summaryrefslogtreecommitdiff
path: root/security/min_addr.c
diff options
context:
space:
mode:
Diffstat (limited to 'security/min_addr.c')
-rw-r--r--security/min_addr.c52
1 files changed, 52 insertions, 0 deletions
diff --git a/security/min_addr.c b/security/min_addr.c
new file mode 100644
index 000000000..f728728f1
--- /dev/null
+++ b/security/min_addr.c
@@ -0,0 +1,52 @@
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/security.h>
+#include <linux/sysctl.h>
+
+/* amount of vm to protect from userspace access by both DAC and the LSM*/
+unsigned long mmap_min_addr;
+/* amount of vm to protect from userspace using CAP_SYS_RAWIO (DAC) */
+unsigned long dac_mmap_min_addr = CONFIG_DEFAULT_MMAP_MIN_ADDR;
+/* amount of vm to protect from userspace using the LSM = CONFIG_LSM_MMAP_MIN_ADDR */
+
+/*
+ * Update mmap_min_addr = max(dac_mmap_min_addr, CONFIG_LSM_MMAP_MIN_ADDR)
+ */
+static void update_mmap_min_addr(void)
+{
+#ifdef CONFIG_LSM_MMAP_MIN_ADDR
+ if (dac_mmap_min_addr > CONFIG_LSM_MMAP_MIN_ADDR)
+ mmap_min_addr = dac_mmap_min_addr;
+ else
+ mmap_min_addr = CONFIG_LSM_MMAP_MIN_ADDR;
+#else
+ mmap_min_addr = dac_mmap_min_addr;
+#endif
+}
+
+/*
+ * sysctl handler which just sets dac_mmap_min_addr = the new value and then
+ * calls update_mmap_min_addr() so non MAP_FIXED hints get rounded properly
+ */
+int mmap_min_addr_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ if (write && !capable(CAP_SYS_RAWIO))
+ return -EPERM;
+
+ ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+
+ update_mmap_min_addr();
+
+ return ret;
+}
+
+static int __init init_mmap_min_addr(void)
+{
+ update_mmap_min_addr();
+
+ return 0;
+}
+pure_initcall(init_mmap_min_addr);