A process credentials point to a Landlock domain, which is underneath implemented with a ruleset. In the following commits, this domain is used to check and enforce the ptrace and filesystem security policies. A domain is inherited from a parent to its child the same way a thread inherits a seccomp policy. Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx> Cc: James Morris <jmorris@xxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Serge E. Hallyn <serge@xxxxxxxxxx> --- Changes since v13: * totally get ride of the seccomp dependency * only keep credential management and LSM setup. Previous version: https://lore.kernel.org/lkml/20191104172146.30797-4-mic@xxxxxxxxxxx/ --- security/Kconfig | 10 +++---- security/landlock/Makefile | 3 ++- security/landlock/cred.c | 47 ++++++++++++++++++++++++++++++++ security/landlock/cred.h | 55 ++++++++++++++++++++++++++++++++++++++ security/landlock/setup.c | 30 +++++++++++++++++++++ security/landlock/setup.h | 18 +++++++++++++ 6 files changed, 157 insertions(+), 6 deletions(-) create mode 100644 security/landlock/cred.c create mode 100644 security/landlock/cred.h create mode 100644 security/landlock/setup.c create mode 100644 security/landlock/setup.h diff --git a/security/Kconfig b/security/Kconfig index 9d9981394fb0..76547b5c694d 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -278,11 +278,11 @@ endchoice config LSM string "Ordered list of enabled LSMs" - default "lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK - default "lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR - default "lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO - default "lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC - default "lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor" + default "landlock,lockdown,yama,loadpin,safesetid,integrity,smack,selinux,tomoyo,apparmor" if DEFAULT_SECURITY_SMACK + default "landlock,lockdown,yama,loadpin,safesetid,integrity,apparmor,selinux,smack,tomoyo" if DEFAULT_SECURITY_APPARMOR + default "landlock,lockdown,yama,loadpin,safesetid,integrity,tomoyo" if DEFAULT_SECURITY_TOMOYO + default "landlock,lockdown,yama,loadpin,safesetid,integrity" if DEFAULT_SECURITY_DAC + default "landlock,lockdown,yama,loadpin,safesetid,integrity,selinux,smack,tomoyo,apparmor" help A comma-separated list of LSMs, in initialization order. Any LSMs left off this list will be ignored. This can be diff --git a/security/landlock/Makefile b/security/landlock/Makefile index d846eba445bb..041ea242e627 100644 --- a/security/landlock/Makefile +++ b/security/landlock/Makefile @@ -1,3 +1,4 @@ obj-$(CONFIG_SECURITY_LANDLOCK) := landlock.o -landlock-y := object.o ruleset.o +landlock-y := setup.o object.o ruleset.o \ + cred.o diff --git a/security/landlock/cred.c b/security/landlock/cred.c new file mode 100644 index 000000000000..69ef93e29a53 --- /dev/null +++ b/security/landlock/cred.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Credential hooks + * + * Copyright © 2017-2019 Mickaël Salaün <mic@xxxxxxxxxxx> + * Copyright © 2018-2019 ANSSI + */ + +#include <linux/cred.h> +#include <linux/lsm_hooks.h> + +#include "cred.h" +#include "ruleset.h" +#include "setup.h" + +static int hook_cred_prepare(struct cred *new, const struct cred *old, + gfp_t gfp) +{ + const struct landlock_cred_security *cred_old = landlock_cred(old); + struct landlock_cred_security *cred_new = landlock_cred(new); + struct landlock_ruleset *dom_old; + + dom_old = cred_old->domain; + if (dom_old) { + landlock_get_ruleset(dom_old); + cred_new->domain = dom_old; + } else { + cred_new->domain = NULL; + } + return 0; +} + +static void hook_cred_free(struct cred *cred) +{ + landlock_put_ruleset_enqueue(landlock_cred(cred)->domain); +} + +static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = { + LSM_HOOK_INIT(cred_prepare, hook_cred_prepare), + LSM_HOOK_INIT(cred_free, hook_cred_free), +}; + +__init void landlock_add_hooks_cred(void) +{ + security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), + LANDLOCK_NAME); +} diff --git a/security/landlock/cred.h b/security/landlock/cred.h new file mode 100644 index 000000000000..1e24682ee27e --- /dev/null +++ b/security/landlock/cred.h @@ -0,0 +1,55 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Credential hooks + * + * Copyright © 2019 Mickaël Salaün <mic@xxxxxxxxxxx> + * Copyright © 2019 ANSSI + */ + +#ifndef _SECURITY_LANDLOCK_CRED_H +#define _SECURITY_LANDLOCK_CRED_H + +#include <linux/cred.h> +#include <linux/init.h> +#include <linux/rcupdate.h> + +#include "ruleset.h" +#include "setup.h" + +struct landlock_cred_security { + struct landlock_ruleset *domain; +}; + +static inline struct landlock_cred_security *landlock_cred( + const struct cred *cred) +{ + return cred->security + landlock_blob_sizes.lbs_cred; +} + +static inline struct landlock_ruleset *landlock_get_current_domain(void) +{ + return landlock_cred(current_cred())->domain; +} + +/* + * The caller needs an RCU lock. + */ +static inline struct landlock_ruleset *landlock_get_task_domain( + struct task_struct *task) +{ + return landlock_cred(__task_cred(task))->domain; +} + +static inline bool landlocked(struct task_struct *task) +{ + bool has_dom; + + rcu_read_lock(); + has_dom = !!landlock_get_task_domain(task); + rcu_read_unlock(); + return has_dom; +} + +__init void landlock_add_hooks_cred(void); + +#endif /* _SECURITY_LANDLOCK_CRED_H */ diff --git a/security/landlock/setup.c b/security/landlock/setup.c new file mode 100644 index 000000000000..fca5fa185465 --- /dev/null +++ b/security/landlock/setup.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün <mic@xxxxxxxxxxx> + * Copyright © 2018-2020 ANSSI + */ + +#include <linux/init.h> +#include <linux/lsm_hooks.h> + +#include "cred.h" +#include "setup.h" + +struct lsm_blob_sizes landlock_blob_sizes __lsm_ro_after_init = { + .lbs_cred = sizeof(struct landlock_cred_security), +}; + +static int __init landlock_init(void) +{ + pr_info(LANDLOCK_NAME ": Registering hooks\n"); + landlock_add_hooks_cred(); + return 0; +} + +DEFINE_LSM(LANDLOCK_NAME) = { + .name = LANDLOCK_NAME, + .init = landlock_init, + .blobs = &landlock_blob_sizes, +}; diff --git a/security/landlock/setup.h b/security/landlock/setup.h new file mode 100644 index 000000000000..52eb8d806376 --- /dev/null +++ b/security/landlock/setup.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Landlock LSM - Security framework setup + * + * Copyright © 2016-2020 Mickaël Salaün <mic@xxxxxxxxxxx> + * Copyright © 2018-2020 ANSSI + */ + +#ifndef _SECURITY_LANDLOCK_SETUP_H +#define _SECURITY_LANDLOCK_SETUP_H + +#include <linux/lsm_hooks.h> + +#define LANDLOCK_NAME "landlock" + +extern struct lsm_blob_sizes landlock_blob_sizes; + +#endif /* _SECURITY_LANDLOCK_SETUP_H */ -- 2.25.0
