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Message-ID: <20150618133239.12722.24971.stgit@warthog.procyon.org.uk>
Date: Thu, 18 Jun 2015 14:32:40 +0100
From: David Howells <dhowells@...hat.com>
To: sds@...ho.nsa.gov, viro@...iv.linux.org.uk, miklos@...redi.hu
Cc: linux-fsdevel@...r.kernel.org, dhowells@...hat.com,
linux-security-module@...r.kernel.org,
linux-unionfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/8] Security: Provide copy-up security hooks for unioned
files
Provide two new security hooks for use with security files that are used when
a file is copied up between layers:
(1) security_inode_copy_up(). This is called so that the security label on
the destination file can be set appropriately.
(2) security_inode_copy_up_xattr(). This is called so that each xattr being
copied up can be vetted - including modification and discard.
Signed-off-by: David Howells <dhowells@...hat.com>
---
include/linux/security.h | 36 ++++++++++++++++++++++++++++++++++++
security/capability.c | 13 +++++++++++++
security/security.c | 13 +++++++++++++
3 files changed, 62 insertions(+)
diff --git a/include/linux/security.h b/include/linux/security.h
index 52febde52479..537c77b4cd5e 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -562,6 +562,25 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* @inode contains a pointer to the inode.
* @secid contains a pointer to the location where result will be saved.
* In case of failure, @secid will be set to zero.
+ * @inode_copy_up:
+ * Appropriately label the destination inode when a unioned file is copied
+ * up from a lower layer to the union/overlay layer.
+ * @src indicates the file that is being copied up.
+ * @dst indicates the file that has being created by the copy up.
+ * Returns 0 on success or a negative error code on error.
+ * @inode_copy_up_xattr:
+ * Filter/modify the xattrs being copied up when a unioned file is copied
+ * up from a lower layer to the union/overlay layer.
+ * @src indicates the file that is being copied up.
+ * @dst indicates the file that has being created by the copy up.
+ * @name indicates the name of the xattr.
+ * @value, *@...e indicate the payload of the xattr.
+ * Returns 0 to accept the xattr, 1 to discard the xattr or a negative
+ * error code to abort the copy up. The xattr buffer must be at least
+ * XATTR_SIZE_MAX in capacity and the contents may be modified and *@...e
+ * changed appropriately. Note that the caller is responsible for reading
+ * and writing the xattrs as this hook is merely a filter.
+ *
*
* Security hooks for file operations
*
@@ -1571,6 +1590,9 @@ struct security_operations {
int (*inode_setsecurity) (struct inode *inode, const char *name, const void *value, size_t size, int flags);
int (*inode_listsecurity) (struct inode *inode, char *buffer, size_t buffer_size);
void (*inode_getsecid) (const struct inode *inode, u32 *secid);
+ int (*inode_copy_up) (struct dentry *src, struct dentry *dst);
+ int (*inode_copy_up_xattr) (struct dentry *src, struct dentry *dst,
+ const char *name, void *value, size_t *size);
int (*file_permission) (struct file *file, int mask);
int (*file_alloc_security) (struct file *file);
@@ -1858,6 +1880,10 @@ int security_inode_getsecurity(const struct inode *inode, const char *name, void
int security_inode_setsecurity(struct inode *inode, const char *name, const void *value, size_t size, int flags);
int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
void security_inode_getsecid(const struct inode *inode, u32 *secid);
+int security_inode_copy_up(struct dentry *src, struct dentry *dst);
+int security_inode_copy_up_xattr(struct dentry *src, struct dentry *dst,
+ const char *name, void *value, size_t *size);
+
int security_file_permission(struct file *file, int mask);
int security_file_alloc(struct file *file);
void security_file_free(struct file *file);
@@ -2323,6 +2349,16 @@ static inline void security_inode_getsecid(const struct inode *inode, u32 *secid
*secid = 0;
}
+static inline int security_inode_copy_up(struct dentry *src, struct dentry *dst)
+{
+ return 0;
+}
+static inline int security_inode_copy_up_xattr(struct dentry *src, struct dentry *dst,
+ const char *name, const void *value, size_t *size)
+{
+ return 0;
+}
+
static inline int security_file_permission(struct file *file, int mask)
{
return 0;
diff --git a/security/capability.c b/security/capability.c
index 7d3f38fe02ba..c59f7c548c7a 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -268,6 +268,17 @@ static void cap_inode_getsecid(const struct inode *inode, u32 *secid)
*secid = 0;
}
+static int cap_inode_copy_up(struct dentry *src, struct dentry *dst)
+{
+ return 0;
+}
+
+static int cap_inode_copy_up_xattr(struct dentry *src, struct dentry *dst,
+ const char *name, void *value, size_t *size)
+{
+ return 0;
+}
+
#ifdef CONFIG_SECURITY_PATH
static int cap_path_mknod(struct path *dir, struct dentry *dentry, umode_t mode,
unsigned int dev)
@@ -1008,6 +1019,8 @@ void __init security_fixup_ops(struct security_operations *ops)
set_to_cap_if_null(ops, inode_setsecurity);
set_to_cap_if_null(ops, inode_listsecurity);
set_to_cap_if_null(ops, inode_getsecid);
+ set_to_cap_if_null(ops, inode_copy_up);
+ set_to_cap_if_null(ops, inode_copy_up_xattr);
#ifdef CONFIG_SECURITY_PATH
set_to_cap_if_null(ops, path_mknod);
set_to_cap_if_null(ops, path_mkdir);
diff --git a/security/security.c b/security/security.c
index 04c8feca081a..cb3563013ef5 100644
--- a/security/security.c
+++ b/security/security.c
@@ -707,6 +707,19 @@ void security_inode_getsecid(const struct inode *inode, u32 *secid)
security_ops->inode_getsecid(inode, secid);
}
+int security_inode_copy_up(struct dentry *src, struct dentry *dst)
+{
+ return security_ops->inode_copy_up(src, dst);
+}
+EXPORT_SYMBOL(security_inode_copy_up);
+
+int security_inode_copy_up_xattr(struct dentry *src, struct dentry *dst,
+ const char *name, void *value, size_t *size)
+{
+ return security_ops->inode_copy_up_xattr(src, dst, name, value, size);
+}
+EXPORT_SYMBOL(security_inode_copy_up_xattr);
+
int security_file_permission(struct file *file, int mask)
{
int ret;
--
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