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authorPaul Moore <paul@paul-moore.com>2019-12-18 21:45:08 -0500
committerPaul Moore <paul@paul-moore.com>2020-01-07 10:19:43 -0500
commit89b223bfb8a89731bea4c84982b5d2ad7ba460e3 (patch)
tree64da9aab8bff75330ed8ac4adb5660ff2d47d0e3 /security
parent7a4b51947475a7f67e2bd06c4a4c768e2e64a975 (diff)
selinux: deprecate disabling SELinux and runtime
Deprecate the CONFIG_SECURITY_SELINUX_DISABLE functionality. The code was originally developed to make it easier for Linux distributions to support architectures where adding parameters to the kernel command line was difficult. Unfortunately, supporting runtime disable meant we had to make some security trade-offs when it came to the LSM hooks, as documented in the Kconfig help text: NOTE: selecting this option will disable the '__ro_after_init' kernel hardening feature for security hooks. Please consider using the selinux=0 boot parameter instead of enabling this option. Fortunately it looks as if that the original motivation for the runtime disable functionality is gone, and Fedora/RHEL appears to be the only major distribution enabling this capability at build time so we are now taking steps to remove it entirely from the kernel. The first step is to mark the functionality as deprecated and print an error when it is used (what this patch is doing). As Fedora/RHEL makes progress in transitioning the distribution away from runtime disable, we will introduce follow-up patches over several kernel releases which will block for increasing periods of time when the runtime disable is used. Finally we will remove the option entirely once we believe all users have moved to the kernel cmdline approach. Acked-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: Ondrej Mosnacek <omosnace@redhat.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/Kconfig3
-rw-r--r--security/selinux/selinuxfs.c7
2 files changed, 10 insertions, 0 deletions
diff --git a/security/selinux/Kconfig b/security/selinux/Kconfig
index 996d35d950f7..580ac24c7aa1 100644
--- a/security/selinux/Kconfig
+++ b/security/selinux/Kconfig
@@ -42,6 +42,9 @@ config SECURITY_SELINUX_DISABLE
using the selinux=0 boot parameter instead of enabling this
option.
+ WARNING: this option is deprecated and will be removed in a future
+ kernel release.
+
If you are unsure how to answer this question, answer N.
config SECURITY_SELINUX_DEVELOP
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index d903574f1f0d..79c710911a3c 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -281,6 +281,13 @@ static ssize_t sel_write_disable(struct file *file, const char __user *buf,
int new_value;
int enforcing;
+ /* NOTE: we are now officially considering runtime disable as
+ * deprecated, and using it will become increasingly painful
+ * (e.g. sleeping/blocking) as we progress through future
+ * kernel releases until eventually it is removed
+ */
+ pr_err("SELinux: Runtime disable is deprecated, use selinux=0 on the kernel cmdline.\n");
+
if (count >= PAGE_SIZE)
return -ENOMEM;