| Message ID | 20190808000721.124691-20-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | security: Add support for locking down the kernel | expand |
+++ Matthew Garrett [07/08/19 17:07 -0700]: >From: David Howells <dhowells@redhat.com> > >Provided an annotation for module parameters that specify hardware >parameters (such as io ports, iomem addresses, irqs, dma channels, fixed >dma buffers and other types). > >Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> >Signed-off-by: David Howells <dhowells@redhat.com> >Signed-off-by: Matthew Garrett <mjg59@google.com> >Reviewed-by: Kees Cook <keescook@chromium.org> >Cc: Jessica Yu <jeyu@kernel.org> >--- > include/linux/security.h | 1 + > kernel/params.c | 27 ++++++++++++++++++++++----- > security/lockdown/lockdown.c | 1 + > 3 files changed, 24 insertions(+), 5 deletions(-) > >diff --git a/include/linux/security.h b/include/linux/security.h >index 8f7048395114..43fa3486522b 100644 >--- a/include/linux/security.h >+++ b/include/linux/security.h >@@ -113,6 +113,7 @@ enum lockdown_reason { > LOCKDOWN_ACPI_TABLES, > LOCKDOWN_PCMCIA_CIS, > LOCKDOWN_TIOCSSERIAL, >+ LOCKDOWN_MODULE_PARAMETERS, > LOCKDOWN_INTEGRITY_MAX, > LOCKDOWN_CONFIDENTIALITY_MAX, > }; >diff --git a/kernel/params.c b/kernel/params.c >index cf448785d058..35f138fce762 100644 >--- a/kernel/params.c >+++ b/kernel/params.c >@@ -12,6 +12,7 @@ > #include <linux/err.h> > #include <linux/slab.h> > #include <linux/ctype.h> >+#include <linux/security.h> > > #ifdef CONFIG_SYSFS > /* Protects all built-in parameters, modules use their own param_lock */ >@@ -96,13 +97,19 @@ bool parameq(const char *a, const char *b) > return parameqn(a, b, strlen(a)+1); > } > >-static void param_check_unsafe(const struct kernel_param *kp) >+static bool param_check_unsafe(const struct kernel_param *kp) > { >+ if (kp->flags & KERNEL_PARAM_FL_HWPARAM && >+ security_locked_down(LOCKDOWN_MODULE_PARAMETERS)) >+ return false; >+ > if (kp->flags & KERNEL_PARAM_FL_UNSAFE) { > pr_notice("Setting dangerous option %s - tainting kernel\n", > kp->name); > add_taint(TAINT_USER, LOCKDEP_STILL_OK); > } >+ >+ return true; > } > > static int parse_one(char *param, >@@ -132,8 +139,10 @@ static int parse_one(char *param, > pr_debug("handling %s with %p\n", param, > params[i].ops->set); > kernel_param_lock(params[i].mod); >- param_check_unsafe(¶ms[i]); >- err = params[i].ops->set(val, ¶ms[i]); >+ if (param_check_unsafe(¶ms[i])) >+ err = params[i].ops->set(val, ¶ms[i]); >+ else >+ err = -EPERM; > kernel_param_unlock(params[i].mod); > return err; > } >@@ -541,6 +550,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr, > return count; > } > >+#ifdef CONFIG_MODULES >+#define mod_name(mod) ((mod)->name) >+#else >+#define mod_name(mod) "unknown" >+#endif >+ Hm, I don't think mod_name is used anywhere? But other than that: Acked-by: Jessica Yu <jeyu@kernel.org> Thanks! Jessica > /* sysfs always hands a nul-terminated string in buf. We rely on that. */ > static ssize_t param_attr_store(struct module_attribute *mattr, > struct module_kobject *mk, >@@ -553,8 +568,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr, > return -EPERM; > > kernel_param_lock(mk->mod); >- param_check_unsafe(attribute->param); >- err = attribute->param->ops->set(buf, attribute->param); >+ if (param_check_unsafe(attribute->param)) >+ err = attribute->param->ops->set(buf, attribute->param); >+ else >+ err = -EPERM; > kernel_param_unlock(mk->mod); > if (!err) > return len; >diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c >index 00a3a6438dd2..5177938cfa0d 100644 >--- a/security/lockdown/lockdown.c >+++ b/security/lockdown/lockdown.c >@@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { > [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", > [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", > [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", >+ [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", > [LOCKDOWN_INTEGRITY_MAX] = "integrity", > [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", > }; >-- >2.22.0.770.g0f2c4a37fd-goog >
On Thu, 8 Aug 2019, Jessica Yu wrote: > > +#ifdef CONFIG_MODULES > > +#define mod_name(mod) ((mod)->name) > > +#else > > +#define mod_name(mod) "unknown" > > +#endif > > + > > Hm, I don't think mod_name is used anywhere? > > But other than that: > > Acked-by: Jessica Yu <jeyu@kernel.org> > Matthew: no need to respin the patchset just for this.
diff --git a/include/linux/security.h b/include/linux/security.h index 8f7048395114..43fa3486522b 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -113,6 +113,7 @@ enum lockdown_reason { LOCKDOWN_ACPI_TABLES, LOCKDOWN_PCMCIA_CIS, LOCKDOWN_TIOCSSERIAL, + LOCKDOWN_MODULE_PARAMETERS, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/kernel/params.c b/kernel/params.c index cf448785d058..35f138fce762 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -12,6 +12,7 @@ #include <linux/err.h> #include <linux/slab.h> #include <linux/ctype.h> +#include <linux/security.h> #ifdef CONFIG_SYSFS /* Protects all built-in parameters, modules use their own param_lock */ @@ -96,13 +97,19 @@ bool parameq(const char *a, const char *b) return parameqn(a, b, strlen(a)+1); } -static void param_check_unsafe(const struct kernel_param *kp) +static bool param_check_unsafe(const struct kernel_param *kp) { + if (kp->flags & KERNEL_PARAM_FL_HWPARAM && + security_locked_down(LOCKDOWN_MODULE_PARAMETERS)) + return false; + if (kp->flags & KERNEL_PARAM_FL_UNSAFE) { pr_notice("Setting dangerous option %s - tainting kernel\n", kp->name); add_taint(TAINT_USER, LOCKDEP_STILL_OK); } + + return true; } static int parse_one(char *param, @@ -132,8 +139,10 @@ static int parse_one(char *param, pr_debug("handling %s with %p\n", param, params[i].ops->set); kernel_param_lock(params[i].mod); - param_check_unsafe(¶ms[i]); - err = params[i].ops->set(val, ¶ms[i]); + if (param_check_unsafe(¶ms[i])) + err = params[i].ops->set(val, ¶ms[i]); + else + err = -EPERM; kernel_param_unlock(params[i].mod); return err; } @@ -541,6 +550,12 @@ static ssize_t param_attr_show(struct module_attribute *mattr, return count; } +#ifdef CONFIG_MODULES +#define mod_name(mod) ((mod)->name) +#else +#define mod_name(mod) "unknown" +#endif + /* sysfs always hands a nul-terminated string in buf. We rely on that. */ static ssize_t param_attr_store(struct module_attribute *mattr, struct module_kobject *mk, @@ -553,8 +568,10 @@ static ssize_t param_attr_store(struct module_attribute *mattr, return -EPERM; kernel_param_lock(mk->mod); - param_check_unsafe(attribute->param); - err = attribute->param->ops->set(buf, attribute->param); + if (param_check_unsafe(attribute->param)) + err = attribute->param->ops->set(buf, attribute->param); + else + err = -EPERM; kernel_param_unlock(mk->mod); if (!err) return len; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 00a3a6438dd2..5177938cfa0d 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -28,6 +28,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables", [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", + [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", };