@@ -126,6 +126,7 @@ struct ima_namespace {
unsigned long ima_ns_flags;
/* Bit numbers for above flags; use BIT() to get flag */
#define IMA_NS_LSM_UPDATE_RULES 0
+#define IMA_NS_ACTIVE 1
struct rb_root ns_status_tree;
rwlock_t ns_tree_lock;
@@ -158,6 +159,11 @@ struct ima_namespace {
} __randomize_layout;
extern struct ima_namespace init_ima_ns;
+static inline bool ns_is_active(struct ima_namespace *ns)
+{
+ return (ns && test_bit(IMA_NS_ACTIVE, &ns->ima_ns_flags));
+}
+
extern const int read_idmap[];
#ifdef CONFIG_HAVE_IMA_KEXEC
@@ -451,6 +451,57 @@ static const struct file_operations ima_measure_policy_ops = {
.llseek = generic_file_llseek,
};
+static ssize_t ima_show_active(struct file *filp,
+ char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct ima_namespace *ns = &init_ima_ns;
+ char tmpbuf[2];
+ ssize_t len;
+
+ len = scnprintf(tmpbuf, sizeof(tmpbuf),
+ "%d\n", !!test_bit(IMA_NS_ACTIVE, &ns->ima_ns_flags));
+ return simple_read_from_buffer(buf, count, ppos, tmpbuf, len);
+}
+
+static ssize_t ima_write_active(struct file *filp,
+ const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ struct ima_namespace *ns = &init_ima_ns;
+ unsigned int active;
+ char *kbuf;
+ int err;
+
+ if (ns_is_active(ns))
+ return -EBUSY;
+
+ /* accepting '1\n' and '1\0' and no partial writes */
+ if (count >= 3 || *ppos != 0)
+ return -EINVAL;
+
+ kbuf = memdup_user_nul(buf, count);
+ if (IS_ERR(kbuf))
+ return PTR_ERR(kbuf);
+
+ err = kstrtouint(kbuf, 10, &active);
+ kfree(kbuf);
+ if (err)
+ return err;
+
+ if (active != 1)
+ return -EINVAL;
+
+ set_bit(IMA_NS_ACTIVE, &ns->ima_ns_flags);
+
+ return count;
+}
+
+static const struct file_operations ima_active_ops = {
+ .read = ima_show_active,
+ .write = ima_write_active,
+};
+
int ima_fs_ns_init(struct user_namespace *user_ns, struct dentry *root)
{
struct ima_namespace *ns = ima_ns_from_user_ns(user_ns);
@@ -461,6 +512,7 @@ int ima_fs_ns_init(struct user_namespace *user_ns, struct dentry *root)
struct dentry *ascii_runtime_measurements = NULL;
struct dentry *runtime_measurements_count = NULL;
struct dentry *violations = NULL;
+ struct dentry *active = NULL;
int ret;
/* FIXME: update when evm and integrity are namespaced */
@@ -531,8 +583,20 @@ int ima_fs_ns_init(struct user_namespace *user_ns, struct dentry *root)
}
}
+ if (ns != &init_ima_ns) {
+ active =
+ securityfs_create_file("active",
+ S_IRUSR | S_IWUSR | S_IRGRP, ima_dir,
+ NULL, &ima_active_ops);
+ if (IS_ERR(active)) {
+ ret = PTR_ERR(active);
+ goto out;
+ }
+ }
+
return 0;
out:
+ securityfs_remove(active);
securityfs_remove(ns->ima_policy);
securityfs_remove(violations);
securityfs_remove(runtime_measurements_count);
@@ -58,5 +58,6 @@ struct ima_namespace init_ima_ns = {
.ima_lsm_policy_notifier = {
.notifier_call = ima_lsm_policy_change,
},
+ .ima_ns_flags = BIT(IMA_NS_ACTIVE),
};
EXPORT_SYMBOL(init_ima_ns);
@@ -441,7 +441,7 @@ static int process_measurement(struct user_namespace *user_ns,
while (user_ns) {
ns = ima_ns_from_user_ns(user_ns);
- if (ns) {
+ if (ns_is_active(ns)) {
int rc;
rc = __process_measurement(ns, file, cred, secid, buf,
Introduce the IMA securityfs file 'active' that users now need to write a "1" into (precisely a '1\0' or '1\n') to activate an IMA namespace. When reading from the file, it shows either '0' or '1'. The rationale for introducing a file to activate an IMA namespace is that subsequent support for IMA-measurement and IMA-appraisal will add configuration files for selecting for example the template that an IMA namespace is supposed to use for logging measurements, which will add an IMA namespace configuration stage (using securityfs files) before its activation. Besides that it allows to create a user namespace with securityfs mounted and an inactive IMA namespace. Also, introduce ns_is_active() to be used in those places where the ima_namespace pointer may either be NULL or where the active flag may not have been set, yet. An inactive IMA namespace should never be accessed since it has not been initialized, yet. Set the init_ima_ns's active flag since it is considered active right from the beginning. Signed-off-by: Stefan Berger <stefanb@linux.ibm.com> --- v12: - Fixed uninitialized ret if IS_ERR(active) was true v11: - Move code from ima_fs_add_ns_files() into ima_fs_ns_init() - Use ima_ns_flags and IMA_NS_ACTIVE instead of 'atomic_t active' v10: - use memdup_user_nul to copy input from user - propagating error returned from ima_fs_add_ns_files() --- security/integrity/ima/ima.h | 6 +++ security/integrity/ima/ima_fs.c | 64 ++++++++++++++++++++++++ security/integrity/ima/ima_init_ima_ns.c | 1 + security/integrity/ima/ima_main.c | 2 +- 4 files changed, 72 insertions(+), 1 deletion(-)