security: allow Yama to be unconditionally stacked

Unconditionally call Yama when CONFIG_SECURITY_YAMA_STACKED is selected,
no matter what LSM module is primary.

Ubuntu and Chrome OS already carry patches to do this, and Fedora
has voiced interest in doing this as well. Instead of having multiple
distributions (or LSM authors) carrying these patches, just allow Yama
to be called unconditionally when selected by the new CONFIG.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: Eric Paris <eparis@redhat.com>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This commit is contained in:
Kees Cook 2012-09-04 13:32:13 -07:00 committed by James Morris
parent 81198078d7
commit c6993e4ac0
4 changed files with 70 additions and 4 deletions

View File

@ -3021,5 +3021,36 @@ static inline void free_secdata(void *secdata)
{ }
#endif /* CONFIG_SECURITY */
#ifdef CONFIG_SECURITY_YAMA
extern int yama_ptrace_access_check(struct task_struct *child,
unsigned int mode);
extern int yama_ptrace_traceme(struct task_struct *parent);
extern void yama_task_free(struct task_struct *task);
extern int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
#else
static inline int yama_ptrace_access_check(struct task_struct *child,
unsigned int mode)
{
return 0;
}
static inline int yama_ptrace_traceme(struct task_struct *parent)
{
return 0;
}
static inline void yama_task_free(struct task_struct *task)
{
}
static inline int yama_task_prctl(int option, unsigned long arg2,
unsigned long arg3, unsigned long arg4,
unsigned long arg5)
{
return -ENOSYS;
}
#endif /* CONFIG_SECURITY_YAMA */
#endif /* ! __LINUX_SECURITY_H */

View File

@ -136,11 +136,23 @@ int __init register_security(struct security_operations *ops)
int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
{
#ifdef CONFIG_SECURITY_YAMA_STACKED
int rc;
rc = yama_ptrace_access_check(child, mode);
if (rc)
return rc;
#endif
return security_ops->ptrace_access_check(child, mode);
}
int security_ptrace_traceme(struct task_struct *parent)
{
#ifdef CONFIG_SECURITY_YAMA_STACKED
int rc;
rc = yama_ptrace_traceme(parent);
if (rc)
return rc;
#endif
return security_ops->ptrace_traceme(parent);
}
@ -761,6 +773,9 @@ int security_task_create(unsigned long clone_flags)
void security_task_free(struct task_struct *task)
{
#ifdef CONFIG_SECURITY_YAMA_STACKED
yama_task_free(task);
#endif
security_ops->task_free(task);
}
@ -876,6 +891,12 @@ int security_task_wait(struct task_struct *p)
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
#ifdef CONFIG_SECURITY_YAMA_STACKED
int rc;
rc = yama_task_prctl(option, arg2, arg3, arg4, arg5);
if (rc != -ENOSYS)
return rc;
#endif
return security_ops->task_prctl(option, arg2, arg3, arg4, arg5);
}

View File

@ -11,3 +11,11 @@ config SECURITY_YAMA
Further information can be found in Documentation/security/Yama.txt.
If you are unsure how to answer this question, answer N.
config SECURITY_YAMA_STACKED
bool "Yama stacked with other LSMs"
depends on SECURITY_YAMA
default n
help
When Yama is built into the kernel, force it to stack with the
selected primary LSM.

View File

@ -100,7 +100,7 @@ static void yama_ptracer_del(struct task_struct *tracer,
* yama_task_free - check for task_pid to remove from exception list
* @task: task being removed
*/
static void yama_task_free(struct task_struct *task)
void yama_task_free(struct task_struct *task)
{
yama_ptracer_del(task, task);
}
@ -116,7 +116,7 @@ static void yama_task_free(struct task_struct *task)
* Return 0 on success, -ve on error. -ENOSYS is returned when Yama
* does not handle the given option.
*/
static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
int rc;
@ -243,7 +243,7 @@ static int ptracer_exception_found(struct task_struct *tracer,
*
* Returns 0 if following the ptrace is allowed, -ve on error.
*/
static int yama_ptrace_access_check(struct task_struct *child,
int yama_ptrace_access_check(struct task_struct *child,
unsigned int mode)
{
int rc;
@ -296,7 +296,7 @@ static int yama_ptrace_access_check(struct task_struct *child,
*
* Returns 0 if following the ptrace is allowed, -ve on error.
*/
static int yama_ptrace_traceme(struct task_struct *parent)
int yama_ptrace_traceme(struct task_struct *parent)
{
int rc;
@ -330,6 +330,7 @@ static int yama_ptrace_traceme(struct task_struct *parent)
return rc;
}
#ifndef CONFIG_SECURITY_YAMA_STACKED
static struct security_operations yama_ops = {
.name = "yama",
@ -338,6 +339,7 @@ static struct security_operations yama_ops = {
.task_prctl = yama_task_prctl,
.task_free = yama_task_free,
};
#endif
#ifdef CONFIG_SYSCTL
static int yama_dointvec_minmax(struct ctl_table *table, int write,
@ -384,13 +386,17 @@ static struct ctl_table yama_sysctl_table[] = {
static __init int yama_init(void)
{
#ifndef CONFIG_SECURITY_YAMA_STACKED
if (!security_module_enable(&yama_ops))
return 0;
#endif
printk(KERN_INFO "Yama: becoming mindful.\n");
#ifndef CONFIG_SECURITY_YAMA_STACKED
if (register_security(&yama_ops))
panic("Yama: kernel registration failed.\n");
#endif
#ifdef CONFIG_SYSCTL
if (!register_sysctl_paths(yama_sysctl_path, yama_sysctl_table))