From: "Mickaël Salaün" <mic@digikod.net>
To: "Günther Noack" <gnoack3000@gmail.com>,
linux-security-module@vger.kernel.org
Cc: James Morris <jmorris@namei.org>,
Paul Moore <paul@paul-moore.com>,
"Serge E . Hallyn" <serge@hallyn.com>
Subject: Re: [PATCH v2 3/4] samples/landlock: Extend sample tool to support LANDLOCK_ACCESS_FS_TRUNCATE
Date: Fri, 29 Jul 2022 12:31:08 +0200 [thread overview]
Message-ID: <a300def1-587f-a770-2c3a-045e4da8d56a@digikod.net> (raw)
In-Reply-To: <20220712211405.14705-4-gnoack3000@gmail.com>
On 12/07/2022 23:14, Günther Noack wrote:
> The sample tool will restrict the truncate operation if possible with
> the current kernel.
"Update the sandboxer sample to restrict truncate actions. This is
automatically enabled by default if the running kernel supports
LANDLOCK_ACCESS_FS_TRUNCATE, except for the paths listed in the LL_FS_RW
environment variable."
>
> Signed-off-by: Günther Noack <gnoack3000@gmail.com>
> Link: https://lore.kernel.org/all/20220707200612.132705-1-gnoack3000@gmail.com/
> ---
> samples/landlock/sandboxer.c | 15 +++++++++++++--
> 1 file changed, 13 insertions(+), 2 deletions(-)
>
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index 3e404e51ec64..4c3ed0097ffd 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -76,7 +76,8 @@ static int parse_path(char *env_path, const char ***const path_list)
> #define ACCESS_FILE ( \
> LANDLOCK_ACCESS_FS_EXECUTE | \
> LANDLOCK_ACCESS_FS_WRITE_FILE | \
> - LANDLOCK_ACCESS_FS_READ_FILE)
> + LANDLOCK_ACCESS_FS_READ_FILE | \
> + LANDLOCK_ACCESS_FS_TRUNCATE)
>
> /* clang-format on */
>
> @@ -160,11 +161,15 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
> LANDLOCK_ACCESS_FS_MAKE_FIFO | \
> LANDLOCK_ACCESS_FS_MAKE_BLOCK | \
> LANDLOCK_ACCESS_FS_MAKE_SYM | \
> - LANDLOCK_ACCESS_FS_REFER)
> + LANDLOCK_ACCESS_FS_REFER | \
> + LANDLOCK_ACCESS_FS_TRUNCATE)
>
> #define ACCESS_ABI_2 ( \
> LANDLOCK_ACCESS_FS_REFER)
>
> +#define ACCESS_ABI_3 ( \
> + LANDLOCK_ACCESS_FS_TRUNCATE)
> +
> /* clang-format on */
>
> int main(const int argc, char *const argv[], char *const *const envp)
> @@ -226,6 +231,12 @@ int main(const int argc, char *const argv[], char *const *const envp)
> return 1;
> }
> /* Best-effort security. */
> + if (abi < 3) {
> + ruleset_attr.handled_access_fs &= ~ACCESS_ABI_3;
> + access_fs_ro &= ~ACCESS_ABI_3;
> + access_fs_rw &= ~ACCESS_ABI_3;
> + }
I think it is a good time to start replacing this "if" check with a
switch one:
switch (abi) {
case 1:
ruleset_attr.handled_access_fs &= ~ACCESS_ABI_2;
access_fs_rw &= ~ACCESS_ABI_2;
__attribute__((fallthrough));
case 2:
ruleset_attr.handled_access_fs &= ~ACCESS_ABI_3;
access_fs_rw &= ~ACCESS_ABI_3;
}
> +
> if (abi < 2) {
> ruleset_attr.handled_access_fs &= ~ACCESS_ABI_2;
> access_fs_ro &= ~ACCESS_ABI_2;
next prev parent reply other threads:[~2022-07-29 10:31 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-12 21:14 [PATCH v2 0/4] landlock: truncate support Günther Noack
2022-07-12 21:14 ` [PATCH v2 1/4] landlock: Support file truncation Günther Noack
2022-07-28 16:25 ` Mickaël Salaün
2022-07-28 19:02 ` Günther Noack
2022-07-29 10:49 ` Mickaël Salaün
2022-07-31 4:02 ` Günther Noack
2022-07-12 21:14 ` [PATCH v2 2/4] selftests/landlock: Selftests for file truncation support Günther Noack
2022-07-29 9:39 ` Mickaël Salaün
2022-08-04 16:15 ` Günther Noack
2022-07-12 21:14 ` [PATCH v2 3/4] samples/landlock: Extend sample tool to support LANDLOCK_ACCESS_FS_TRUNCATE Günther Noack
2022-07-29 10:31 ` Mickaël Salaün [this message]
2022-07-29 10:38 ` Mickaël Salaün
2022-07-29 10:43 ` Mickaël Salaün
2022-08-04 16:34 ` Günther Noack
2022-07-12 21:14 ` [PATCH v2 4/4] landlock: Document Landlock's file truncation support Günther Noack
2022-07-29 10:47 ` Mickaël Salaün
2022-08-04 16:45 ` Günther Noack
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