@@ -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 "
+ "<cmd> [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=\"${PATH}:/lib:/usr:/proc:/etc:/dev/urandom\" "
+ "%s=\"/dev/null:/dev/full:/dev/zero:/dev/pts:/tmp\" "
+ "%s=\"9418\" "
+ "%s=\"80:443\" "
+ "%s bash -i\n\n",
+ ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
+ ENV_TCP_CONNECT_NAME, prog);
+ fprintf(stderr,
+ "This sandboxer can use Landlock features "
+ "up to ABI version %d.\n",
+ LANDLOCK_ABI_LAST);
+}
+
int main(const int argc, char *const argv[], char *const *const envp)
{
const char *cmd_path;
@@ -237,44 +284,7 @@ int main(const int argc, char *const argv[], char *const *const envp)
};
if (argc < 2) {
- fprintf(stderr,
- "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s "
- "<cmd> [args]...\n\n",
- ENV_FS_RO_NAME, ENV_FS_RW_NAME, ENV_TCP_BIND_NAME,
- ENV_TCP_CONNECT_NAME, argv[0]);
- fprintf(stderr,
- "Execute a command in a restricted environment.\n\n");
- fprintf(stderr,
- "Environment variables containing paths and ports "
- "each separated by a colon:\n");
- fprintf(stderr,
- "* %s: list of paths allowed to be used in a read-only way.\n",
- ENV_FS_RO_NAME);
- fprintf(stderr,
- "* %s: list of paths allowed to be used in a read-write way.\n\n",
- ENV_FS_RW_NAME);
- fprintf(stderr,
- "Environment variables containing ports are optional "
- "and could be skipped.\n");
- fprintf(stderr,
- "* %s: list of ports allowed to bind (server).\n",
- ENV_TCP_BIND_NAME);
- fprintf(stderr,
- "* %s: list of ports allowed to connect (client).\n",
- ENV_TCP_CONNECT_NAME);
- fprintf(stderr,
- "\nexample:\n"
- "%s=\"${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;
}
- 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 <matthieu@buffet.re> --- samples/landlock/sandboxer.c | 86 ++++++++++++++++++++---------------- 1 file changed, 48 insertions(+), 38 deletions(-)