| Message ID | 20200729175845.1745471-11-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce partial kernel_read_file() support | expand |
On Wed, 2020-07-29 at 10:58 -0700, Kees Cook wrote: > Now that security_post_load_data() is wired up, use it instead > of the NULL file argument style of security_post_read_file(), > and update the security_kernel_load_data() call to indicate that a > security_kernel_post_load_data() call is expected. > > Wire up the IMA check to match earlier logic. Perhaps a generalized > change to ima_post_load_data() might look something like this: > > return process_buffer_measurement(buf, size, > kernel_load_data_id_str(load_id), > read_idmap[load_id] ?: FILE_CHECK, > 0, NULL); > > Signed-off-by: Kees Cook <keescook@chromium.org> Other than one change and one question below, it looks good. Reviewed-by: Mimi Zohar <zohar@linux.ibm.com> <snip> > diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c > index 85000dc8595c..1a7bc4c7437d 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -706,7 +697,7 @@ int ima_load_data(enum kernel_load_data_id id, bool contents) > } > break; > case LOADING_FIRMWARE: > - if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { > + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) { > pr_err("Prevent firmware sysfs fallback loading.\n"); Appended signatures are limited to kernel modules and, more recently, to the kexec kernel image, not firmware. Without a file descriptor, file signatures stored as an xattrs are not applicable either. We might as well fail earlier, rather than later. Adding "!contents" is unnecessary. > return -EACCES; /* INTEGRITY_UNKNOWN */ > } > @@ -739,6 +730,15 @@ int ima_load_data(enum kernel_load_data_id id, bool contents) > */ > int ima_post_load_data(char *buf, loff_t size, enum kernel_load_data_id load_id) > { > + if (load_id == LOADING_FIRMWARE) { > + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && > + (ima_appraise & IMA_APPRAISE_ENFORCE)) { > + pr_err("Prevent firmware loading_store.\n"); > + return -EACCES; /* INTEGRITY_UNKNOWN */ > + } > + return 0; > + } Even with failing LOADING_FIRMWARE early in ima_load_data(), is this still needed for fw_sysfs_loading()? thanks, Mimi > + > return 0; > } >
diff --git a/drivers/base/firmware_loader/fallback.c b/drivers/base/firmware_loader/fallback.c index a196aacce22c..7cfdfdcb819c 100644 --- a/drivers/base/firmware_loader/fallback.c +++ b/drivers/base/firmware_loader/fallback.c @@ -272,9 +272,9 @@ static ssize_t firmware_loading_store(struct device *dev, dev_err(dev, "%s: map pages failed\n", __func__); else - rc = security_kernel_post_read_file(NULL, - fw_priv->data, fw_priv->size, - READING_FIRMWARE); + rc = security_kernel_post_load_data(fw_priv->data, + fw_priv->size, + LOADING_FIRMWARE); /* * Same logic as fw_load_abort, only the DONE bit @@ -613,7 +613,7 @@ static bool fw_run_sysfs_fallback(u32 opt_flags) return false; /* Also permit LSMs and IMA to fail firmware sysfs fallback */ - ret = security_kernel_load_data(LOADING_FIRMWARE, false); + ret = security_kernel_load_data(LOADING_FIRMWARE, true); if (ret < 0) return false; diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c index a12c79d47efc..4d1157af0e86 100644 --- a/drivers/base/firmware_loader/fallback_platform.c +++ b/drivers/base/firmware_loader/fallback_platform.c @@ -17,7 +17,7 @@ int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags) if (!(opt_flags & FW_OPT_FALLBACK_PLATFORM)) return -ENOENT; - rc = security_kernel_load_data(LOADING_FIRMWARE, false); + rc = security_kernel_load_data(LOADING_FIRMWARE, true); if (rc) return rc; @@ -27,6 +27,11 @@ int firmware_fallback_platform(struct fw_priv *fw_priv, u32 opt_flags) if (fw_priv->data && size > fw_priv->allocated_size) return -ENOMEM; + + rc = security_kernel_post_load_data((u8 *)data, size, LOADING_FIRMWARE); + if (rc) + return rc; + if (!fw_priv->data) fw_priv->data = vmalloc(size); if (!fw_priv->data) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 85000dc8595c..1a7bc4c7437d 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -648,15 +648,6 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size, enum ima_hooks func; u32 secid; - if (!file && read_id == READING_FIRMWARE) { - if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && - (ima_appraise & IMA_APPRAISE_ENFORCE)) { - pr_err("Prevent firmware loading_store.\n"); - return -EACCES; /* INTEGRITY_UNKNOWN */ - } - return 0; - } - /* permit signed certs */ if (!file && read_id == READING_X509_CERTIFICATE) return 0; @@ -706,7 +697,7 @@ int ima_load_data(enum kernel_load_data_id id, bool contents) } break; case LOADING_FIRMWARE: - if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE)) { + if (ima_enforce && (ima_appraise & IMA_APPRAISE_FIRMWARE) && !contents) { pr_err("Prevent firmware sysfs fallback loading.\n"); return -EACCES; /* INTEGRITY_UNKNOWN */ } @@ -739,6 +730,15 @@ int ima_load_data(enum kernel_load_data_id id, bool contents) */ int ima_post_load_data(char *buf, loff_t size, enum kernel_load_data_id load_id) { + if (load_id == LOADING_FIRMWARE) { + if ((ima_appraise & IMA_APPRAISE_FIRMWARE) && + (ima_appraise & IMA_APPRAISE_ENFORCE)) { + pr_err("Prevent firmware loading_store.\n"); + return -EACCES; /* INTEGRITY_UNKNOWN */ + } + return 0; + } + return 0; }
Now that security_post_load_data() is wired up, use it instead of the NULL file argument style of security_post_read_file(), and update the security_kernel_load_data() call to indicate that a security_kernel_post_load_data() call is expected. Wire up the IMA check to match earlier logic. Perhaps a generalized change to ima_post_load_data() might look something like this: return process_buffer_measurement(buf, size, kernel_load_data_id_str(load_id), read_idmap[load_id] ?: FILE_CHECK, 0, NULL); Signed-off-by: Kees Cook <keescook@chromium.org> --- drivers/base/firmware_loader/fallback.c | 8 ++++---- .../base/firmware_loader/fallback_platform.c | 7 ++++++- security/integrity/ima/ima_main.c | 20 +++++++++---------- 3 files changed, 20 insertions(+), 15 deletions(-)