| Message ID | 20190718194415.108476-2-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | security: Add kernel lockdown functionality | expand |
On 7/18/2019 12:43 PM, 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> Acked-by: Casey Schaufler <casey@schaufler-ca.com> > --- > 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 ca42182992a5..6cc6174a2a4c 100644 > --- a/include/asm-generic/vmlinux.lds.h > +++ b/include/asm-generic/vmlinux.lds.h > @@ -215,8 +215,13 @@ > __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) > @@ -616,7 +621,8 @@ > 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 df1318d85f7d..aebb0e032072 100644 > --- a/include/linux/lsm_hooks.h > +++ b/include/linux/lsm_hooks.h > @@ -2104,12 +2104,18 @@ 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 5f7441abbf42..66a2fcbe6ab0 100644 > --- a/include/linux/security.h > +++ b/include/linux/security.h > @@ -195,6 +195,7 @@ 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); > diff --git a/init/main.c b/init/main.c > index ff5803b0841c..0fefca3fd43c 100644 > --- a/init/main.c > +++ b/init/main.c > @@ -593,6 +593,7 @@ 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); > mm_init_cpumask(&init_mm); > setup_command_line(command_line); > diff --git a/security/security.c b/security/security.c > index 250ee2d76406..90f1e291c800 100644 > --- a/security/security.c > +++ b/security/security.c > @@ -33,6 +33,7 @@ > > /* 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 BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain); > @@ -277,6 +278,8 @@ 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; > @@ -323,6 +326,26 @@ 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 > * > @@ -330,14 +353,18 @@ 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(); > @@ -384,7 +411,7 @@ 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; > > @@ -422,8 +449,15 @@ 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_blocking_lsm_notifier(enum lsm_event event, void *data)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index ca42182992a5..6cc6174a2a4c 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -215,8 +215,13 @@ __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) @@ -616,7 +621,8 @@ 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 df1318d85f7d..aebb0e032072 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -2104,12 +2104,18 @@ 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 5f7441abbf42..66a2fcbe6ab0 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -195,6 +195,7 @@ 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); diff --git a/init/main.c b/init/main.c index ff5803b0841c..0fefca3fd43c 100644 --- a/init/main.c +++ b/init/main.c @@ -593,6 +593,7 @@ 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); mm_init_cpumask(&init_mm); setup_command_line(command_line); diff --git a/security/security.c b/security/security.c index 250ee2d76406..90f1e291c800 100644 --- a/security/security.c +++ b/security/security.c @@ -33,6 +33,7 @@ /* 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 BLOCKING_NOTIFIER_HEAD(blocking_lsm_notifier_chain); @@ -277,6 +278,8 @@ 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; @@ -323,6 +326,26 @@ 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 * @@ -330,14 +353,18 @@ 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(); @@ -384,7 +411,7 @@ 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; @@ -422,8 +449,15 @@ 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_blocking_lsm_notifier(enum lsm_event event, void *data)