Add an LSM hook prior to allowing firmware sysfs fallback loading.
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx>
Cc: David Howells <dhowells@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxx>
---
drivers/base/firmware_loader/fallback.c | 7 +++++++
include/linux/fs.h | 1 +
2 files changed, 8 insertions(+)
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c
index 31b5015b59fe..23d2af30474e 100644
--- a/drivers/base/firmware_loader/fallback.c
+++ b/drivers/base/firmware_loader/fallback.c
@@ -651,6 +651,8 @@ static bool fw_force_sysfs_fallback(unsigned int opt_flags)
static bool fw_run_sysfs_fallback(unsigned int opt_flags)
{
+ int ret;
+
if (fw_fallback_config.ignore_sysfs_fallback) {
pr_info_once("Ignoring firmware sysfs fallback due to sysctl knob\n");
return false;
@@ -659,6 +661,11 @@ static bool fw_run_sysfs_fallback(unsigned int opt_flags)
if ((opt_flags & FW_OPT_NOFALLBACK))
return false;
+ /* Also permit LSMs and IMA to fail firmware sysfs fallback */
+ ret = security_kernel_read_file(NULL, READING_FIRMWARE_FALLBACK);
+ if (ret < 0)
+ return ret;
+
return fw_force_sysfs_fallback(opt_flags);
}
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 760d8da1b6c7..dc16a73c3d38 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2810,6 +2810,7 @@ extern int do_pipe_flags(int *, int);
id(UNKNOWN, unknown) \
id(FIRMWARE, firmware) \
id(FIRMWARE_PREALLOC_BUFFER, firmware) \
+ id(FIRMWARE_FALLBACK, firmware) \
id(MODULE, kernel-module) \
id(KEXEC_IMAGE, kexec-image) \
id(KEXEC_INITRAMFS, kexec-initramfs) \
--
2.7.5
