Re: [RFC PATCH v2 9/9] samples/landlock: Support LANDLOCK_ACCESS_NET_LISTEN

[Mikhail Ivanov <ivanov.mikhail1@xxxxxxxxxxxxxxxxxxx>]

On 10/5/2024 7:57 PM, Günther Noack wrote:
> On Wed, Aug 14, 2024 at 11:01:51AM +0800, Mikhail Ivanov wrote:
> > Extend sample with TCP listen control logic.
> >
> > Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@xxxxxxxxxxxxxxxxxxx>
> > ---
> >   samples/landlock/sandboxer.c | 31 ++++++++++++++++++++++++++-----
> >   1 file changed, 26 insertions(+), 5 deletions(-)
> >
> > diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> > index e8223c3e781a..3f50cb3f8039 100644
> > --- a/samples/landlock/sandboxer.c
> > +++ b/samples/landlock/sandboxer.c
> > @@ -55,6 +55,7 @@ static inline int landlock_restrict_self(const int ruleset_fd,
> >   #define ENV_FS_RW_NAME "LL_FS_RW"
> >   #define ENV_TCP_BIND_NAME "LL_TCP_BIND"
> >   #define ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT"
> > +#define ENV_TCP_LISTEN_NAME "LL_TCP_LISTEN"
> >   #define ENV_DELIMITER ":"
> >   
> >   static int parse_path(char *env_path, const char ***const path_list)
> > @@ -208,7 +209,7 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
> >   
> >   /* clang-format on */
> >   
> > -#define LANDLOCK_ABI_LAST 5
> > +#define LANDLOCK_ABI_LAST 6
> >   
> >   int main(const int argc, char *const argv[], char *const *const envp)
> >   {
> > @@ -222,15 +223,16 @@ int main(const int argc, char *const argv[], char *const *const envp)
> >   	struct landlock_ruleset_attr ruleset_attr = {
> >   		.handled_access_fs = access_fs_rw,
> >   		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
> > -				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
> > +				      LANDLOCK_ACCESS_NET_CONNECT_TCP |
> > +				      LANDLOCK_ACCESS_NET_LISTEN_TCP,
> >   	};
> >   
> >   	if (argc < 2) {
> >   		fprintf(stderr,
> > -			"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s "
> > +			"usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s "
> >   			"<cmd> [args]...\n\n",
> >   			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
> > -			ENV_TCP_CONNECT_NAME, argv[0]);
> > +			ENV_TCP_CONNECT_NAME, ENV_TCP_LISTEN_NAME, argv[0]);
> >   		fprintf(stderr,
> >   			"Execute a command in a restricted environment.\n\n");
> >   		fprintf(stderr,
> > @@ -251,15 +253,19 @@ int main(const int argc, char *const argv[], char *const *const envp)
> >   		fprintf(stderr,
> >   			"* %s: list of ports allowed to connect (client).\n",
> >   			ENV_TCP_CONNECT_NAME);
> > +		fprintf(stderr,
> > +			"* %s: list of ports allowed to listen (server).\n",
> > +			ENV_TCP_LISTEN_NAME);
> >   		fprintf(stderr,
> >   			"\nexample:\n"
> >   			"%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
> >   			"%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
> >   			"%s=\"9418\" "
> >   			"%s=\"80:443\" "
> > +			"%s=\"9418\" "
> >   			"%s bash -i\n\n",
> >   			ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
> > -			ENV_TCP_CONNECT_NAME, argv[0]);
> > +			ENV_TCP_CONNECT_NAME, ENV_TCP_LISTEN_NAME, argv[0]);
> >   		fprintf(stderr,
> >   			"This sandboxer can use Landlock features "
> >   			"up to ABI version %d.\n",
> > @@ -326,6 +332,11 @@ int main(const int argc, char *const argv[], char *const *const envp)
> >   	case 4:
> >   		/* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */
> >   		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV;
> > +		__attribute__((fallthrough));
> > +	case 5:
> > +		/* Removes LANDLOCK_ACCESS_NET_LISTEN support for ABI < 6 */
> > +		ruleset_attr.handled_access_net &=
> > +			~(LANDLOCK_ACCESS_NET_LISTEN_TCP);
>
> (same remark as on other patch set)
>
> ABI version has shifted by one in the meantime.

Thanks, I'll update it for the next version.

> >   
> >   		fprintf(stderr,
> >   			"Hint: You should update the running kernel "
> > @@ -357,6 +368,12 @@ int main(const int argc, char *const argv[], char *const *const envp)
> >   		ruleset_attr.handled_access_net &=
> >   			~LANDLOCK_ACCESS_NET_CONNECT_TCP;
> >   	}
> > +	/* Removes listen access attribute if not supported by a user. */
>
> (also same remark as on other patch set)
>
> Please s/supported/requested/, for consistency.

Ok, thanks!

> > +	env_port_name = getenv(ENV_TCP_LISTEN_NAME);
> > +	if (!env_port_name) {
> > +		ruleset_attr.handled_access_net &=
> > +			~LANDLOCK_ACCESS_NET_LISTEN_TCP;
> > +	}
> >   
> >   	ruleset_fd =
> >   		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
> > @@ -380,6 +397,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
> >   				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
> >   		goto err_close_ruleset;
> >   	}
> > +	if (populate_ruleset_net(ENV_TCP_LISTEN_NAME, ruleset_fd,
> > +				 LANDLOCK_ACCESS_NET_LISTEN_TCP)) {
> > +		goto err_close_ruleset;
> > +	}
> >   
> >   	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
> >   		perror("Failed to restrict privileges");
> > --
> > 2.34.1
>
> Reviewed-by: Günther Noack <gnoack3000@xxxxxxxxx>