Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull integrity updates from James Morris:
 "In Linux 4.19, a new LSM hook named security_kernel_load_data was
  upstreamed, allowing LSMs and IMA to prevent the kexec_load syscall.
  Different signature verification methods exist for verifying the
  kexec'ed kernel image. This adds additional support in IMA to prevent
  loading unsigned kernel images via the kexec_load syscall,
  independently of the IMA policy rules, based on the runtime "secure
  boot" flag. An initial IMA kselftest is included.

  In addition, this pull request defines a new, separate keyring named
  ".platform" for storing the preboot/firmware keys needed for verifying
  the kexec'ed kernel image's signature and includes the associated IMA
  kexec usage of the ".platform" keyring.

  (David Howell's and Josh Boyer's patches for reading the
  preboot/firmware keys, which were previously posted for a different
  use case scenario, are included here)"

* 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  integrity: Remove references to module keyring
  ima: Use inode_is_open_for_write
  ima: Support platform keyring for kernel appraisal
  efi: Allow the "db" UEFI variable to be suppressed
  efi: Import certificates from UEFI Secure Boot
  efi: Add an EFI signature blob parser
  efi: Add EFI signature data types
  integrity: Load certs to the platform keyring
  integrity: Define a trusted platform keyring
  selftests/ima: kexec_load syscall test
  ima: don't measure/appraise files on efivarfs
  x86/ima: retry detecting secure boot mode
  docs: Extend trusted keys documentation for TPM 2.0
  x86/ima: define arch_get_ima_policy() for x86
  ima: add support for arch specific policies
  ima: refactor ima_init_policy()
  ima: prevent kexec_load syscall based on runtime secureboot flag
  x86/ima: define arch_ima_get_secureboot
  integrity: support new struct public_key_signature encoding field

1 files changed, 14 insertions, 7 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 616a88f95b92..4ffac4f5c647 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -105,7 +105,7 @@ static void ima_rdwr_violation_check(struct file *file,
 	} else {
 		if (must_measure)
 			set_bit(IMA_MUST_MEASURE, &iint->atomic_flags);
-		if ((atomic_read(&inode->i_writecount) > 0) && must_measure)
+		if (inode_is_open_for_write(inode) && must_measure)
 			send_writers = true;
 	}
 
@@ -507,20 +507,26 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
  */
 int ima_load_data(enum kernel_load_data_id id)
 {
-	bool sig_enforce;
+	bool ima_enforce, sig_enforce;
 
-	if ((ima_appraise & IMA_APPRAISE_ENFORCE) != IMA_APPRAISE_ENFORCE)
-		return 0;
+	ima_enforce =
+		(ima_appraise & IMA_APPRAISE_ENFORCE) == IMA_APPRAISE_ENFORCE;
 
 	switch (id) {
 	case LOADING_KEXEC_IMAGE:
-		if (ima_appraise & IMA_APPRAISE_KEXEC) {
+		if (IS_ENABLED(CONFIG_KEXEC_VERIFY_SIG)
+		    && arch_ima_get_secureboot()) {
+			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
+			return -EACCES;
+		}
+
+		if (ima_enforce && (ima_appraise & IMA_APPRAISE_KEXEC)) {
 			pr_err("impossible to appraise a kernel image without a file descriptor; try using kexec_file_load syscall.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
 		break;
 	case LOADING_FIRMWARE:
-		if (ima_appraise & IMA_APPRAISE_FIRMWARE) {
+		if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) {
 			pr_err("Prevent firmware sysfs fallback loading.\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}
@@ -528,7 +534,8 @@ int ima_load_data(enum kernel_load_data_id id)
 	case LOADING_MODULE:
 		sig_enforce = is_module_sig_enforced();
 
-		if (!sig_enforce && (ima_appraise & IMA_APPRAISE_MODULES)) {
+		if (ima_enforce && (!sig_enforce
+				    && (ima_appraise & IMA_APPRAISE_MODULES))) {
 			pr_err("impossible to appraise a module without a file descriptor. sig_enforce kernel parameter might help\n");
 			return -EACCES;	/* INTEGRITY_UNKNOWN */
 		}