sysctl: require CAP_SYS_RAWIO to set mmap_min_addr

Currently the mmap_min_addr value can only be bypassed during mmap when the task has CAP_SYS_RAWIO. However, the mmap_min_addr sysctl value itself can be adjusted to 0 if euid == 0, allowing a bypass without CAP_SYS_RAWIO. This patch adds a check for the capability before allowing mmap_min_addr to be changed. Signed-off-by: Kees Cook <[email protected]> Acked-by: Serge Hallyn <[email protected]> Signed-off-by: James Morris <[email protected]>
berg · Nov 8, 2009 · 0e1a6ef · 0e1a6ef
1 parent 31bde71
commit 0e1a6ef
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/security/min_addr.c b/security/min_addr.c
@@ -33,6 +33,9 @@ int mmap_min_addr_handler(struct ctl_table *table, int write,
 {
 	int ret;
 
+	if (!capable(CAP_SYS_RAWIO))
+		return -EPERM;
+
 	ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
 
 	update_mmap_min_addr();