path: root/include/linux
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authorLinus Torvalds <torvalds@linux-foundation.org>2019-09-28 08:14:15 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2019-09-28 08:14:15 -0700
commitaefcf2f4b58155d27340ba5f9ddbe9513da8286d (patch)
treea8ae994ca71b2e43e3075c796165e5ed62e28e42 /include/linux
parentf1f2f614d535564992f32e720739cb53cf03489f (diff)
parent45893a0abee6b5fd52994a3a1095735aeaec472b (diff)
Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull kernel lockdown mode from James Morris: "This is the latest iteration of the kernel lockdown patchset, from Matthew Garrett, David Howells and others. From the original description: This patchset introduces an optional kernel lockdown feature, intended to strengthen the boundary between UID 0 and the kernel. When enabled, various pieces of kernel functionality are restricted. Applications that rely on low-level access to either hardware or the kernel may cease working as a result - therefore this should not be enabled without appropriate evaluation beforehand. The majority of mainstream distributions have been carrying variants of this patchset for many years now, so there's value in providing a doesn't meet every distribution requirement, but gets us much closer to not requiring external patches. There are two major changes since this was last proposed for mainline: - Separating lockdown from EFI secure boot. Background discussion is covered here: https://lwn.net/Articles/751061/ - Implementation as an LSM, with a default stackable lockdown LSM module. This allows the lockdown feature to be policy-driven, rather than encoding an implicit policy within the mechanism. The new locked_down LSM hook is provided to allow LSMs to make a policy decision around whether kernel functionality that would allow tampering with or examining the runtime state of the kernel should be permitted. The included lockdown LSM provides an implementation with a simple policy intended for general purpose use. This policy provides a coarse level of granularity, controllable via the kernel command line: lockdown={integrity|confidentiality} Enable the kernel lockdown feature. If set to integrity, kernel features that allow userland to modify the running kernel are disabled. If set to confidentiality, kernel features that allow userland to extract confidential information from the kernel are also disabled. This may also be controlled via /sys/kernel/security/lockdown and overriden by kernel configuration. New or existing LSMs may implement finer-grained controls of the lockdown features. Refer to the lockdown_reason documentation in include/linux/security.h for details. The lockdown feature has had signficant design feedback and review across many subsystems. This code has been in linux-next for some weeks, with a few fixes applied along the way. Stephen Rothwell noted that commit 9d1f8be5cf42 ("bpf: Restrict bpf when kernel lockdown is in confidentiality mode") is missing a Signed-off-by from its author. Matthew responded that he is providing this under category (c) of the DCO" * 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits) kexec: Fix file verification on S390 security: constify some arrays in lockdown LSM lockdown: Print current->comm in restriction messages efi: Restrict efivar_ssdt_load when the kernel is locked down tracefs: Restrict tracefs when the kernel is locked down debugfs: Restrict debugfs when the kernel is locked down kexec: Allow kexec_file() with appropriate IMA policy when locked down lockdown: Lock down perf when in confidentiality mode bpf: Restrict bpf when kernel lockdown is in confidentiality mode lockdown: Lock down tracing and perf kprobes when in confidentiality mode lockdown: Lock down /proc/kcore x86/mmiotrace: Lock down the testmmiotrace module lockdown: Lock down module params that specify hardware parameters (eg. ioport) lockdown: Lock down TIOCSSERIAL lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down acpi: Disable ACPI table override if the kernel is locked down acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down ACPI: Limit access to custom_method when the kernel is locked down x86/msr: Restrict MSR access when the kernel is locked down x86: Lock down IO port access when the kernel is locked down ...
Diffstat (limited to 'include/linux')
5 files changed, 89 insertions, 2 deletions
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index 978cc239f23b..8b4e516bac00 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -643,6 +643,12 @@ bool acpi_gtdt_c3stop(int type);
int acpi_arch_timer_mem_init(struct arch_timer_mem *timer_mem, int *timer_count);
+static inline void acpi_arch_set_root_pointer(u64 addr)
static inline u64 acpi_arch_get_root_pointer(void)
diff --git a/include/linux/ima.h b/include/linux/ima.h
index a20ad398d260..1c37f17f7203 100644
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -131,4 +131,13 @@ static inline int ima_inode_removexattr(struct dentry *dentry,
return 0;
+extern bool ima_appraise_signature(enum kernel_read_file_id func);
+static inline bool ima_appraise_signature(enum kernel_read_file_id func)
+ return false;
#endif /* _LINUX_IMA_H */
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index cc162f3e6461..1776eb2e43a4 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -125,7 +125,7 @@ typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf,
unsigned long cmdline_len);
typedef int (kexec_cleanup_t)(void *loader_data);
typedef int (kexec_verify_sig_t)(const char *kernel_buf,
unsigned long kernel_len);
@@ -134,7 +134,7 @@ struct kexec_file_ops {
kexec_probe_t *probe;
kexec_load_t *load;
kexec_cleanup_t *cleanup;
kexec_verify_sig_t *verify_sig;
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 3fced5824aee..a3763247547c 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1449,6 +1449,11 @@
* @bpf_prog_free_security:
* Clean up the security information stored inside bpf prog.
+ * @locked_down
+ * Determine whether a kernel feature that potentially enables arbitrary
+ * code execution in kernel space should be permitted.
+ *
+ * @what: kernel feature being accessed
union security_list_options {
int (*binder_set_context_mgr)(struct task_struct *mgr);
@@ -1812,6 +1817,7 @@ union security_list_options {
int (*bpf_prog_alloc_security)(struct bpf_prog_aux *aux);
void (*bpf_prog_free_security)(struct bpf_prog_aux *aux);
+ int (*locked_down)(enum lockdown_reason what);
struct security_hook_heads {
@@ -2053,6 +2059,7 @@ struct security_hook_heads {
struct hlist_head bpf_prog_alloc_security;
struct hlist_head bpf_prog_free_security;
+ struct hlist_head locked_down;
} __randomize_layout;
@@ -2111,12 +2118,18 @@ struct lsm_info {
extern struct lsm_info __start_lsm_info[], __end_lsm_info[];
+extern struct lsm_info __start_early_lsm_info[], __end_early_lsm_info[];
#define DEFINE_LSM(lsm) \
static struct lsm_info __lsm_##lsm \
__used __section(.lsm_info.init) \
__aligned(sizeof(unsigned long))
+#define DEFINE_EARLY_LSM(lsm) \
+ static struct lsm_info __early_lsm_##lsm \
+ __used __section(.early_lsm_info.init) \
+ __aligned(sizeof(unsigned long))
* Assuring the safety of deleting a security module is up to
diff --git a/include/linux/security.h b/include/linux/security.h
index ace6fdb604f9..a8d59d612d27 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -77,6 +77,54 @@ enum lsm_event {
+ * These are reasons that can be passed to the security_locked_down()
+ * LSM hook. Lockdown reasons that protect kernel integrity (ie, the
+ * ability for userland to modify kernel code) are placed before
+ * LOCKDOWN_INTEGRITY_MAX. Lockdown reasons that protect kernel
+ * confidentiality (ie, the ability for userland to extract
+ * information from the running kernel that would otherwise be
+ * restricted) are placed before LOCKDOWN_CONFIDENTIALITY_MAX.
+ *
+ * LSM authors should note that the semantics of any given lockdown
+ * reason are not guaranteed to be stable - the same reason may block
+ * one set of features in one kernel release, and a slightly different
+ * set of features in a later kernel release. LSMs that seek to expose
+ * lockdown policy at any level of granularity other than "none",
+ * "integrity" or "confidentiality" are responsible for either
+ * ensuring that they expose a consistent level of functionality to
+ * userland, or ensuring that userland is aware that this is
+ * potentially a moving target. It is easy to misuse this information
+ * in a way that could break userspace. Please be careful not to do
+ * so.
+ *
+ * If you add to this, remember to extend lockdown_reasons in
+ * security/lockdown/lockdown.c.
+ */
+enum lockdown_reason {
/* These functions are in security/commoncap.c */
extern int cap_capable(const struct cred *cred, struct user_namespace *ns,
int cap, unsigned int opts);
@@ -195,6 +243,7 @@ int unregister_blocking_lsm_notifier(struct notifier_block *nb);
/* prototypes */
extern int security_init(void);
+extern int early_security_init(void);
/* Security operations */
int security_binder_set_context_mgr(struct task_struct *mgr);
@@ -392,6 +441,7 @@ void security_inode_invalidate_secctx(struct inode *inode);
int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
+int security_locked_down(enum lockdown_reason what);
static inline int call_blocking_lsm_notifier(enum lsm_event event, void *data)
@@ -423,6 +473,11 @@ static inline int security_init(void)
return 0;
+static inline int early_security_init(void)
+ return 0;
static inline int security_binder_set_context_mgr(struct task_struct *mgr)
return 0;
@@ -1210,6 +1265,10 @@ static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32
+static inline int security_locked_down(enum lockdown_reason what)
+ return 0;
#endif /* CONFIG_SECURITY */

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