[PATCH 5.19 160/192] selinux: implement the security_uring_cmd() LSM hook

Greg Kroah-Hartman
2022-09-13T14:25:49Z

From: Paul Moore <paul@paul-moore.com>

commit f4d653dcaa4e4056e1630423e6a8ece4869b544f upstream.

Add a SELinux access control for the iouring IORING_OP_URING_CMD
command. This includes the addition of a new permission in the
existing "io_uring" object class: "cmd". The subject of the new
permission check is the domain of the process requesting access, the
object is the open file which points to the device/file that is the
target of the IORING_OP_URING_CMD operation. A sample policy rule
is shown below:

allow <domain> <file>:io_uring { cmd };

Cc: stable@vger.kernel.org
Fixes: ee692a21e9bf ("fs,io_uring: add infrastructure for uring-cmd")
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/selinux/hooks.c | 24 ++++++++++++++++++++++++
security/selinux/include/classmap.h | 2 +-
2 files changed, 25 insertions(+), 1 deletion(-)

--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -91,6 +91,7 @@
#include <uapi/linux/mount.h>
#include <linux/fsnotify.h>
#include <linux/fanotify.h>
+#include <linux/io_uring.h>

#include "avc.h"
#include "objsec.h"
@@ -6990,6 +6991,28 @@ static int selinux_uring_sqpoll(void)
return avc_has_perm(&selinux_state, sid, sid,
SECCLASS_IO_URING, IO_URING__SQPOLL, NULL);
}
+
+/**
+ * selinux_uring_cmd - check if IORING_OP_URING_CMD is allowed
+ * @ioucmd: the io_uring command structure
+ *
+ * Check to see if the current domain is allowed to execute an
+ * IORING_OP_URING_CMD against the device/file specified in @ioucmd.
+ *
+ */
+static int selinux_uring_cmd(struct io_uring_cmd *ioucmd)
+{
+ struct file *file = ioucmd->file;
+ struct inode *inode = file_inode(file);
+ struct inode_security_struct *isec = selinux_inode(inode);
+ struct common_audit_data ad;
+
+ ad.type = LSM_AUDIT_DATA_FILE;
+ ad.u.file = file;
+
+ return avc_has_perm(&selinux_state, current_sid(), isec->sid,
+ SECCLASS_IO_URING, IO_URING__CMD, &ad);
+}
#endif /* CONFIG_IO_URING */

/*
@@ -7234,6 +7257,7 @@ static struct security_hook_list selinux
#ifdef CONFIG_IO_URING
LSM_HOOK_INIT(uring_override_creds, selinux_uring_override_creds),
LSM_HOOK_INIT(uring_sqpoll, selinux_uring_sqpoll),
+ LSM_HOOK_INIT(uring_cmd, selinux_uring_cmd),
#endif

/*
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -253,7 +253,7 @@ const struct security_class_mapping secc
{ "anon_inode",
{ COMMON_FILE_PERMS, NULL } },
{ "io_uring",
- { "override_creds", "sqpoll", NULL } },
+ { "override_creds", "sqpoll", "cmd", NULL } },
{ NULL }
};