[PATCH -V7 23/26] vfs: Add richacl permission check

["Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>]

From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>

Acked-by: David Howells <dhowells@xxxxxxxxxx>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
---
 fs/attr.c               |    6 +++-
 fs/namei.c              |   13 ++++++++++-
 fs/richacl_base.c       |   54 +++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h      |    2 +-
 include/linux/richacl.h |    2 +
 5 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/fs/attr.c b/fs/attr.c
index 00578b9..2b445ba 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -13,6 +13,7 @@
 #include <linux/fsnotify.h>
 #include <linux/fcntl.h>
 #include <linux/security.h>
+#include <linux/richacl.h>
 
 static int richacl_change_ok(struct inode *inode, int mask)
 {
@@ -21,8 +22,9 @@ static int richacl_change_ok(struct inode *inode, int mask)
 
 	if (inode->i_op->permission)
 		return inode->i_op->permission(inode, mask);
-
-	return check_acl(inode, mask);
+	if (inode->i_op->get_richacl)
+		return check_richacl(inode, mask);
+	return -EPERM;
 }
 
 static bool inode_uid_change_ok(struct inode *inode, uid_t ia_uid)
diff --git a/fs/namei.c b/fs/namei.c
index 0c28f95..5d8f21e 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -33,6 +33,7 @@
 #include <linux/device_cgroup.h>
 #include <linux/fs_struct.h>
 #include <linux/posix_acl.h>
+#include <linux/richacl.h>
 #include <asm/uaccess.h>
 
 #include "internal.h"
@@ -174,7 +175,7 @@ void putname(const char *name)
 EXPORT_SYMBOL(putname);
 #endif
 
-int check_acl(struct inode *inode, int mask)
+static int check_posix_acl(struct inode *inode, int mask)
 {
 #ifdef CONFIG_FS_POSIX_ACL
 	struct posix_acl *acl;
@@ -220,6 +221,16 @@ int check_acl(struct inode *inode, int mask)
 	return -EAGAIN;
 }
 
+static int check_acl(struct inode *inode, int mask)
+{
+	if (IS_POSIXACL(inode))
+		return check_posix_acl(inode, mask);
+	else if (IS_RICHACL(inode))
+		return check_richacl(inode, mask);
+	else
+		return -EAGAIN;
+}
+
 /*
  * This does the basic permission checking
  */
diff --git a/fs/richacl_base.c b/fs/richacl_base.c
index bde2eea..9a57039 100644
--- a/fs/richacl_base.c
+++ b/fs/richacl_base.c
@@ -622,3 +622,57 @@ richacl_equiv_mode(const struct richacl *acl, mode_t *mode_p)
 	return 0;
 }
 EXPORT_SYMBOL_GPL(richacl_equiv_mode);
+
+int check_richacl(struct inode *inode, int want)
+{
+#ifdef CONFIG_FS_RICHACL
+	struct richacl *acl;
+	int richacl_mask = richacl_want_to_mask(want);
+
+	if (want & MAY_NOT_BLOCK) {
+		acl = rcu_dereference(inode->i_richacl);
+		if (!acl)
+			return -EAGAIN;
+		/* no ->get_acl() calls in RCU mode... */
+		if (acl == ACL_NOT_CACHED)
+			return -ECHILD;
+		return richacl_permission(inode, acl, richacl_mask);
+	}
+	return richacl_check_acl(inode, richacl_mask);
+#endif
+	return -EAGAIN;
+}
+
+int richacl_check_acl(struct inode *inode, int richacl_mask)
+{
+
+#ifdef CONFIG_FS_RICHACL
+	struct richacl *acl;
+	acl = get_cached_richacl(inode);
+	/*
+	 * A filesystem can force a ACL callback by just never filling the
+	 * ACL cache. But normally you'd fill the cache either at inode
+	 * instantiation time, or on the first ->get_acl call.
+	 *
+	 * If the filesystem doesn't have a get_acl() function at all, we'll
+	 * just create the negative cache entry.
+	 */
+	if (acl == ACL_NOT_CACHED) {
+		if (inode->i_op->get_acl) {
+			acl = inode->i_op->get_richacl(inode);
+			if (IS_ERR(acl))
+				return PTR_ERR(acl);
+		} else {
+			set_cached_richacl(inode, NULL);
+			return -EAGAIN;
+		}
+	}
+	if (acl) {
+		int error = richacl_permission(inode, acl, richacl_mask);
+		richacl_put(acl);
+		return error;
+	}
+#endif
+	return -EAGAIN;
+}
+EXPORT_SYMBOL_GPL(richacl_check_acl);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 771955c..e01bad7 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1624,6 +1624,7 @@ struct inode_operations {
 	void * (*follow_link) (struct dentry *, struct nameidata *);
 	int (*permission) (struct inode *, int);
 	struct posix_acl * (*get_acl)(struct inode *, int);
+	struct richacl * (*get_richacl)(struct inode *);
 
 	int (*readlink) (struct dentry *, char __user *,int);
 	void (*put_link) (struct dentry *, struct nameidata *, void *);
@@ -2243,7 +2244,6 @@ extern sector_t bmap(struct inode *, sector_t);
 extern int notify_change(struct dentry *, struct iattr *);
 extern int inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int);
-extern int check_acl(struct inode *, int);
 
 static inline bool execute_ok(struct inode *inode)
 {
diff --git a/include/linux/richacl.h b/include/linux/richacl.h
index 694b7dc..4af6d22 100644
--- a/include/linux/richacl.h
+++ b/include/linux/richacl.h
@@ -367,6 +367,8 @@ extern int richacl_permission(struct inode *, const struct richacl *,
 			      unsigned int);
 extern struct richacl *richacl_inherit(const struct richacl *, int);
 extern int richacl_equiv_mode(const struct richacl *, mode_t *);
+extern int check_richacl(struct inode *, int);
+extern int richacl_check_acl(struct inode *, int);
 
 /* richacl_inode.c */
 extern struct richacl *richacl_inherit_inode(const struct richacl *,
-- 
1.7.5.4

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