kernel: Add the ability to manually elevate privileges for programs using prctl by specifying UID or PID.

kernel/manual_su.c

@@ -0,0 +1,45 @@
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/printk.h>
+#include <linux/cred.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/file.h>
+#include "kernel_compat.h"
+#include "manual_su.h"
+#include "ksu.h"
+#include "allowlist.h"
+#include "manager.h"
+
+static const char *ksu_su_password = "zakozako";
+extern void escape_to_root_for_cmd_su(uid_t, pid_t);
+
+int ksu_manual_su_escalate(uid_t target_uid, pid_t target_pid,
+                           const char __user *user_password)
+{
+    if (ksu_is_current_verified())
+        goto allowed;
+
+    if (current_uid().val == 0 || is_manager() || ksu_is_allow_uid(current_uid().val))
+        goto allowed;
+
+    if (!user_password) {
+        pr_warn("manual_su: password required\n");
+        return -EACCES;
+    }
+    char buf[64];
+    if (strncpy_from_user(buf, user_password, sizeof(buf) - 1) < 0)
+        return -EFAULT;
+    buf[sizeof(buf) - 1] = '\0';
+
+    if (strcmp(buf, ksu_su_password) != 0) {
+        pr_warn("manual_su: wrong password\n");
+        return -EACCES;
+    }
+
+    ksu_mark_current_verified();
+
+allowed:
+    escape_to_root_for_cmd_su(target_uid, target_pid);
+    return 0;
+}