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-rw-r--r--fs/proc/base.c3
-rw-r--r--init/Kconfig14
-rw-r--r--kernel/auditsc.c11
3 files changed, 24 insertions, 4 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index e3cbebbabebd..482df23036b5 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1197,9 +1197,6 @@ static ssize_t proc_loginuid_write(struct file * file, const char __user * buf,
ssize_t length;
uid_t loginuid;
- if (!capable(CAP_AUDIT_CONTROL))
- return -EPERM;
-
rcu_read_lock();
if (current != pid_task(proc_pid(inode), PIDTYPE_PID)) {
rcu_read_unlock();
diff --git a/init/Kconfig b/init/Kconfig
index a075765d5fbe..5ad8b775f2ac 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -372,6 +372,20 @@ config AUDIT_TREE
depends on AUDITSYSCALL
select FSNOTIFY
+config AUDIT_LOGINUID_IMMUTABLE
+ bool "Make audit loginuid immutable"
+ depends on AUDIT
+ help
+ The config option toggles if a task setting it's loginuid requires
+ CAP_SYS_AUDITCONTROL or if that task should require no special permissions
+ but should instead only allow setting its loginuid if it was never
+ previously set. On systems which use systemd or a similar central
+ process to restart login services this should be set to true. On older
+ systems in which an admin would typically have to directly stop and
+ start processes this should be set to false. Setting this to true allows
+ one to drop potentially dangerous capabilites from the login tasks,
+ but may not be backwards compatible with older init systems.
+
source "kernel/irq/Kconfig"
menu "RCU Subsystem"
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index 9d6dd7d869c0..bd084a13c719 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -2173,9 +2173,18 @@ static atomic_t session_id = ATOMIC_INIT(0);
int audit_set_loginuid(uid_t loginuid)
{
struct task_struct *task = current;
- unsigned int sessionid = atomic_inc_return(&session_id);
struct audit_context *context = task->audit_context;
+ unsigned int sessionid;
+
+#ifdef CONFIG_AUDIT_LOGINUID_IMMUTABLE
+ if (task->loginuid != -1)
+ return -EPERM;
+#else /* CONFIG_AUDIT_LOGINUID_IMMUTABLE */
+ if (!capable(CAP_AUDIT_CONTROL))
+ return -EPERM;
+#endif /* CONFIG_AUDIT_LOGINUID_IMMUTABLE */
+ sessionid = atomic_inc_return(&session_id);
if (context && context->in_syscall) {
struct audit_buffer *ab;