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From: Laszlo Ersek <lersek@redhat.com>
To: Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-efi@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org, leif@nuviainc.com,
	pjones@redhat.com, mjg59@google.com, agraf@csgraf.de,
	ilias.apalodimas@linaro.org, daniel.kiper@oracle.com
Subject: Re: [PATCH 1/2] efi/libstub: add support for loading the initrd from a device path
Date: Fri, 7 Feb 2020 12:03:37 +0100	[thread overview]
Message-ID: <5972fdf8-6b35-483b-5c0c-01a53665e885@redhat.com> (raw)
In-Reply-To: <a6d7fefb-2f02-86a3-66aa-c3c129a91fb1@gmx.de>

On 02/06/20 19:26, Heinrich Schuchardt wrote:
> On 2/6/20 3:03 PM, Ard Biesheuvel wrote:

>> +    status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
>> +                 (void **)&lf2);
>> +    if (status != EFI_SUCCESS)
>> +        return status;
> 
> You require here that there is a handle exposing the device path
> protocol with the initrd specific device path. On the same handle the
> EFI_LOAD_FILE2_PROTOCOL must be installed which will load the initrd
> file when called with the same device path.
> 
> An alternative implementation would simple loop over all instances of
> the EFI_LOAD_FILE2_PROTOCOL and try to load the initrd.

That's not a great idea IMO. EFI_LOAD_FILE2_PROTOCOL instances take
device-specific filenames / pathnames to load. If you pass any
particular pathname (e.g. "initrd" or "\\initrd") to random
EFI_LOAD_FILE2_PROTOCOL instance in the protocol database, there could
be undesired results / side effects. (It could cause network activity,
for example.)

Sticking with a VenMedia (i.e. GUID-ed) devpath is much safer; it
practically lets us define our own device-specific filename / pathname
space. (And in my other email, I suggested "use an empty devpath" for
device-specific pathname, because that's the simplest, it looks
spec-conformat, and it's safe, because our GUID makes the load attempt
unique already.)

I do agree with your question though: "Please, indicate which software
you expect to expose the initrd related EFI_LOAD_FILE2_PROTOCOL."

Thanks
Laszlo


WARNING: multiple messages have this Message-ID
From: Laszlo Ersek <lersek@redhat.com>
To: Heinrich Schuchardt <xypron.glpk@gmx.de>,
	Ard Biesheuvel <ardb@kernel.org>,
	linux-efi@vger.kernel.org
Cc: agraf@csgraf.de, daniel.kiper@oracle.com,
	ilias.apalodimas@linaro.org, mjg59@google.com, pjones@redhat.com,
	leif@nuviainc.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 1/2] efi/libstub: add support for loading the initrd from a device path
Date: Fri, 7 Feb 2020 12:03:37 +0100	[thread overview]
Message-ID: <5972fdf8-6b35-483b-5c0c-01a53665e885@redhat.com> (raw)
In-Reply-To: <a6d7fefb-2f02-86a3-66aa-c3c129a91fb1@gmx.de>

On 02/06/20 19:26, Heinrich Schuchardt wrote:
> On 2/6/20 3:03 PM, Ard Biesheuvel wrote:

>> +    status = efi_bs_call(handle_protocol, handle, &lf2_proto_guid,
>> +                 (void **)&lf2);
>> +    if (status != EFI_SUCCESS)
>> +        return status;
> 
> You require here that there is a handle exposing the device path
> protocol with the initrd specific device path. On the same handle the
> EFI_LOAD_FILE2_PROTOCOL must be installed which will load the initrd
> file when called with the same device path.
> 
> An alternative implementation would simple loop over all instances of
> the EFI_LOAD_FILE2_PROTOCOL and try to load the initrd.

That's not a great idea IMO. EFI_LOAD_FILE2_PROTOCOL instances take
device-specific filenames / pathnames to load. If you pass any
particular pathname (e.g. "initrd" or "\\initrd") to random
EFI_LOAD_FILE2_PROTOCOL instance in the protocol database, there could
be undesired results / side effects. (It could cause network activity,
for example.)

Sticking with a VenMedia (i.e. GUID-ed) devpath is much safer; it
practically lets us define our own device-specific filename / pathname
space. (And in my other email, I suggested "use an empty devpath" for
device-specific pathname, because that's the simplest, it looks
spec-conformat, and it's safe, because our GUID makes the load attempt
unique already.)

I do agree with your question though: "Please, indicate which software
you expect to expose the initrd related EFI_LOAD_FILE2_PROTOCOL."

Thanks
Laszlo


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  parent reply	other threads:[~2020-02-07 11:03 UTC|newest]

Thread overview: 77+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-06 14:03 [PATCH 0/2] arch-agnostic initrd loading method for EFI systems Ard Biesheuvel
2020-02-06 14:03 ` Ard Biesheuvel
2020-02-06 14:03 ` [PATCH 1/2] efi/libstub: add support for loading the initrd from a device path Ard Biesheuvel
2020-02-06 14:03   ` Ard Biesheuvel
2020-02-06 18:26   ` Heinrich Schuchardt
2020-02-06 18:26     ` Heinrich Schuchardt
2020-02-06 18:46     ` Ilias Apalodimas
2020-02-06 18:46       ` Ilias Apalodimas
2020-02-06 19:15       ` Heinrich Schuchardt
2020-02-06 19:15         ` Heinrich Schuchardt
2020-02-06 20:09         ` Ilias Apalodimas
2020-02-06 20:09           ` Ilias Apalodimas
2020-02-06 22:49           ` Heinrich Schuchardt
2020-02-06 22:49             ` Heinrich Schuchardt
2020-02-07  7:35             ` Ilias Apalodimas
2020-02-07  7:35               ` Ilias Apalodimas
2020-02-06 22:35     ` Ard Biesheuvel
2020-02-06 22:35       ` Ard Biesheuvel
2020-02-07  0:01       ` Heinrich Schuchardt
2020-02-07  0:01         ` Heinrich Schuchardt
2020-02-07  0:21         ` Ard Biesheuvel
2020-02-07  0:21           ` Ard Biesheuvel
2020-02-07  0:57           ` Heinrich Schuchardt
2020-02-07  0:57             ` Heinrich Schuchardt
2020-02-07  8:12             ` Ard Biesheuvel
2020-02-07  8:12               ` Ard Biesheuvel
2020-02-07 13:30               ` Heinrich Schuchardt
2020-02-07 13:30                 ` Heinrich Schuchardt
2020-02-07 13:58                 ` Ard Biesheuvel
2020-02-07 13:58                   ` Ard Biesheuvel
2020-02-07 14:18                   ` Alexander Graf
2020-02-07 14:18                     ` Alexander Graf
2020-02-07 15:30                     ` Ard Biesheuvel
2020-02-07 15:30                       ` Ard Biesheuvel
2020-02-07 15:35                     ` Heinrich Schuchardt
2020-02-07 15:35                       ` Heinrich Schuchardt
2020-02-07 11:09       ` Laszlo Ersek
2020-02-07 11:09         ` Laszlo Ersek
2020-02-07 11:03     ` Laszlo Ersek [this message]
2020-02-07 11:03       ` Laszlo Ersek
2020-02-07  9:48   ` Laszlo Ersek
2020-02-07  9:48     ` Laszlo Ersek
2020-02-07 12:36     ` Ard Biesheuvel
2020-02-07 12:36       ` Ard Biesheuvel
2020-02-10 14:26       ` Laszlo Ersek
2020-02-10 14:26         ` Laszlo Ersek
2020-02-09  6:39   ` Lukas Wunner
2020-02-09 11:35     ` Ard Biesheuvel
2020-02-09 11:35       ` Ard Biesheuvel
2020-02-06 14:03 ` [PATCH 2/2] efi/libstub: take noinitrd cmdline argument into account for devpath initrd Ard Biesheuvel
2020-02-06 14:03   ` Ard Biesheuvel
2020-02-06 18:33   ` Heinrich Schuchardt
2020-02-06 18:33     ` Heinrich Schuchardt
2020-02-06 23:44     ` Ard Biesheuvel
2020-02-06 23:44       ` Ard Biesheuvel
2020-02-12 16:01   ` Peter Jones
2020-02-12 16:01     ` Peter Jones
2020-02-07  9:09 ` [PATCH 0/2] arch-agnostic initrd loading method for EFI systems Laszlo Ersek
2020-02-07  9:09   ` Laszlo Ersek
2020-02-07  9:22   ` Laszlo Ersek
2020-02-07  9:22     ` Laszlo Ersek
2020-02-07 12:23     ` Ard Biesheuvel
2020-02-07 12:23       ` Ard Biesheuvel
2020-02-07 16:20       ` James Bottomley
2020-02-07 16:20         ` James Bottomley
2020-02-07 18:31         ` Ard Biesheuvel
2020-02-07 18:31           ` Ard Biesheuvel
2020-02-07 19:54           ` James Bottomley
2020-02-07 19:54             ` James Bottomley
2020-02-07 20:03             ` Ard Biesheuvel
2020-02-07 20:03               ` Ard Biesheuvel
2020-02-07 18:45 ` Arvind Sankar
2020-02-07 18:45   ` Arvind Sankar
2020-02-07 19:47   ` Ard Biesheuvel
2020-02-07 19:47     ` Ard Biesheuvel
2020-02-07 20:26     ` Arvind Sankar
2020-02-07 20:26       ` Arvind Sankar

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