Re: [PATCH v23 06/22] richacl: In-memory representation and helper functions

[Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Tue, Jul 5, 2016 at 1:34 PM, Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> wrote:
> On Thu, 2016-06-30 at 15:46 +0200, Andreas Gruenbacher wrote:
>> A richacl consists of an NFSv4 acl and an owner, group, and other mask.
>> These three masks correspond to the owner, group, and other file
>> permission bits, but they contain NFSv4 permissions instead of POSIX
>> permissions.
>>
>> Each entry in the NFSv4 acl applies to the file owner (OWNER@), the
>> owning group (GROUP@), everyone (EVERYONE@), or to a specific uid or
>> gid.
>>
>> As in the standard POSIX file permission model, each process is the
>> owner, group, or other file class.  A richacl grants a requested access
>> only if the NFSv4 acl in the richacl grants the access (according to the
>> NFSv4 permission check algorithm), and the file mask that applies to the
>> process includes the requested permissions.
>>
>> Signed-off-by: Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> Reviewed-by: J. Bruce Fields <bfields-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> ---
>>  fs/Makefile                  |   1 +
>>  fs/richacl.c                 |  65 ++++++++++++++++
>>  include/linux/richacl.h      | 179 +++++++++++++++++++++++++++++++++++++++++++
>>  include/uapi/linux/Kbuild    |   1 +
>>  include/uapi/linux/richacl.h |  99 ++++++++++++++++++++++++
>>  5 files changed, 345 insertions(+)
>>  create mode 100644 fs/richacl.c
>>  create mode 100644 include/linux/richacl.h
>>  create mode 100644 include/uapi/linux/richacl.h
>>
>> diff --git a/fs/Makefile b/fs/Makefile
>> index 85b6e13..2b3e6f1 100644
>> --- a/fs/Makefile
>> +++ b/fs/Makefile
>> @@ -49,6 +49,7 @@ obj-$(CONFIG_COREDUMP)              += coredump.o
>>  obj-$(CONFIG_SYSCTL)         += drop_caches.o
>>
>>  obj-$(CONFIG_FHANDLE)                += fhandle.o
>> +obj-$(CONFIG_FS_RICHACL)     += richacl.o
>>
>>  obj-y                                += quota/
>>
>> diff --git a/fs/richacl.c b/fs/richacl.c
>> new file mode 100644
>> index 0000000..bcc6591
>> --- /dev/null
>> +++ b/fs/richacl.c
>> @@ -0,0 +1,65 @@
>> +/*
>> + * Copyright (C) 2006, 2010  Novell, Inc.
>> + * Copyright (C) 2015  Red Hat, Inc.
>> + * Written by Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License as published by the
>> + * Free Software Foundation; either version 2, or (at your option) any
>> + * later version.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * General Public License for more details.
>> + */
>> +
>> +#include
>> +#include
>> +#include
>> +#include
>> +#include
>> +
>> +/**
>> + * richacl_alloc  -  allocate a richacl
>> + * @count:   number of entries
>> + */
>> +struct richacl *
>> +richacl_alloc(int count, gfp_t gfp)
>> +{
>> +     size_t size = sizeof(struct richacl) + count * sizeof(struct richace);
>> +     struct richacl *acl = kzalloc(size, gfp);
>> +
>> +     if (acl) {
>> +             atomic_set(&acl->a_refcount, 1);
>> +             acl->a_count = count;
>> +     }
>> +     return acl;
>> +}
>> +EXPORT_SYMBOL_GPL(richacl_alloc);
>> +
>
> I imagine we could have a lot of these at any given time. It might be
> nice to consider how to do this with dedicated slabcaches for better
> packing, but I think that would add to the complexity, unfortunately.

The objects are variable in size, so that wouldn't work.

>> +/**
>> + * richacl_clone  -  create a copy of a richacl
>> + */
>> +struct richacl *
>> +richacl_clone(const struct richacl *acl, gfp_t gfp)
>> +{
>> +     int count = acl->a_count;
>> +     size_t size = sizeof(struct richacl) + count * sizeof(struct richace);
>> +     struct richacl *dup = kmalloc(size, gfp);
>> +
>> +     if (dup) {
>> +             memcpy(dup, acl, size);
>> +             atomic_set(&dup->a_refcount, 1);
>> +     }
>> +     return dup;
>> +}
>> +
>> +/**
>> + * richace_copy  -  copy an acl entry
>> + */
>> +void
>> +richace_copy(struct richace *to, const struct richace *from)
>> +{
>> +     memcpy(to, from, sizeof(struct richace));
>> +}
>> diff --git a/include/linux/richacl.h b/include/linux/richacl.h
>> new file mode 100644
>> index 0000000..edb8480
>> --- /dev/null
>> +++ b/include/linux/richacl.h
>> @@ -0,0 +1,179 @@
>> +/*
>> + * Copyright (C) 2006, 2010  Novell, Inc.
>> + * Copyright (C) 2015  Red Hat, Inc.
>> + * Written by Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms of the GNU General Public License as published by the
>> + * Free Software Foundation; either version 2, or (at your option) any
>> + * later version.
>> + *
>> + * This program is distributed in the hope that it will be useful, but
>> + * WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * General Public License for more details.
>> + */
>> +
>> +#ifndef __RICHACL_H
>> +#define __RICHACL_H
>> +
>> +#include
>> +
>> +struct richace {
>> +     unsigned short  e_type;
>> +     unsigned short  e_flags;
>> +     unsigned int    e_mask;
>> +     union {
>> +             kuid_t          uid;
>> +             kgid_t          gid;
>> +             unsigned int    special;
>> +     } e_id;
>> +};
>> +
>> +struct richacl {
>> +     atomic_t        a_refcount;
>> +     unsigned int    a_owner_mask;
>> +     unsigned int    a_group_mask;
>> +     unsigned int    a_other_mask;
>> +     unsigned short  a_count;
>> +     unsigned short  a_flags;
>> +     struct richace  a_entries[0];
>> +};
>> +
>> +#define richacl_for_each_entry(_ace, _acl)                   \
>> +     for (_ace = (_acl)->a_entries;                          \
>> +          _ace != (_acl)->a_entries + (_acl)->a_count;       \
>> +          _ace++)
>> +
>> +#define richacl_for_each_entry_reverse(_ace, _acl)           \
>> +     for (_ace = (_acl)->a_entries + (_acl)->a_count - 1;    \
>> +          _ace != (_acl)->a_entries - 1;                     \
>> +          _ace--)
>> +
>> +/**
>> + * richacl_get  -  grab another reference to a richacl handle
>> + */
>> +static inline struct richacl *
>> +richacl_get(struct richacl *acl)
>> +{
>> +     if (acl)
>> +             atomic_inc(&acl->a_refcount);
>> +     return acl;
>> +}
>> +
>> +/**
>> + * richacl_put  -  free a richacl handle
>> + */
>> +static inline void
>> +richacl_put(struct richacl *acl)
>> +{
>> +     if (acl && atomic_dec_and_test(&acl->a_refcount))
>> +             kfree(acl);
>> +}
>> +
>> +/**
>> + * richace_is_owner  -  check if @ace is an OWNER@ entry
>> + */
>> +static inline bool
>> +richace_is_owner(const struct richace *ace)
>> +{
>> +     return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
>> +            ace->e_id.special == RICHACE_OWNER_SPECIAL_ID;
>> +}
>> +
>> +/**
>> + * richace_is_group  -  check if @ace is a GROUP@ entry
>> + */
>> +static inline bool
>> +richace_is_group(const struct richace *ace)
>> +{
>> +     return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
>> +            ace->e_id.special == RICHACE_GROUP_SPECIAL_ID;
>> +}
>> +
>> +/**
>> + * richace_is_everyone  -  check if @ace is an EVERYONE@ entry
>> + */
>> +static inline bool
>> +richace_is_everyone(const struct richace *ace)
>> +{
>> +     return (ace->e_flags & RICHACE_SPECIAL_WHO) &&
>> +            ace->e_id.special == RICHACE_EVERYONE_SPECIAL_ID;
>> +}
>> +
>> +/**
>> + * richace_is_unix_user  -  check if @ace applies to a specific user
>> + */
>> +static inline bool
>> +richace_is_unix_user(const struct richace *ace)
>> +{
>> +     return !(ace->e_flags & RICHACE_SPECIAL_WHO) &&
>> +            !(ace->e_flags & RICHACE_IDENTIFIER_GROUP);
>> +}
>> +
>> +/**
>> + * richace_is_unix_group  -  check if @ace applies to a specific group
>> + */
>> +static inline bool
>> +richace_is_unix_group(const struct richace *ace)
>> +{
>> +     return !(ace->e_flags & RICHACE_SPECIAL_WHO) &&
>> +            (ace->e_flags & RICHACE_IDENTIFIER_GROUP);
>> +}
>> +
>> +/**
>> + * richace_is_inherit_only  -  check if @ace is for inheritance only
>> + *
>> + * ACEs with the %RICHACE_INHERIT_ONLY_ACE flag set have no effect during
>> + * permission checking.
>> + */
>> +static inline bool
>> +richace_is_inherit_only(const struct richace *ace)
>> +{
>> +     return ace->e_flags & RICHACE_INHERIT_ONLY_ACE;
>> +}
>> +
>> +/**
>> + * richace_is_inheritable  -  check if @ace is inheritable
>> + */
>> +static inline bool
>> +richace_is_inheritable(const struct richace *ace)
>> +{
>> +     return ace->e_flags & (RICHACE_FILE_INHERIT_ACE |
>> +                            RICHACE_DIRECTORY_INHERIT_ACE);
>> +}
>> +
>> +/**
>> + * richace_is_allow  -  check if @ace is an %ALLOW type entry
>> + */
>> +static inline bool
>> +richace_is_allow(const struct richace *ace)
>> +{
>> +     return ace->e_type == RICHACE_ACCESS_ALLOWED_ACE_TYPE;
>> +}
>> +
>> +/**
>> + * richace_is_deny  -  check if @ace is a %DENY type entry
>> + */
>> +static inline bool
>> +richace_is_deny(const struct richace *ace)
>> +{
>> +     return ace->e_type == RICHACE_ACCESS_DENIED_ACE_TYPE;
>> +}
>> +
>> +/**
>> + * richace_is_same_identifier  -  are both identifiers the same?
>> + */
>> +static inline bool
>> +richace_is_same_identifier(const struct richace *a, const struct richace *b)
>> +{
>> +     return !((a->e_flags ^ b->e_flags) &
>> +              (RICHACE_SPECIAL_WHO | RICHACE_IDENTIFIER_GROUP)) &&
>> +            !memcmp(&a->e_id, &b->e_id, sizeof(a->e_id));
>> +}
>> +
>> +extern struct richacl *richacl_alloc(int, gfp_t);
>> +extern struct richacl *richacl_clone(const struct richacl *, gfp_t);
>> +extern void richace_copy(struct richace *, const struct richace *);
>> +
>> +#endif /* __RICHACL_H */
>> diff --git a/include/uapi/linux/Kbuild b/include/uapi/linux/Kbuild
>> index 8bdae34..abeaa98 100644
>> --- a/include/uapi/linux/Kbuild
>> +++ b/include/uapi/linux/Kbuild
>> @@ -355,6 +355,7 @@ header-y += reboot.h
>>  header-y += reiserfs_fs.h
>>  header-y += reiserfs_xattr.h
>>  header-y += resource.h
>> +header-y += richacl.h
>>  header-y += rfkill.h
>>  header-y += rio_mport_cdev.h
>>  header-y += romfs_fs.h
>> diff --git a/include/uapi/linux/richacl.h b/include/uapi/linux/richacl.h
>> new file mode 100644
>> index 0000000..08856f8
>> --- /dev/null
>> +++ b/include/uapi/linux/richacl.h
>> @@ -0,0 +1,99 @@
>> +/*
>> + * Copyright (C) 2006, 2010  Novell, Inc.
>> + * Copyright (C) 2015  Red Hat, Inc.
>> + * Written by Andreas Gruenbacher <agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
>> + *
>> + * This file is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU Lesser General Public
>> + * License as published by the Free Software Foundation; either
>> + * version 2.1 of the License, or (at your option) any later version.
>> + *
>> + * This file is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>> + * Lesser General Public License for more details.
>> + */
>> +
>> +#ifndef __UAPI_RICHACL_H
>> +#define __UAPI_RICHACL_H
>> +
>> +/* a_flags values */
>> +#define RICHACL_WRITE_THROUGH                        0x40
>> +#define RICHACL_MASKED                               0x80
>> +
>> +/* e_type values */
>> +#define RICHACE_ACCESS_ALLOWED_ACE_TYPE              0x0000
>> +#define RICHACE_ACCESS_DENIED_ACE_TYPE               0x0001
>> +
>> +/* e_flags bitflags */
>> +#define RICHACE_FILE_INHERIT_ACE             0x0001
>> +#define RICHACE_DIRECTORY_INHERIT_ACE                0x0002
>> +#define RICHACE_NO_PROPAGATE_INHERIT_ACE     0x0004
>> +#define RICHACE_INHERIT_ONLY_ACE             0x0008
>> +#define RICHACE_IDENTIFIER_GROUP             0x0040
>> +#define RICHACE_SPECIAL_WHO                  0x4000
>> +
>> +/* e_mask bitflags */
>> +#define RICHACE_READ_DATA                    0x00000001
>> +#define RICHACE_LIST_DIRECTORY                       0x00000001
>> +#define RICHACE_WRITE_DATA                   0x00000002
>> +#define RICHACE_ADD_FILE                     0x00000002
>> +#define RICHACE_APPEND_DATA                  0x00000004
>> +#define RICHACE_ADD_SUBDIRECTORY             0x00000004
>> +#define RICHACE_READ_NAMED_ATTRS             0x00000008
>> +#define RICHACE_WRITE_NAMED_ATTRS            0x00000010
>> +#define RICHACE_EXECUTE                              0x00000020
>> +#define RICHACE_DELETE_CHILD                 0x00000040
>> +#define RICHACE_READ_ATTRIBUTES                      0x00000080
>> +#define RICHACE_WRITE_ATTRIBUTES             0x00000100
>> +#define RICHACE_WRITE_RETENTION                      0x00000200
>> +#define RICHACE_WRITE_RETENTION_HOLD         0x00000400
>> +#define RICHACE_DELETE                               0x00010000
>> +#define RICHACE_READ_ACL                     0x00020000
>> +#define RICHACE_WRITE_ACL                    0x00040000
>> +#define RICHACE_WRITE_OWNER                  0x00080000
>> +#define RICHACE_SYNCHRONIZE                  0x00100000
>> +
>> +/* e_id values */
>> +#define RICHACE_OWNER_SPECIAL_ID             0
>> +#define RICHACE_GROUP_SPECIAL_ID             1
>> +#define RICHACE_EVERYONE_SPECIAL_ID          2
>> +
>> +#define RICHACL_VALID_FLAGS (                                        \
>> +     RICHACL_WRITE_THROUGH |                                 \
>> +     RICHACL_MASKED )
>> +
>> +#define RICHACE_VALID_FLAGS (                                        \
>> +     RICHACE_FILE_INHERIT_ACE |                              \
>> +     RICHACE_DIRECTORY_INHERIT_ACE |                         \
>> +     RICHACE_NO_PROPAGATE_INHERIT_ACE |                      \
>> +     RICHACE_INHERIT_ONLY_ACE |                              \
>> +     RICHACE_IDENTIFIER_GROUP |                              \
>> +     RICHACE_SPECIAL_WHO )
>> +
>> +#define RICHACE_INHERITANCE_FLAGS (                          \
>> +     RICHACE_FILE_INHERIT_ACE |                              \
>> +     RICHACE_DIRECTORY_INHERIT_ACE |                         \
>> +     RICHACE_NO_PROPAGATE_INHERIT_ACE |                      \
>> +     RICHACE_INHERIT_ONLY_ACE )
>> +
>> +/* Valid RICHACE_* flags for directories and non-directories */
>> +#define RICHACE_VALID_MASK (                                 \
>> +     RICHACE_READ_DATA | RICHACE_LIST_DIRECTORY |            \
>> +     RICHACE_WRITE_DATA | RICHACE_ADD_FILE |                 \
>> +     RICHACE_APPEND_DATA | RICHACE_ADD_SUBDIRECTORY |        \
>> +     RICHACE_READ_NAMED_ATTRS |                              \
>> +     RICHACE_WRITE_NAMED_ATTRS |                             \
>> +     RICHACE_EXECUTE |                                       \
>> +     RICHACE_DELETE_CHILD |                                  \
>> +     RICHACE_READ_ATTRIBUTES |                               \
>> +     RICHACE_WRITE_ATTRIBUTES |                              \
>> +     RICHACE_WRITE_RETENTION |                               \
>> +     RICHACE_WRITE_RETENTION_HOLD |                          \
>> +     RICHACE_DELETE |                                        \
>> +     RICHACE_READ_ACL |                                      \
>> +     RICHACE_WRITE_ACL |                                     \
>> +     RICHACE_WRITE_OWNER |                                   \
>> +     RICHACE_SYNCHRONIZE )
>> +
>> +#endif /* __UAPI_RICHACL_H */
>
> Reviewed-by: Jeff Layton <jlayton-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>

Thanks,
Andreas