RICHACL_PROTECTED | \ + RICHACL_DEFAULTED | \ RICHACL_WRITE_THROUGH | \ RICHACL_MASKED) @@ -50,13 +53,15 @@ struct richacl { RICHACE_NO_PROPAGATE_INHERIT_ACE | \ RICHACE_INHERIT_ONLY_ACE | \ RICHACE_IDENTIFIER_GROUP | \ + RICHACE_INHERITED_ACE | \ RICHACE_SPECIAL_WHO) #define RICHACE_INHERITANCE_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) /* Valid RICHACE_* flags for directories and non-directories */ #define RICHACE_VALID_MASK ( \ @@ -113,6 +118,18 @@ 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 */