| Message ID | 20180925001832.18322-14-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | LSM: Explict LSM ordering | expand |
On 09/24/2018 05:18 PM, Kees Cook wrote: > LoadPin's "enable" setting is really about enforcement, not whether > or not the LSM is using LSM hooks. Instead, split this out so that LSM > enabling can be logically distinct from whether enforcement is happening > (for example, the pinning happens when the LSM is enabled, but the pin > is only checked when "enforce" is set). This allows LoadPin to continue > to operate sanely in test environments once LSM enable/disable is > centrally handled (i.e. we want LoadPin to be enabled separately from > its enforcement). > > Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: John Johansen <john.johansen@canonical.com> > --- > security/loadpin/Kconfig | 4 ++-- > security/loadpin/loadpin.c | 21 +++++++++++---------- > 2 files changed, 13 insertions(+), 12 deletions(-) > > diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig > index dd01aa91e521..8653608a3693 100644 > --- a/security/loadpin/Kconfig > +++ b/security/loadpin/Kconfig > @@ -10,10 +10,10 @@ config SECURITY_LOADPIN > have a root filesystem backed by a read-only device such as > dm-verity or a CDROM. > > -config SECURITY_LOADPIN_ENABLED > +config SECURITY_LOADPIN_ENFORCING > bool "Enforce LoadPin at boot" > depends on SECURITY_LOADPIN > help > If selected, LoadPin will enforce pinning at boot. If not > selected, it can be enabled at boot with the kernel parameter > - "loadpin.enabled=1". > + "loadpin.enforcing=1". > diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c > index 0716af28808a..d8a68a6f6fef 100644 > --- a/security/loadpin/loadpin.c > +++ b/security/loadpin/loadpin.c > @@ -44,7 +44,7 @@ static void report_load(const char *origin, struct file *file, char *operation) > kfree(pathname); > } > > -static int enabled = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENABLED); > +static int enforcing = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENFORCING); > static struct super_block *pinned_root; > static DEFINE_SPINLOCK(pinned_root_spinlock); > > @@ -60,8 +60,8 @@ static struct ctl_path loadpin_sysctl_path[] = { > > static struct ctl_table loadpin_sysctl_table[] = { > { > - .procname = "enabled", > - .data = &enabled, > + .procname = "enforcing", > + .data = &enforcing, > .maxlen = sizeof(int), > .mode = 0644, > .proc_handler = proc_dointvec_minmax, > @@ -97,7 +97,7 @@ static void check_pinning_enforcement(struct super_block *mnt_sb) > loadpin_sysctl_table)) > pr_notice("sysctl registration failed!\n"); > else > - pr_info("load pinning can be disabled.\n"); > + pr_info("enforcement can be disabled.\n"); > } else > pr_info("load pinning engaged.\n"); > } > @@ -128,7 +128,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) > > /* This handles the older init_module API that has a NULL file. */ > if (!file) { > - if (!enabled) { > + if (!enforcing) { > report_load(origin, NULL, "old-api-pinning-ignored"); > return 0; > } > @@ -151,7 +151,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) > * Unlock now since it's only pinned_root we care about. > * In the worst case, we will (correctly) report pinning > * failures before we have announced that pinning is > - * enabled. This would be purely cosmetic. > + * enforcing. This would be purely cosmetic. > */ > spin_unlock(&pinned_root_spinlock); > check_pinning_enforcement(pinned_root); > @@ -161,7 +161,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) > } > > if (IS_ERR_OR_NULL(pinned_root) || load_root != pinned_root) { > - if (unlikely(!enabled)) { > + if (unlikely(!enforcing)) { > report_load(origin, file, "pinning-ignored"); > return 0; > } > @@ -186,10 +186,11 @@ static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = { > > void __init loadpin_add_hooks(void) > { > - pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis"); > + pr_info("ready to pin (currently %senforcing)\n", > + enforcing ? "" : "not "); > security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin"); > } > > /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */ > -module_param(enabled, int, 0); > -MODULE_PARM_DESC(enabled, "Pin module/firmware loading (default: true)"); > +module_param(enforcing, int, 0); > +MODULE_PARM_DESC(enforcing, "Enforce module/firmware pinning"); >
diff --git a/security/loadpin/Kconfig b/security/loadpin/Kconfig index dd01aa91e521..8653608a3693 100644 --- a/security/loadpin/Kconfig +++ b/security/loadpin/Kconfig @@ -10,10 +10,10 @@ config SECURITY_LOADPIN have a root filesystem backed by a read-only device such as dm-verity or a CDROM. -config SECURITY_LOADPIN_ENABLED +config SECURITY_LOADPIN_ENFORCING bool "Enforce LoadPin at boot" depends on SECURITY_LOADPIN help If selected, LoadPin will enforce pinning at boot. If not selected, it can be enabled at boot with the kernel parameter - "loadpin.enabled=1". + "loadpin.enforcing=1". diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index 0716af28808a..d8a68a6f6fef 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -44,7 +44,7 @@ static void report_load(const char *origin, struct file *file, char *operation) kfree(pathname); } -static int enabled = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENABLED); +static int enforcing = IS_ENABLED(CONFIG_SECURITY_LOADPIN_ENFORCING); static struct super_block *pinned_root; static DEFINE_SPINLOCK(pinned_root_spinlock); @@ -60,8 +60,8 @@ static struct ctl_path loadpin_sysctl_path[] = { static struct ctl_table loadpin_sysctl_table[] = { { - .procname = "enabled", - .data = &enabled, + .procname = "enforcing", + .data = &enforcing, .maxlen = sizeof(int), .mode = 0644, .proc_handler = proc_dointvec_minmax, @@ -97,7 +97,7 @@ static void check_pinning_enforcement(struct super_block *mnt_sb) loadpin_sysctl_table)) pr_notice("sysctl registration failed!\n"); else - pr_info("load pinning can be disabled.\n"); + pr_info("enforcement can be disabled.\n"); } else pr_info("load pinning engaged.\n"); } @@ -128,7 +128,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) /* This handles the older init_module API that has a NULL file. */ if (!file) { - if (!enabled) { + if (!enforcing) { report_load(origin, NULL, "old-api-pinning-ignored"); return 0; } @@ -151,7 +151,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) * Unlock now since it's only pinned_root we care about. * In the worst case, we will (correctly) report pinning * failures before we have announced that pinning is - * enabled. This would be purely cosmetic. + * enforcing. This would be purely cosmetic. */ spin_unlock(&pinned_root_spinlock); check_pinning_enforcement(pinned_root); @@ -161,7 +161,7 @@ static int loadpin_read_file(struct file *file, enum kernel_read_file_id id) } if (IS_ERR_OR_NULL(pinned_root) || load_root != pinned_root) { - if (unlikely(!enabled)) { + if (unlikely(!enforcing)) { report_load(origin, file, "pinning-ignored"); return 0; } @@ -186,10 +186,11 @@ static struct security_hook_list loadpin_hooks[] __lsm_ro_after_init = { void __init loadpin_add_hooks(void) { - pr_info("ready to pin (currently %sabled)", enabled ? "en" : "dis"); + pr_info("ready to pin (currently %senforcing)\n", + enforcing ? "" : "not "); security_add_hooks(loadpin_hooks, ARRAY_SIZE(loadpin_hooks), "loadpin"); } /* Should not be mutable after boot, so not listed in sysfs (perm == 0). */ -module_param(enabled, int, 0); -MODULE_PARM_DESC(enabled, "Pin module/firmware loading (default: true)"); +module_param(enforcing, int, 0); +MODULE_PARM_DESC(enforcing, "Enforce module/firmware pinning");
LoadPin's "enable" setting is really about enforcement, not whether or not the LSM is using LSM hooks. Instead, split this out so that LSM enabling can be logically distinct from whether enforcement is happening (for example, the pinning happens when the LSM is enabled, but the pin is only checked when "enforce" is set). This allows LoadPin to continue to operate sanely in test environments once LSM enable/disable is centrally handled (i.e. we want LoadPin to be enabled separately from its enforcement). Signed-off-by: Kees Cook <keescook@chromium.org> --- security/loadpin/Kconfig | 4 ++-- security/loadpin/loadpin.c | 21 +++++++++++---------- 2 files changed, 13 insertions(+), 12 deletions(-)