From: Daniel Colascione <dancol@google.com>
To: dancol@google.com, timmurray@google.com, nosh@google.com,
nnk@google.com, lokeshgidra@google.com,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
selinux@vger.kernel.org
Subject: [PATCH v2 2/6] Add a concept of a "secure" anonymous file
Date: Tue, 11 Feb 2020 14:55:43 -0800 [thread overview]
Message-ID: <20200211225547.235083-3-dancol@google.com> (raw)
In-Reply-To: <20200211225547.235083-1-dancol@google.com>
A secure anonymous file is one we hooked up to its own inode (as
opposed to the shared inode we use for non-secure anonymous files). A
new selinux hook gives security modules a chance to initialize, label,
and veto the creation of these secure anonymous files. Security
modules had limit ability to interact with non-secure anonymous files
due to all of these files sharing a single inode.
Signed-off-by: Daniel Colascione <dancol@google.com>
---
fs/anon_inodes.c | 45 ++++++++++++++++++++++++++++++---------
include/linux/lsm_hooks.h | 8 +++++++
include/linux/security.h | 2 ++
security/security.c | 8 +++++++
4 files changed, 53 insertions(+), 10 deletions(-)
diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c
index caa36019afca..d68d76523ad3 100644
--- a/fs/anon_inodes.c
+++ b/fs/anon_inodes.c
@@ -55,6 +55,23 @@ static struct file_system_type anon_inode_fs_type = {
.kill_sb = kill_anon_super,
};
+struct inode *anon_inode_make_secure_inode(const char *name,
+ const struct file_operations *fops)
+{
+ struct inode *inode;
+ int error;
+ inode = alloc_anon_inode(anon_inode_mnt->mnt_sb);
+ if (IS_ERR(inode))
+ return ERR_PTR(PTR_ERR(inode));
+ inode->i_flags &= ~S_PRIVATE;
+ error = security_inode_init_security_anon(inode, name, fops);
+ if (error) {
+ iput(inode);
+ return ERR_PTR(error);
+ }
+ return inode;
+}
+
/**
* anon_inode_getfile2 - creates a new file instance by hooking it up to
* an anonymous inode, and a dentry that describe
@@ -72,7 +89,9 @@ static struct file_system_type anon_inode_fs_type = {
* hence saving memory and avoiding code duplication for the file/inode/dentry
* setup. Returns the newly created file* or an error pointer.
*
- * anon_inode_flags must be zero.
+ * If anon_inode_flags contains ANON_INODE_SECURE, create a new inode
+ * and enable security checks for it. Otherwise, attach a new file to
+ * a singleton placeholder inode with security checks disabled.
*/
struct file *anon_inode_getfile2(const char *name,
const struct file_operations *fops,
@@ -81,17 +100,23 @@ struct file *anon_inode_getfile2(const char *name,
struct inode *inode;
struct file *file;
- if (anon_inode_flags)
+ if (anon_inode_flags & ~ANON_INODE_SECURE)
return ERR_PTR(-EINVAL);
- inode = anon_inode_inode;
- if (IS_ERR(inode))
- return ERR_PTR(-ENODEV);
- /*
- * We know the anon_inode inode count is always
- * greater than zero, so ihold() is safe.
- */
- ihold(inode);
+ if (anon_inode_flags & ANON_INODE_SECURE) {
+ inode = anon_inode_make_secure_inode(name, fops);
+ if (IS_ERR(inode))
+ return ERR_PTR(PTR_ERR(inode));
+ } else {
+ inode = anon_inode_inode;
+ if (IS_ERR(inode))
+ return ERR_PTR(-ENODEV);
+ /*
+ * We know the anon_inode inode count is always
+ * greater than zero, so ihold() is safe.
+ */
+ ihold(inode);
+ }
if (fops->owner && !try_module_get(fops->owner)) {
file = ERR_PTR(-ENOENT);
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 20d8cf194fb7..ba208ce5711d 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -215,6 +215,10 @@
* Returns 0 if @name and @value have been successfully set,
* -EOPNOTSUPP if no security attribute is needed, or
* -ENOMEM on memory allocation failure.
+ * @inode_init_security_anon:
+ * Set up a secure anonymous inode.
+ * Returns 0 on success. Returns -EPERM if the security module denies
+ * the creation of this inode.
* @inode_create:
* Check permission to create a regular file.
* @dir contains inode structure of the parent of the new file.
@@ -1552,6 +1556,9 @@ union security_list_options {
const struct qstr *qstr,
const char **name, void **value,
size_t *len);
+ int (*inode_init_security_anon)(struct inode *inode,
+ const char *name,
+ const struct file_operations *fops);
int (*inode_create)(struct inode *dir, struct dentry *dentry,
umode_t mode);
int (*inode_link)(struct dentry *old_dentry, struct inode *dir,
@@ -1884,6 +1891,7 @@ struct security_hook_heads {
struct hlist_head inode_alloc_security;
struct hlist_head inode_free_security;
struct hlist_head inode_init_security;
+ struct hlist_head inode_init_security_anon;
struct hlist_head inode_create;
struct hlist_head inode_link;
struct hlist_head inode_unlink;
diff --git a/include/linux/security.h b/include/linux/security.h
index 64b19f050343..8625b647dd0b 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -320,6 +320,8 @@ void security_inode_free(struct inode *inode);
int security_inode_init_security(struct inode *inode, struct inode *dir,
const struct qstr *qstr,
initxattrs initxattrs, void *fs_data);
+int security_inode_init_security_anon(struct inode *inode, const char *name,
+ const struct file_operations *fops);
int security_old_inode_init_security(struct inode *inode, struct inode *dir,
const struct qstr *qstr, const char **name,
void **value, size_t *len);
diff --git a/security/security.c b/security/security.c
index 565bc9b67276..78dc6096b30f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1033,6 +1033,14 @@ int security_inode_init_security(struct inode *inode, struct inode *dir,
}
EXPORT_SYMBOL(security_inode_init_security);
+int
+security_inode_init_security_anon(struct inode *inode,
+ const char *name,
+ const struct file_operations *fops)
+{
+ return call_int_hook(inode_init_security_anon, 0, inode, name, fops);
+}
+
int security_old_inode_init_security(struct inode *inode, struct inode *dir,
const struct qstr *qstr, const char **name,
void **value, size_t *len)
--
2.25.0.225.g125e21ebc7-goog
next prev parent reply other threads:[~2020-02-11 22:56 UTC|newest]
Thread overview: 80+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 22:55 [PATCH v2 0/6] Harden userfaultfd Daniel Colascione
2020-02-11 22:55 ` [PATCH v2 1/6] Add a new flags-accepting interface for anonymous inodes Daniel Colascione
2020-02-12 16:37 ` Stephen Smalley
2020-02-12 17:23 ` Daniel Colascione
2020-02-11 22:55 ` Daniel Colascione [this message]
2020-02-12 16:49 ` [PATCH v2 2/6] Add a concept of a "secure" anonymous file Stephen Smalley
2020-02-14 22:13 ` kbuild test robot
2020-02-11 22:55 ` [PATCH v2 3/6] Teach SELinux about a new userfaultfd class Daniel Colascione
2020-02-12 17:05 ` Stephen Smalley
2020-02-12 17:19 ` Daniel Colascione
2020-02-12 18:04 ` Stephen Smalley
2020-02-12 18:59 ` Stephen Smalley
2020-02-12 19:04 ` Daniel Colascione
2020-02-12 19:11 ` Stephen Smalley
2020-02-12 19:13 ` Daniel Colascione
2020-02-12 19:17 ` Stephen Smalley
2020-02-11 22:55 ` [PATCH v2 4/6] Wire UFFD up to SELinux Daniel Colascione
2020-02-11 22:55 ` [PATCH v2 5/6] Let userfaultfd opt out of handling kernel-mode faults Daniel Colascione
2020-02-11 22:55 ` [PATCH v2 6/6] Add a new sysctl for limiting userfaultfd to user mode faults Daniel Colascione
2020-02-11 23:13 ` [PATCH v2 0/6] Harden userfaultfd Casey Schaufler
2020-02-11 23:27 ` Daniel Colascione
2020-02-12 16:09 ` Stephen Smalley
2020-02-21 17:56 ` James Morris
2020-02-12 7:50 ` Kees Cook
2020-02-12 16:54 ` Jann Horn
2020-02-12 17:14 ` Peter Xu
2020-02-12 19:41 ` Andrea Arcangeli
2020-02-12 20:04 ` Daniel Colascione
2020-02-12 23:41 ` Andrea Arcangeli
2020-02-12 17:12 ` Daniel Colascione
2020-02-14 3:26 ` [PATCH 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-02-14 3:26 ` [PATCH 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione
2020-02-14 3:26 ` [PATCH 2/3] Teach SELinux about anonymous inodes Daniel Colascione
2020-02-14 16:39 ` Stephen Smalley
2020-02-14 17:21 ` Daniel Colascione
2020-02-14 18:02 ` Stephen Smalley
2020-02-14 18:08 ` Stephen Smalley
2020-02-14 20:24 ` Stephen Smalley
2020-02-14 3:26 ` [PATCH 3/3] Wire UFFD up to SELinux Daniel Colascione
2020-03-25 23:02 ` [PATCH v2 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-03-25 23:02 ` [PATCH v2 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione
2020-03-26 13:53 ` Stephen Smalley
2020-03-25 23:02 ` [PATCH v2 2/3] Teach SELinux about anonymous inodes Daniel Colascione
2020-03-26 13:58 ` Stephen Smalley
2020-03-26 17:59 ` Daniel Colascione
2020-03-26 17:37 ` Stephen Smalley
2020-03-25 23:02 ` [PATCH v2 3/3] Wire UFFD up to SELinux Daniel Colascione
2020-03-25 23:49 ` Casey Schaufler
2020-03-26 18:14 ` [PATCH v3 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-03-26 18:14 ` [PATCH v3 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione
2020-03-26 19:00 ` Stephen Smalley
2020-03-26 18:14 ` [PATCH v3 2/3] Teach SELinux about anonymous inodes Daniel Colascione
2020-03-26 19:02 ` Stephen Smalley
2020-03-26 18:14 ` [PATCH v3 3/3] Wire UFFD up to SELinux Daniel Colascione
2020-03-26 20:06 ` [PATCH v4 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-03-26 20:06 ` [PATCH v4 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione
2020-03-27 13:40 ` Stephen Smalley
2020-03-26 20:06 ` [PATCH v4 2/3] Teach SELinux about anonymous inodes Daniel Colascione
2020-03-27 13:41 ` Stephen Smalley
2020-03-26 20:06 ` [PATCH v4 3/3] Wire UFFD up to SELinux Daniel Colascione
2020-04-01 21:39 ` [PATCH v5 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-04-01 21:39 ` [PATCH v5 1/3] Add a new LSM-supporting anonymous inode interface Daniel Colascione
2020-05-07 16:02 ` James Morris
2020-08-04 21:22 ` Eric Biggers
2020-04-01 21:39 ` [PATCH v5 2/3] Teach SELinux about anonymous inodes Daniel Colascione
2020-04-01 21:39 ` [PATCH v5 3/3] Wire UFFD up to SELinux Daniel Colascione
2020-08-04 21:16 ` Eric Biggers
2020-04-13 13:29 ` [PATCH v5 0/3] SELinux support for anonymous inodes and UFFD Daniel Colascione
2020-04-22 16:55 ` James Morris
2020-04-22 17:12 ` Casey Schaufler
2020-04-23 22:24 ` Casey Schaufler
2020-04-27 16:18 ` Casey Schaufler
2020-04-27 16:48 ` Stephen Smalley
2020-04-27 17:12 ` Casey Schaufler
2020-04-29 17:02 ` Stephen Smalley
2020-04-27 17:15 ` Casey Schaufler
2020-04-27 19:40 ` Stephen Smalley
2020-06-04 3:56 ` James Morris
2020-06-04 18:51 ` Stephen Smalley
2020-06-04 19:24 ` Lokesh Gidra
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