diff mbox series

[v8,11/12] samples/landlock: Add network demo

Message ID 20221021152644.155136-12-konstantin.meskhidze@huawei.com (mailing list archive)
State Not Applicable
Headers show
Series Network support for Landlock | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch, async

Commit Message

Konstantin Meskhidze (A) Oct. 21, 2022, 3:26 p.m. UTC 
This commit adds network demo. It's possible to allow a sandboxer to
bind/connect to a list of particular ports restricting network
actions to the rest of ports.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
---

Changes since v7:
* Removes network support if ABI < 4.
* Removes network support if not set by a user.

Changes since v6:
* Removes network support if ABI < 3.

Changes since v5:
* Makes network ports sandboxing optional.
* Fixes some logic errors.
* Formats code with clang-format-14.

Changes since v4:
* Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and
ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables
to insert TCP ports.
* Renames populate_ruleset() to populate_ruleset_fs().
* Adds populate_ruleset_net() and parse_port_num() helpers.
* Refactors main() to support network sandboxing.

---
 samples/landlock/sandboxer.c | 129 +++++++++++++++++++++++++++++++----
 1 file changed, 116 insertions(+), 13 deletions(-)

--
2.25.1

Comments

Mickaël Salaün Nov. 16, 2022, 2:25 p.m. UTC | #1 
On 21/10/2022 17:26, Konstantin Meskhidze wrote:
> This commit adds network demo. It's possible to allow a sandboxer to
> bind/connect to a list of particular ports restricting network
> actions to the rest of ports.
> 
> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
> ---
> 
> Changes since v7:
> * Removes network support if ABI < 4.
> * Removes network support if not set by a user.
> 
> Changes since v6:
> * Removes network support if ABI < 3.
> 
> Changes since v5:
> * Makes network ports sandboxing optional.
> * Fixes some logic errors.
> * Formats code with clang-format-14.
> 
> Changes since v4:
> * Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and
> ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables
> to insert TCP ports.
> * Renames populate_ruleset() to populate_ruleset_fs().
> * Adds populate_ruleset_net() and parse_port_num() helpers.
> * Refactors main() to support network sandboxing.
> 
> ---
>   samples/landlock/sandboxer.c | 129 +++++++++++++++++++++++++++++++----
>   1 file changed, 116 insertions(+), 13 deletions(-)
> 
> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
> index fd4237c64fb2..68582b0d7c85 100644
> --- a/samples/landlock/sandboxer.c
> +++ b/samples/landlock/sandboxer.c
> @@ -51,6 +51,8 @@ static inline int landlock_restrict_self(const int ruleset_fd,
> 
>   #define ENV_FS_RO_NAME "LL_FS_RO"
>   #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_PATH_TOKEN ":"
> 
>   static int parse_path(char *env_path, const char ***const path_list)
> @@ -71,6 +73,20 @@ static int parse_path(char *env_path, const char ***const path_list)
>   	return num_paths;
>   }
> 
> +static int parse_port_num(char *env_port)
> +{
> +	int i, num_ports = 0;
> +
> +	if (env_port) {
> +		num_ports++;
> +		for (i = 0; env_port[i]; i++) {
> +			if (env_port[i] == ENV_PATH_TOKEN[0])
> +				num_ports++;
> +		}
> +	}
> +	return num_ports;
> +}
> +
>   /* clang-format off */
> 
>   #define ACCESS_FILE ( \
> @@ -81,8 +97,8 @@ static int parse_path(char *env_path, const char ***const path_list)
> 
>   /* clang-format on */
> 
> -static int populate_ruleset(const char *const env_var, const int ruleset_fd,
> -			    const __u64 allowed_access)
> +static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
> +			       const __u64 allowed_access)
>   {
>   	int num_paths, i, ret = 1;
>   	char *env_path_name;
> @@ -143,6 +159,48 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>   	return ret;
>   }
> 
> +static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
> +				const __u64 allowed_access)
> +{
> +	int num_ports, i, ret = 1;
> +	char *env_port_name;
> +	struct landlock_net_service_attr net_service = {
> +		.allowed_access = 0,
> +		.port = 0,
> +	};
> +
> +	env_port_name = getenv(env_var);
> +	if (!env_port_name) {
> +		ret = 0;
> +		goto out_free_name;

This is a bug because env_port_name is not allocated. This should simply 
return 0.


> +	}
> +	env_port_name = strdup(env_port_name);
> +	unsetenv(env_var);
> +	num_ports = parse_port_num(env_port_name);
> +
> +	if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) {
> +		ret = 0;
> +		goto out_free_name;
> +	}
> +
> +	for (i = 0; i < num_ports; i++) {
> +		net_service.allowed_access = allowed_access;
> +		net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN));
> +		if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
> +				      &net_service, 0)) {
> +			fprintf(stderr,
> +				"Failed to update the ruleset with port \"%d\": %s\n",
> +				net_service.port, strerror(errno));
> +			goto out_free_name;
> +		}
> +	}
> +	ret = 0;
> +
> +out_free_name:
> +	free(env_port_name);
> +	return ret;
> +}
> +
>   /* clang-format off */
> 
>   #define ACCESS_FS_ROUGHLY_READ ( \
> @@ -164,41 +222,63 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>   	LANDLOCK_ACCESS_FS_REFER | \
>   	LANDLOCK_ACCESS_FS_TRUNCATE)
> 
> +#define ACCESS_NET_BIND_CONNECT ( \
> +	LANDLOCK_ACCESS_NET_BIND_TCP | \
> +	LANDLOCK_ACCESS_NET_CONNECT_TCP)

You can remove ACCESS_NET_BIND_CONNECT and make the underlying access 
rights explicit.


> +
>   /* clang-format on */
> 
> -#define LANDLOCK_ABI_LAST 3
> +#define LANDLOCK_ABI_LAST 4
> 
>   int main(const int argc, char *const argv[], char *const *const envp)
>   {
>   	const char *cmd_path;
>   	char *const *cmd_argv;
>   	int ruleset_fd, abi;
> +	char *env_port_name;
>   	__u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ,
> -	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE;
> +	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE,
> +	      access_net_tcp = ACCESS_NET_BIND_CONNECT;
>   	struct landlock_ruleset_attr ruleset_attr = {
>   		.handled_access_fs = access_fs_rw,
> +		.handled_access_net = access_net_tcp,
>   	};
> 
>   	if (argc < 2) {
>   		fprintf(stderr,
> -			"usage: %s=\"...\" %s=\"...\" %s <cmd> [args]...\n\n",
> -			ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
> +			"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,
>   			"Launch a command in a restricted environment.\n\n");
> -		fprintf(stderr, "Environment variables containing paths, "
> -				"each separated by a colon:\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",
> +			"* %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=\"/bin:/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, argv[0]);
> +			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",
> @@ -240,7 +320,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
>   	case 2:
>   		/* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */
>   		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
> -
> +		__attribute__((fallthrough));
> +	case 3:
> +		/* Removes network support for ABI < 4 */
> +		ruleset_attr.handled_access_net &= ~ACCESS_NET_BIND_CONNECT;

You can check the TCP environment variables here and error out if one is 
set.

Please keep the newline here.


>   		fprintf(stderr,
>   			"Hint: You should update the running kernel "
>   			"to leverage Landlock features "
> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp)
>   	access_fs_ro &= ruleset_attr.handled_access_fs;
>   	access_fs_rw &= ruleset_attr.handled_access_fs;
> 
> +	/* Removes bind access attribute if not supported by a user. */
> +	env_port_name = getenv(ENV_TCP_BIND_NAME);
> +	if (!env_port_name) {

You can move this logic at the populate_ruleset_net() call site and 
update this helper to not call getenv() twice for the same variable.


> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
> +	}
> +	/* Removes connect access attribute if not supported by a user. */
> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
> +	if (!env_port_name) {
> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
> +	}
> +	ruleset_attr.handled_access_net &= access_net_tcp;

There is no need for access_net_tcp.

> +
>   	ruleset_fd =
>   		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>   	if (ruleset_fd < 0) {
>   		perror("Failed to create a ruleset");
>   		return 1;
>   	}

newline

> -	if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
> +	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
> +		goto err_close_ruleset;
> +	}
> +	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
> +		goto err_close_ruleset;
> +	}

newline

> +	if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd,
> +				 LANDLOCK_ACCESS_NET_BIND_TCP)) {
>   		goto err_close_ruleset;
>   	}
> -	if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
> +	if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd,
> +				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
>   		goto err_close_ruleset;
>   	}

newline

>   	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
> --
> 2.25.1
>
Konstantin Meskhidze (A) Nov. 28, 2022, 2:49 a.m. UTC | #2 
11/16/2022 5:25 PM, Mickaël Salaün пишет:
> 
> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>> This commit adds network demo. It's possible to allow a sandboxer to
>> bind/connect to a list of particular ports restricting network
>> actions to the rest of ports.
>> 
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>> ---
>> 
>> Changes since v7:
>> * Removes network support if ABI < 4.
>> * Removes network support if not set by a user.
>> 
>> Changes since v6:
>> * Removes network support if ABI < 3.
>> 
>> Changes since v5:
>> * Makes network ports sandboxing optional.
>> * Fixes some logic errors.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and
>> ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables
>> to insert TCP ports.
>> * Renames populate_ruleset() to populate_ruleset_fs().
>> * Adds populate_ruleset_net() and parse_port_num() helpers.
>> * Refactors main() to support network sandboxing.
>> 
>> ---
>>   samples/landlock/sandboxer.c | 129 +++++++++++++++++++++++++++++++----
>>   1 file changed, 116 insertions(+), 13 deletions(-)
>> 
>> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
>> index fd4237c64fb2..68582b0d7c85 100644
>> --- a/samples/landlock/sandboxer.c
>> +++ b/samples/landlock/sandboxer.c
>> @@ -51,6 +51,8 @@ static inline int landlock_restrict_self(const int ruleset_fd,
>> 
>>   #define ENV_FS_RO_NAME "LL_FS_RO"
>>   #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_PATH_TOKEN ":"
>> 
>>   static int parse_path(char *env_path, const char ***const path_list)
>> @@ -71,6 +73,20 @@ static int parse_path(char *env_path, const char ***const path_list)
>>   	return num_paths;
>>   }
>> 
>> +static int parse_port_num(char *env_port)
>> +{
>> +	int i, num_ports = 0;
>> +
>> +	if (env_port) {
>> +		num_ports++;
>> +		for (i = 0; env_port[i]; i++) {
>> +			if (env_port[i] == ENV_PATH_TOKEN[0])
>> +				num_ports++;
>> +		}
>> +	}
>> +	return num_ports;
>> +}
>> +
>>   /* clang-format off */
>> 
>>   #define ACCESS_FILE ( \
>> @@ -81,8 +97,8 @@ static int parse_path(char *env_path, const char ***const path_list)
>> 
>>   /* clang-format on */
>> 
>> -static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>> -			    const __u64 allowed_access)
>> +static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
>> +			       const __u64 allowed_access)
>>   {
>>   	int num_paths, i, ret = 1;
>>   	char *env_path_name;
>> @@ -143,6 +159,48 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>>   	return ret;
>>   }
>> 
>> +static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
>> +				const __u64 allowed_access)
>> +{
>> +	int num_ports, i, ret = 1;
>> +	char *env_port_name;
>> +	struct landlock_net_service_attr net_service = {
>> +		.allowed_access = 0,
>> +		.port = 0,
>> +	};
>> +
>> +	env_port_name = getenv(env_var);
>> +	if (!env_port_name) {
>> +		ret = 0;
>> +		goto out_free_name;
> 
> This is a bug because env_port_name is not allocated. This should simply
> return 0.

   Ok. I got it. Thanks.
> 
> 
>> +	}
>> +	env_port_name = strdup(env_port_name);
>> +	unsetenv(env_var);
>> +	num_ports = parse_port_num(env_port_name);
>> +
>> +	if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) {
>> +		ret = 0;
>> +		goto out_free_name;
>> +	}
>> +
>> +	for (i = 0; i < num_ports; i++) {
>> +		net_service.allowed_access = allowed_access;
>> +		net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN));
>> +		if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
>> +				      &net_service, 0)) {
>> +			fprintf(stderr,
>> +				"Failed to update the ruleset with port \"%d\": %s\n",
>> +				net_service.port, strerror(errno));
>> +			goto out_free_name;
>> +		}
>> +	}
>> +	ret = 0;
>> +
>> +out_free_name:
>> +	free(env_port_name);
>> +	return ret;
>> +}
>> +
>>   /* clang-format off */
>> 
>>   #define ACCESS_FS_ROUGHLY_READ ( \
>> @@ -164,41 +222,63 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>>   	LANDLOCK_ACCESS_FS_REFER | \
>>   	LANDLOCK_ACCESS_FS_TRUNCATE)
>> 
>> +#define ACCESS_NET_BIND_CONNECT ( \
>> +	LANDLOCK_ACCESS_NET_BIND_TCP | \
>> +	LANDLOCK_ACCESS_NET_CONNECT_TCP)
> 
> You can remove ACCESS_NET_BIND_CONNECT and make the underlying access
> rights explicit.
> 
   Ok.
> 
>> +
>>   /* clang-format on */
>> 
>> -#define LANDLOCK_ABI_LAST 3
>> +#define LANDLOCK_ABI_LAST 4
>> 
>>   int main(const int argc, char *const argv[], char *const *const envp)
>>   {
>>   	const char *cmd_path;
>>   	char *const *cmd_argv;
>>   	int ruleset_fd, abi;
>> +	char *env_port_name;
>>   	__u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ,
>> -	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE;
>> +	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE,
>> +	      access_net_tcp = ACCESS_NET_BIND_CONNECT;
>>   	struct landlock_ruleset_attr ruleset_attr = {
>>   		.handled_access_fs = access_fs_rw,
>> +		.handled_access_net = access_net_tcp,
>>   	};
>> 
>>   	if (argc < 2) {
>>   		fprintf(stderr,
>> -			"usage: %s=\"...\" %s=\"...\" %s <cmd> [args]...\n\n",
>> -			ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
>> +			"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,
>>   			"Launch a command in a restricted environment.\n\n");
>> -		fprintf(stderr, "Environment variables containing paths, "
>> -				"each separated by a colon:\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",
>> +			"* %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=\"/bin:/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, argv[0]);
>> +			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",
>> @@ -240,7 +320,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>   	case 2:
>>   		/* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */
>>   		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
>> -
>> +		__attribute__((fallthrough));
>> +	case 3:
>> +		/* Removes network support for ABI < 4 */
>> +		ruleset_attr.handled_access_net &= ~ACCESS_NET_BIND_CONNECT;
> 
> You can check the TCP environment variables here and error out if one is
> set.
> 
> Please keep the newline here.

   Ok. got it.
> 
> 
>>   		fprintf(stderr,
>>   			"Hint: You should update the running kernel "
>>   			"to leverage Landlock features "
>> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>   	access_fs_ro &= ruleset_attr.handled_access_fs;
>>   	access_fs_rw &= ruleset_attr.handled_access_fs;
>> 
>> +	/* Removes bind access attribute if not supported by a user. */
>> +	env_port_name = getenv(ENV_TCP_BIND_NAME);
>> +	if (!env_port_name) {
> 
> You can move this logic at the populate_ruleset_net() call site and
> update this helper to not call getenv() twice for the same variable.
> 
   Ok. Thanks for the tip.
> 
>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>> +	}
>> +	/* Removes connect access attribute if not supported by a user. */
>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>> +	if (!env_port_name) {
>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>> +	}
>> +	ruleset_attr.handled_access_net &= access_net_tcp;
> 
> There is no need for access_net_tcp.

   Do you mean to delete this var?
> 
>> +
>>   	ruleset_fd =
>>   		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>>   	if (ruleset_fd < 0) {
>>   		perror("Failed to create a ruleset");
>>   		return 1;
>>   	}
> 
> newline

   Got it.
> 
>> -	if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
>> +	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
>> +		goto err_close_ruleset;
>> +	}
>> +	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
>> +		goto err_close_ruleset;
>> +	}
> 
> newline

   Ok.
> 
>> +	if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd,
>> +				 LANDLOCK_ACCESS_NET_BIND_TCP)) {
>>   		goto err_close_ruleset;
>>   	}
>> -	if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
>> +	if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd,
>> +				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
>>   		goto err_close_ruleset;
>>   	}
> 
> newline

   Got it. Thnaks.
> 
>>   	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
>> --
>> 2.25.1
>> 
> .
Mickaël Salaün Nov. 28, 2022, 8:26 p.m. UTC | #3 
On 28/11/2022 03:49, Konstantin Meskhidze (A) wrote:
> 
> 
> 11/16/2022 5:25 PM, Mickaël Salaün пишет:
>>
>> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>>> This commit adds network demo. It's possible to allow a sandboxer to
>>> bind/connect to a list of particular ports restricting network
>>> actions to the rest of ports.
>>>
>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>>> ---

[...]

>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>>> +	}
>>> +	/* Removes connect access attribute if not supported by a user. */
>>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>>> +	if (!env_port_name) {
>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>>> +	}
>>> +	ruleset_attr.handled_access_net &= access_net_tcp;
>>
>> There is no need for access_net_tcp.
> 
>     Do you mean to delete this var?

Yes
Konstantin Meskhidze (A) Dec. 2, 2022, 2:48 a.m. UTC | #4 
11/28/2022 11:26 PM, Mickaël Salaün пишет:
> 
> On 28/11/2022 03:49, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 11/16/2022 5:25 PM, Mickaël Salaün пишет:
>>>
>>> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>>>> This commit adds network demo. It's possible to allow a sandboxer to
>>>> bind/connect to a list of particular ports restricting network
>>>> actions to the rest of ports.
>>>>
>>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>>>> ---
> 
> [...]
> 
>>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>>>> +	}
>>>> +	/* Removes connect access attribute if not supported by a user. */
>>>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>>>> +	if (!env_port_name) {
>>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>>>> +	}
>>>> +	ruleset_attr.handled_access_net &= access_net_tcp;
>>>
>>> There is no need for access_net_tcp.
>> 
>>     Do you mean to delete this var?
> 
> Yes

   Got it.
> .
Konstantin Meskhidze (A) Jan. 5, 2023, 3:46 a.m. UTC | #5 
11/16/2022 5:25 PM, Mickaël Salaün пишет:
> 
> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>> This commit adds network demo. It's possible to allow a sandboxer to
>> bind/connect to a list of particular ports restricting network
>> actions to the rest of ports.
>> 
>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
>> ---
>> 
>> Changes since v7:
>> * Removes network support if ABI < 4.
>> * Removes network support if not set by a user.
>> 
>> Changes since v6:
>> * Removes network support if ABI < 3.
>> 
>> Changes since v5:
>> * Makes network ports sandboxing optional.
>> * Fixes some logic errors.
>> * Formats code with clang-format-14.
>> 
>> Changes since v4:
>> * Adds ENV_TCP_BIND_NAME "LL_TCP_BIND" and
>> ENV_TCP_CONNECT_NAME "LL_TCP_CONNECT" variables
>> to insert TCP ports.
>> * Renames populate_ruleset() to populate_ruleset_fs().
>> * Adds populate_ruleset_net() and parse_port_num() helpers.
>> * Refactors main() to support network sandboxing.
>> 
>> ---
>>   samples/landlock/sandboxer.c | 129 +++++++++++++++++++++++++++++++----
>>   1 file changed, 116 insertions(+), 13 deletions(-)
>> 
>> diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
>> index fd4237c64fb2..68582b0d7c85 100644
>> --- a/samples/landlock/sandboxer.c
>> +++ b/samples/landlock/sandboxer.c
>> @@ -51,6 +51,8 @@ static inline int landlock_restrict_self(const int ruleset_fd,
>> 
>>   #define ENV_FS_RO_NAME "LL_FS_RO"
>>   #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_PATH_TOKEN ":"
>> 
>>   static int parse_path(char *env_path, const char ***const path_list)
>> @@ -71,6 +73,20 @@ static int parse_path(char *env_path, const char ***const path_list)
>>   	return num_paths;
>>   }
>> 
>> +static int parse_port_num(char *env_port)
>> +{
>> +	int i, num_ports = 0;
>> +
>> +	if (env_port) {
>> +		num_ports++;
>> +		for (i = 0; env_port[i]; i++) {
>> +			if (env_port[i] == ENV_PATH_TOKEN[0])
>> +				num_ports++;
>> +		}
>> +	}
>> +	return num_ports;
>> +}
>> +
>>   /* clang-format off */
>> 
>>   #define ACCESS_FILE ( \
>> @@ -81,8 +97,8 @@ static int parse_path(char *env_path, const char ***const path_list)
>> 
>>   /* clang-format on */
>> 
>> -static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>> -			    const __u64 allowed_access)
>> +static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
>> +			       const __u64 allowed_access)
>>   {
>>   	int num_paths, i, ret = 1;
>>   	char *env_path_name;
>> @@ -143,6 +159,48 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>>   	return ret;
>>   }
>> 
>> +static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
>> +				const __u64 allowed_access)
>> +{
>> +	int num_ports, i, ret = 1;
>> +	char *env_port_name;
>> +	struct landlock_net_service_attr net_service = {
>> +		.allowed_access = 0,
>> +		.port = 0,
>> +	};
>> +
>> +	env_port_name = getenv(env_var);
>> +	if (!env_port_name) {
>> +		ret = 0;
>> +		goto out_free_name;
> 
> This is a bug because env_port_name is not allocated. This should simply
> return 0.
> 
> 
>> +	}
>> +	env_port_name = strdup(env_port_name);
>> +	unsetenv(env_var);
>> +	num_ports = parse_port_num(env_port_name);
>> +
>> +	if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) {
>> +		ret = 0;
>> +		goto out_free_name;
>> +	}
>> +
>> +	for (i = 0; i < num_ports; i++) {
>> +		net_service.allowed_access = allowed_access;
>> +		net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN));
>> +		if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
>> +				      &net_service, 0)) {
>> +			fprintf(stderr,
>> +				"Failed to update the ruleset with port \"%d\": %s\n",
>> +				net_service.port, strerror(errno));
>> +			goto out_free_name;
>> +		}
>> +	}
>> +	ret = 0;
>> +
>> +out_free_name:
>> +	free(env_port_name);
>> +	return ret;
>> +}
>> +
>>   /* clang-format off */
>> 
>>   #define ACCESS_FS_ROUGHLY_READ ( \
>> @@ -164,41 +222,63 @@ static int populate_ruleset(const char *const env_var, const int ruleset_fd,
>>   	LANDLOCK_ACCESS_FS_REFER | \
>>   	LANDLOCK_ACCESS_FS_TRUNCATE)
>> 
>> +#define ACCESS_NET_BIND_CONNECT ( \
>> +	LANDLOCK_ACCESS_NET_BIND_TCP | \
>> +	LANDLOCK_ACCESS_NET_CONNECT_TCP)
> 
> You can remove ACCESS_NET_BIND_CONNECT and make the underlying access
> rights explicit.
> 
> 
>> +
>>   /* clang-format on */
>> 
>> -#define LANDLOCK_ABI_LAST 3
>> +#define LANDLOCK_ABI_LAST 4
>> 
>>   int main(const int argc, char *const argv[], char *const *const envp)
>>   {
>>   	const char *cmd_path;
>>   	char *const *cmd_argv;
>>   	int ruleset_fd, abi;
>> +	char *env_port_name;
>>   	__u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ,
>> -	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE;
>> +	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE,
>> +	      access_net_tcp = ACCESS_NET_BIND_CONNECT;
>>   	struct landlock_ruleset_attr ruleset_attr = {
>>   		.handled_access_fs = access_fs_rw,
>> +		.handled_access_net = access_net_tcp,
>>   	};
>> 
>>   	if (argc < 2) {
>>   		fprintf(stderr,
>> -			"usage: %s=\"...\" %s=\"...\" %s <cmd> [args]...\n\n",
>> -			ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
>> +			"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,
>>   			"Launch a command in a restricted environment.\n\n");
>> -		fprintf(stderr, "Environment variables containing paths, "
>> -				"each separated by a colon:\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",
>> +			"* %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=\"/bin:/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, argv[0]);
>> +			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",
>> @@ -240,7 +320,10 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>   	case 2:
>>   		/* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */
>>   		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
>> -
>> +		__attribute__((fallthrough));
>> +	case 3:
>> +		/* Removes network support for ABI < 4 */
>> +		ruleset_attr.handled_access_net &= ~ACCESS_NET_BIND_CONNECT;
> 
> You can check the TCP environment variables here and error out if one is
> set.
> 
> Please keep the newline here.
> 
> 
>>   		fprintf(stderr,
>>   			"Hint: You should update the running kernel "
>>   			"to leverage Landlock features "
>> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>   	access_fs_ro &= ruleset_attr.handled_access_fs;
>>   	access_fs_rw &= ruleset_attr.handled_access_fs;
>> 
>> +	/* Removes bind access attribute if not supported by a user. */
>> +	env_port_name = getenv(ENV_TCP_BIND_NAME);
>> +	if (!env_port_name) {
> 
> You can move this logic at the populate_ruleset_net() call site and
> update this helper to not call getenv() twice for the same variable.

   But here I exclude ruleset attributes, not rule itself. It will break
   the logic: creating a ruleset then applying rules.
   I suggest to leave here as its.
> 
> 
>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>> +	}
>> +	/* Removes connect access attribute if not supported by a user. */
>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>> +	if (!env_port_name) {
>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>> +	}
>> +	ruleset_attr.handled_access_net &= access_net_tcp;
> 
> There is no need for access_net_tcp.
> 
>> +
>>   	ruleset_fd =
>>   		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>>   	if (ruleset_fd < 0) {
>>   		perror("Failed to create a ruleset");
>>   		return 1;
>>   	}
> 
> newline
> 
>> -	if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
>> +	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
>> +		goto err_close_ruleset;
>> +	}
>> +	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
>> +		goto err_close_ruleset;
>> +	}
> 
> newline
> 
>> +	if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd,
>> +				 LANDLOCK_ACCESS_NET_BIND_TCP)) {
>>   		goto err_close_ruleset;
>>   	}
>> -	if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
>> +	if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd,
>> +				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
>>   		goto err_close_ruleset;
>>   	}
> 
> newline
> 
>>   	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
>> --
>> 2.25.1
>> 
> .
Mickaël Salaün Jan. 6, 2023, 7:34 p.m. UTC | #6 
On 05/01/2023 04:46, Konstantin Meskhidze (A) wrote:
> 
> 
> 11/16/2022 5:25 PM, Mickaël Salaün пишет:

[...]

>>
>>>    		fprintf(stderr,
>>>    			"Hint: You should update the running kernel "
>>>    			"to leverage Landlock features "
>>> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>>    	access_fs_ro &= ruleset_attr.handled_access_fs;
>>>    	access_fs_rw &= ruleset_attr.handled_access_fs;
>>>
>>> +	/* Removes bind access attribute if not supported by a user. */
>>> +	env_port_name = getenv(ENV_TCP_BIND_NAME);
>>> +	if (!env_port_name) {
>>
>> You can move this logic at the populate_ruleset_net() call site and
>> update this helper to not call getenv() twice for the same variable.
> 
>     But here I exclude ruleset attributes, not rule itself. It will break
>     the logic: creating a ruleset then applying rules.
>     I suggest to leave here as its.

Right, but you can still avoid the duplicate getenv() calls.


>>
>>
>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>>> +	}
>>> +	/* Removes connect access attribute if not supported by a user. */
>>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>>> +	if (!env_port_name) {
>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>>> +	}
>>> +	ruleset_attr.handled_access_net &= access_net_tcp;
Konstantin Meskhidze (A) Jan. 9, 2023, 7:57 a.m. UTC | #7 
1/6/2023 10:34 PM, Mickaël Salaün пишет:
> 
> On 05/01/2023 04:46, Konstantin Meskhidze (A) wrote:
>> 
>> 
>> 11/16/2022 5:25 PM, Mickaël Salaün пишет:
> 
> [...]
> 
>>>
>>>>    		fprintf(stderr,
>>>>    			"Hint: You should update the running kernel "
>>>>    			"to leverage Landlock features "
>>>> @@ -259,16 +342,36 @@ int main(const int argc, char *const argv[], char *const *const envp)
>>>>    	access_fs_ro &= ruleset_attr.handled_access_fs;
>>>>    	access_fs_rw &= ruleset_attr.handled_access_fs;
>>>>
>>>> +	/* Removes bind access attribute if not supported by a user. */
>>>> +	env_port_name = getenv(ENV_TCP_BIND_NAME);
>>>> +	if (!env_port_name) {
>>>
>>> You can move this logic at the populate_ruleset_net() call site and
>>> update this helper to not call getenv() twice for the same variable.
>> 
>>     But here I exclude ruleset attributes, not rule itself. It will break
>>     the logic: creating a ruleset then applying rules.
>>     I suggest to leave here as its.
> 
> Right, but you can still avoid the duplicate getenv() calls.

   OK. Will fix it.
> 
> 
>>>
>>>
>>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
>>>> +	}
>>>> +	/* Removes connect access attribute if not supported by a user. */
>>>> +	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
>>>> +	if (!env_port_name) {
>>>> +		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
>>>> +	}
>>>> +	ruleset_attr.handled_access_net &= access_net_tcp;
> .
diff mbox series

Patch

diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c
index fd4237c64fb2..68582b0d7c85 100644
--- a/samples/landlock/sandboxer.c
+++ b/samples/landlock/sandboxer.c
@@ -51,6 +51,8 @@  static inline int landlock_restrict_self(const int ruleset_fd,

 #define ENV_FS_RO_NAME "LL_FS_RO"
 #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_PATH_TOKEN ":"

 static int parse_path(char *env_path, const char ***const path_list)
@@ -71,6 +73,20 @@  static int parse_path(char *env_path, const char ***const path_list)
 	return num_paths;
 }

+static int parse_port_num(char *env_port)
+{
+	int i, num_ports = 0;
+
+	if (env_port) {
+		num_ports++;
+		for (i = 0; env_port[i]; i++) {
+			if (env_port[i] == ENV_PATH_TOKEN[0])
+				num_ports++;
+		}
+	}
+	return num_ports;
+}
+
 /* clang-format off */

 #define ACCESS_FILE ( \
@@ -81,8 +97,8 @@  static int parse_path(char *env_path, const char ***const path_list)

 /* clang-format on */

-static int populate_ruleset(const char *const env_var, const int ruleset_fd,
-			    const __u64 allowed_access)
+static int populate_ruleset_fs(const char *const env_var, const int ruleset_fd,
+			       const __u64 allowed_access)
 {
 	int num_paths, i, ret = 1;
 	char *env_path_name;
@@ -143,6 +159,48 @@  static int populate_ruleset(const char *const env_var, const int ruleset_fd,
 	return ret;
 }

+static int populate_ruleset_net(const char *const env_var, const int ruleset_fd,
+				const __u64 allowed_access)
+{
+	int num_ports, i, ret = 1;
+	char *env_port_name;
+	struct landlock_net_service_attr net_service = {
+		.allowed_access = 0,
+		.port = 0,
+	};
+
+	env_port_name = getenv(env_var);
+	if (!env_port_name) {
+		ret = 0;
+		goto out_free_name;
+	}
+	env_port_name = strdup(env_port_name);
+	unsetenv(env_var);
+	num_ports = parse_port_num(env_port_name);
+
+	if (num_ports == 1 && (strtok(env_port_name, ENV_PATH_TOKEN) == NULL)) {
+		ret = 0;
+		goto out_free_name;
+	}
+
+	for (i = 0; i < num_ports; i++) {
+		net_service.allowed_access = allowed_access;
+		net_service.port = atoi(strsep(&env_port_name, ENV_PATH_TOKEN));
+		if (landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
+				      &net_service, 0)) {
+			fprintf(stderr,
+				"Failed to update the ruleset with port \"%d\": %s\n",
+				net_service.port, strerror(errno));
+			goto out_free_name;
+		}
+	}
+	ret = 0;
+
+out_free_name:
+	free(env_port_name);
+	return ret;
+}
+
 /* clang-format off */

 #define ACCESS_FS_ROUGHLY_READ ( \
@@ -164,41 +222,63 @@  static int populate_ruleset(const char *const env_var, const int ruleset_fd,
 	LANDLOCK_ACCESS_FS_REFER | \
 	LANDLOCK_ACCESS_FS_TRUNCATE)

+#define ACCESS_NET_BIND_CONNECT ( \
+	LANDLOCK_ACCESS_NET_BIND_TCP | \
+	LANDLOCK_ACCESS_NET_CONNECT_TCP)
+
 /* clang-format on */

-#define LANDLOCK_ABI_LAST 3
+#define LANDLOCK_ABI_LAST 4

 int main(const int argc, char *const argv[], char *const *const envp)
 {
 	const char *cmd_path;
 	char *const *cmd_argv;
 	int ruleset_fd, abi;
+	char *env_port_name;
 	__u64 access_fs_ro = ACCESS_FS_ROUGHLY_READ,
-	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE;
+	      access_fs_rw = ACCESS_FS_ROUGHLY_READ | ACCESS_FS_ROUGHLY_WRITE,
+	      access_net_tcp = ACCESS_NET_BIND_CONNECT;
 	struct landlock_ruleset_attr ruleset_attr = {
 		.handled_access_fs = access_fs_rw,
+		.handled_access_net = access_net_tcp,
 	};

 	if (argc < 2) {
 		fprintf(stderr,
-			"usage: %s=\"...\" %s=\"...\" %s <cmd> [args]...\n\n",
-			ENV_FS_RO_NAME, ENV_FS_RW_NAME, argv[0]);
+			"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,
 			"Launch a command in a restricted environment.\n\n");
-		fprintf(stderr, "Environment variables containing paths, "
-				"each separated by a colon:\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",
+			"* %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=\"/bin:/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, argv[0]);
+			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",
@@ -240,7 +320,10 @@  int main(const int argc, char *const argv[], char *const *const envp)
 	case 2:
 		/* Removes LANDLOCK_ACCESS_FS_TRUNCATE for ABI < 3 */
 		ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
-
+		__attribute__((fallthrough));
+	case 3:
+		/* Removes network support for ABI < 4 */
+		ruleset_attr.handled_access_net &= ~ACCESS_NET_BIND_CONNECT;
 		fprintf(stderr,
 			"Hint: You should update the running kernel "
 			"to leverage Landlock features "
@@ -259,16 +342,36 @@  int main(const int argc, char *const argv[], char *const *const envp)
 	access_fs_ro &= ruleset_attr.handled_access_fs;
 	access_fs_rw &= ruleset_attr.handled_access_fs;

+	/* Removes bind access attribute if not supported by a user. */
+	env_port_name = getenv(ENV_TCP_BIND_NAME);
+	if (!env_port_name) {
+		access_net_tcp &= ~LANDLOCK_ACCESS_NET_BIND_TCP;
+	}
+	/* Removes connect access attribute if not supported by a user. */
+	env_port_name = getenv(ENV_TCP_CONNECT_NAME);
+	if (!env_port_name) {
+		access_net_tcp &= ~LANDLOCK_ACCESS_NET_CONNECT_TCP;
+	}
+	ruleset_attr.handled_access_net &= access_net_tcp;
+
 	ruleset_fd =
 		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
 	if (ruleset_fd < 0) {
 		perror("Failed to create a ruleset");
 		return 1;
 	}
-	if (populate_ruleset(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
+	if (populate_ruleset_fs(ENV_FS_RO_NAME, ruleset_fd, access_fs_ro)) {
+		goto err_close_ruleset;
+	}
+	if (populate_ruleset_fs(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
+		goto err_close_ruleset;
+	}
+	if (populate_ruleset_net(ENV_TCP_BIND_NAME, ruleset_fd,
+				 LANDLOCK_ACCESS_NET_BIND_TCP)) {
 		goto err_close_ruleset;
 	}
-	if (populate_ruleset(ENV_FS_RW_NAME, ruleset_fd, access_fs_rw)) {
+	if (populate_ruleset_net(ENV_TCP_CONNECT_NAME, ruleset_fd,
+				 LANDLOCK_ACCESS_NET_CONNECT_TCP)) {
 		goto err_close_ruleset;
 	}
 	if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {