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authorDaniel Colascione <dancol@google.com>2021-01-08 14:22:22 -0800
committerPaul Moore <paul@paul-moore.com>2021-01-14 17:38:10 -0500
commit29cd6591ab6fee3125ea5c1bf350f5013bc615e1 (patch)
treef21fb4dbfb14d257b7eb58a1707da549388b9449 /security
parente7e832ce6fa769f800cd7eaebdb0459ad31e0416 (diff)
selinux: teach SELinux about anonymous inodes
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@google.com> Signed-off-by: Lokesh Gidra <lokeshgidra@google.com> Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/hooks.c57
-rw-r--r--security/selinux/include/classmap.h2
2 files changed, 59 insertions, 0 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f2b272c9eaf3..af2994adf9dd 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2962,6 +2962,62 @@ 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);
+ if (context_isec->initialized != LABEL_INITIALIZED) {
+ pr_err("SELinux: context_inode is not initialized");
+ return -EACCES;
+ }
+
+ 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);
@@ -7032,6 +7088,7 @@ 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 }
};