@@ -31,6 +31,7 @@ place where this information is gathered.
sysfs-platform_profile
vduse
futex2
+ lsm
.. only:: subproject and html
new file mode 100644
@@ -0,0 +1,55 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. Copyright (C) 2022 Casey Schaufler <casey@schaufler-ca.com>
+.. Copyright (C) 2022 Intel Corporation
+
+=====================================
+Linux Security Modules
+=====================================
+
+:Author: Casey Schaufler
+:Date: November 2022
+
+Linux security modules (LSM) provide a mechanism to implement
+additional access controls to the Linux security policies.
+
+The various security modules may support any of these attributes:
+
+``LSM_ATTR_CURRENT`` is the current, active security context of the
+process.
+The proc filesystem provides this value in ``/proc/self/attr/current``.
+This is supported by the SELinux, Smack and AppArmor security modules.
+Smack also provides this value in ``/proc/self/attr/smack/current``.
+AppArmor also provides this value in ``/proc/self/attr/apparmor/current``.
+
+``LSM_ATTR_EXEC`` is the security context of the process at the time the
+current image was executed.
+The proc filesystem provides this value in ``/proc/self/attr/exec``.
+This is supported by the SELinux and AppArmor security modules.
+AppArmor also provides this value in ``/proc/self/attr/apparmor/exec``.
+
+``LSM_ATTR_FSCREATE`` is the security context of the process used when
+creating file system objects.
+The proc filesystem provides this value in ``/proc/self/attr/fscreate``.
+This is supported by the SELinux security module.
+
+``LSM_ATTR_KEYCREATE`` is the security context of the process used when
+creating key objects.
+The proc filesystem provides this value in ``/proc/self/attr/keycreate``.
+This is supported by the SELinux security module.
+
+``LSM_ATTR_PREV`` is the security context of the process at the time the
+current security context was set.
+The proc filesystem provides this value in ``/proc/self/attr/prev``.
+This is supported by the SELinux and AppArmor security modules.
+AppArmor also provides this value in ``/proc/self/attr/apparmor/prev``.
+
+``LSM_ATTR_SOCKCREATE`` is the security context of the process used when
+creating socket objects.
+The proc filesystem provides this value in ``/proc/self/attr/sockcreate``.
+This is supported by the SELinux security module.
+
+Additional documentation
+========================
+
+* Documentation/security/lsm.rst
+* Documentation/security/lsm-development.rst
@@ -18813,6 +18813,7 @@ S: Supported
W: http://kernsec.org/
T: git git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm.git
F: security/
+F: include/uapi/linux/lsm.h
X: security/selinux/
SELINUX SECURITY MODULE
@@ -1665,6 +1665,20 @@ struct security_hook_heads {
#undef LSM_HOOK
} __randomize_layout;
+/**
+ * struct lsm_id - Identify a Linux Security Module.
+ * @lsm: name of the LSM, must be approved by the LSM maintainers
+ * @id: LSM ID number from uapi/linux/lsm.h
+ * @attrs: which attributes this LSM supports
+ *
+ * Contains the information that identifies the LSM.
+ */
+struct lsm_id {
+ const u8 *lsm;
+ u64 id;
+ u64 attrs;
+};
+
/*
* Security module hook list structure.
* For use with generic list macros for common operations.
@@ -1673,7 +1687,7 @@ struct security_hook_list {
struct hlist_node list;
struct hlist_head *head;
union security_list_options hook;
- const char *lsm;
+ struct lsm_id *lsmid;
} __randomize_layout;
/*
@@ -1708,7 +1722,7 @@ extern struct security_hook_heads security_hook_heads;
extern char *lsm_names;
extern void security_add_hooks(struct security_hook_list *hooks, int count,
- const char *lsm);
+ struct lsm_id *lsmid);
#define LSM_FLAG_LEGACY_MAJOR BIT(0)
#define LSM_FLAG_EXCLUSIVE BIT(1)
new file mode 100644
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Linux Security Modules (LSM) - User space API
+ *
+ * Copyright (C) 2022 Casey Schaufler <casey@schaufler-ca.com>
+ * Copyright (C) 2022 Intel Corporation
+ */
+
+#ifndef _UAPI_LINUX_LSM_H
+#define _UAPI_LINUX_LSM_H
+
+/*
+ * ID tokens to identify Linux Security Modules (LSMs)
+ *
+ * These token values are used to uniquely identify specific LSMs
+ * in the kernel as well as in the kernel's LSM userspace API.
+ *
+ * A value of zero/0 is considered undefined and should not be used
+ * outside the kernel. Values 1-99 are reserved for potential
+ * future use.
+ */
+#define LSM_ID_UNDEF 0
+#define LSM_ID_CAPABILITY 100
+#define LSM_ID_SELINUX 101
+#define LSM_ID_SMACK 102
+#define LSM_ID_TOMOYO 103
+#define LSM_ID_IMA 104
+#define LSM_ID_APPARMOR 105
+#define LSM_ID_YAMA 106
+#define LSM_ID_LOADPIN 107
+#define LSM_ID_SAFESETID 108
+#define LSM_ID_LOCKDOWN 109
+#define LSM_ID_BPF 110
+#define LSM_ID_LANDLOCK 111
+
+/*
+ * LSM_ATTR_XXX definitions identify different LSM attributes
+ * which are used in the kernel's LSM userspace API. Support
+ * for these attributes vary across the different LSMs. None
+ * are required.
+ *
+ * A value of zero/0 is considered undefined and should not be used
+ * outside the kernel. Values 1-99 are reserved for potential
+ * future use.
+ */
+#define LSM_ATTR_CURRENT 100
+#define LSM_ATTR_EXEC 101
+#define LSM_ATTR_FSCREATE 102
+#define LSM_ATTR_KEYCREATE 103
+#define LSM_ATTR_PREV 104
+#define LSM_ATTR_SOCKCREATE 105
+
+#endif /* _UAPI_LINUX_LSM_H */
@@ -24,6 +24,7 @@
#include <linux/zstd.h>
#include <net/sock.h>
#include <uapi/linux/mount.h>
+#include <uapi/linux/lsm.h>
#include "include/apparmor.h"
#include "include/apparmorfs.h"
@@ -1215,6 +1216,11 @@ struct lsm_blob_sizes apparmor_blob_sizes __lsm_ro_after_init = {
.lbs_task = sizeof(struct aa_task_ctx),
};
+static struct lsm_id apparmor_lsmid __lsm_ro_after_init = {
+ .lsm = "apparmor",
+ .id = LSM_ID_APPARMOR,
+};
+
static struct security_hook_list apparmor_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, apparmor_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, apparmor_ptrace_traceme),
@@ -1910,7 +1916,7 @@ static int __init apparmor_init(void)
goto buffers_out;
}
security_add_hooks(apparmor_hooks, ARRAY_SIZE(apparmor_hooks),
- "apparmor");
+ &apparmor_lsmid);
/* Report that AppArmor successfully initialized */
apparmor_initialized = 1;
@@ -5,6 +5,7 @@
*/
#include <linux/lsm_hooks.h>
#include <linux/bpf_lsm.h>
+#include <uapi/linux/lsm.h>
static struct security_hook_list bpf_lsm_hooks[] __lsm_ro_after_init = {
#define LSM_HOOK(RET, DEFAULT, NAME, ...) \
@@ -15,9 +16,15 @@ static struct security_hook_list bpf_lsm_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(task_free, bpf_task_storage_free),
};
+static struct lsm_id bpf_lsmid __lsm_ro_after_init = {
+ .lsm = "bpf",
+ .id = LSM_ID_BPF,
+};
+
static int __init bpf_lsm_init(void)
{
- security_add_hooks(bpf_lsm_hooks, ARRAY_SIZE(bpf_lsm_hooks), "bpf");
+ security_add_hooks(bpf_lsm_hooks, ARRAY_SIZE(bpf_lsm_hooks),
+ &bpf_lsmid);
pr_info("LSM support for eBPF active\n");
return 0;
}
@@ -25,6 +25,7 @@
#include <linux/binfmts.h>
#include <linux/personality.h>
#include <linux/mnt_idmapping.h>
+#include <uapi/linux/lsm.h>
/*
* If a non-root user executes a setuid-root binary in
@@ -1440,6 +1441,11 @@ int cap_mmap_file(struct file *file, unsigned long reqprot,
#ifdef CONFIG_SECURITY
+static struct lsm_id capability_lsmid __lsm_ro_after_init = {
+ .lsm = "capability",
+ .id = LSM_ID_CAPABILITY,
+};
+
static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(capable, cap_capable),
LSM_HOOK_INIT(settime, cap_settime),
@@ -1464,7 +1470,7 @@ static struct security_hook_list capability_hooks[] __lsm_ro_after_init = {
static int __init capability_init(void)
{
security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks),
- "capability");
+ &capability_lsmid);
return 0;
}
@@ -42,5 +42,5 @@ static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = {
__init void landlock_add_cred_hooks(void)
{
security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
- LANDLOCK_NAME);
+ &landlock_lsmid);
}
@@ -1307,5 +1307,5 @@ static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = {
__init void landlock_add_fs_hooks(void)
{
security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
- LANDLOCK_NAME);
+ &landlock_lsmid);
}
@@ -116,5 +116,5 @@ static struct security_hook_list landlock_hooks[] __lsm_ro_after_init = {
__init void landlock_add_ptrace_hooks(void)
{
security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks),
- LANDLOCK_NAME);
+ &landlock_lsmid);
}
@@ -8,6 +8,7 @@
#include <linux/init.h>
#include <linux/lsm_hooks.h>
+#include <uapi/linux/lsm.h>
#include "common.h"
#include "cred.h"
@@ -24,6 +25,11 @@ struct lsm_blob_sizes landlock_blob_sizes __lsm_ro_after_init = {
.lbs_superblock = sizeof(struct landlock_superblock_security),
};
+struct lsm_id landlock_lsmid __lsm_ro_after_init = {
+ .lsm = LANDLOCK_NAME,
+ .id = LSM_ID_LANDLOCK,
+};
+
static int __init landlock_init(void)
{
landlock_add_cred_hooks();
@@ -14,5 +14,6 @@
extern bool landlock_initialized;
extern struct lsm_blob_sizes landlock_blob_sizes;
+extern struct lsm_id landlock_lsmid;
#endif /* _SECURITY_LANDLOCK_SETUP_H */
@@ -20,6 +20,7 @@
#include <linux/string_helpers.h>
#include <linux/dm-verity-loadpin.h>
#include <uapi/linux/loadpin.h>
+#include <uapi/linux/lsm.h>
#define VERITY_DIGEST_FILE_HEADER "# LOADPIN_TRUSTED_VERITY_ROOT_DIGESTS"
@@ -214,6 +215,11 @@ static int loadpin_load_data(enum kernel_load_data_id id, bool contents)
return loadpin_check(NULL, (enum kernel_read_file_id) id);
}
+static struct lsm_id loadpin_lsmid __lsm_ro_after_init = {
+ .lsm = "loadpin",
+ .id = LSM_ID_LOADPIN,
+};
+
static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(sb_free_security, loadpin_sb_free_security),
LSM_HOOK_INIT(kernel_read_file, loadpin_read_file),
@@ -265,7 +271,8 @@ static int __init loadpin_init(void)
if (!register_sysctl_paths(loadpin_sysctl_path, loadpin_sysctl_table))
pr_notice("sysctl registration failed!\n");
#endif
- security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin");
+ security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks),
+ &loadpin_lsmid);
return 0;
}
@@ -13,6 +13,7 @@
#include <linux/security.h>
#include <linux/export.h>
#include <linux/lsm_hooks.h>
+#include <uapi/linux/lsm.h>
static enum lockdown_reason kernel_locked_down;
@@ -75,6 +76,11 @@ static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),
};
+static struct lsm_id lockdown_lsmid __lsm_ro_after_init = {
+ .lsm = "lockdown",
+ .id = LSM_ID_LOCKDOWN,
+};
+
static int __init lockdown_lsm_init(void)
{
#if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY)
@@ -83,7 +89,7 @@ static int __init lockdown_lsm_init(void)
lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX);
#endif
security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks),
- "lockdown");
+ &lockdown_lsmid);
return 0;
}
@@ -19,6 +19,7 @@
#include <linux/ptrace.h>
#include <linux/sched/task_stack.h>
#include <linux/security.h>
+#include <uapi/linux/lsm.h>
#include "lsm.h"
/* Flag indicating whether initialization completed */
@@ -261,6 +262,11 @@ static int safesetid_task_fix_setgroups(struct cred *new, const struct cred *old
return 0;
}
+static struct lsm_id safesetid_lsmid __lsm_ro_after_init = {
+ .lsm = "safesetid",
+ .id = LSM_ID_SAFESETID,
+};
+
static struct security_hook_list safesetid_security_hooks[] = {
LSM_HOOK_INIT(task_fix_setuid, safesetid_task_fix_setuid),
LSM_HOOK_INIT(task_fix_setgid, safesetid_task_fix_setgid),
@@ -271,7 +277,8 @@ static struct security_hook_list safesetid_security_hooks[] = {
static int __init safesetid_security_init(void)
{
security_add_hooks(safesetid_security_hooks,
- ARRAY_SIZE(safesetid_security_hooks), "safesetid");
+ ARRAY_SIZE(safesetid_security_hooks),
+ &safesetid_lsmid);
/* Report that SafeSetID successfully initialized */
safesetid_initialized = 1;
@@ -504,17 +504,17 @@ static int lsm_append(const char *new, char **result)
* security_add_hooks - Add a modules hooks to the hook lists.
* @hooks: the hooks to add
* @count: the number of hooks to add
- * @lsm: the name of the security module
+ * @lsmid: the identification information for the security module
*
* Each LSM has to register its hooks with the infrastructure.
*/
void __init security_add_hooks(struct security_hook_list *hooks, int count,
- const char *lsm)
+ struct lsm_id *lsmid)
{
int i;
for (i = 0; i < count; i++) {
- hooks[i].lsm = lsm;
+ hooks[i].lsmid = lsmid;
hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
}
@@ -523,7 +523,7 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
* and fix this up afterwards.
*/
if (slab_is_available()) {
- if (lsm_append(lsm, &lsm_names) < 0)
+ if (lsm_append(lsmid->lsm, &lsm_names) < 0)
panic("%s - Cannot get early memory.\n", __func__);
}
}
@@ -2146,7 +2146,7 @@ int security_getprocattr(struct task_struct *p, const char *lsm,
struct security_hook_list *hp;
hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
- if (lsm != NULL && strcmp(lsm, hp->lsm))
+ if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
continue;
return hp->hook.getprocattr(p, name, value);
}
@@ -2159,7 +2159,7 @@ int security_setprocattr(const char *lsm, const char *name, void *value,
struct security_hook_list *hp;
hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
- if (lsm != NULL && strcmp(lsm, hp->lsm))
+ if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
continue;
return hp->hook.setprocattr(name, value, size);
}
@@ -92,6 +92,7 @@
#include <linux/fsnotify.h>
#include <linux/fanotify.h>
#include <linux/io_uring.h>
+#include <uapi/linux/lsm.h>
#include "avc.h"
#include "objsec.h"
@@ -7032,6 +7033,11 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd)
}
#endif /* CONFIG_IO_URING */
+static struct lsm_id selinux_lsmid __lsm_ro_after_init = {
+ .lsm = "selinux",
+ .id = LSM_ID_SELINUX,
+};
+
/*
* IMPORTANT NOTE: When adding new hooks, please be careful to keep this order:
* 1. any hooks that don't belong to (2.) or (3.) below,
@@ -7355,7 +7361,8 @@ static __init int selinux_init(void)
hashtab_cache_init();
- security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks), "selinux");
+ security_add_hooks(selinux_hooks, ARRAY_SIZE(selinux_hooks),
+ &selinux_lsmid);
if (avc_add_callback(selinux_netcache_avc_callback, AVC_CALLBACK_RESET))
panic("SELinux: Unable to register AVC netcache callback\n");
@@ -43,6 +43,7 @@
#include <linux/fs_parser.h>
#include <linux/watch_queue.h>
#include <linux/io_uring.h>
+#include <uapi/linux/lsm.h>
#include "smack.h"
#define TRANS_TRUE "TRUE"
@@ -4856,6 +4857,11 @@ struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
.lbs_superblock = sizeof(struct superblock_smack),
};
+static struct lsm_id smack_lsmid __lsm_ro_after_init = {
+ .lsm = "smack",
+ .id = LSM_ID_SMACK,
+};
+
static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme),
@@ -5062,7 +5068,7 @@ static __init int smack_init(void)
/*
* Register with LSM
*/
- security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), "smack");
+ security_add_hooks(smack_hooks, ARRAY_SIZE(smack_hooks), &smack_lsmid);
smack_enabled = 1;
pr_info("Smack: Initializing.\n");
@@ -6,6 +6,7 @@
*/
#include <linux/lsm_hooks.h>
+#include <uapi/linux/lsm.h>
#include "common.h"
/**
@@ -542,6 +543,11 @@ static void tomoyo_task_free(struct task_struct *task)
}
}
+static struct lsm_id tomoyo_lsmid __lsm_ro_after_init = {
+ .lsm = "tomoyo",
+ .id = LSM_ID_TOMOYO,
+};
+
/*
* tomoyo_security_ops is a "struct security_operations" which is used for
* registering TOMOYO.
@@ -595,7 +601,8 @@ static int __init tomoyo_init(void)
struct tomoyo_task *s = tomoyo_task(current);
/* register ourselves with the security framework */
- security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks), "tomoyo");
+ security_add_hooks(tomoyo_hooks, ARRAY_SIZE(tomoyo_hooks),
+ &tomoyo_lsmid);
pr_info("TOMOYO Linux initialized\n");
s->domain_info = &tomoyo_kernel_domain;
atomic_inc(&tomoyo_kernel_domain.users);
@@ -18,6 +18,7 @@
#include <linux/task_work.h>
#include <linux/sched.h>
#include <linux/spinlock.h>
+#include <uapi/linux/lsm.h>
#define YAMA_SCOPE_DISABLED 0
#define YAMA_SCOPE_RELATIONAL 1
@@ -421,6 +422,11 @@ static int yama_ptrace_traceme(struct task_struct *parent)
return rc;
}
+static struct lsm_id yama_lsmid __lsm_ro_after_init = {
+ .lsm = "yama",
+ .id = LSM_ID_YAMA,
+};
+
static struct security_hook_list yama_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(ptrace_access_check, yama_ptrace_access_check),
LSM_HOOK_INIT(ptrace_traceme, yama_ptrace_traceme),
@@ -477,7 +483,7 @@ static inline void yama_init_sysctl(void) { }
static int __init yama_init(void)
{
pr_info("Yama: becoming mindful.\n");
- security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), "yama");
+ security_add_hooks(yama_hooks, ARRAY_SIZE(yama_hooks), &yama_lsmid);
yama_init_sysctl();
return 0;
}
Create a struct lsm_id to contain identifying information about Linux Security Modules (LSMs). At inception this contains the name of the module, an identifier associated with the security module and an integer member "attrs" which identifies the API related data associated with each security module. The initial set of features maps to information that has traditionaly been available in /proc/self/attr. They are documented in a new userspace-api file. Change the security_add_hooks() interface to use this structure. Change the individual modules to maintain their own struct lsm_id and pass it to security_add_hooks(). The values are for LSM identifiers are defined in a new UAPI header file linux/lsm.h. Each existing LSM has been updated to include it's LSMID in the lsm_id. The LSM ID values are sequential, with the oldest module LSM_ID_CAPABILITY being the lowest value and the existing modules numbered in the order they were included in the main line kernel. This is an arbitrary convention for assigning the values, but none better presents itself. The value 0 is defined as being invalid. The values 1-99 are reserved for any special case uses which may arise in the future. This may include attributes of the LSM infrastructure itself, possibly related to namespacing or network attribute management. A special range is identified for such attributes to help reduce confusion for developers unfamiliar with LSMs. LSM attribute values are defined for the attributes presented by modules that are available today. As with the LSM IDs, The value 0 is defined as being invalid. The values 1-99 are reserved for any special case uses which may arise in the future. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Cc: linux-security-module <linux-security-module@vger.kernel.org> --- Documentation/userspace-api/index.rst | 1 + Documentation/userspace-api/lsm.rst | 55 +++++++++++++++++++++++++++ MAINTAINERS | 1 + include/linux/lsm_hooks.h | 18 ++++++++- include/uapi/linux/lsm.h | 53 ++++++++++++++++++++++++++ security/apparmor/lsm.c | 8 +++- security/bpf/hooks.c | 9 ++++- security/commoncap.c | 8 +++- security/landlock/cred.c | 2 +- security/landlock/fs.c | 2 +- security/landlock/ptrace.c | 2 +- security/landlock/setup.c | 6 +++ security/landlock/setup.h | 1 + security/loadpin/loadpin.c | 9 ++++- security/lockdown/lockdown.c | 8 +++- security/safesetid/lsm.c | 9 ++++- security/security.c | 12 +++--- security/selinux/hooks.c | 9 ++++- security/smack/smack_lsm.c | 8 +++- security/tomoyo/tomoyo.c | 9 ++++- security/yama/yama_lsm.c | 8 +++- 21 files changed, 217 insertions(+), 21 deletions(-) create mode 100644 Documentation/userspace-api/lsm.rst create mode 100644 include/uapi/linux/lsm.h