From: Kees Cook <keescook@chromium.org>
To: Matthew Garrett <matthewgarrett@google.com>
Cc: jmorris@namei.org, linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Matthew Garrett <mjg59@google.com>
Subject: Re: [PATCH V34 01/29] security: Support early LSMs
Date: Sat, 22 Jun 2019 16:36:55 -0700 [thread overview]
Message-ID: <201906221636.AABF971@keescook> (raw)
In-Reply-To: <20190622000358.19895-2-matthewgarrett@google.com>
On Fri, Jun 21, 2019 at 05:03:30PM -0700, Matthew Garrett wrote:
> The lockdown module is intended to allow for kernels to be locked down
> early in boot - sufficiently early that we don't have the ability to
> kmalloc() yet. Add support for early initialisation of some LSMs, and
> then add them to the list of names when we do full initialisation later.
> Early LSMs are initialised in link order and cannot be overridden via
> boot parameters, and cannot make use of kmalloc() (since the allocator
> isn't initialised yet).
>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
-Kees
> ---
> include/asm-generic/vmlinux.lds.h | 8 ++++-
> include/linux/lsm_hooks.h | 6 ++++
> include/linux/security.h | 1 +
> init/main.c | 1 +
> security/security.c | 50 ++++++++++++++++++++++++++-----
> 5 files changed, 57 insertions(+), 9 deletions(-)
>
> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
> index f8f6f04c4453..e1963352fdb6 100644
> --- a/include/asm-generic/vmlinux.lds.h
> +++ b/include/asm-generic/vmlinux.lds.h
> @@ -208,8 +208,13 @@
> __start_lsm_info = .; \
> KEEP(*(.lsm_info.init)) \
> __end_lsm_info = .;
> +#define EARLY_LSM_TABLE() . = ALIGN(8); \
> + __start_early_lsm_info = .; \
> + KEEP(*(.early_lsm_info.init)) \
> + __end_early_lsm_info = .;
> #else
> #define LSM_TABLE()
> +#define EARLY_LSM_TABLE()
> #endif
>
> #define ___OF_TABLE(cfg, name) _OF_TABLE_##cfg(name)
> @@ -610,7 +615,8 @@
> ACPI_PROBE_TABLE(irqchip) \
> ACPI_PROBE_TABLE(timer) \
> EARLYCON_TABLE() \
> - LSM_TABLE()
> + LSM_TABLE() \
> + EARLY_LSM_TABLE()
>
> #define INIT_TEXT \
> *(.init.text .init.text.*) \
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index a240a3fc5fc4..66fd1eac7a32 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -2085,12 +2085,18 @@ 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))
> +
> #ifdef CONFIG_SECURITY_SELINUX_DISABLE
> /*
> * Assuring the safety of deleting a security module is up to
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 49f2685324b0..1bb6fb2f1523 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -194,6 +194,7 @@ int unregister_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);
> diff --git a/init/main.c b/init/main.c
> index 598e278b46f7..f3faeb89c75f 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -563,6 +563,7 @@ asmlinkage __visible void __init start_kernel(void)
> boot_cpu_init();
> page_address_init();
> pr_notice("%s", linux_banner);
> + early_security_init();
> setup_arch(&command_line);
> /*
> * Set up the the initial canary and entropy after arch
> diff --git a/security/security.c b/security/security.c
> index 23cbb1a295a3..487e1f3eb2df 100644
> --- a/security/security.c
> +++ b/security/security.c
> @@ -37,6 +37,7 @@
>
> /* How many LSMs were built into the kernel? */
> #define LSM_COUNT (__end_lsm_info - __start_lsm_info)
> +#define EARLY_LSM_COUNT (__end_early_lsm_info - __start_early_lsm_info)
>
> struct security_hook_heads security_hook_heads __lsm_ro_after_init;
> static ATOMIC_NOTIFIER_HEAD(lsm_notifier_chain);
> @@ -281,6 +282,8 @@ static void __init ordered_lsm_parse(const char *order, const char *origin)
> static void __init lsm_early_cred(struct cred *cred);
> static void __init lsm_early_task(struct task_struct *task);
>
> +static int lsm_append(const char *new, char **result);
> +
> static void __init ordered_lsm_init(void)
> {
> struct lsm_info **lsm;
> @@ -327,6 +330,26 @@ static void __init ordered_lsm_init(void)
> kfree(ordered_lsms);
> }
>
> +int __init early_security_init(void)
> +{
> + int i;
> + struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
> + struct lsm_info *lsm;
> +
> + for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
> + i++)
> + INIT_HLIST_HEAD(&list[i]);
> +
> + for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
> + if (!lsm->enabled)
> + lsm->enabled = &lsm_enabled_true;
> + prepare_lsm(lsm);
> + initialize_lsm(lsm);
> + }
> +
> + return 0;
> +}
> +
> /**
> * security_init - initializes the security framework
> *
> @@ -334,14 +357,18 @@ static void __init ordered_lsm_init(void)
> */
> int __init security_init(void)
> {
> - int i;
> - struct hlist_head *list = (struct hlist_head *) &security_hook_heads;
> + struct lsm_info *lsm;
>
> pr_info("Security Framework initializing\n");
>
> - for (i = 0; i < sizeof(security_hook_heads) / sizeof(struct hlist_head);
> - i++)
> - INIT_HLIST_HEAD(&list[i]);
> + /*
> + * Append the names of the early LSM modules now that kmalloc() is
> + * available
> + */
> + for (lsm = __start_early_lsm_info; lsm < __end_early_lsm_info; lsm++) {
> + if (lsm->enabled)
> + lsm_append(lsm->name, &lsm_names);
> + }
>
> /* Load LSMs in specified order. */
> ordered_lsm_init();
> @@ -388,7 +415,7 @@ static bool match_last_lsm(const char *list, const char *lsm)
> return !strcmp(last, lsm);
> }
>
> -static int lsm_append(char *new, char **result)
> +static int lsm_append(const char *new, char **result)
> {
> char *cp;
>
> @@ -426,8 +453,15 @@ void __init security_add_hooks(struct security_hook_list *hooks, int count,
> hooks[i].lsm = lsm;
> hlist_add_tail_rcu(&hooks[i].list, hooks[i].head);
> }
> - if (lsm_append(lsm, &lsm_names) < 0)
> - panic("%s - Cannot get early memory.\n", __func__);
> +
> + /*
> + * Don't try to append during early_security_init(), we'll come back
> + * and fix this up afterwards.
> + */
> + if (slab_is_available()) {
> + if (lsm_append(lsm, &lsm_names) < 0)
> + panic("%s - Cannot get early memory.\n", __func__);
> + }
> }
>
> int call_lsm_notifier(enum lsm_event event, void *data)
> --
> 2.22.0.410.gd8fdbe21b5-goog
>
--
Kees Cook
next prev parent reply other threads:[~2019-06-22 23:37 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-22 0:03 [PATCH V34 00/29] Lockdown as an LSM Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 01/29] security: Support early LSMs Matthew Garrett
2019-06-22 23:36 ` Kees Cook [this message]
2019-06-22 0:03 ` [PATCH V34 02/29] security: Add a "locked down" LSM hook Matthew Garrett
2019-06-22 23:37 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 03/29] security: Add a static lockdown policy LSM Matthew Garrett
2019-06-22 23:37 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 04/29] Enforce module signatures if the kernel is locked down Matthew Garrett
2019-06-22 23:48 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 05/29] Restrict /dev/{mem,kmem,port} when " Matthew Garrett
2019-06-22 23:52 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 06/29] kexec_load: Disable at runtime if " Matthew Garrett
2019-06-22 23:52 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 07/29] Copy secure_boot flag in boot params across kexec reboot Matthew Garrett
2019-06-22 23:53 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 08/29] kexec_file: split KEXEC_VERIFY_SIG into KEXEC_SIG and KEXEC_SIG_FORCE Matthew Garrett
2019-06-24 2:01 ` Dave Young
2019-06-25 2:35 ` Dave Young
2019-06-22 0:03 ` [PATCH V34 09/29] kexec_file: Restrict at runtime if the kernel is locked down Matthew Garrett
2019-06-22 23:54 ` Kees Cook
2019-06-27 4:59 ` James Morris
2019-06-27 15:28 ` Matthew Garrett
2019-06-27 18:14 ` James Morris
2019-06-27 23:17 ` Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 10/29] hibernate: Disable when " Matthew Garrett
2019-06-22 17:52 ` Pavel Machek
2019-06-24 13:21 ` Jiri Kosina
2019-07-10 15:26 ` Joey Lee
2019-07-11 4:11 ` joeyli
2019-06-22 23:55 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 11/29] PCI: Lock down BAR access " Matthew Garrett
2019-06-22 23:55 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 12/29] x86: Lock down IO port " Matthew Garrett
2019-06-22 23:58 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 13/29] x86/msr: Restrict MSR " Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 14/29] ACPI: Limit access to custom_method " Matthew Garrett
2019-06-22 23:59 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-06-22 23:59 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-06-23 0:00 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 17/29] Prohibit PCMCIA CIS storage when " Matthew Garrett
2019-06-23 0:00 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 18/29] Lock down TIOCSSERIAL Matthew Garrett
2019-06-23 0:01 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 19/29] Lock down module params that specify hardware parameters (eg. ioport) Matthew Garrett
2019-06-23 0:04 ` Kees Cook
2019-06-27 1:49 ` Daniel Axtens
2019-06-27 15:30 ` Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 20/29] x86/mmiotrace: Lock down the testmmiotrace module Matthew Garrett
2019-06-23 0:04 ` Kees Cook
2019-06-23 11:08 ` Thomas Gleixner
2019-06-22 0:03 ` [PATCH V34 21/29] Lock down /proc/kcore Matthew Garrett
2019-06-23 0:05 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 22/29] Lock down tracing and perf kprobes when in confidentiality mode Matthew Garrett
2019-06-23 0:09 ` Kees Cook
2019-06-23 1:57 ` Masami Hiramatsu
2019-06-22 0:03 ` [PATCH V34 23/29] bpf: Restrict bpf when kernel lockdown is " Matthew Garrett
2019-06-23 0:09 ` Kees Cook
2019-06-24 15:15 ` Daniel Borkmann
2019-06-24 19:54 ` Matthew Garrett
2019-06-24 20:08 ` Andy Lutomirski
2019-06-24 20:15 ` Matthew Garrett
2019-06-24 20:59 ` Daniel Borkmann
2019-06-24 21:30 ` Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 24/29] Lock down perf when " Matthew Garrett
2019-06-23 0:12 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 25/29] kexec: Allow kexec_file() with appropriate IMA policy when locked down Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 26/29] debugfs: Restrict debugfs when the kernel is " Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 27/29] tracefs: Restrict tracefs " Matthew Garrett
2019-06-22 0:03 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load " Matthew Garrett
2019-06-23 0:14 ` Kees Cook
2019-06-25 15:00 ` Ard Biesheuvel
2019-06-22 0:03 ` [PATCH V34 29/29] lockdown: Print current->comm in restriction messages Matthew Garrett
2019-06-23 0:25 ` Kees Cook
2019-06-24 23:01 ` [PATCH V34 00/29] Lockdown as an LSM James Morris
2019-06-24 23:47 ` Casey Schaufler
2019-06-24 23:56 ` Matthew Garrett
2019-06-25 6:04 ` James Morris
2019-06-25 8:16 ` John Johansen
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