[PATCH v7 12/14] ima: Use mac_admin_ns_capable() to check corresponding capability

[Stefan Berger]

From: Stefan Berger <stefanb@xxxxxxxxxxxxx>

Use mac_admin_ns_capable() to check corresponding capability to allow
read/write IMA policy without CAP_SYS_ADMIN but with CAP_MAC_ADMIN.

Signed-off-by: Denis Semakin <denis.semakin@xxxxxxxxxx>
Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
---
 include/linux/capability.h      | 6 ++++++
 security/integrity/ima/ima_fs.c | 5 +++--
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/linux/capability.h b/include/linux/capability.h
index 65efb74c3585..991579178f32 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -270,6 +270,12 @@ static inline bool checkpoint_restore_ns_capable(struct user_namespace *ns)
 		ns_capable(ns, CAP_SYS_ADMIN);
 }
 
+static inline bool mac_admin_ns_capable(struct user_namespace *ns)
+{
+	return ns_capable(ns, CAP_MAC_ADMIN) ||
+		ns_capable(ns, CAP_SYS_ADMIN);
+}
+
 /* audit system wants to get cap info from files as well */
 int get_vfs_caps_from_disk(struct user_namespace *mnt_userns,
 			   const struct dentry *dentry,
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index b2ca9bcd185f..611c4271d474 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -385,7 +385,8 @@ static const struct seq_operations ima_policy_seqops = {
  */
 static int ima_open_policy(struct inode *inode, struct file *filp)
 {
-	struct ima_namespace *ns = ima_ns_from_file(filp);
+	struct user_namespace *user_ns = ima_user_ns_from_file(filp);
+	struct ima_namespace *ns = user_ns->ima_ns;
 
 	if (!(filp->f_flags & O_WRONLY)) {
 #ifndef	CONFIG_IMA_READ_POLICY
@@ -393,7 +394,7 @@ static int ima_open_policy(struct inode *inode, struct file *filp)
 #else
 		if ((filp->f_flags & O_ACCMODE) != O_RDONLY)
 			return -EACCES;
-		if (!capable(CAP_SYS_ADMIN))
+		if (!mac_admin_ns_capable(user_ns))
 			return -EPERM;
 		return seq_open(filp, &ima_policy_seqops);
 #endif
-- 
2.31.1