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Message-Id: <20201106155626.3395468-4-lokeshgidra@google.com>
Date: Fri, 6 Nov 2020 07:56:25 -0800
From: Lokesh Gidra <lokeshgidra@...gle.com>
To: Andrea Arcangeli <aarcange@...hat.com>,
Alexander Viro <viro@...iv.linux.org.uk>,
James Morris <jmorris@...ei.org>,
Stephen Smalley <stephen.smalley.work@...il.com>,
Casey Schaufler <casey@...aufler-ca.com>,
Eric Biggers <ebiggers@...nel.org>
Cc: "Serge E. Hallyn" <serge@...lyn.com>,
Paul Moore <paul@...l-moore.com>,
Eric Paris <eparis@...isplace.org>,
Lokesh Gidra <lokeshgidra@...gle.com>,
Daniel Colascione <dancol@...col.org>,
Kees Cook <keescook@...omium.org>,
"Eric W. Biederman" <ebiederm@...ssion.com>,
KP Singh <kpsingh@...gle.com>,
David Howells <dhowells@...hat.com>,
Thomas Cedeno <thomascedeno@...gle.com>,
Anders Roxell <anders.roxell@...aro.org>,
Sami Tolvanen <samitolvanen@...gle.com>,
Matthew Garrett <matthewgarrett@...gle.com>,
Aaron Goidel <acgoide@...ho.nsa.gov>,
Randy Dunlap <rdunlap@...radead.org>,
"Joel Fernandes (Google)" <joel@...lfernandes.org>,
YueHaibing <yuehaibing@...wei.com>,
Christian Brauner <christian.brauner@...ntu.com>,
Alexei Starovoitov <ast@...nel.org>,
Alexey Budankov <alexey.budankov@...ux.intel.com>,
Adrian Reber <areber@...hat.com>,
Aleksa Sarai <cyphar@...har.com>,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...r.kernel.org,
kaleshsingh@...gle.com, calin@...gle.com, surenb@...gle.com,
nnk@...gle.com, jeffv@...gle.com, kernel-team@...roid.com,
linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
hch@...radead.org, Daniel Colascione <dancol@...gle.com>
Subject: [PATCH v12 3/4] selinux: teach SELinux about anonymous inodes
From: Daniel Colascione <dancol@...gle.com>
This change uses the anon_inodes and LSM infrastructure introduced in
the previous patches to give SELinux the ability to control
anonymous-inode files that are created using the new
anon_inode_getfd_secure() function.
A SELinux policy author detects and controls these anonymous inodes by
adding a name-based type_transition rule that assigns a new security
type to anonymous-inode files created in some domain. The name used
for the name-based transition is the name associated with the
anonymous inode for file listings --- e.g., "[userfaultfd]" or
"[perf_event]".
Example:
type uffd_t;
type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]";
allow sysadm_t uffd_t:anon_inode { create };
(The next patch in this series is necessary for making userfaultfd
support this new interface. The example above is just
for exposition.)
Signed-off-by: Daniel Colascione <dancol@...gle.com>
Signed-off-by: Lokesh Gidra <lokeshgidra@...gle.com>
---
security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++
security/selinux/include/classmap.h | 2 ++
2 files changed, 55 insertions(+)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6b1826fc3658..1c0adcdce7a8 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2927,6 +2927,58 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir,
return 0;
}
+static int selinux_inode_init_security_anon(struct inode *inode,
+ const struct qstr *name,
+ const struct inode *context_inode)
+{
+ const struct task_security_struct *tsec = selinux_cred(current_cred());
+ struct common_audit_data ad;
+ struct inode_security_struct *isec;
+ int rc;
+
+ if (unlikely(!selinux_initialized(&selinux_state)))
+ return 0;
+
+ isec = selinux_inode(inode);
+
+ /*
+ * We only get here once per ephemeral inode. The inode has
+ * been initialized via inode_alloc_security but is otherwise
+ * untouched.
+ */
+
+ if (context_inode) {
+ struct inode_security_struct *context_isec =
+ selinux_inode(context_inode);
+ isec->sclass = context_isec->sclass;
+ isec->sid = context_isec->sid;
+ } else {
+ isec->sclass = SECCLASS_ANON_INODE;
+ rc = security_transition_sid(
+ &selinux_state, tsec->sid, tsec->sid,
+ isec->sclass, name, &isec->sid);
+ if (rc)
+ return rc;
+ }
+
+ isec->initialized = LABEL_INITIALIZED;
+
+ /*
+ * Now that we've initialized security, check whether we're
+ * allowed to actually create this type of anonymous inode.
+ */
+
+ ad.type = LSM_AUDIT_DATA_INODE;
+ ad.u.inode = inode;
+
+ return avc_has_perm(&selinux_state,
+ tsec->sid,
+ isec->sid,
+ isec->sclass,
+ FILE__CREATE,
+ &ad);
+}
+
static int selinux_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode)
{
return may_create(dir, dentry, SECCLASS_FILE);
@@ -6992,6 +7044,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(inode_free_security, selinux_inode_free_security),
LSM_HOOK_INIT(inode_init_security, selinux_inode_init_security),
+ LSM_HOOK_INIT(inode_init_security_anon, selinux_inode_init_security_anon),
LSM_HOOK_INIT(inode_create, selinux_inode_create),
LSM_HOOK_INIT(inode_link, selinux_inode_link),
LSM_HOOK_INIT(inode_unlink, selinux_inode_unlink),
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index 40cebde62856..ba2e01a6955c 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -249,6 +249,8 @@ struct security_class_mapping secclass_map[] = {
{"open", "cpu", "kernel", "tracepoint", "read", "write"} },
{ "lockdown",
{ "integrity", "confidentiality", NULL } },
+ { "anon_inode",
+ { COMMON_FILE_PERMS, NULL } },
{ NULL }
};
--
2.29.1.341.ge80a0c044ae-goog
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