From f3b8788cde61b02f1e6c202f8fac4360e6adbafc Mon Sep 17 00:00:00 2001 From: Casey Schaufler Date: Tue, 12 Sep 2023 13:56:46 -0700 Subject: [PATCH] LSM: Identify modules by more than name Create a struct lsm_id to contain identifying information about Linux Security Modules (LSMs). At inception this contains the name of the module and an identifier associated with the security module. 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. Cc: linux-security-module Signed-off-by: Casey Schaufler Reviewed-by: Kees Cook Reviewed-by: Serge Hallyn Reviewed-by: Mickael Salaun Reviewed-by: John Johansen Signed-off-by: Kees Cook Nacked-by: Tetsuo Handa [PM: forward ported beyond v6.6 due merge window changes] Signed-off-by: Paul Moore --- Documentation/userspace-api/index.rst | 1 + MAINTAINERS | 1 + include/linux/lsm_hooks.h | 16 +++++++- include/uapi/linux/lsm.h | 54 +++++++++++++++++++++++++++ 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/net.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, 162 insertions(+), 22 deletions(-) create mode 100644 include/uapi/linux/lsm.h diff --git a/Documentation/userspace-api/index.rst b/Documentation/userspace-api/index.rst index 031df47a7c19..8be8b1979194 100644 --- a/Documentation/userspace-api/index.rst +++ b/Documentation/userspace-api/index.rst @@ -33,6 +33,7 @@ place where this information is gathered. sysfs-platform_profile vduse futex2 + lsm .. only:: subproject and html diff --git a/MAINTAINERS b/MAINTAINERS index 97f51d5ec1cf..f1d41fd9159a 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -19511,6 +19511,7 @@ L: linux-security-module@vger.kernel.org (suggested Cc:) S: Supported W: http://kernsec.org/ T: git git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm.git +F: include/uapi/linux/lsm.h F: security/ X: security/selinux/ diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index dcb5e5b5eb13..7f0adb33caaa 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -42,6 +42,18 @@ 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 + * + * Contains the information that identifies the LSM. + */ +struct lsm_id { + const char *name; + u64 id; +}; + /* * Security module hook list structure. * For use with generic list macros for common operations. @@ -50,7 +62,7 @@ struct security_hook_list { struct hlist_node list; struct hlist_head *head; union security_list_options hook; - const char *lsm; + const struct lsm_id *lsmid; } __randomize_layout; /* @@ -104,7 +116,7 @@ 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); + const struct lsm_id *lsmid); #define LSM_FLAG_LEGACY_MAJOR BIT(0) #define LSM_FLAG_EXCLUSIVE BIT(1) diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h new file mode 100644 index 000000000000..f27c9a9cc376 --- /dev/null +++ b/include/uapi/linux/lsm.h @@ -0,0 +1,54 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * Linux Security Modules (LSM) - User space API + * + * Copyright (C) 2022 Casey Schaufler + * 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_UNDEF 0 +#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 */ diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c index 4981bdf02993..093da0a9dbd8 100644 --- a/security/apparmor/lsm.c +++ b/security/apparmor/lsm.c @@ -24,6 +24,7 @@ #include #include #include +#include #include "include/apparmor.h" #include "include/apparmorfs.h" @@ -1385,6 +1386,11 @@ struct lsm_blob_sizes apparmor_blob_sizes __ro_after_init = { .lbs_task = sizeof(struct aa_task_ctx), }; +const struct lsm_id apparmor_lsmid = { + .name = "apparmor", + .id = LSM_ID_APPARMOR, +}; + static struct security_hook_list apparmor_hooks[] __ro_after_init = { LSM_HOOK_INIT(ptrace_access_check, apparmor_ptrace_access_check), LSM_HOOK_INIT(ptrace_traceme, apparmor_ptrace_traceme), @@ -2202,7 +2208,7 @@ 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; diff --git a/security/bpf/hooks.c b/security/bpf/hooks.c index cfaf1d0e6a5f..91011e0c361a 100644 --- a/security/bpf/hooks.c +++ b/security/bpf/hooks.c @@ -5,6 +5,7 @@ */ #include #include +#include static struct security_hook_list bpf_lsm_hooks[] __ro_after_init = { #define LSM_HOOK(RET, DEFAULT, NAME, ...) \ @@ -15,9 +16,15 @@ static struct security_hook_list bpf_lsm_hooks[] __ro_after_init = { LSM_HOOK_INIT(task_free, bpf_task_storage_free), }; +const struct lsm_id bpf_lsmid = { + .name = "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; } diff --git a/security/commoncap.c b/security/commoncap.c index 8e8c630ce204..a64c0c8592bb 100644 --- a/security/commoncap.c +++ b/security/commoncap.c @@ -25,6 +25,7 @@ #include #include #include +#include /* * 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 +const struct lsm_id capability_lsmid = { + .name = "capability", + .id = LSM_ID_CAPABILITY, +}; + static struct security_hook_list capability_hooks[] __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[] __ro_after_init = { static int __init capability_init(void) { security_add_hooks(capability_hooks, ARRAY_SIZE(capability_hooks), - "capability"); + &capability_lsmid); return 0; } diff --git a/security/landlock/cred.c b/security/landlock/cred.c index 13dff2a31545..786af18c4a1c 100644 --- a/security/landlock/cred.c +++ b/security/landlock/cred.c @@ -42,5 +42,5 @@ static struct security_hook_list landlock_hooks[] __ro_after_init = { __init void landlock_add_cred_hooks(void) { security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), - LANDLOCK_NAME); + &landlock_lsmid); } diff --git a/security/landlock/fs.c b/security/landlock/fs.c index bc7c126deea2..490655d09b43 100644 --- a/security/landlock/fs.c +++ b/security/landlock/fs.c @@ -1223,5 +1223,5 @@ static struct security_hook_list landlock_hooks[] __ro_after_init = { __init void landlock_add_fs_hooks(void) { security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), - LANDLOCK_NAME); + &landlock_lsmid); } diff --git a/security/landlock/net.c b/security/landlock/net.c index aaa92c2b1f08..efa1b644a4af 100644 --- a/security/landlock/net.c +++ b/security/landlock/net.c @@ -196,5 +196,5 @@ static struct security_hook_list landlock_hooks[] __ro_after_init = { __init void landlock_add_net_hooks(void) { security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), - LANDLOCK_NAME); + &landlock_lsmid); } diff --git a/security/landlock/ptrace.c b/security/landlock/ptrace.c index 8a06d6c492bf..2bfc533d36e4 100644 --- a/security/landlock/ptrace.c +++ b/security/landlock/ptrace.c @@ -116,5 +116,5 @@ static struct security_hook_list landlock_hooks[] __ro_after_init = { __init void landlock_add_ptrace_hooks(void) { security_add_hooks(landlock_hooks, ARRAY_SIZE(landlock_hooks), - LANDLOCK_NAME); + &landlock_lsmid); } diff --git a/security/landlock/setup.c b/security/landlock/setup.c index 3e11d303542f..f6dd33143b7f 100644 --- a/security/landlock/setup.c +++ b/security/landlock/setup.c @@ -8,6 +8,7 @@ #include #include +#include #include "common.h" #include "cred.h" @@ -25,6 +26,11 @@ struct lsm_blob_sizes landlock_blob_sizes __ro_after_init = { .lbs_superblock = sizeof(struct landlock_superblock_security), }; +const struct lsm_id landlock_lsmid = { + .name = LANDLOCK_NAME, + .id = LSM_ID_LANDLOCK, +}; + static int __init landlock_init(void) { landlock_add_cred_hooks(); diff --git a/security/landlock/setup.h b/security/landlock/setup.h index 1daffab1ab4b..c4252d46d49d 100644 --- a/security/landlock/setup.h +++ b/security/landlock/setup.h @@ -14,5 +14,6 @@ extern bool landlock_initialized; extern struct lsm_blob_sizes landlock_blob_sizes; +extern const struct lsm_id landlock_lsmid; #endif /* _SECURITY_LANDLOCK_SETUP_H */ diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index a9d40456a064..d682a851de58 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -20,6 +20,7 @@ #include #include #include +#include #define VERITY_DIGEST_FILE_HEADER "# LOADPIN_TRUSTED_VERITY_ROOT_DIGESTS" @@ -208,6 +209,11 @@ static int loadpin_load_data(enum kernel_load_data_id id, bool contents) return loadpin_check(NULL, (enum kernel_read_file_id) id); } +const struct lsm_id loadpin_lsmid = { + .name = "loadpin", + .id = LSM_ID_LOADPIN, +}; + static struct security_hook_list loadpin_hooks[] __ro_after_init = { LSM_HOOK_INIT(sb_free_security, loadpin_sb_free_security), LSM_HOOK_INIT(kernel_read_file, loadpin_read_file), @@ -259,7 +265,8 @@ static int __init loadpin_init(void) if (!register_sysctl("kernel/loadpin", 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; } diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 68d19632aeb7..cd84d8ea1dfb 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -13,6 +13,7 @@ #include #include #include +#include static enum lockdown_reason kernel_locked_down; @@ -75,6 +76,11 @@ static struct security_hook_list lockdown_hooks[] __ro_after_init = { LSM_HOOK_INIT(locked_down, lockdown_is_locked_down), }; +const struct lsm_id lockdown_lsmid = { + .name = "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; } diff --git a/security/safesetid/lsm.c b/security/safesetid/lsm.c index 5be5894aa0ea..f42d5af5ffb0 100644 --- a/security/safesetid/lsm.c +++ b/security/safesetid/lsm.c @@ -19,6 +19,7 @@ #include #include #include +#include #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; } +const struct lsm_id safesetid_lsmid = { + .name = "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; diff --git a/security/security.c b/security/security.c index dcb3e7014f9b..08b1bd9457a9 100644 --- a/security/security.c +++ b/security/security.c @@ -513,17 +513,17 @@ 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) + const 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); } @@ -532,7 +532,7 @@ 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->name, &lsm_names) < 0) panic("%s - Cannot get early memory.\n", __func__); } } @@ -3817,7 +3817,7 @@ 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->name)) continue; return hp->hook.getprocattr(p, name, value); } @@ -3842,7 +3842,7 @@ 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->name)) continue; return hp->hook.setprocattr(name, value, size); } diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index feda711c6b7b..f2423dfd19cd 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -92,6 +92,7 @@ #include #include #include +#include #include "avc.h" #include "objsec.h" @@ -6950,6 +6951,11 @@ static int selinux_uring_cmd(struct io_uring_cmd *ioucmd) } #endif /* CONFIG_IO_URING */ +const struct lsm_id selinux_lsmid = { + .name = "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, @@ -7270,7 +7276,8 @@ 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"); diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c index 65130a791f57..f73f9a2834eb 100644 --- a/security/smack/smack_lsm.c +++ b/security/smack/smack_lsm.c @@ -43,6 +43,7 @@ #include #include #include +#include #include "smack.h" #define TRANS_TRUE "TRUE" @@ -4933,6 +4934,11 @@ struct lsm_blob_sizes smack_blob_sizes __ro_after_init = { .lbs_xattr_count = SMACK_INODE_INIT_XATTRS, }; +const struct lsm_id smack_lsmid = { + .name = "smack", + .id = LSM_ID_SMACK, +}; + static struct security_hook_list smack_hooks[] __ro_after_init = { LSM_HOOK_INIT(ptrace_access_check, smack_ptrace_access_check), LSM_HOOK_INIT(ptrace_traceme, smack_ptrace_traceme), @@ -5140,7 +5146,7 @@ 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"); diff --git a/security/tomoyo/tomoyo.c b/security/tomoyo/tomoyo.c index 255f1b470295..722205433105 100644 --- a/security/tomoyo/tomoyo.c +++ b/security/tomoyo/tomoyo.c @@ -6,6 +6,7 @@ */ #include +#include #include "common.h" /** @@ -542,6 +543,11 @@ static void tomoyo_task_free(struct task_struct *task) } } +const struct lsm_id tomoyo_lsmid = { + .name = "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); diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index 2503cf153d4a..5cdff292fcae 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -18,6 +18,7 @@ #include #include #include +#include #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; } +const struct lsm_id yama_lsmid = { + .name = "yama", + .id = LSM_ID_YAMA, +}; + static struct security_hook_list yama_hooks[] __ro_after_init = { LSM_HOOK_INIT(ptrace_access_check, yama_ptrace_access_check), LSM_HOOK_INIT(ptrace_traceme, yama_ptrace_traceme), @@ -471,7 +477,7 @@ 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; }