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Hallyn" , linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, Matthieu Buffet Subject: [RFC PATCH v1 2/7] samples/landlock: Clarify option parsing behaviour Date: Mon, 16 Sep 2024 14:22:25 +0200 Message-Id: <20240916122230.114800-3-matthieu@buffet.re> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240916122230.114800-1-matthieu@buffet.re> References: <20240916122230.114800-1-matthieu@buffet.re> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-State: RFC - Clarify which environment variables are optional, which ones are mandatory - Clarify the difference between unset variables and empty ones - Move the (larger) help message to a helper function Signed-off-by: Matthieu Buffet --- samples/landlock/sandboxer.c | 86 ++++++++++++++++++++---------------- 1 file changed, 48 insertions(+), 38 deletions(-) diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index a84ae3a15482..08704504dc51 100644 --- a/samples/landlock/sandboxer.c +++ b/samples/landlock/sandboxer.c @@ -221,6 +221,53 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, #define LANDLOCK_ABI_LAST 5 +static void print_help(const char *prog) +{ + fprintf(stderr, + "usage: %s=\"...\" %s=\"...\" [other environment variables] %s " + " [args]...\n\n", + ENV_FS_RO_NAME, ENV_FS_RW_NAME, prog); + fprintf(stderr, + "Execute a command in a restricted environment.\n\n"); + fprintf(stderr, + "Environment variables containing paths and ports " + "can be multi-valued, with a colon delimiter.\n" + "\n" + "Mandatory settings:\n"); + 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_RW_NAME); + fprintf(stderr, + "\n" + "Optional settings (when not set, their associated access " + "check is always allowed) (for lists, an empty string means " + "to allow nothing, e.g. %s=\"\"):\n", + ENV_TCP_BIND_NAME); + fprintf(stderr, + "* %s: list of ports allowed to bind (server).\n", + ENV_TCP_BIND_NAME); + fprintf(stderr, + "* %s: list of ports allowed to connect (client).\n", + ENV_TCP_CONNECT_NAME); + fprintf(stderr, + "\n" + "Example:\n" + "%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" " + "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" " + "%s=\"9418\" " + "%s=\"80:443\" " + "%s bash -i\n\n", + ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, + ENV_TCP_CONNECT_NAME, prog); + fprintf(stderr, + "This sandboxer can use Landlock features " + "up to ABI version %d.\n", + LANDLOCK_ABI_LAST); +} + int main(const int argc, char *const argv[], char *const *const envp) { const char *cmd_path; @@ -237,44 +284,7 @@ int main(const int argc, char *const argv[], char *const *const envp) }; if (argc < 2) { - fprintf(stderr, - "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " - " [args]...\n\n", - ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, - ENV_TCP_CONNECT_NAME, argv[0]); - fprintf(stderr, - "Execute a command in a restricted environment.\n\n"); - fprintf(stderr, - "Environment variables containing paths and ports " - "each separated by a colon:\n"); - fprintf(stderr, - "* %s: list of paths allowed to be used in a read-only way.\n", - ENV_FS_RO_NAME); - fprintf(stderr, - "* %s: list of paths allowed to be used in a read-write way.\n\n", - ENV_FS_RW_NAME); - fprintf(stderr, - "Environment variables containing ports are optional " - "and could be skipped.\n"); - fprintf(stderr, - "* %s: list of ports allowed to bind (server).\n", - ENV_TCP_BIND_NAME); - fprintf(stderr, - "* %s: list of ports allowed to connect (client).\n", - ENV_TCP_CONNECT_NAME); - fprintf(stderr, - "\nexample:\n" - "%s=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" " - "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" " - "%s=\"9418\" " - "%s=\"80:443\" " - "%s bash -i\n\n", - ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME, - ENV_TCP_CONNECT_NAME, argv[0]); - fprintf(stderr, - "This sandboxer can use Landlock features " - "up to ABI version %d.\n", - LANDLOCK_ABI_LAST); + print_help(argv[0]); return 1; }