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Message-ID: <CAGXu5j+H4_f0FmEh9=zZnisDu-xB1dGo6c6oDOTV-=LDD1-gtw@mail.gmail.com> Date: Tue, 22 Jul 2014 10:39:00 -0700 From: Kees Cook <keescook@...omium.org> To: Takashi Iwai <tiwai@...e.de> Cc: LKML <linux-kernel@...r.kernel.org>, James Morris <james.l.morris@...cle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Ming Lei <ming.lei@...onical.com>, linux-security-module <linux-security-module@...r.kernel.org> Subject: Re: [PATCH v2 2/2] firmware_class: perform new LSM checks On Mon, Jul 21, 2014 at 11:55 PM, Takashi Iwai <tiwai@...e.de> wrote: > At Mon, 21 Jul 2014 12:06:41 -0700, > Kees Cook wrote: >> >> This attaches LSM hooks to the existing firmware loading interfaces: >> filesystem-found firmware and demand-loaded blobs. >> >> Signed-off-by: Kees Cook <keescook@...omium.org> >> Acked-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> >> --- >> drivers/base/firmware_class.c | 16 ++++++++++++++-- >> 1 file changed, 14 insertions(+), 2 deletions(-) >> >> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c >> index d276e33880be..7399bab71ced 100644 >> --- a/drivers/base/firmware_class.c >> +++ b/drivers/base/firmware_class.c >> @@ -28,6 +28,7 @@ >> #include <linux/suspend.h> >> #include <linux/syscore_ops.h> >> #include <linux/reboot.h> >> +#include <linux/security.h> >> >> #include <generated/utsrelease.h> >> >> @@ -308,12 +309,17 @@ static int fw_read_file_contents(struct file *file, struct firmware_buf *fw_buf) >> if (rc != size) { >> if (rc > 0) >> rc = -EIO; >> - vfree(buf); >> - return rc; >> + goto fail; >> } >> + rc = security_kernel_fw_from_file(file, buf, size); >> + if (rc) >> + goto fail; >> fw_buf->data = buf; >> fw_buf->size = size; >> return 0; >> +fail: >> + vfree(buf); >> + return rc; >> } >> >> static int fw_get_filesystem_firmware(struct device *device, >> @@ -640,6 +646,12 @@ static ssize_t firmware_loading_store(struct device *dev, >> break; >> case 0: >> if (test_bit(FW_STATUS_LOADING, &fw_buf->status)) { >> + if (security_kernel_fw_from_file(NULL, fw_buf->data, >> + fw_buf->size)) { >> + fw_load_abort(fw_priv); >> + break; >> + } >> set_bit(FW_STATUS_DONE, &fw_buf->status); >> clear_bit(FW_STATUS_LOADING, &fw_buf->status); > > security_kernel_fw_from_file() should be called after > fw_map_pages_buf() call (that is found after these lines). > Otherwise fw_buf->buf won't contain a valid buffer pointer. Ah! Good to know. I guess I was getting lucky in my testing. Is this a race condition? -Kees -- Kees Cook Chrome OS Security -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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