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Date: Tue, 24 Oct 2017 18:54:57 -0400 From: Mimi Zohar <zohar@...ux.vnet.ibm.com> To: "Bruno E. O. Meneguele" <brdeoliv@...hat.com>, linux-kernel@...r.kernel.org Cc: linux-security-module@...r.kernel.org, linux-integrity@...r.kernel.org, serge@...lyn.com, james.l.morris@...cle.com, dmitry.kasatkin@...il.com, rusty@...tcorp.com.au, jeyu@...nel.org Subject: Re: [PATCH v3 2/2] ima: check signature enforcement against cmdline param instead of CONFIG On Tue, 2017-10-24 at 15:37 -0200, Bruno E. O. Meneguele wrote: > When the user requests MODULE_CHECK policy and its kernel is compiled > with CONFIG_MODULE_SIG_FORCE not set, all modules would not load, just > those loaded in initram time. One option the user would have would be > set a kernel cmdline param (module.sig_enforce) to true, but the IMA > module check code doesn't rely on this value, it checks just > CONFIG_MODULE_SIG_FORCE. > > This patch solves this problem checking for the exported value of > module.sig_enforce cmdline param intead of CONFIG_MODULE_SIG_FORCE, > which holds the effective value (CONFIG || param). > > Signed-off-by: Bruno E. O. Meneguele <brdeoliv@...hat.com> > --- > security/integrity/ima/ima_main.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > index e4ab8ef8016e..d11a7fcc5c8b 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -356,12 +356,12 @@ void ima_post_path_mknod(struct dentry *dentry) > */ > int ima_read_file(struct file *file, enum kernel_read_file_id read_id) > { > + bool sig_enforce = is_module_sig_enforced(); > + > if (!file && read_id == READING_MODULE) { The only reason for getting here is that you're using the old module load syscall. Is there a reason for not using the new one, which passes the file descriptor? thanks, Mimi > -#ifndef CONFIG_MODULE_SIG_FORCE > - if ((ima_appraise & IMA_APPRAISE_MODULES) && > + if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES) && > (ima_appraise & IMA_APPRAISE_ENFORCE)) > return -EACCES; /* INTEGRITY_UNKNOWN */ > -#endif > return 0; /* We rely on module signature checking */ > } > return 0;
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