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Date: Tue, 22 Aug 2017 23:59:33 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: linux-kernel@...r.kernel.org
Cc: Alexei Starovoitov <ast@...nel.org>,
Andy Lutomirski
<luto@...capital.net>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Casey Schaufler <casey@...aufler-ca.com>,
Daniel Borkmann <daniel@...earbox.net>,
David Drysdale
<drysdale@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <james.l.morris@...cle.com>, Jann Horn <jann@...jh.net>,
Jonathan Corbet <corbet@....net>,
Matthew Garrett <mjg59@...f.ucam.org>,
Michael Kerrisk <mtk.manpages@...il.com>,
Kees Cook <keescook@...omium.org>, Paul Moore <paul@...l-moore.com>,
Sargun Dhillon <sargun@...gun.me>,
"Serge E . Hallyn" <serge@...lyn.com>, Shuah Khan <shuah@...nel.org>,
Tejun Heo <tj@...nel.org>, Thomas Graf <tgraf@...g.ch>,
Will Drewry <wad@...omium.org>, kernel-hardening@...ts.openwall.com,
linux-api@...r.kernel.org, linux-security-module@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [PATCH net-next v7 05/10] landlock: Add LSM hooks related to
filesystem
On 21/08/2017 02:09, Mickaël Salaün wrote:
> Handle 33 filesystem-related LSM hooks for the Landlock filesystem
> event: LANDLOCK_SUBTYPE_EVENT_FS.
>
> A Landlock event wrap LSM hooks for similar kernel object types (e.g.
> struct file, struct path...). Multiple LSM hooks can trigger the same
> Landlock event.
>
> Landlock handle nine coarse-grained actions: read, write, execute, new,
> get, remove, ioctl, lock and fcntl. Each of them abstract LSM hook
> access control in a way that can be extended in the future.
>
> The Landlock LSM hook registration is done after other LSM to only run
> actions from user-space, via eBPF programs, if the access was granted by
> major (privileged) LSMs.
>
> Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> Cc: Alexei Starovoitov <ast@...nel.org>
> Cc: Andy Lutomirski <luto@...capital.net>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: David S. Miller <davem@...emloft.net>
> Cc: James Morris <james.l.morris@...cle.com>
> Cc: Kees Cook <keescook@...omium.org>
> Cc: Serge E. Hallyn <serge@...lyn.com>
> ---
>
> Changes since v6:
> * add 3 more sub-events: IOCTL, LOCK, FCNTL
> https://lkml.kernel.org/r/2fbc99a6-f190-f335-bd14-04bdeed35571@digikod.net
> * use the new security_add_hooks()
> * explain the -Werror=unused-function
> * constify pointers
> * cleanup headers
>
> Changes since v5:
> * split hooks.[ch] into hooks.[ch] and hooks_fs.[ch]
> * add more documentation
> * cosmetic fixes
> * rebase (SCALAR_VALUE)
>
> Changes since v4:
> * add LSM hook abstraction called Landlock event
> * use the compiler type checking to verify hooks use by an event
> * handle all filesystem related LSM hooks (e.g. file_permission,
> mmap_file, sb_mount...)
> * register BPF programs for Landlock just after LSM hooks registration
> * move hooks registration after other LSMs
> * add failsafes to check if a hook is not used by the kernel
> * allow partial raw value access form the context (needed for programs
> generated by LLVM)
>
> Changes since v3:
> * split commit
> * add hooks dealing with struct inode and struct path pointers:
> inode_permission and inode_getattr
> * add abstraction over eBPF helper arguments thanks to wrapping structs
> ---
> include/linux/lsm_hooks.h | 5 +
> security/landlock/Makefile | 7 +-
> security/landlock/common.h | 2 +
> security/landlock/hooks.c | 83 ++++++
> security/landlock/hooks.h | 177 +++++++++++++
> security/landlock/hooks_fs.c | 586 +++++++++++++++++++++++++++++++++++++++++++
> security/landlock/hooks_fs.h | 19 ++
> security/landlock/init.c | 10 +
> security/security.c | 12 +-
> 9 files changed, 899 insertions(+), 2 deletions(-)
> create mode 100644 security/landlock/hooks.c
> create mode 100644 security/landlock/hooks.h
> create mode 100644 security/landlock/hooks_fs.c
> create mode 100644 security/landlock/hooks_fs.h
> diff --git a/security/landlock/init.c b/security/landlock/init.c
> index 09acbc74abd6..1e6660fed697 100644
> --- a/security/landlock/init.c
> +++ b/security/landlock/init.c
> @@ -10,8 +10,10 @@
>
> #include <linux/bpf.h> /* enum bpf_access_type */
> #include <linux/capability.h> /* capable */
> +#include <linux/lsm_hooks.h>
>
> #include "common.h" /* LANDLOCK_* */
> +#include "hooks_fs.h"
>
>
> static inline bool bpf_landlock_is_valid_access(int off, int size,
> @@ -23,6 +25,8 @@ static inline bool bpf_landlock_is_valid_access(int off, int size,
>
> switch (prog_subtype->landlock_rule.event) {
> case LANDLOCK_SUBTYPE_EVENT_FS:
> + return landlock_is_valid_access_event_FS(off, size, type,
> + &info->reg_type, prog_subtype);
I forgot to handle LANDLOCK_SUBTYPE_EVENT_FS_{IOCTL,LOCK_FCNTL} here and
I included some hunks in the wrong patches. I will fix this in the next
series and add tests for those anyway. :)
Regards,
Mickaël
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