Re: [PATCH RFC v10 9/17] ipe: add permissive toggle

Fan Wu
2023-07-15T04:00:36Z

On Sat, Jul 08, 2023 at 12:23:06AM -0400, Paul Moore wrote:
> On Jun 28, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
> >
> > IPE, like SELinux, supports a permissive mode. This mode allows policy
> > authors to test and evaluate IPE policy without it effecting their
> > programs. When the mode is changed, a 1404 AUDIT_MAC_STATUS
> > be reported.
> >
> > This patch adds the following audit records:
> >
> > audit: MAC_STATUS enforcing=0 old_enforcing=1 auid=4294967295
> > ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
> > audit: MAC_STATUS enforcing=1 old_enforcing=0 auid=4294967295
> > ses=4294967295 enabled=1 old-enabled=1 lsm=ipe res=1
> >
> > The audit record only emit when the value from the user input is
> > different from the current enforce value.
> >
> > Signed-off-by: Deven Bowers <deven.desai@linux.microsoft.com>
> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> > ---
> > security/ipe/audit.c | 22 ++++++++++++++
> > security/ipe/audit.h | 1 +
> > security/ipe/eval.c | 9 ++++++
> > security/ipe/eval.h | 1 +
> > security/ipe/fs.c | 69 ++++++++++++++++++++++++++++++++++++++++++++
> > 5 files changed, 102 insertions(+)
>
> ...
>
> > diff --git a/security/ipe/fs.c b/security/ipe/fs.c
> > index 6bd2aa84831b..1761d39e4d04 100644
> > --- a/security/ipe/fs.c
> > +++ b/security/ipe/fs.c
> > @@ -16,6 +16,7 @@ static struct dentry *np __ro_after_init;
> > static struct dentry *root __ro_after_init;
> > struct dentry *policy_root __ro_after_init;
> > static struct dentry *audit_node __ro_after_init;
> > +static struct dentry *enforce_node __ro_after_init;
> >
> > /**
> > * setaudit - Write handler for the securityfs node, "ipe/success_audit"
> > @@ -68,6 +69,61 @@ static ssize_t getaudit(struct file *f, char __user *data,
> > return simple_read_from_buffer(data, len, offset, result, 1);
> > }
> >
> > +/**
> > + * setenforce - Write handler for the securityfs node, "ipe/enforce"
> > + * @f: Supplies a file structure representing the securityfs node.
> > + * @data: Supplies a buffer passed to the write syscall.
> > + * @len: Supplies the length of @data.
> > + * @offset: unused.
> > + *
> > + * Return:
> > + * * >0 - Success, Length of buffer written
> > + * * <0 - Error
> > + */
> > +static ssize_t setenforce(struct file *f, const char __user *data,
> > + size_t len, loff_t *offset)
> > +{
> > + int rc = 0;
> > + bool new_value, old_value;
> > +
> > + if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
> > + return -EPERM;
> > +
> > + old_value = READ_ONCE(enforce);
> > + new_value = old_value;
>
> Why set @new_value equal to @old_value here?
>
Sorry this mistake is the same as the one for audit switch.
kstrtobool_from_user will return error if new_value is not set,
I will remove the above line.

-Fan
> > + rc = kstrtobool_from_user(data, len, &new_value);
> > + if (rc)
> > + return rc;
> > +
> > + if (new_value != old_value) {
> > + ipe_audit_enforce(new_value, old_value);
> > + WRITE_ONCE(enforce, new_value);
> > + }
> > +
> > + return len;
> > +}
>
> --
> paul-moore.com