[PATCH 5.10 003/116] ima: Allow template selection with ima_template[_fmt]= after ima_hash=

Greg Kroah-Hartman
2022-02-14T09:49:12Z

From: Roberto Sassu <roberto.sassu@huawei.com>

commit bb8e52e4906f148c2faf6656b5106cf7233e9301 upstream.

Commit c2426d2ad5027 ("ima: added support for new kernel cmdline parameter
ima_template_fmt") introduced an additional check on the ima_template
variable to avoid multiple template selection.

Unfortunately, ima_template could be also set by the setup function of the
ima_hash= parameter, when it calls ima_template_desc_current(). This causes
attempts to choose a new template with ima_template= or with
ima_template_fmt=, after ima_hash=, to be ignored.

Achieve the goal of the commit mentioned with the new static variable
template_setup_done, so that template selection requests after ima_hash=
are not ignored.

Finally, call ima_init_template_list(), if not already done, to initialize
the list of templates before lookup_template_desc() is called.

Reported-by: Guo Zihua <guozihua@huawei.com>
Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
Cc: stable@vger.kernel.org
Fixes: c2426d2ad5027 ("ima: added support for new kernel cmdline parameter ima_template_fmt")
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/integrity/ima/ima_template.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -27,6 +27,7 @@ static struct ima_template_desc builtin_

static LIST_HEAD(defined_templates);
static DEFINE_SPINLOCK(template_list);
+static int template_setup_done;

static const struct ima_template_field supported_fields[] = {
{.field_id = "d", .field_init = ima_eventdigest_init,
@@ -80,10 +81,11 @@ static int __init ima_template_setup(cha
struct ima_template_desc *template_desc;
int template_len = strlen(str);

- if (ima_template)
+ if (template_setup_done)
return 1;

- ima_init_template_list();
+ if (!ima_template)
+ ima_init_template_list();

/*
* Verify that a template with the supplied name exists.
@@ -107,6 +109,7 @@ static int __init ima_template_setup(cha
}

ima_template = template_desc;
+ template_setup_done = 1;
return 1;
}
__setup("ima_template=", ima_template_setup);
@@ -115,7 +118,7 @@ static int __init ima_template_fmt_setup
{
int num_templates = ARRAY_SIZE(builtin_templates);

- if (ima_template)
+ if (template_setup_done)
return 1;

if (template_desc_init_fields(str, NULL, NULL) < 0) {
@@ -126,6 +129,7 @@ static int __init ima_template_fmt_setup

builtin_templates[num_templates - 1].fmt = str;
ima_template = builtin_templates + num_templates - 1;
+ template_setup_done = 1;

return 1;
}