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List:       git-commits-head
Subject:    selinux: implement the security_uring_cmd() LSM hook
From:       Linux Kernel Mailing List <linux-kernel () vger ! kernel ! org>
Date:       2022-08-31 17:20:08
Message-ID: git-mailbomb-linux-master-f4d653dcaa4e4056e1630423e6a8ece4869b544f () kernel ! org
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Commit:     f4d653dcaa4e4056e1630423e6a8ece4869b544f
Parent:     2a5840124009f133bd09fd855963551fb2cefe22
Refname:    refs/heads/master
Web:        https://git.kernel.org/torvalds/c/f4d653dcaa4e4056e1630423e6a8ece4869b544f
Author:     Paul Moore <paul@paul-moore.com>
AuthorDate: Wed Aug 10 15:55:36 2022 -0400
Committer:  Paul Moore <paul@paul-moore.com>
CommitDate: Fri Aug 26 11:19:43 2022 -0400

    selinux: implement the security_uring_cmd() LSM hook
    
    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>
---
 security/selinux/hooks.c            | 24 ++++++++++++++++++++++++
 security/selinux/include/classmap.h |  2 +-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 79573504783bb..03bca97c8b297 100644
--- 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"
@@ -6987,6 +6988,28 @@ 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 */
 
 /*
@@ -7231,6 +7254,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
 #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
 
 	/*
diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
index ff757ae5f2537..1c2f41ff4e551 100644
--- a/security/selinux/include/classmap.h
+++ b/security/selinux/include/classmap.h
@@ -253,7 +253,7 @@ const struct security_class_mapping secclass_map[] = {
 	{ "anon_inode",
 	  { COMMON_FILE_PERMS, NULL } },
 	{ "io_uring",
-	  { "override_creds", "sqpoll", NULL } },
+	  { "override_creds", "sqpoll", "cmd", NULL } },
 	{ NULL }
   };
 
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