Add policybrief field to struct policydb. It holds a brief info
of the policydb, in the following form:
<0 or 1 for enforce>:<0 or 1 for checkreqprot>:<hashalg>=<checksum>
Policy brief is computed every time the policy is loaded, and when
enforce or checkreqprot are changed.
Add security_policy_brief hook to give access to policy brief to
the rest of the kernel. Lustre client makes use of this information.
Signed-off-by: Sebastien Buisson <sbuisson@xxxxxxx>
---
include/linux/lsm_hooks.h | 2 +
include/linux/security.h | 7 ++++
security/security.c | 6 +++
security/selinux/hooks.c | 11 +++++-
security/selinux/include/security.h | 2 +
security/selinux/selinuxfs.c | 6 ++-
security/selinux/ss/policydb.c | 70 +++++++++++++++++++++++++++++++++++
security/selinux/ss/policydb.h | 3 ++
security/selinux/ss/services.c | 73 +++++++++++++++++++++++++++++++++++++
9 files changed, 178 insertions(+), 2 deletions(-)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 080f34e..7139a07 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1568,6 +1568,7 @@
int (*inode_setsecctx)(struct dentry *dentry, void *ctx, u32 ctxlen);
int (*inode_getsecctx)(struct inode *inode, void **ctx, u32 *ctxlen);
+ int (*policy_brief)(char **brief, size_t *len, bool alloc);
#ifdef CONFIG_SECURITY_NETWORK
int (*unix_stream_connect)(struct sock *sock, struct sock *other,
struct sock *newsk);
@@ -1813,6 +1814,7 @@ struct security_hook_heads {
struct list_head inode_notifysecctx;
struct list_head inode_setsecctx;
struct list_head inode_getsecctx;
+ struct list_head policy_brief;
#ifdef CONFIG_SECURITY_NETWORK
struct list_head unix_stream_connect;
struct list_head unix_may_send;
diff --git a/include/linux/security.h b/include/linux/security.h
index af675b5..3b72053 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -377,6 +377,8 @@ int security_sem_semop(struct sem_array *sma, struct sembuf *sops,
int security_inode_notifysecctx(struct inode *inode, void *ctx, u32 ctxlen);
int security_inode_setsecctx(struct dentry *dentry, void *ctx, u32 ctxlen);
int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen);
+
+int security_policy_brief(char **brief, size_t *len, bool alloc);
#else /* CONFIG_SECURITY */
struct security_mnt_opts {
};
@@ -1166,6 +1168,11 @@ static inline int security_inode_getsecctx(struct inode *inode, void **ctx, u32
{
return -EOPNOTSUPP;
}
+
+static inline int security_policy_brief(char **brief, size_t *len, bool alloc)
+{
+ return -EOPNOTSUPP;
+}
#endif /* CONFIG_SECURITY */
#ifdef CONFIG_SECURITY_NETWORK
diff --git a/security/security.c b/security/security.c
index b9fea39..954b391 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1285,6 +1285,12 @@ int security_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
}
EXPORT_SYMBOL(security_inode_getsecctx);
+int security_policy_brief(char **brief, size_t *len, bool alloc)
+{
+ return call_int_hook(policy_brief, -EOPNOTSUPP, brief, len, alloc);
+}
+EXPORT_SYMBOL(security_policy_brief);
+
#ifdef CONFIG_SECURITY_NETWORK
int security_unix_stream_connect(struct sock *sock, struct sock *other, struct sock *newsk)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index e67a526..b4dd605 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -104,8 +104,10 @@
static int __init enforcing_setup(char *str)
{
unsigned long enforcing;
- if (!kstrtoul(str, 0, &enforcing))
+ if (!kstrtoul(str, 0, &enforcing)) {
selinux_enforcing = enforcing ? 1 : 0;
+ security_policydb_update_info(NULL);
+ }
return 1;
}
__setup("enforcing=", enforcing_setup);
@@ -6063,6 +6065,11 @@ static int selinux_inode_getsecctx(struct inode *inode, void **ctx, u32 *ctxlen)
*ctxlen = len;
return 0;
}
+
+static int selinux_policy_brief(char **brief, size_t *len, bool alloc)
+{
+ return security_policydb_brief(brief, len, alloc);
+}
#ifdef CONFIG_KEYS
static int selinux_key_alloc(struct key *k, const struct cred *cred,
@@ -6277,6 +6284,8 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer)
LSM_HOOK_INIT(inode_setsecctx, selinux_inode_setsecctx),
LSM_HOOK_INIT(inode_getsecctx, selinux_inode_getsecctx),
+ LSM_HOOK_INIT(policy_brief, selinux_policy_brief),
+
LSM_HOOK_INIT(unix_stream_connect, selinux_socket_unix_stream_connect),
LSM_HOOK_INIT(unix_may_send, selinux_socket_unix_may_send),
diff --git a/security/selinux/include/security.h b/security/selinux/include/security.h
index f979c35..167e274 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -97,6 +97,8 @@ enum {
int security_load_policy(void *data, size_t len);
int security_read_policy(void **data, size_t *len);
size_t security_policydb_len(void);
+int security_policydb_brief(char **brief, size_t *len, bool alloc);
+void security_policydb_update_info(void *p);
int security_policycap_supported(unsigned int req_cap);
diff --git a/security/selinux/selinuxfs.c b/security/selinux/selinuxfs.c
index ce71718..b959ee7 100644
--- a/security/selinux/selinuxfs.c
+++ b/security/selinux/selinuxfs.c
@@ -55,8 +55,10 @@
static int __init checkreqprot_setup(char *str)
{
unsigned long checkreqprot;
- if (!kstrtoul(str, 0, &checkreqprot))
+ if (!kstrtoul(str, 0, &checkreqprot)) {
selinux_checkreqprot = checkreqprot ? 1 : 0;
+ security_policydb_update_info(NULL);
+ }
return 1;
}
__setup("checkreqprot=", checkreqprot_setup);
@@ -159,6 +161,7 @@ static ssize_t sel_write_enforce(struct file *file, const char __user *buf,
from_kuid(&init_user_ns, audit_get_loginuid(current)),
audit_get_sessionid(current));
selinux_enforcing = new_value;
+ security_policydb_update_info(NULL);
if (selinux_enforcing)
avc_ss_reset(0);
selnl_notify_setenforce(selinux_enforcing);
@@ -621,6 +624,7 @@ static ssize_t sel_write_checkreqprot(struct file *file, const char __user *buf,
goto out;
selinux_checkreqprot = new_value ? 1 : 0;
+ security_policydb_update_info(NULL);
length = count;
out:
kfree(page);
diff --git a/security/selinux/ss/policydb.c b/security/selinux/ss/policydb.c
index 0080122..9eb2f82 100644
--- a/security/selinux/ss/policydb.c
+++ b/security/selinux/ss/policydb.c
@@ -32,6 +32,8 @@
#include <linux/errno.h>
#include <linux/audit.h>
#include <linux/flex_array.h>
+#include <crypto/hash.h>
+#include <crypto/sha.h>
#include "security.h"
#include "policydb.h"
@@ -879,6 +881,8 @@ void policydb_destroy(struct policydb *p)
ebitmap_destroy(&p->filename_trans_ttypes);
ebitmap_destroy(&p->policycaps);
ebitmap_destroy(&p->permissive_map);
+
+ kfree(p->policybrief);
}
/*
@@ -2220,6 +2224,67 @@ static int ocontext_read(struct policydb *p, struct policydb_compat_info *info,
}
/*
+ * Compute summary of a policy database binary representation file,
+ * and store it into a policy database structure.
+ */
+static int policydb_brief(struct policydb *policydb, void *ptr)
+{
+ struct policy_file *fp = ptr;
+ struct crypto_shash *tfm;
+ char hashalg[] = "sha256";
+ int hashsize = SHA256_DIGEST_SIZE;
+ char hashval[hashsize];
+ int idx;
+ unsigned char *p;
+
+ if (policydb->policybrief)
+ return -EINVAL;
+
+ tfm = crypto_alloc_shash(hashalg, 0, 0);
+ if (IS_ERR(tfm)) {
+ printk(KERN_ERR "Failed to alloc crypto hash %s\n", hashalg);
+ return PTR_ERR(tfm);
+ }
+
+ {
+ int rc;
+
+ SHASH_DESC_ON_STACK(desc, tfm);
+ desc->tfm = tfm;
+ desc->flags = 0;
+ rc = crypto_shash_init(desc);
+ if (rc) {
+ printk(KERN_ERR "Failed to init shash\n");
+ crypto_free_shash(tfm);
+ return rc;
+ }
+
+ crypto_shash_update(desc, fp->data, fp->len);
+ crypto_shash_final(desc, hashval);
+ crypto_free_shash(tfm);
+ }
+
+ /* policy brief is in the form:
+ * <0 or 1 for enforce>:<0 or 1 for checkreqprot>:<hashalg>=<checksum>
+ */
+ policydb->policybrief = kzalloc(5 + strlen(hashalg) + 2*hashsize + 1,
+ GFP_KERNEL);
+ if (policydb->policybrief == NULL)
+ return -ENOMEM;
+
+ sprintf(policydb->policybrief, "x:x:%s=", hashalg);
+ security_policydb_update_info(policydb);
+ p = policydb->policybrief + strlen(policydb->policybrief);
+ for (idx = 0; idx < hashsize; idx++) {
+ snprintf(p, 3, "%02x", (unsigned char)(hashval[idx]));
+ p += 2;
+ }
+ policydb->policybrief_len = (size_t)(p - policydb->policybrief);
+
+ return 0;
+}
+
+/*
* Read the configuration data from a policy database binary
* representation file into a policy database structure.
*/
@@ -2238,6 +2303,11 @@ int policydb_read(struct policydb *p, void *fp)
if (rc)
return rc;
+ /* Compute sumarry of policy, and store it in policydb */
+ rc = policydb_brief(p, fp);
+ if (rc)
+ goto bad;
+
/* Read the magic number and string length. */
rc = next_entry(buf, fp, sizeof(u32) * 2);
if (rc)
diff --git a/security/selinux/ss/policydb.h b/security/selinux/ss/policydb.h
index 725d594..1fca438 100644
--- a/security/selinux/ss/policydb.h
+++ b/security/selinux/ss/policydb.h
@@ -293,6 +293,9 @@ struct policydb {
size_t len;
unsigned int policyvers;
+ /* summary computed on the policy */
+ unsigned char *policybrief;
+ size_t policybrief_len;
unsigned int reject_unknown : 1;
unsigned int allow_unknown : 1;
diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
index 60d9b02..9a94f8e 100644
--- a/security/selinux/ss/services.c
+++ b/security/selinux/ss/services.c
@@ -2170,6 +2170,79 @@ size_t security_policydb_len(void)
}
/**
+ * security_policydb_brief - Get policydb brief
+ * @brief: pointer to buffer holding brief
+ * @len: in: brief buffer length if no alloc, out: brief string len
+ * @alloc: whether to allocate buffer for brief or not
+ *
+ * On success 0 is returned , or negative value on error.
+ **/
+int security_policydb_brief(char **brief, size_t *len, bool alloc)
+{
+ int rc = 0;
+ size_t policybrief_len;
+
+ if (brief == NULL)
+ return -EINVAL;
+
+ read_lock(&policy_rwlock);
+ policybrief_len = policydb.policybrief_len;
+ if (policydb.policybrief == NULL)
+ rc = -EAGAIN;
+ read_unlock(&policy_rwlock);
+
+ if (rc)
+ return rc;
+
+ if (alloc)
+ /* *brief must be kfreed by caller in this case */
+ *brief = kzalloc(policybrief_len + 1, GFP_KERNEL);
+ else
+ /*
+ * if !alloc, caller must pass a buffer that
+ * can hold policybrief_len+1 chars
+ */
+ if (*len < policybrief_len + 1) {
+ /* put in *len the string size we need to write */
+ *len = policybrief_len;
+ return -ENAMETOOLONG;
+ }
+
+ if (*brief == NULL)
+ return -ENOMEM;
+
+ read_lock(&policy_rwlock);
+ strncpy(*brief, policydb.policybrief, policydb.policybrief_len);
+ *len = policydb.policybrief_len;
+ read_unlock(&policy_rwlock);
+
+ return rc;
+}
+
+void security_policydb_update_info(void *p)
+{
+ /* policy brief is in the form:
+ * <0 or 1 for enforce>:<0 or 1 for checkreqprot>:<hashalg>=<checksum>
+ */
+ if (p) {
+ struct policydb *poldb = p;
+ /* update policydb given as parameter if possible */
+ if (poldb->policybrief) {
+ poldb->policybrief[0] = '0' + selinux_enforcing;
+ poldb->policybrief[2] = '0' + selinux_checkreqprot;
+ }
+ } else {
+ /* update global policydb, needs write lock */
+ write_lock_irq(&policy_rwlock);
+ if (policydb.policybrief) {
+ policydb.policybrief[0] = '0' + selinux_enforcing;
+ policydb.policybrief[2] = '0' + selinux_checkreqprot;
+ }
+ write_unlock_irq(&policy_rwlock);
+ }
+}
+
+/**
* security_port_sid - Obtain the SID for a port.
* @protocol: protocol number
* @port: port number
--
1.8.3.1
