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Hallyn" Subject: Re: [PATCH v2 3/4] samples/landlock: Extend sample tool to support LANDLOCK_ACCESS_FS_TRUNCATE Message-ID: References: <20220712211405.14705-1-gnoack3000@gmail.com> <20220712211405.14705-4-gnoack3000@gmail.com> <731b40e2-a95d-5eef-077b-375a50061a11@digikod.net> <62c37433-b9bd-ce7d-0b45-18ecfb15b248@digikod.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <62c37433-b9bd-ce7d-0b45-18ecfb15b248@digikod.net> Precedence: bulk List-ID: On Fri, Jul 29, 2022 at 12:43:47PM +0200, Mickaël Salaün wrote: > > On 29/07/2022 12:38, Mickaël Salaün wrote: > > > > On 29/07/2022 12:31, Mickaël Salaün wrote: > > > > > > 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." Done. > > > > > > > > > > > > > > Signed-off-by: Günther Noack > > > > 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; > > > } > > > > Well, we can just mask ruleset_attr.handled_access_fs in this > > switch/case and after mask access_fs_ro and access_fs_rw after. > > In fact, we can remove ACCESS_ABI_2 and ACCESS_ABI_3 (which are only used > here). Done (all three). --