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 <kees.cook@canonical.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/min_addr.c b/security/min_addr.c
index c844eed..fc43c9d 100644
--- a/security/min_addr.c
+++ b/security/min_addr.c
@@ -33,6 +33,9 @@
{
int ret;
+ if (!capable(CAP_SYS_RAWIO))
+ return -EPERM;
+
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
update_mmap_min_addr();