Merge tag 'lsm-pr-20220829' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

Pull LSM support for IORING_OP_URING_CMD from Paul Moore:
 "Add SELinux and Smack controls to the io_uring IORING_OP_URING_CMD.

  These are necessary as without them the IORING_OP_URING_CMD remains
  outside the purview of the LSMs (Luis' LSM patch, Casey's Smack patch,
  and my SELinux patch). They have been discussed at length with the
  io_uring folks, and Jens has given his thumbs-up on the relevant
  patches (see the commit descriptions).

  There is one patch that is not strictly necessary, but it makes
  testing much easier and is very trivial: the /dev/null
  IORING_OP_URING_CMD patch."

* tag 'lsm-pr-20220829' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  Smack: Provide read control for io_uring_cmd
  /dev/null: add IORING_OP_URING_CMD support
  selinux: implement the security_uring_cmd() LSM hook
  lsm,io_uring: add LSM hooks for the new uring_cmd file op

4 files changed, 61 insertions, 1 deletions

diff --git a/security/security.c b/security/security.c
index 14d30fec8a00..4b95de24bc8d 100644
--- a/security/security.c
+++ b/security/security.c
@@ -2660,4 +2660,8 @@ int security_uring_sqpoll(void)
 {
 	return call_int_hook(uring_sqpoll, 0);
 }
+int security_uring_cmd(struct io_uring_cmd *ioucmd)
+{
+	return call_int_hook(uring_cmd, 0, ioucmd);
+}
 #endif /* CONFIG_IO_URING */
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 79573504783b..03bca97c8b29 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 ff757ae5f253..1c2f41ff4e55 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 }
   };
 
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 001831458fa2..bffccdc494cb 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -42,6 +42,7 @@
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
 #include <linux/watch_queue.h>
+#include <linux/io_uring.h>
 #include "smack.h"
 
 #define TRANS_TRUE	"TRUE"
@@ -4732,6 +4733,36 @@ static int smack_uring_sqpoll(void)
 	return -EPERM;
 }
 
+/**
+ * smack_uring_cmd - check on file operations for io_uring
+ * @ioucmd: the command in question
+ *
+ * Make a best guess about whether a io_uring "command" should
+ * be allowed. Use the same logic used for determining if the
+ * file could be opened for read in the absence of better criteria.
+ */
+static int smack_uring_cmd(struct io_uring_cmd *ioucmd)
+{
+	struct file *file = ioucmd->file;
+	struct smk_audit_info ad;
+	struct task_smack *tsp;
+	struct inode *inode;
+	int rc;
+
+	if (!file)
+		return -EINVAL;
+
+	tsp = smack_cred(file->f_cred);
+	inode = file_inode(file);
+
+	smk_ad_init(&ad, __func__, LSM_AUDIT_DATA_PATH);
+	smk_ad_setfield_u_fs_path(&ad, file->f_path);
+	rc = smk_tskacc(tsp, smk_of_inode(inode), MAY_READ, &ad);
+	rc = smk_bu_credfile(file->f_cred, file, MAY_READ, rc);
+
+	return rc;
+}
+
 #endif /* CONFIG_IO_URING */
 
 struct lsm_blob_sizes smack_blob_sizes __lsm_ro_after_init = {
@@ -4889,6 +4920,7 @@ static struct security_hook_list smack_hooks[] __lsm_ro_after_init = {
 #ifdef CONFIG_IO_URING
 	LSM_HOOK_INIT(uring_override_creds, smack_uring_override_creds),
 	LSM_HOOK_INIT(uring_sqpoll, smack_uring_sqpoll),
+	LSM_HOOK_INIT(uring_cmd, smack_uring_cmd),
 #endif
 };