From: Luis Chamberlain <mcgrof@kernel.org>
Date: Fri, 15 Jul 2022 19:16:22 +0000 (-0700)
Subject: lsm,io_uring: add LSM hooks for the new uring_cmd file op
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=2a5840124009f133bd09fd855963551fb2cefe22;p=linux.git

lsm,io_uring: add LSM hooks for the new uring_cmd file op

io-uring cmd support was added through ee692a21e9bf ("fs,io_uring:
add infrastructure for uring-cmd"), this extended the struct
file_operations to allow a new command which each subsystem can use
to enable command passthrough. Add an LSM specific for the command
passthrough which enables LSMs to inspect the command details.

This was discussed long ago without no clear pointer for something
conclusive, so this enables LSMs to at least reject this new file
operation.

[0] https://lkml.kernel.org/r/8adf55db-7bab-f59d-d612-ed906b948d19@schaufler-ca.com

Cc: stable@vger.kernel.org
Fixes: ee692a21e9bf ("fs,io_uring: add infrastructure for uring-cmd")
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Paul Moore <paul@paul-moore.com>
---

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 8064481730333..60fff133c0b17 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -407,4 +407,5 @@ LSM_HOOK(int, 0, perf_event_write, struct perf_event *event)
 #ifdef CONFIG_IO_URING
 LSM_HOOK(int, 0, uring_override_creds, const struct cred *new)
 LSM_HOOK(int, 0, uring_sqpoll, void)
+LSM_HOOK(int, 0, uring_cmd, struct io_uring_cmd *ioucmd)
 #endif /* CONFIG_IO_URING */
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 84a0d7e021769..3aa6030302f5b 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -1582,6 +1582,9 @@
  *      Check whether the current task is allowed to spawn a io_uring polling
  *      thread (IORING_SETUP_SQPOLL).
  *
+ * @uring_cmd:
+ *      Check whether the file_operations uring_cmd is allowed to run.
+ *
  */
 union security_list_options {
 	#define LSM_HOOK(RET, DEFAULT, NAME, ...) RET (*NAME)(__VA_ARGS__);
diff --git a/include/linux/security.h b/include/linux/security.h
index 1bc362cb413f2..7bd0c490703d3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -2060,6 +2060,7 @@ static inline int security_perf_event_write(struct perf_event *event)
 #ifdef CONFIG_SECURITY
 extern int security_uring_override_creds(const struct cred *new);
 extern int security_uring_sqpoll(void);
+extern int security_uring_cmd(struct io_uring_cmd *ioucmd);
 #else
 static inline int security_uring_override_creds(const struct cred *new)
 {
@@ -2069,6 +2070,10 @@ static inline int security_uring_sqpoll(void)
 {
 	return 0;
 }
+static inline int security_uring_cmd(struct io_uring_cmd *ioucmd)
+{
+	return 0;
+}
 #endif /* CONFIG_SECURITY */
 #endif /* CONFIG_IO_URING */
 
diff --git a/io_uring/uring_cmd.c b/io_uring/uring_cmd.c
index 8e0cc2d9205ea..0f7ad956ddcbb 100644
--- a/io_uring/uring_cmd.c
+++ b/io_uring/uring_cmd.c
@@ -3,6 +3,7 @@
 #include <linux/errno.h>
 #include <linux/file.h>
 #include <linux/io_uring.h>
+#include <linux/security.h>
 
 #include <uapi/linux/io_uring.h>
 
@@ -88,6 +89,10 @@ int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags)
 	if (!req->file->f_op->uring_cmd)
 		return -EOPNOTSUPP;
 
+	ret = security_uring_cmd(ioucmd);
+	if (ret)
+		return ret;
+
 	if (ctx->flags & IORING_SETUP_SQE128)
 		issue_flags |= IO_URING_F_SQE128;
 	if (ctx->flags & IORING_SETUP_CQE32)
diff --git a/security/security.c b/security/security.c
index 14d30fec8a003..4b95de24bc8dc 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 */