From: Vivek Goyal <vgoyal@redhat.com>
To: miklos@szeredi.hu, sds@tycho.nsa.gov, pmoore@redhat.com,
casey@schaufler-ca.com, linux-kernel@vger.kernel.org,
linux-unionfs@vger.kernel.org,
linux-security-module@vger.kernel.org
Cc: dwalsh@redhat.com, dhowells@redhat.com, viro@ZenIV.linux.org.uk,
vgoyal@redhat.com, linux-fsdevel@vger.kernel.org
Subject: [PATCH 3/9] security,overlayfs: Provide security hook for copy up of xattrs for overlay file
Date: Wed, 13 Jul 2016 10:44:49 -0400 [thread overview]
Message-ID: <1468421095-22322-4-git-send-email-vgoyal@redhat.com> (raw)
In-Reply-To: <1468421095-22322-1-git-send-email-vgoyal@redhat.com>
Provide a security hook which is called when xattrs of a file are being
copied up. This hook is called once for each xattr and LSM can return
0 if the security module wants the xattr to be copied up, 1 if the
security module wants the xattr to be discarded on the copy, -EOPNOTSUPP
if the security module does not handle/manage the xattr, or a -errno
upon an error.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
fs/overlayfs/copy_up.c | 7 +++++++
include/linux/lsm_hooks.h | 10 ++++++++++
include/linux/security.h | 6 ++++++
security/security.c | 8 ++++++++
4 files changed, 31 insertions(+)
diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c
index 8ebea18..68cefb2 100644
--- a/fs/overlayfs/copy_up.c
+++ b/fs/overlayfs/copy_up.c
@@ -103,6 +103,13 @@ retry:
goto retry;
}
+ error = security_inode_copy_up_xattr(name);
+ if (error < 0 && error != -EOPNOTSUPP)
+ break;
+ if (error == 1) {
+ error = 0;
+ continue; /* Discard */
+ }
error = vfs_setxattr(new, name, value, size, 0);
if (error)
break;
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index c1f95be..84caead 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -410,6 +410,14 @@
* @src indicates the union dentry of file that is being copied up.
* @new pointer to pointer to return newly allocated creds.
* Returns 0 on success or a negative error code on error.
+ * @inode_copy_up_xattr:
+ * Filter the xattrs being copied up when a unioned file is copied
+ * up from a lower layer to the union/overlay layer.
+ * @name indicates the name of the xattr.
+ * Returns 0 to accept the xattr, 1 to discard the xattr, -EOPNOTSUPP if
+ * security module does not know about attribute or a negative error code
+ * to abort the copy up. Note that the caller is responsible for reading
+ * and writing the xattrs as this hook is merely a filter.
*
* Security hooks for file operations
*
@@ -1435,6 +1443,7 @@ union security_list_options {
size_t buffer_size);
void (*inode_getsecid)(struct inode *inode, u32 *secid);
int (*inode_copy_up) (struct dentry *src, struct cred **new);
+ int (*inode_copy_up_xattr) (const char *name);
int (*file_permission)(struct file *file, int mask);
int (*file_alloc_security)(struct file *file);
@@ -1707,6 +1716,7 @@ struct security_hook_heads {
struct list_head inode_listsecurity;
struct list_head inode_getsecid;
struct list_head inode_copy_up;
+ struct list_head inode_copy_up_xattr;
struct list_head file_permission;
struct list_head file_alloc_security;
struct list_head file_free_security;
diff --git a/include/linux/security.h b/include/linux/security.h
index c976d79..4a3b8bc 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -283,6 +283,7 @@ int security_inode_setsecurity(struct inode *inode, const char *name, const void
int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size);
void security_inode_getsecid(struct inode *inode, u32 *secid);
int security_inode_copy_up(struct dentry *src, struct cred **new);
+int security_inode_copy_up_xattr(const char *name);
int security_file_permission(struct file *file, int mask);
int security_file_alloc(struct file *file);
void security_file_free(struct file *file);
@@ -764,6 +765,11 @@ static inline int security_inode_copy_up(struct dentry *src, struct cred **new)
return 0;
}
+static inline int security_inode_copy_up_xattr(const char *name)
+{
+ return -EOPNOTSUPP;
+}
+
static inline int security_file_permission(struct file *file, int mask)
{
return 0;
diff --git a/security/security.c b/security/security.c
index 3d142aa..3321e31 100644
--- a/security/security.c
+++ b/security/security.c
@@ -733,6 +733,12 @@ int security_inode_copy_up(struct dentry *src, struct cred **new)
}
EXPORT_SYMBOL(security_inode_copy_up);
+int security_inode_copy_up_xattr(const char *name)
+{
+ return call_int_hook(inode_copy_up_xattr, -EOPNOTSUPP, name);
+}
+EXPORT_SYMBOL(security_inode_copy_up_xattr);
+
int security_file_permission(struct file *file, int mask)
{
int ret;
@@ -1671,6 +1677,8 @@ struct security_hook_heads security_hook_heads = {
LIST_HEAD_INIT(security_hook_heads.inode_getsecid),
.inode_copy_up =
LIST_HEAD_INIT(security_hook_heads.inode_copy_up),
+ .inode_copy_up_xattr =
+ LIST_HEAD_INIT(security_hook_heads.inode_copy_up_xattr),
.file_permission =
LIST_HEAD_INIT(security_hook_heads.file_permission),
.file_alloc_security =
--
2.7.4
next prev parent reply other threads:[~2016-07-13 14:46 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-13 14:44 [RFC PATCH 0/9][V3] Overlayfs SELinux Support Vivek Goyal
2016-07-13 14:44 ` [PATCH 1/9] security, overlayfs: provide copy up security hook for unioned files Vivek Goyal
2016-07-13 14:52 ` Stephen Smalley
2016-07-13 14:56 ` Vivek Goyal
2016-07-13 15:13 ` Vivek Goyal
2016-07-14 14:32 ` Stephen Smalley
2016-07-13 14:44 ` [PATCH 2/9] selinux: Implementation for inode_copy_up() hook Vivek Goyal
2016-07-13 14:53 ` Stephen Smalley
2016-07-13 14:44 ` Vivek Goyal [this message]
2016-07-14 14:20 ` [PATCH 3/9] security,overlayfs: Provide security hook for copy up of xattrs for overlay file Stephen Smalley
2016-07-13 14:44 ` [PATCH 4/9] selinux: Implementation for inode_copy_up_xattr() hook Vivek Goyal
2016-07-13 14:54 ` Stephen Smalley
2016-07-13 14:44 ` [PATCH 5/9] selinux: Pass security pointer to determine_inode_label() Vivek Goyal
2016-07-13 14:56 ` Stephen Smalley
2016-07-13 14:44 ` [PATCH 6/9] security, overlayfs: Provide hook to correctly label newly created files Vivek Goyal
2016-07-13 14:57 ` Stephen Smalley
2016-07-13 14:59 ` Stephen Smalley
2016-07-14 14:29 ` Stephen Smalley
2016-07-13 14:44 ` [PATCH 7/9] selinux: Implement dentry_create_files_as() hook Vivek Goyal
2016-07-13 14:59 ` Stephen Smalley
2016-07-13 14:44 ` [PATCH 8/9] overlayfs: Dilute permission checks on lower only if not special file Vivek Goyal
2016-07-14 6:51 ` Miklos Szeredi
2016-07-13 14:44 ` [PATCH 9/9] overlayfs: Append MAY_READ when diluting write checks Vivek Goyal
2016-07-14 6:49 ` Miklos Szeredi
2016-07-21 21:16 ` [RFC PATCH 0/9][V3] Overlayfs SELinux Support Paul Moore
2016-07-21 23:09 ` James Morris
2016-07-22 7:05 ` Miklos Szeredi
2016-07-22 15:33 ` Paul Moore
2016-08-08 12:46 ` Miklos Szeredi
2016-08-08 13:18 ` Paul Moore
2016-08-09 1:19 ` Paul Moore
2016-08-10 9:11 ` Miklos Szeredi
2016-08-10 12:32 ` Paul Moore
2016-08-10 12:52 ` Daniel J Walsh
2016-08-11 12:36 ` Paul Moore
2016-08-11 12:39 ` Daniel J Walsh
2016-08-11 14:06 ` Daniel J Walsh
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