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From: "Mickaël Salaün" <mic@digikod.net>
To: Jann Horn <jannh@google.com>
Cc: "James Morris" <jmorris@namei.org>,
	"Serge E . Hallyn" <serge@hallyn.com>,
	"Al Viro" <viro@zeniv.linux.org.uk>,
	"Andy Lutomirski" <luto@amacapital.net>,
	"Anton Ivanov" <anton.ivanov@cambridgegreys.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Casey Schaufler" <casey@schaufler-ca.com>,
	"Jeff Dike" <jdike@addtoit.com>,
	"Jonathan Corbet" <corbet@lwn.net>,
	"Kees Cook" <keescook@chromium.org>,
	"Michael Kerrisk" <mtk.manpages@gmail.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Shuah Khan" <shuah@kernel.org>,
	"Vincent Dagonneau" <vincent.dagonneau@ssi.gouv.fr>,
	"Kernel Hardening" <kernel-hardening@lists.openwall.com>,
	"Linux API" <linux-api@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"kernel list" <linux-kernel@vger.kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK"
	<linux-kselftest@vger.kernel.org>,
	linux-security-module <linux-security-module@vger.kernel.org>,
	"the arch/x86 maintainers" <x86@kernel.org>,
	"Mickaël Salaün" <mic@linux.microsoft.com>
Subject: Re: [PATCH v26 11/12] samples/landlock: Add a sandbox manager example
Date: Thu, 14 Jan 2021 19:59:57 +0100
Message-ID: <f3ca5fb2-64c6-b525-0f16-5353f1f7eddb@digikod.net> (raw)
In-Reply-To: <CAG48ez2yQNvcCrmCCBZKy_cxoZzNgremxWMia1YHsgaj4edqrA@mail.gmail.com>


On 14/01/2021 04:21, Jann Horn wrote:
> On Wed, Dec 9, 2020 at 8:29 PM Mickaël Salaün <mic@digikod.net> wrote:
>> Add a basic sandbox tool to launch a command which can only access a
>> whitelist of file hierarchies in a read-only or read-write way.
> 
> I have to admit that I didn't really look at this closely before
> because it's just sample code... but I guess I should. You can add
> 
> Reviewed-by: Jann Horn <jannh@google.com>
> 
> if you fix the following nits:

OK, I will!

> 
> [...]
>> diff --git a/samples/Kconfig b/samples/Kconfig
> [...]
>> +config SAMPLE_LANDLOCK
>> +       bool "Build Landlock sample code"
>> +       depends on HEADERS_INSTALL
>> +       help
>> +         Build a simple Landlock sandbox manager able to launch a process
>> +         restricted by a user-defined filesystem access control.
> 
> nit: s/filesystem access control/filesystem access control policy/
> 
> [...]
>> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> [...]
>> +/*
>> + * Simple Landlock sandbox manager able to launch a process restricted by a
>> + * user-defined filesystem access control.
> 
> nit: s/filesystem access control/filesystem access control policy/
> 
> [...]
>> +int main(const int argc, char *const argv[], char *const *const envp)
>> +{
> [...]
>> +       if (argc < 2) {
> [...]
>> +               fprintf(stderr, "* %s: list of paths allowed to be used in a read-only way.\n",
>> +                               ENV_FS_RO_NAME);
>> +               fprintf(stderr, "* %s: list of paths allowed to be used in a read-write way.\n",
>> +                               ENV_FS_RO_NAME);
> 
> s/ENV_FS_RO_NAME/ENV_FS_RW_NAME/
> 
>> +               fprintf(stderr, "\nexample:\n"
>> +                               "%s=\"/bin:/lib:/usr:/proc:/etc:/dev/urandom\" "
>> +                               "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
>> +                               "%s bash -i\n",
>> +                               ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
>> +               return 1;
>> +       }
>> +
>> +       ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +       if (ruleset_fd < 0) {
>> +               perror("Failed to create a ruleset");
>> +               switch (errno) {
> 
> (Just as a note: In theory perror() can change the value of errno, as
> far as I know - so AFAIK you'd theoretically have to do something
> like:
> 
> int errno_ = errno;
> perror("...");
> switch (errno_) {
>  ...
> }

Indeed :)

> 
> I'll almost certainly work fine as-is in practice though.)
> 

  reply index

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-09 19:28 [PATCH v26 00/12] Landlock LSM Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 01/12] landlock: Add object management Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 02/12] landlock: Add ruleset and domain management Mickaël Salaün
2021-01-14  3:21   ` Jann Horn
2020-12-09 19:28 ` [PATCH v26 03/12] landlock: Set up the security framework and manage credentials Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 04/12] landlock: Add ptrace restrictions Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 05/12] LSM: Infrastructure management of the superblock Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 06/12] fs,security: Add sb_delete hook Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 07/12] landlock: Support filesystem access-control Mickaël Salaün
2021-01-14  3:22   ` Jann Horn
2021-01-14 18:54     ` Mickaël Salaün
2021-01-14 22:43       ` Jann Horn
2021-01-15  9:10         ` Mickaël Salaün
2021-01-15 18:31           ` Jann Horn
2021-01-16 17:16             ` Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 08/12] landlock: Add syscall implementations Mickaël Salaün
2020-12-10 10:38   ` Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 09/12] arch: Wire up Landlock syscalls Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 10/12] selftests/landlock: Add user space tests Mickaël Salaün
2020-12-09 19:28 ` [PATCH v26 11/12] samples/landlock: Add a sandbox manager example Mickaël Salaün
2021-01-14  3:21   ` Jann Horn
2021-01-14 18:59     ` Mickaël Salaün [this message]
2020-12-09 19:28 ` [PATCH v26 12/12] landlock: Add user and kernel documentation Mickaël Salaün
2021-01-14  3:22 ` [PATCH v26 00/12] Landlock LSM Jann Horn
2021-01-14 19:03   ` Mickaël Salaün

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