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AJvYcCXYRKK+I4RH+FgWkCRyn0FhF8wrh9ZK43axtqoc9iAZkVH0+qXpbC8yCeaE034PXgYW8RSBvPEd6VoIRPy55T4P+GLvU1DDx2iXiS5K7l323KjelP4dZcW5g/6WS18w7pF3t/WHLrn37uejnzbNXxNXiafU1jGX0NhpN/xRNxuLvsLa4n/01QSC1TAH X-Gm-Message-State: AOJu0YzdHQHtyP/Gwy8JWXMkNhdOA2c9WUoSJmwCeVukRLtb8ilxAWWr 2F7Medv2AgvXkuuEvsOPZ1KbHxS4z78rWh+EJp/66YuXziptr831 X-Google-Smtp-Source: AGHT+IFVoZPochyOfuDQ+SlstEbMIoO1KxFIxh7A1gCZ0HELnXmlpRbHjIqEFQp2l1KO0DZPRNgxTQ== X-Received: by 2002:a05:6871:23c1:b0:268:9d6b:672 with SMTP id 586e51a60fabf-2689d6b4e84mr556145fac.42.1722571388699; Thu, 01 Aug 2024 21:03:08 -0700 (PDT) Received: from tahera-OptiPlex-5000.tail3bf47f.ts.net ([136.159.49.123]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7106ec41465sm542099b3a.60.2024.08.01.21.03.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Aug 2024 21:03:07 -0700 (PDT) From: Tahera Fahimi To: outreachy@lists.linux.dev Cc: mic@digikod.net, gnoack@google.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn3_gh@protonmail.com, jannh@google.com, netdev@vger.kernel.org, Tahera Fahimi Subject: [PATCH v8 1/4] Landlock: Add abstract unix socket connect restriction Date: Thu, 1 Aug 2024 22:02:33 -0600 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 This patch introduces a new "scoped" attribute to the landlock_ruleset_attr that can specify "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" to scope abstract Unix sockets from connecting to a process outside of the same landlock domain. It implements two hooks, unix_stream_connect and unix_may_send to enforce this restriction. Closes: https://github.com/landlock-lsm/linux/issues/7 Signed-off-by: Tahera Fahimi --- v8: - Code refactoring (improve code readability, renaming variable, etc.) based on reviews by Mickaël Salaün on version 7. - Adding warn_on_once to check (impossible) inconsistencies. - Adding inline comments. - Adding check_unix_address_format to check if the scoping socket is an abstract unix sockets. v7: - Using socket's file credentials for both connected(STREAM) and non-connected(DGRAM) sockets. - Adding "domain_sock_scope" instead of the domain scoping mechanism used in ptrace ensures that if a server's domain is accessible from the client's domain (where the client is more privileged than the server), the client can connect to the server in all edge cases. - Removing debug codes. v6: - Removing curr_ruleset from landlock_hierarchy, and switching back to use the same domain scoping as ptrace. - code clean up. v5: - Renaming "LANDLOCK_*_ACCESS_SCOPE" to "LANDLOCK_*_SCOPE" - Adding curr_ruleset to hierarachy_ruleset structure to have access from landlock_hierarchy to its respective landlock_ruleset. - Using curr_ruleset to check if a domain is scoped while walking in the hierarchy of domains. - Modifying inline comments. V4: - Rebased on Günther's Patch: https://lore.kernel.org/all/20240610082115.1693267-1-gnoack@google.com/ so there is no need for "LANDLOCK_SHIFT_ACCESS_SCOPE", then it is removed. - Adding get_scope_accesses function to check all scoped access masks in a ruleset. - Using socket's file credentials instead of credentials stored in peer_cred for datagram sockets. (see discussion in [1]) - Modifying inline comments. V3: - Improving commit description. - Introducing "scoped" attribute to landlock_ruleset_attr for IPC scoping purpose, and adding related functions. - Changing structure of ruleset based on "scoped". - Removing rcu lock and using unix_sk lock instead. - Introducing scoping for datagram sockets in unix_may_send. V2: - Removing wrapper functions [1]https://lore.kernel.org/all/20240610.Aifee5ingugh@digikod.net/ ---- --- include/uapi/linux/landlock.h | 30 +++++++ security/landlock/limits.h | 3 + security/landlock/ruleset.c | 7 +- security/landlock/ruleset.h | 23 ++++- security/landlock/syscalls.c | 14 ++- security/landlock/task.c | 155 ++++++++++++++++++++++++++++++++++ 6 files changed, 225 insertions(+), 7 deletions(-) diff --git a/include/uapi/linux/landlock.h b/include/uapi/linux/landlock.h index 68625e728f43..ab31e9f53e55 100644 --- a/include/uapi/linux/landlock.h +++ b/include/uapi/linux/landlock.h @@ -37,6 +37,12 @@ struct landlock_ruleset_attr { * rule explicitly allow them. */ __u64 handled_access_net; + /** + * @scoped: Bitmask of scopes (cf. `Scope flags`_) + * restricting a Landlock domain from accessing outside + * resources(e.g. IPCs). + */ + __u64 scoped; }; /* @@ -266,4 +272,28 @@ struct landlock_net_port_attr { #define LANDLOCK_ACCESS_NET_BIND_TCP (1ULL << 0) #define LANDLOCK_ACCESS_NET_CONNECT_TCP (1ULL << 1) /* clang-format on */ + +/** + * DOC: scope + * + * scoped attribute handles a set of restrictions on kernel IPCs through + * the following flags. + * + * Scope flags + * ~~~~~~~~~~~ + * + * These flags enable to restrict a sandboxed process from a set of IPC + * actions. Setting a flag for a ruleset will isolate the Landlock domain + * to forbid connections to resources outside the domain. + * + * IPCs with scoped actions: + * + * - %LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET: Restrict a sandboxed process + * from connecting to an abstract unix socket created by a process + * outside the related Landlock domain (e.g. a parent domain or a + * non-sandboxed process). + */ +/* clang-format off */ +#define LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET (1ULL << 0) +/* clang-format on*/ #endif /* _UAPI_LINUX_LANDLOCK_H */ diff --git a/security/landlock/limits.h b/security/landlock/limits.h index 4eb643077a2a..eb01d0fb2165 100644 --- a/security/landlock/limits.h +++ b/security/landlock/limits.h @@ -26,6 +26,9 @@ #define LANDLOCK_MASK_ACCESS_NET ((LANDLOCK_LAST_ACCESS_NET << 1) - 1) #define LANDLOCK_NUM_ACCESS_NET __const_hweight64(LANDLOCK_MASK_ACCESS_NET) +#define LANDLOCK_LAST_SCOPE LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET +#define LANDLOCK_MASK_SCOPE ((LANDLOCK_LAST_SCOPE << 1) - 1) +#define LANDLOCK_NUM_SCOPE __const_hweight64(LANDLOCK_MASK_SCOPE) /* clang-format on */ #endif /* _SECURITY_LANDLOCK_LIMITS_H */ diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c index 6ff232f58618..a93bdbf52fff 100644 --- a/security/landlock/ruleset.c +++ b/security/landlock/ruleset.c @@ -52,12 +52,13 @@ static struct landlock_ruleset *create_ruleset(const u32 num_layers) struct landlock_ruleset * landlock_create_ruleset(const access_mask_t fs_access_mask, - const access_mask_t net_access_mask) + const access_mask_t net_access_mask, + const access_mask_t scope_mask) { struct landlock_ruleset *new_ruleset; /* Informs about useless ruleset. */ - if (!fs_access_mask && !net_access_mask) + if (!fs_access_mask && !net_access_mask && !scope_mask) return ERR_PTR(-ENOMSG); new_ruleset = create_ruleset(1); if (IS_ERR(new_ruleset)) @@ -66,6 +67,8 @@ landlock_create_ruleset(const access_mask_t fs_access_mask, landlock_add_fs_access_mask(new_ruleset, fs_access_mask, 0); if (net_access_mask) landlock_add_net_access_mask(new_ruleset, net_access_mask, 0); + if (scope_mask) + landlock_add_scope_mask(new_ruleset, scope_mask, 0); return new_ruleset; } diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h index 0f1b5b4c8f6b..c749fa0b3ecd 100644 --- a/security/landlock/ruleset.h +++ b/security/landlock/ruleset.h @@ -35,6 +35,8 @@ typedef u16 access_mask_t; static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS); /* Makes sure all network access rights can be stored. */ static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET); +/* Makes sure all scoped rights can be stored*/ +static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_SCOPE); /* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */ static_assert(sizeof(unsigned long) >= sizeof(access_mask_t)); @@ -42,6 +44,7 @@ static_assert(sizeof(unsigned long) >= sizeof(access_mask_t)); struct access_masks { access_mask_t fs : LANDLOCK_NUM_ACCESS_FS; access_mask_t net : LANDLOCK_NUM_ACCESS_NET; + access_mask_t scoped : LANDLOCK_NUM_SCOPE; }; typedef u16 layer_mask_t; @@ -233,7 +236,8 @@ struct landlock_ruleset { struct landlock_ruleset * landlock_create_ruleset(const access_mask_t access_mask_fs, - const access_mask_t access_mask_net); + const access_mask_t access_mask_net, + const access_mask_t scope_mask); void landlock_put_ruleset(struct landlock_ruleset *const ruleset); void landlock_put_ruleset_deferred(struct landlock_ruleset *const ruleset); @@ -280,6 +284,16 @@ landlock_add_net_access_mask(struct landlock_ruleset *const ruleset, ruleset->access_masks[layer_level].net |= net_mask; } +static inline void +landlock_add_scope_mask(struct landlock_ruleset *const ruleset, + const access_mask_t scope_mask, const u16 layer_level) +{ + access_mask_t scoped_mask = scope_mask & LANDLOCK_MASK_SCOPE; + + WARN_ON_ONCE(scope_mask != scoped_mask); + ruleset->access_masks[layer_level].scoped |= scoped_mask; +} + static inline access_mask_t landlock_get_raw_fs_access_mask(const struct landlock_ruleset *const ruleset, const u16 layer_level) @@ -303,6 +317,13 @@ landlock_get_net_access_mask(const struct landlock_ruleset *const ruleset, return ruleset->access_masks[layer_level].net; } +static inline access_mask_t +landlock_get_scope_mask(const struct landlock_ruleset *const ruleset, + const u16 layer_level) +{ + return ruleset->access_masks[layer_level].scoped; +} + bool landlock_unmask_layers(const struct landlock_rule *const rule, const access_mask_t access_request, layer_mask_t (*const layer_masks)[], diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index 03b470f5a85a..f51b29521d6b 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -97,8 +97,9 @@ static void build_check_abi(void) */ ruleset_size = sizeof(ruleset_attr.handled_access_fs); ruleset_size += sizeof(ruleset_attr.handled_access_net); + ruleset_size += sizeof(ruleset_attr.scoped); BUILD_BUG_ON(sizeof(ruleset_attr) != ruleset_size); - BUILD_BUG_ON(sizeof(ruleset_attr) != 16); + BUILD_BUG_ON(sizeof(ruleset_attr) != 24); path_beneath_size = sizeof(path_beneath_attr.allowed_access); path_beneath_size += sizeof(path_beneath_attr.parent_fd); @@ -149,7 +150,7 @@ static const struct file_operations ruleset_fops = { .write = fop_dummy_write, }; -#define LANDLOCK_ABI_VERSION 5 +#define LANDLOCK_ABI_VERSION 6 /** * sys_landlock_create_ruleset - Create a new ruleset @@ -170,7 +171,7 @@ static const struct file_operations ruleset_fops = { * Possible returned errors are: * * - %EOPNOTSUPP: Landlock is supported by the kernel but disabled at boot time; - * - %EINVAL: unknown @flags, or unknown access, or too small @size; + * - %EINVAL: unknown @flags, or unknown access, or unknown scope, or too small @size; * - %E2BIG or %EFAULT: @attr or @size inconsistencies; * - %ENOMSG: empty &landlock_ruleset_attr.handled_access_fs. */ @@ -213,9 +214,14 @@ SYSCALL_DEFINE3(landlock_create_ruleset, LANDLOCK_MASK_ACCESS_NET) return -EINVAL; + /* Checks IPC scoping content (and 32-bits cast). */ + if ((ruleset_attr.scoped | LANDLOCK_MASK_SCOPE) != LANDLOCK_MASK_SCOPE) + return -EINVAL; + /* Checks arguments and transforms to kernel struct. */ ruleset = landlock_create_ruleset(ruleset_attr.handled_access_fs, - ruleset_attr.handled_access_net); + ruleset_attr.handled_access_net, + ruleset_attr.scoped); if (IS_ERR(ruleset)) return PTR_ERR(ruleset); diff --git a/security/landlock/task.c b/security/landlock/task.c index 849f5123610b..7e8579ebae83 100644 --- a/security/landlock/task.c +++ b/security/landlock/task.c @@ -13,6 +13,8 @@ #include #include #include +#include +#include #include "common.h" #include "cred.h" @@ -108,9 +110,162 @@ static int hook_ptrace_traceme(struct task_struct *const parent) return task_ptrace(parent, current); } +static bool walk_and_check(const struct landlock_ruleset *const child, + struct landlock_hierarchy **walker, + size_t base_layer, size_t deep_layer, + access_mask_t check_scoping) +{ + if (!child || base_layer < 0 || !(*walker)) + return false; + + for (deep_layer; base_layer < deep_layer; deep_layer--) { + if (check_scoping & landlock_get_scope_mask(child, deep_layer)) + return false; + *walker = (*walker)->parent; + if (WARN_ON_ONCE(!*walker)) + /* there is an inconsistency between num_layers + * and landlock_hierarchy in the ruleset + */ + return false; + } + return true; +} + +/** + * domain_IPC_scope - Checks if the client domain is scoped in the same + * domain as the server. + * + * @client: IPC sender domain. + * @server: IPC receiver domain. + * + * Check if the @client domain is scoped to access the @server; the @server + * must be scoped in the same domain. + */ +static bool domain_IPC_scope(const struct landlock_ruleset *const client, + const struct landlock_ruleset *const server, + access_mask_t ipc_type) +{ + size_t client_layer, server_layer = 0; + int base_layer; + struct landlock_hierarchy *client_walker, *server_walker; + bool is_scoped; + + /* Quick return if client has no domain */ + if (!client) + return true; + + client_layer = client->num_layers - 1; + client_walker = client->hierarchy; + if (server) { + server_layer = server->num_layers - 1; + server_walker = server->hierarchy; + } + base_layer = (client_layer > server_layer) ? server_layer : + client_layer; + + /* For client domain, walk_and_check ensures the client domain is + * not scoped until gets to base_layer. + * For server_domain, it only ensures that the server domain exist. + */ + if (client_layer != server_layer) { + if (client_layer > server_layer) + is_scoped = walk_and_check(client, &client_walker, + server_layer, client_layer, + ipc_type); + else + is_scoped = walk_and_check(server, &server_walker, + client_layer, server_layer, + ipc_type & 0); + if (!is_scoped) + return false; + } + /* client and server are at the same level in hierarchy. If client is + * scoped, the server must be scoped in the same domain + */ + for (base_layer; base_layer >= 0; base_layer--) { + if (landlock_get_scope_mask(client, base_layer) & ipc_type) { + /* This check must be here since access would be denied only if + * the client is scoped and the server has no domain, so + * if the client has a domain but is not scoped and the server + * has no domain, access is guaranteed. + */ + if (!server) + return false; + + if (server_walker == client_walker) + return true; + + return false; + } + client_walker = client_walker->parent; + server_walker = server_walker->parent; + /* Warn if there is an incosistenncy between num_layers and + * landlock_hierarchy in each of rulesets + */ + if (WARN_ON_ONCE(base_layer > 0 && + (!server_walker || !client_walker))) + return false; + } + return true; +} + +static bool sock_is_scoped(struct sock *const other) +{ + const struct landlock_ruleset *dom_other; + const struct landlock_ruleset *const dom = + landlock_get_current_domain(); + + /* the credentials will not change */ + lockdep_assert_held(&unix_sk(other)->lock); + dom_other = landlock_cred(other->sk_socket->file->f_cred)->domain; + return domain_IPC_scope(dom, dom_other, + LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET); +} + +static bool check_unix_address_format(struct sock *const sock) +{ + struct unix_address *addr = unix_sk(sock)->addr; + + if (!addr) + return true; + + if (addr->len > sizeof(AF_UNIX)) { + /* handling unspec sockets */ + if (!addr->name[0].sun_path) + return true; + + if (addr->name[0].sun_path[0] == '\0') + if (!sock_is_scoped(sock)) + return false; + } + + return true; +} + +static int hook_unix_stream_connect(struct sock *const sock, + struct sock *const other, + struct sock *const newsk) +{ + if (check_unix_address_format(other)) + return 0; + + return -EPERM; +} + +static int hook_unix_may_send(struct socket *const sock, + struct socket *const other) +{ + if (check_unix_address_format(other->sk)) + return 0; + + return -EPERM; +} + static struct security_hook_list landlock_hooks[] __ro_after_init = { LSM_HOOK_INIT(ptrace_access_check, hook_ptrace_access_check), LSM_HOOK_INIT(ptrace_traceme, hook_ptrace_traceme), + LSM_HOOK_INIT(unix_stream_connect, hook_unix_stream_connect), + LSM_HOOK_INIT(unix_may_send, hook_unix_may_send), }; 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AJvYcCV7RD+64wF3NzZxsZCEC4I7qSyGDh27pHexDF3fWUnXTrzFt1DOcE7Dkg8j0rik/dlm57W6oXmJ+ZQjSJEdqWskCDvZTRkdycaDgdbU0o194vikr5SgHhnOfauNSpXE6uMeMZqv76BdCQ7gRtEy4yAM7Y8mVhQvl5e5mJJsYPf3JoK0brtyqwYEhbzH X-Gm-Message-State: AOJu0YzpWiBk/9rpHQn/cj4nn7Iy1V8VVnTYD+F70Ty04l6Wb9Bll/AT fNWbYkTyomY1eHDeV09yWHtzXEqxTPsOGG1QPWrCyejNv32inPt3 X-Google-Smtp-Source: AGHT+IFnPegTXtPGPS8OmCwhkDpNHF8wIYHl1mv9Vnc5H2krNXOcgoe0HhI54WW5IYq4pwq+ibSuNg== X-Received: by 2002:a05:6870:3c07:b0:260:fdda:5068 with SMTP id 586e51a60fabf-26891ab181cmr2678160fac.4.1722571390054; Thu, 01 Aug 2024 21:03:10 -0700 (PDT) Received: from tahera-OptiPlex-5000.tail3bf47f.ts.net ([136.159.49.123]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7106ec41465sm542099b3a.60.2024.08.01.21.03.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Aug 2024 21:03:09 -0700 (PDT) From: Tahera Fahimi To: outreachy@lists.linux.dev Cc: mic@digikod.net, gnoack@google.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn3_gh@protonmail.com, jannh@google.com, netdev@vger.kernel.org, Tahera Fahimi Subject: [PATCH v8 2/4] selftests/landlock: Abstract unix socket restriction tests Date: Thu, 1 Aug 2024 22:02:34 -0600 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 The patch introduces Landlock ABI version 6 and has four types of tests: 1) unix_socket: base tests of the abstract socket scoping mechanism for a landlocked process, same as the ptrace test. 2) optional_scoping: generates three processes with different domains and tests if a process with a non-scoped domain can connect to other processes. 3) unix_sock_special_cases: since the socket's creator credentials are used for scoping sockets, this test examines the cases where the socket's credentials are different from the process using it. 4) pathname_address_sockets: ensures that Unix sockets bound to a null-terminated filesystem can still connect to a socket outside of their scoped domain. This means that even if the domain is scoped with LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, the socket can connect to a socket outside the scoped domain. Signed-off-by: Tahera Fahimi --- Changes in versions: V8: - Move tests to scoped_abstract_unix_test.c file. - To avoid potential conflicts among Unix socket names in different tests, set_unix_address is added to common.h to set different sun_path for Unix sockets. - protocol_variant and service_fixture structures are also moved to common.h - Adding pathname_address_sockets to cover all types of address formats for unix sockets, and moving remove_path() to common.h to reuse in this test. V7: - Introducing landlock ABI version 6. - Adding some edge test cases to optional_scoping test. - Using `enum` for different domains in optional_scoping tests. - Extend unix_sock_special_cases test cases for connected(SOCK_STREAM) sockets. - Modifying inline comments. V6: - Introducing optional_scoping test which ensures a sandboxed process with a non-scoped domain can still connect to another abstract unix socket(either sandboxed or non-sandboxed). - Introducing unix_sock_special_cases test which tests examines scenarios where the connecting sockets have different domain than the process using them. V4: - Introducing unix_socket to evaluate the basic scoping mechanism for abstract unix sockets. --- tools/testing/selftests/landlock/base_test.c | 2 +- tools/testing/selftests/landlock/common.h | 72 ++ tools/testing/selftests/landlock/fs_test.c | 34 - tools/testing/selftests/landlock/net_test.c | 31 +- .../landlock/scoped_abstract_unix_test.c | 1136 +++++++++++++++++ 5 files changed, 1210 insertions(+), 65 deletions(-) create mode 100644 tools/testing/selftests/landlock/scoped_abstract_unix_test.c diff --git a/tools/testing/selftests/landlock/base_test.c b/tools/testing/selftests/landlock/base_test.c index 3c1e9f35b531..52b00472a487 100644 --- a/tools/testing/selftests/landlock/base_test.c +++ b/tools/testing/selftests/landlock/base_test.c @@ -75,7 +75,7 @@ TEST(abi_version) const struct landlock_ruleset_attr ruleset_attr = { .handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE, }; - ASSERT_EQ(5, landlock_create_ruleset(NULL, 0, + ASSERT_EQ(6, landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION)); ASSERT_EQ(-1, landlock_create_ruleset(&ruleset_attr, 0, diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h index 7e2b431b9f90..a0c8126d94b4 100644 --- a/tools/testing/selftests/landlock/common.h +++ b/tools/testing/selftests/landlock/common.h @@ -16,8 +16,11 @@ #include #include #include +#include +#include #include "../kselftest_harness.h" +#define TMP_DIR "tmp" #ifndef __maybe_unused #define __maybe_unused __attribute__((__unused__)) @@ -226,3 +229,72 @@ enforce_ruleset(struct __test_metadata *const _metadata, const int ruleset_fd) TH_LOG("Failed to enforce ruleset: %s", strerror(errno)); } } + +struct protocol_variant { + int domain; + int type; +}; + +struct service_fixture { + struct protocol_variant protocol; + /* port is also stored in ipv4_addr.sin_port or ipv6_addr.sin6_port */ + unsigned short port; + union { + struct sockaddr_in ipv4_addr; + struct sockaddr_in6 ipv6_addr; + struct { + struct sockaddr_un unix_addr; + socklen_t unix_addr_len; + }; + }; +}; + +static pid_t __maybe_unused sys_gettid(void) +{ + return syscall(__NR_gettid); +} + +static void __maybe_unused set_unix_address(struct service_fixture *const srv, + const unsigned short index) +{ + srv->unix_addr.sun_family = AF_UNIX; + sprintf(srv->unix_addr.sun_path, + "_selftests-landlock-abstract-unix-tid%d-index%d", sys_gettid(), + index); + srv->unix_addr_len = SUN_LEN(&srv->unix_addr); + srv->unix_addr.sun_path[0] = '\0'; +} + +static int __maybe_unused remove_path(const char *const path) +{ + char *walker; + int i, ret, err = 0; + + walker = strdup(path); + if (!walker) { + err = ENOMEM; + goto out; + } + if (unlink(path) && rmdir(path)) { + if (errno != ENOENT && errno != ENOTDIR) + err = errno; + goto out; + } + for (i = strlen(walker); i > 0; i--) { + if (walker[i] != '/') + continue; + walker[i] = '\0'; + ret = rmdir(walker); + if (ret) { + if (errno != ENOTEMPTY && errno != EBUSY) + err = errno; + goto out; + } + if (strcmp(walker, TMP_DIR) == 0) + goto out; + } + +out: + free(walker); + return err; +} diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c index 7d063c652be1..fc74cab6dfb8 100644 --- a/tools/testing/selftests/landlock/fs_test.c +++ b/tools/testing/selftests/landlock/fs_test.c @@ -221,40 +221,6 @@ static void create_file(struct __test_metadata *const _metadata, } } -static int remove_path(const char *const path) -{ - char *walker; - int i, ret, err = 0; - - walker = strdup(path); - if (!walker) { - err = ENOMEM; - goto out; - } - if (unlink(path) && rmdir(path)) { - if (errno != ENOENT && errno != ENOTDIR) - err = errno; - goto out; - } - for (i = strlen(walker); i > 0; i--) { - if (walker[i] != '/') - continue; - walker[i] = '\0'; - ret = rmdir(walker); - if (ret) { - if (errno != ENOTEMPTY && errno != EBUSY) - err = errno; - goto out; - } - if (strcmp(walker, TMP_DIR) == 0) - goto out; - } - -out: - free(walker); - return err; -} - struct mnt_opt { const char *const source; const char *const type; diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c index f21cfbbc3638..4e0aeb53b225 100644 --- a/tools/testing/selftests/landlock/net_test.c +++ b/tools/testing/selftests/landlock/net_test.c @@ -36,30 +36,6 @@ enum sandbox_type { TCP_SANDBOX, }; -struct protocol_variant { - int domain; - int type; -}; - -struct service_fixture { - struct protocol_variant protocol; - /* port is also stored in ipv4_addr.sin_port or ipv6_addr.sin6_port */ - unsigned short port; - union { - struct sockaddr_in ipv4_addr; - struct sockaddr_in6 ipv6_addr; - struct { - struct sockaddr_un unix_addr; - socklen_t unix_addr_len; - }; - }; -}; - -static pid_t sys_gettid(void) -{ - return syscall(__NR_gettid); -} - static int set_service(struct service_fixture *const srv, const struct protocol_variant prot, const unsigned short index) @@ -92,12 +68,7 @@ static int set_service(struct service_fixture *const srv, return 0; case AF_UNIX: - srv->unix_addr.sun_family = prot.domain; - sprintf(srv->unix_addr.sun_path, - "_selftests-landlock-net-tid%d-index%d", sys_gettid(), - index); - srv->unix_addr_len = SUN_LEN(&srv->unix_addr); - srv->unix_addr.sun_path[0] = '\0'; + set_unix_address(srv, index); return 0; } return 1; diff --git a/tools/testing/selftests/landlock/scoped_abstract_unix_test.c b/tools/testing/selftests/landlock/scoped_abstract_unix_test.c new file mode 100644 index 000000000000..ffa1f01dbbce --- /dev/null +++ b/tools/testing/selftests/landlock/scoped_abstract_unix_test.c @@ -0,0 +1,1136 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Landlock tests - Abstract Unix Socket + * + * Copyright © 2017-2020 Mickaël Salaün + * Copyright © 2019-2020 ANSSI + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "common.h" + +static void create_fs_domain(struct __test_metadata *const _metadata) +{ + int ruleset_fd; + struct landlock_ruleset_attr ruleset_attr = { + .handled_access_fs = LANDLOCK_ACCESS_FS_READ_DIR, + }; + + ruleset_fd = + landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); + EXPECT_LE(0, ruleset_fd) + { + TH_LOG("Failed to create a ruleset: %s", strerror(errno)); + } + EXPECT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)); + EXPECT_EQ(0, landlock_restrict_self(ruleset_fd, 0)); + EXPECT_EQ(0, close(ruleset_fd)); +} + +static void create_unix_domain(struct __test_metadata *const _metadata) +{ + int ruleset_fd; + const struct landlock_ruleset_attr ruleset_attr = { + .scoped = LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, + }; + + ruleset_fd = + landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); + EXPECT_LE(0, ruleset_fd) + { + TH_LOG("Failed to create a ruleset: %s", strerror(errno)); + } + enforce_ruleset(_metadata, ruleset_fd); + EXPECT_EQ(0, close(ruleset_fd)); +} + +/* clang-format off */ +FIXTURE(unix_socket) +{ + struct service_fixture stream_address, dgram_address; + int server, client, dgram_server, dgram_client; +}; + +/* clang-format on */ +FIXTURE_VARIANT(unix_socket) +{ + bool domain_both; + bool domain_parent; + bool domain_child; + bool connect_to_parent; +}; + +FIXTURE_SETUP(unix_socket) +{ + memset(&self->stream_address, 0, sizeof(self->stream_address)); + memset(&self->dgram_address, 0, sizeof(self->dgram_address)); + + set_unix_address(&self->stream_address, 0); + set_unix_address(&self->dgram_address, 1); +} + +FIXTURE_TEARDOWN(unix_socket) +{ + close(self->server); + close(self->client); + close(self->dgram_server); + close(self->dgram_client); +} + +/* + * No domain + * + * P1-. P1 -> P2 : allow + * \ P2 -> P1 : allow + * 'P2 + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_without_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = false, + .domain_parent = false, + .domain_child = false, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_without_domain_connect_to_child) { + /* clang-format on */ + .domain_both = false, + .domain_parent = false, + .domain_child = false, + .connect_to_parent = false, +}; + +/* + * Child domain + * + * P1--. P1 -> P2 : allow + * \ P2 -> P1 : deny + * .'-----. + * | P2 | + * '------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_one_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = false, + .domain_parent = false, + .domain_child = true, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_with_one_domain_connect_to_child) { + /* clang-format on */ + .domain_both = false, + .domain_parent = false, + .domain_child = true, + .connect_to_parent = false, +}; + +/* + * Parent domain + * .------. + * | P1 --. P1 -> P2 : deny + * '------' \ P2 -> P1 : allow + * ' + * P2 + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_with_parent_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = false, + .domain_parent = true, + .domain_child = false, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_parent_domain_connect_to_child) { + /* clang-format on */ + .domain_both = false, + .domain_parent = true, + .domain_child = false, + .connect_to_parent = false, +}; + +/* + * Parent + child domain (siblings) + * .------. + * | P1 ---. P1 -> P2 : deny + * '------' \ P2 -> P1 : deny + * .---'--. + * | P2 | + * '------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_sibling_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = false, + .domain_parent = true, + .domain_child = true, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_sibling_domain_connect_to_child) { + /* clang-format on */ + .domain_both = false, + .domain_parent = true, + .domain_child = true, + .connect_to_parent = false, +}; + +/* + * Same domain (inherited) + * .-------------. + * | P1----. | P1 -> P2 : allow + * | \ | P2 -> P1 : allow + * | ' | + * | P2 | + * '-------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_inherited_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = true, + .domain_parent = false, + .domain_child = false, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_inherited_domain_connect_to_child) { + /* clang-format on */ + .domain_both = true, + .domain_parent = false, + .domain_child = false, + .connect_to_parent = false, +}; + +/* + * Inherited + child domain + * .-----------------. + * | P1----. | P1 -> P2 : allow + * | \ | P2 -> P1 : deny + * | .-'----. | + * | | P2 | | + * | '------' | + * '-----------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_nested_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = true, + .domain_parent = false, + .domain_child = true, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_nested_domain_connect_to_child) { + /* clang-format on */ + .domain_both = true, + .domain_parent = false, + .domain_child = true, + .connect_to_parent = false, +}; + +/* + * Inherited + parent domain + * .-----------------. + * |.------. | P1 -> P2 : deny + * || P1 ----. | P2 -> P1 : allow + * |'------' \ | + * | ' | + * | P2 | + * '-----------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, allow_with_nested_and_parent_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = true, + .domain_parent = true, + .domain_child = false, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_nested_and_parent_domain_connect_to_child) { + /* clang-format on */ + .domain_both = true, + .domain_parent = true, + .domain_child = false, + .connect_to_parent = false, +}; + +/* + * Inherited + parent and child domain (siblings) + * .-----------------. + * | .------. | P1 -> P2 : deny + * | | P1 . | P2 -> P1 : deny + * | '------'\ | + * | \ | + * | .--'---. | + * | | P2 | | + * | '------' | + * '-----------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_forked_domain_connect_to_parent) { + /* clang-format on */ + .domain_both = true, + .domain_parent = true, + .domain_child = true, + .connect_to_parent = true, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_socket, deny_with_forked_domain_connect_to_child) { + /* clang-format on */ + .domain_both = true, + .domain_parent = true, + .domain_child = true, + .connect_to_parent = false, +}; + +/* Test UNIX_STREAM_CONNECT and UNIX_MAY_SEND for parent and child, + * when they have scoped domain or no domain. + */ +TEST_F(unix_socket, abstract_unix_socket) +{ + int status; + pid_t child; + bool can_connect_to_parent, can_connect_to_child; + int err, err_dgram; + int pipe_child[2], pipe_parent[2]; + char buf_parent; + + /* + * can_connect_to_child is true if a parent process can connect to its + * child process. The parent process is not isolated from the child + * with a dedicated Landlock domain. + */ + can_connect_to_child = !variant->domain_parent; + /* + * can_connect_to_parent is true if a child process can connect to its + * parent process. This depends on the child process is not isolated from + * the parent with a dedicated Landlock domain. + */ + can_connect_to_parent = !variant->domain_child; + + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC)); + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); + if (variant->domain_both) { + create_unix_domain(_metadata); + if (!__test_passed(_metadata)) + return; + } + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + char buf_child; + + ASSERT_EQ(0, close(pipe_parent[1])); + ASSERT_EQ(0, close(pipe_child[0])); + if (variant->domain_child) + create_unix_domain(_metadata); + + /* Waits for the parent to be in a domain, if any. */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + + if (variant->connect_to_parent) { + self->client = socket(AF_UNIX, SOCK_STREAM, 0); + self->dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0); + + ASSERT_NE(-1, self->client); + ASSERT_NE(-1, self->dgram_client); + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + + err = connect(self->client, + &self->stream_address.unix_addr, + (self->stream_address).unix_addr_len); + err_dgram = + connect(self->dgram_client, + &self->dgram_address.unix_addr, + (self->dgram_address).unix_addr_len); + + if (can_connect_to_parent) { + EXPECT_EQ(0, err); + EXPECT_EQ(0, err_dgram); + } else { + EXPECT_EQ(-1, err); + EXPECT_EQ(-1, err_dgram); + EXPECT_EQ(EPERM, errno); + } + } else { + self->server = socket(AF_UNIX, SOCK_STREAM, 0); + self->dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0); + ASSERT_NE(-1, self->server); + ASSERT_NE(-1, self->dgram_server); + + ASSERT_EQ(0, + bind(self->server, + &self->stream_address.unix_addr, + (self->stream_address).unix_addr_len)); + ASSERT_EQ(0, bind(self->dgram_server, + &self->dgram_address.unix_addr, + (self->dgram_address).unix_addr_len)); + ASSERT_EQ(0, listen(self->server, 32)); + + /* signal to parent that child is listening */ + ASSERT_EQ(1, write(pipe_child[1], ".", 1)); + /* wait to connect */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + } + _exit(_metadata->exit_code); + return; + } + + ASSERT_EQ(0, close(pipe_child[1])); + ASSERT_EQ(0, close(pipe_parent[0])); + + if (variant->domain_parent) + create_unix_domain(_metadata); + + /* Signals that the parent is in a domain, if any. */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + + if (!variant->connect_to_parent) { + self->client = socket(AF_UNIX, SOCK_STREAM, 0); + self->dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0); + + ASSERT_NE(-1, self->client); + ASSERT_NE(-1, self->dgram_client); + + /* Waits for the child to listen */ + ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1)); + err = connect(self->client, &self->stream_address.unix_addr, + (self->stream_address).unix_addr_len); + err_dgram = connect(self->dgram_client, + &self->dgram_address.unix_addr, + (self->dgram_address).unix_addr_len); + + if (can_connect_to_child) { + EXPECT_EQ(0, err); + EXPECT_EQ(0, err_dgram); + } else { + EXPECT_EQ(-1, err); + EXPECT_EQ(-1, err_dgram); + EXPECT_EQ(EPERM, errno); + } + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + } else { + self->server = socket(AF_UNIX, SOCK_STREAM, 0); + self->dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0); + ASSERT_NE(-1, self->server); + ASSERT_NE(-1, self->dgram_server); + ASSERT_EQ(0, bind(self->server, &self->stream_address.unix_addr, + (self->stream_address).unix_addr_len)); + ASSERT_EQ(0, bind(self->dgram_server, + &self->dgram_address.unix_addr, + (self->dgram_address).unix_addr_len)); + ASSERT_EQ(0, listen(self->server, 32)); + + /* signal to child that parent is listening */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + } + + ASSERT_EQ(child, waitpid(child, &status, 0)); + + if (WIFSIGNALED(status) || !WIFEXITED(status) || + WEXITSTATUS(status) != EXIT_SUCCESS) + _metadata->exit_code = KSFT_FAIL; +} + +enum sandbox_type { + NO_SANDBOX, + SCOPE_SANDBOX, + /* Any other type of sandboxing domain */ + OTHER_SANDBOX, +}; + +/* clang-format off */ +FIXTURE(optional_scoping) +{ + struct service_fixture parent_address, child_address; + int parent_server, child_server, client; +}; + +/* clang-format on */ +FIXTURE_VARIANT(optional_scoping) +{ + const int domain_all; + const int domain_parent; + const int domain_children; + const int domain_child; + const int domain_grand_child; + const int type; +}; + +FIXTURE_SETUP(optional_scoping) +{ + memset(&self->parent_address, 0, sizeof(self->parent_address)); + memset(&self->child_address, 0, sizeof(self->child_address)); + + set_unix_address(&self->parent_address, 0); + set_unix_address(&self->child_address, 1); +} + +FIXTURE_TEARDOWN(optional_scoping) +{ + close(self->parent_server); + close(self->child_server); + close(self->client); +} + +/* + * .-----------------. + * | ####### | P3 -> P2 : allow + * | P1----# P2 # | P3 -> P1 : deny + * | # | # | + * | # P3 # | + * | ####### | + * '-----------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(optional_scoping, deny_scoped) { + .domain_all = OTHER_SANDBOX, + .domain_parent = NO_SANDBOX, + .domain_children = SCOPE_SANDBOX, + .domain_child = NO_SANDBOX, + .domain_grand_child = NO_SANDBOX, + .type = SOCK_DGRAM, + /* clang-format on */ +}; + +/* + * .-----------------. + * | .-----. | P3 -> P2 : allow + * | P1----| P2 | | P3 -> P1 : allow + * | | | | + * | | P3 | | + * | '-----' | + * '-----------------' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(optional_scoping, allow_with_other_domain) { + .domain_all = OTHER_SANDBOX, + .domain_parent = NO_SANDBOX, + .domain_children = OTHER_SANDBOX, + .domain_child = NO_SANDBOX, + .domain_grand_child = NO_SANDBOX, + .type = SOCK_DGRAM, + /* clang-format on */ +}; + +/* + * .----. ###### P3 -> P2 : allow + * | P1 |----# P2 # P3 -> P1 : allow + * '----' ###### + * | + * P3 + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(optional_scoping, allow_with_one_domain) { + .domain_all = NO_SANDBOX, + .domain_parent = OTHER_SANDBOX, + .domain_children = NO_SANDBOX, + .domain_child = SCOPE_SANDBOX, + .domain_grand_child = NO_SANDBOX, + .type = SOCK_DGRAM, + /* clang-format on */ +}; + +/* + * ###### .-----. P3 -> P2 : allow + * # P1 #----| P2 | P3 -> P1 : allow + * ###### '-----' + * | + * P3 + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(optional_scoping, allow_with_grand_parent_scoped) { + .domain_all = NO_SANDBOX, + .domain_parent = SCOPE_SANDBOX, + .domain_children = NO_SANDBOX, + .domain_child = OTHER_SANDBOX, + .domain_grand_child = NO_SANDBOX, + .type = SOCK_STREAM, + /* clang-format on */ +}; + +/* + * ###### ###### P3 -> P2 : allow + * # P1 #----# P2 # P3 -> P1 : allow + * ###### ###### + * | + * .----. + * | P3 | + * '----' + */ +/* clang-format off */ +FIXTURE_VARIANT_ADD(optional_scoping, allow_with_parents_domain) { + .domain_all = NO_SANDBOX, + .domain_parent = SCOPE_SANDBOX, + .domain_children = NO_SANDBOX, + .domain_child = SCOPE_SANDBOX, + .domain_grand_child = NO_SANDBOX, + .type = SOCK_STREAM, + /* clang-format on */ +}; + +/* Test UNIX_STREAM_CONNECT and UNIX_MAY_SEND for parent, child + * and grand child processes when they can have scoped or non-scoped + * domains. + **/ +TEST_F(optional_scoping, unix_scoping) +{ + pid_t child; + int status; + bool can_connect_to_parent, can_connect_to_child; + int pipe_parent[2]; + + if (variant->domain_grand_child == SCOPE_SANDBOX) + can_connect_to_child = false; + else + can_connect_to_child = true; + + if (!can_connect_to_child || variant->domain_children == SCOPE_SANDBOX) + can_connect_to_parent = false; + else + can_connect_to_parent = true; + + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); + + if (variant->domain_all == OTHER_SANDBOX) + create_fs_domain(_metadata); + else if (variant->domain_all == SCOPE_SANDBOX) + create_unix_domain(_metadata); + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + int pipe_child[2]; + + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC)); + pid_t grand_child; + + if (variant->domain_children == OTHER_SANDBOX) + create_fs_domain(_metadata); + else if (variant->domain_children == SCOPE_SANDBOX) + create_unix_domain(_metadata); + + grand_child = fork(); + ASSERT_LE(0, grand_child); + if (grand_child == 0) { + ASSERT_EQ(0, close(pipe_parent[1])); + ASSERT_EQ(0, close(pipe_child[1])); + + char buf1, buf2; + int err; + + if (variant->domain_grand_child == OTHER_SANDBOX) + create_fs_domain(_metadata); + else if (variant->domain_grand_child == SCOPE_SANDBOX) + create_unix_domain(_metadata); + + self->client = socket(AF_UNIX, variant->type, 0); + ASSERT_NE(-1, self->client); + + ASSERT_EQ(1, read(pipe_child[0], &buf2, 1)); + err = connect(self->client, + &self->child_address.unix_addr, + (self->child_address).unix_addr_len); + if (can_connect_to_child) { + EXPECT_EQ(0, err); + } else { + EXPECT_EQ(-1, err); + EXPECT_EQ(EPERM, errno); + } + + if (variant->type == SOCK_STREAM) { + EXPECT_EQ(0, close(self->client)); + self->client = + socket(AF_UNIX, variant->type, 0); + ASSERT_NE(-1, self->client); + } + + ASSERT_EQ(1, read(pipe_parent[0], &buf1, 1)); + err = connect(self->client, + &self->parent_address.unix_addr, + (self->parent_address).unix_addr_len); + if (can_connect_to_parent) { + EXPECT_EQ(0, err); + } else { + EXPECT_EQ(-1, err); + EXPECT_EQ(EPERM, errno); + } + EXPECT_EQ(0, close(self->client)); + + _exit(_metadata->exit_code); + return; + } + + ASSERT_EQ(0, close(pipe_child[0])); + if (variant->domain_child == OTHER_SANDBOX) + create_fs_domain(_metadata); + else if (variant->domain_child == SCOPE_SANDBOX) + create_unix_domain(_metadata); + + self->child_server = socket(AF_UNIX, variant->type, 0); + ASSERT_NE(-1, self->child_server); + ASSERT_EQ(0, bind(self->child_server, + &self->child_address.unix_addr, + (self->child_address).unix_addr_len)); + if (variant->type == SOCK_STREAM) + ASSERT_EQ(0, listen(self->child_server, 32)); + + ASSERT_EQ(1, write(pipe_child[1], ".", 1)); + ASSERT_EQ(grand_child, waitpid(grand_child, &status, 0)); + return; + } + ASSERT_EQ(0, close(pipe_parent[0])); + + if (variant->domain_parent == OTHER_SANDBOX) + create_fs_domain(_metadata); + else if (variant->domain_parent == SCOPE_SANDBOX) + create_unix_domain(_metadata); + + self->parent_server = socket(AF_UNIX, variant->type, 0); + ASSERT_NE(-1, self->parent_server); + ASSERT_EQ(0, bind(self->parent_server, &self->parent_address.unix_addr, + (self->parent_address).unix_addr_len)); + + if (variant->type == SOCK_STREAM) + ASSERT_EQ(0, listen(self->parent_server, 32)); + + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + ASSERT_EQ(child, waitpid(child, &status, 0)); + if (WIFSIGNALED(status) || !WIFEXITED(status) || + WEXITSTATUS(status) != EXIT_SUCCESS) + _metadata->exit_code = KSFT_FAIL; +} + +/* + * Since the special case of scoping only happens when the connecting socket + * is scoped, the client's domain is true for all the following test cases. + */ +/* clang-format off */ +FIXTURE(unix_sock_special_cases) { + int server_socket, client; + int stream_server, stream_client; + struct service_fixture address, transit_address; +}; + +/* clang-format on */ +FIXTURE_VARIANT(unix_sock_special_cases) +{ + const bool domain_server; + const bool domain_server_socket; + const int type; +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_sock_special_cases, allow_dgram_server_sock_domain) { + /* clang-format on */ + .domain_server = false, + .domain_server_socket = true, + .type = SOCK_DGRAM, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_sock_special_cases, deny_dgram_server_domain) { + /* clang-format on */ + .domain_server = true, + .domain_server_socket = false, + .type = SOCK_DGRAM, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_sock_special_cases, allow_stream_server_sock_domain) { + /* clang-format on */ + .domain_server = false, + .domain_server_socket = true, + .type = SOCK_STREAM, +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(unix_sock_special_cases, deny_stream_server_domain) { + /* clang-format on */ + .domain_server = true, + .domain_server_socket = false, + .type = SOCK_STREAM, +}; + +FIXTURE_SETUP(unix_sock_special_cases) +{ + memset(&self->transit_address, 0, sizeof(self->transit_address)); + memset(&self->address, 0, sizeof(self->address)); + set_unix_address(&self->transit_address, 0); + set_unix_address(&self->address, 1); +} + +FIXTURE_TEARDOWN(unix_sock_special_cases) +{ + close(self->client); + close(self->server_socket); + close(self->stream_server); + close(self->stream_client); +} + +/* Test UNIX_STREAM_CONNECT and UNIX_MAY_SEND for parent and + * child processes when connecting socket has different domain + * than the process using it. + **/ +TEST_F(unix_sock_special_cases, socket_with_different_domain) +{ + pid_t child; + int err, status; + int pipe_child[2], pipe_parent[2]; + char buf_parent; + + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC)); + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + char buf_child; + + ASSERT_EQ(0, close(pipe_parent[1])); + ASSERT_EQ(0, close(pipe_child[0])); + + /* client always has domain */ + create_unix_domain(_metadata); + + if (variant->domain_server_socket) { + int data_socket; + int fd_sock = socket(AF_UNIX, variant->type, 0); + + ASSERT_NE(-1, fd_sock); + + self->stream_server = socket(AF_UNIX, SOCK_STREAM, 0); + + ASSERT_NE(-1, self->stream_server); + ASSERT_EQ(0, + bind(self->stream_server, + &self->transit_address.unix_addr, + (self->transit_address).unix_addr_len)); + ASSERT_EQ(0, listen(self->stream_server, 32)); + + ASSERT_EQ(1, write(pipe_child[1], ".", 1)); + + data_socket = accept(self->stream_server, NULL, NULL); + + ASSERT_EQ(0, send_fd(data_socket, fd_sock)); + ASSERT_EQ(0, close(fd_sock)); + } + + self->client = socket(AF_UNIX, variant->type, 0); + ASSERT_NE(-1, self->client); + /* wait for parent signal for connection */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + + err = connect(self->client, &self->address.unix_addr, + (self->address).unix_addr_len); + if (!variant->domain_server_socket) { + EXPECT_EQ(-1, err); + EXPECT_EQ(EPERM, errno); + } else { + EXPECT_EQ(0, err); + } + _exit(_metadata->exit_code); + return; + } + + ASSERT_EQ(0, close(pipe_child[1])); + ASSERT_EQ(0, close(pipe_parent[0])); + + if (!variant->domain_server_socket) { + self->server_socket = socket(AF_UNIX, variant->type, 0); + } else { + int cli = socket(AF_UNIX, SOCK_STREAM, 0); + + ASSERT_NE(-1, cli); + ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1)); + ASSERT_EQ(0, connect(cli, &self->transit_address.unix_addr, + (self->transit_address).unix_addr_len)); + + self->server_socket = recv_fd(cli); + ASSERT_LE(0, self->server_socket); + ASSERT_EQ(0, close(cli)); + } + + ASSERT_NE(-1, self->server_socket); + + if (variant->domain_server) + create_unix_domain(_metadata); + + ASSERT_EQ(0, bind(self->server_socket, &self->address.unix_addr, + (self->address).unix_addr_len)); + if (variant->type == SOCK_STREAM) + ASSERT_EQ(0, listen(self->server_socket, 32)); + /* signal to child that parent is listening */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); + + ASSERT_EQ(child, waitpid(child, &status, 0)); + + if (WIFSIGNALED(status) || !WIFEXITED(status) || + WEXITSTATUS(status) != EXIT_SUCCESS) + _metadata->exit_code = KSFT_FAIL; +} + +static const char path1_variant1[] = TMP_DIR "/s1_variant1"; +static const char path2_variant1[] = TMP_DIR "/s2_variant1"; + +/* clang-format off */ +FIXTURE(pathname_address_sockets) { + struct service_fixture stream_address, dgram_address; +}; + +/* clang-format on */ +FIXTURE_VARIANT(pathname_address_sockets) +{ + const int domain; + const char *stream_path; + const char *dgram_path; +}; + +/* clang-format off */ +FIXTURE_VARIANT_ADD(pathname_address_sockets, pathname_socket_scoped_domain) { + /* clang-format on */ + .domain = SCOPE_SANDBOX, + .stream_path = path1_variant1, + .dgram_path = path2_variant1, +}; + +FIXTURE_SETUP(pathname_address_sockets) +{ + /* setup abstract addresses */ + memset(&self->stream_address, 0, sizeof(self->stream_address)); + set_unix_address(&self->stream_address, 0); + + memset(&self->dgram_address, 0, sizeof(self->dgram_address)); + set_unix_address(&self->dgram_address, 0); + + const char *s_path = variant->stream_path; + const char *dg_path = variant->dgram_path; + + disable_caps(_metadata); + umask(0077); + ASSERT_EQ(0, mkdir(TMP_DIR, 0700)); + + ASSERT_EQ(0, mknod(s_path, S_IFREG | 0700, 0)) + { + TH_LOG("Failed to create file \"%s\": %s", s_path, + strerror(errno)); + remove_path(TMP_DIR); + } + ASSERT_EQ(0, mknod(dg_path, S_IFREG | 0700, 0)) + { + TH_LOG("Failed to create file \"%s\": %s", dg_path, + strerror(errno)); + remove_path(TMP_DIR); + } +} + +FIXTURE_TEARDOWN(pathname_address_sockets) +{ + const char *s_path = variant->stream_path; + const char *dg_path = variant->dgram_path; + + ASSERT_EQ(0, remove_path(dg_path)); + ASSERT_EQ(0, remove_path(s_path)); + ASSERT_EQ(0, remove_path(TMP_DIR)); +} + +TEST_F(pathname_address_sockets, scoped_pathname_sockets) +{ + const char *const stream_path = variant->stream_path; + const char *const dgram_path = variant->dgram_path; + int srv_fd, srv_fd_dg; + socklen_t size, size_dg; + struct sockaddr_un srv_un, srv_un_dg; + int pipe_parent[2]; + pid_t child; + int status; + char buf_child; + int socket_fds_stream[2]; + int server, client, dgram_server, dgram_client; + int recv_data; + + ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0, + socket_fds_stream)); + + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC)); + + child = fork(); + ASSERT_LE(0, child); + if (child == 0) { + struct sockaddr_un cli_un, cli_un_dg; + int cli_fd, cli_fd_dg; + socklen_t size, size_dg; + int sample = socket(AF_UNIX, SOCK_STREAM, 0); + int err, err_dg; + + ASSERT_LE(0, sample); + + ASSERT_EQ(0, close(pipe_parent[1])); + + /* scope the domain */ + if (variant->domain == SCOPE_SANDBOX) + create_unix_domain(_metadata); + else if (variant->domain == OTHER_SANDBOX) + create_fs_domain(_metadata); + ASSERT_EQ(0, close(socket_fds_stream[1])); + ASSERT_EQ(0, send_fd(socket_fds_stream[0], sample)); + ASSERT_EQ(0, close(sample)); + ASSERT_EQ(0, close(socket_fds_stream[0])); + + /* wait for server to listen */ + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1)); + + cli_un.sun_family = AF_UNIX; + cli_fd = socket(AF_UNIX, SOCK_STREAM, 0); + ASSERT_LE(0, cli_fd); + + size = offsetof(struct sockaddr_un, sun_path) + + strlen(cli_un.sun_path); + ASSERT_EQ(0, bind(cli_fd, (struct sockaddr *)&cli_un, size)); + + bzero(&cli_un, sizeof(cli_un)); + cli_un.sun_family = AF_UNIX; + snprintf(cli_un.sun_path, sizeof(cli_un.sun_path), "%s", + stream_path); + size = offsetof(struct sockaddr_un, sun_path) + + strlen(cli_un.sun_path); + + ASSERT_EQ(0, connect(cli_fd, (struct sockaddr *)&cli_un, size)); + + ASSERT_EQ(0, close(cli_fd)); + + cli_un_dg.sun_family = AF_UNIX; + cli_fd_dg = socket(AF_UNIX, SOCK_DGRAM, 0); + ASSERT_LE(0, cli_fd_dg); + + size_dg = offsetof(struct sockaddr_un, sun_path) + + strlen(cli_un_dg.sun_path); + ASSERT_EQ(0, bind(cli_fd_dg, (struct sockaddr *)&cli_un_dg, + size_dg)); + + bzero(&cli_un_dg, sizeof(cli_un_dg)); + cli_un_dg.sun_family = AF_UNIX; + snprintf(cli_un_dg.sun_path, sizeof(cli_un_dg.sun_path), "%s", + dgram_path); + size_dg = offsetof(struct sockaddr_un, sun_path) + + strlen(cli_un_dg.sun_path); + + ASSERT_EQ(0, connect(cli_fd_dg, (struct sockaddr *)&cli_un_dg, + size_dg)); + + ASSERT_EQ(0, close(cli_fd_dg)); + + /* check connection with abstract sockets */ + + client = socket(AF_UNIX, SOCK_STREAM, 0); + dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0); + + ASSERT_NE(-1, client); + ASSERT_NE(-1, dgram_client); + + err = connect(client, &(self->stream_address).unix_addr, + (self->stream_address).unix_addr_len); + err_dg = connect(dgram_client, &(self->dgram_address).unix_addr, + (self->dgram_address).unix_addr_len); + if (variant->domain == SCOPE_SANDBOX) { + EXPECT_EQ(-1, err); + EXPECT_EQ(-1, err_dg); + EXPECT_EQ(EPERM, errno); + } else { + EXPECT_EQ(0, err); + EXPECT_EQ(0, err_dg); + } + ASSERT_EQ(0, close(client)); + ASSERT_EQ(0, close(dgram_client)); + + _exit(_metadata->exit_code); + return; + } + + ASSERT_EQ(0, close(pipe_parent[0])); + + recv_data = recv_fd(socket_fds_stream[1]); + ASSERT_LE(0, recv_data); + ASSERT_LE(0, close(socket_fds_stream[1])); + + /* Sets up a server */ + srv_un.sun_family = AF_UNIX; + snprintf(srv_un.sun_path, sizeof(srv_un.sun_path), "%s", stream_path); + + ASSERT_EQ(0, unlink(stream_path)); + srv_fd = socket(AF_UNIX, SOCK_STREAM, 0); + ASSERT_LE(0, srv_fd); + + size = offsetof(struct sockaddr_un, sun_path) + strlen(srv_un.sun_path); + ASSERT_EQ(0, bind(srv_fd, (struct sockaddr *)&srv_un, size)); + ASSERT_EQ(0, listen(srv_fd, 10)); + + /* set up a datagram server */ + srv_un_dg.sun_family = AF_UNIX; + snprintf(srv_un_dg.sun_path, sizeof(srv_un_dg.sun_path), "%s", + dgram_path); + + ASSERT_EQ(0, unlink(dgram_path)); + srv_fd_dg = socket(AF_UNIX, SOCK_DGRAM, 0); + ASSERT_LE(0, srv_fd_dg); + + size_dg = offsetof(struct sockaddr_un, sun_path) + + strlen(srv_un_dg.sun_path); + ASSERT_EQ(0, bind(srv_fd_dg, (struct sockaddr *)&srv_un_dg, size_dg)); + + /*set up abstract servers */ + + server = socket(AF_UNIX, SOCK_STREAM, 0); + dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0); + ASSERT_NE(-1, server); + ASSERT_NE(-1, dgram_server); + + ASSERT_EQ(0, bind(server, &(self->stream_address).unix_addr, + self->stream_address.unix_addr_len)); + ASSERT_EQ(0, bind(dgram_server, &(self->dgram_address).unix_addr, + self->dgram_address.unix_addr_len)); + ASSERT_EQ(0, listen(server, 32)); + + /* signal to child! */ + ASSERT_EQ(1, write(pipe_parent[1], ".", 1)); 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Thu, 01 Aug 2024 21:03:10 -0700 (PDT) From: Tahera Fahimi To: outreachy@lists.linux.dev Cc: mic@digikod.net, gnoack@google.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn3_gh@protonmail.com, jannh@google.com, netdev@vger.kernel.org, Tahera Fahimi Subject: [PATCH v8 3/4] sample/Landlock: Support abstract unix socket restriction Date: Thu, 1 Aug 2024 22:02:35 -0600 Message-Id: <2b1ac6822d852ea70dd2dcdf41065076d9ee8028.1722570749.git.fahimitahera@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 A sandboxer can receive the character "a" as input from the environment variable LL_SCOPE to restrict the abstract unix sockets from connecting to a process outside its scoped domain. Example ======= Create an abstract unix socket to listen with socat(1): socat abstract-listen:mysocket - Create a sandboxed shell and pass the character "a" to LL_SCOPED: LL_FS_RO=/ LL_FS_RW=. LL_SCOPED="a" ./sandboxer /bin/bash If the sandboxed process tries to connect to the listening socket with command "socat - abstract-connect:mysocket", the connection will fail. Signed-off-by: Tahera Fahimi --- v8: - Adding check_ruleset_scope function to parse the scope environment variable and update the landlock attribute based on the restriction provided by the user. - Adding Mickaël Salaün reviews on version 7. v7: - Adding IPC scoping to the sandbox demo by defining a new "LL_SCOPED" environment variable. "LL_SCOPED" gets value "a" to restrict abstract unix sockets. - Change LANDLOCK_ABI_LAST to 6. --- samples/landlock/sandboxer.c | 56 +++++++++++++++++++++++++++++++++--- 1 file changed, 52 insertions(+), 4 deletions(-) diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index e8223c3e781a..98132fd823ad 100644 --- a/samples/landlock/sandboxer.c +++ b/samples/landlock/sandboxer.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include #include @@ -22,6 +23,7 @@ #include #include #include +#include #ifndef landlock_create_ruleset static inline int @@ -55,6 +57,7 @@ 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_SCOPED_NAME "LL_SCOPED" #define ENV_DELIMITER ":" static int parse_path(char *env_path, const char ***const path_list) @@ -184,6 +187,38 @@ static int populate_ruleset_net(const char *const env_var, const int ruleset_fd, return ret; } +static bool check_ruleset_scope(const char *const env_var, + struct landlock_ruleset_attr *ruleset_attr) +{ + bool ret = true; + char *env_type_scope, *env_type_scope_next, *ipc_scoping_name; + + ruleset_attr->scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; + env_type_scope = getenv(env_var); + /* scoping is not supported by the user */ + if (!env_type_scope) + return true; + env_type_scope = strdup(env_type_scope); + unsetenv(env_var); + + env_type_scope_next = env_type_scope; + while ((ipc_scoping_name = + strsep(&env_type_scope_next, ENV_DELIMITER))) { + if (strcmp("a", ipc_scoping_name) == 0) { + ruleset_attr->scoped |= + LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; + } else { + fprintf(stderr, "Unsupported scoping \"%s\"\n", + ipc_scoping_name); + ret = false; + goto out_free_name; + } + } +out_free_name: + free(env_type_scope); + return ret; +} + /* clang-format off */ #define ACCESS_FS_ROUGHLY_READ ( \ @@ -208,7 +243,7 @@ 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) { @@ -223,14 +258,15 @@ int main(const int argc, char *const argv[], char *const *const envp) .handled_access_fs = access_fs_rw, .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | LANDLOCK_ACCESS_NET_CONNECT_TCP, + .scoped = LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, }; if (argc < 2) { fprintf(stderr, - "usage: %s=\"...\" %s=\"...\" %s=\"...\" %s=\"...\"%s " + "usage: %s=\"...\" %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]); + ENV_TCP_CONNECT_NAME, ENV_SCOPED_NAME, argv[0]); fprintf(stderr, "Execute a command in a restricted environment.\n\n"); fprintf(stderr, @@ -251,15 +287,18 @@ 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 restrictions on IPCs.\n", + ENV_SCOPED_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=\"a\" " "%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_SCOPED_NAME, argv[0]); 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Thu, 01 Aug 2024 21:03:12 -0700 (PDT) Received: from tahera-OptiPlex-5000.tail3bf47f.ts.net ([136.159.49.123]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7106ec41465sm542099b3a.60.2024.08.01.21.03.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 01 Aug 2024 21:03:11 -0700 (PDT) From: Tahera Fahimi To: outreachy@lists.linux.dev Cc: mic@digikod.net, gnoack@google.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, bjorn3_gh@protonmail.com, jannh@google.com, netdev@vger.kernel.org, Tahera Fahimi Subject: [PATCH v8 4/4] Landlock: Document LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET and ABI versioning Date: Thu, 1 Aug 2024 22:02:36 -0600 Message-Id: X-Mailer: git-send-email 2.34.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Introducing LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET as an IPC scoping mechanism in Landlock ABI version 6, and updating ruleset_attr, Landlock ABI version, and access rights code blocks based on that. Signed-off-by: Tahera Fahimi --- v8: - Improving documentation by specifying differences between scoped and non-scoped domains. - Adding review notes of version 7. - Update date v7: - Add "LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET" explanation to IPC scoping section and updating ABI to version 6. - Adding "scoped" attribute to the Access rights section. - In current limitation, unnamed sockets are specified as sockets that are not restricted. - Update date --- Documentation/userspace-api/landlock.rst | 33 ++++++++++++++++++++++-- 1 file changed, 31 insertions(+), 2 deletions(-) diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst index 07b63aec56fa..d602567b5139 100644 --- a/Documentation/userspace-api/landlock.rst +++ b/Documentation/userspace-api/landlock.rst @@ -8,7 +8,7 @@ Landlock: unprivileged access control ===================================== :Author: Mickaël Salaün -:Date: April 2024 +:Date: August 2024 The goal of Landlock is to enable to restrict ambient rights (e.g. global filesystem or network access) for a set of processes. Because Landlock @@ -81,6 +81,8 @@ to be explicit about the denied-by-default access rights. .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP | LANDLOCK_ACCESS_NET_CONNECT_TCP, + .scoped = + LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET, }; Because we may not know on which kernel version an application will be @@ -119,6 +121,9 @@ version, and only use the available subset of access rights: case 4: /* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV; + case 5: + /* Removes LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET for ABI < 6 */ + ruleset_attr.scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; } This enables to create an inclusive ruleset that will contain our rules. @@ -306,6 +311,23 @@ To be allowed to use :manpage:`ptrace(2)` and related syscalls on a target process, a sandboxed process should have a subset of the target process rules, which means the tracee must be in a sub-domain of the tracer. +IPC Scoping +----------- + +Similar to the implicit `Ptrace restrictions`_, we may want to further restrict +interactions between sandboxes. Each Landlock domain can be explicitly scoped +for a set of actions by specifying it on a ruleset. For example, if a sandboxed +process should not be able to :manpage:`connect(2)` to a non-sandboxed process +through abstract :manpage:`unix(7)` sockets, we can specify such restriction +with ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``. + +A sandboxed process can connect to a non-sandboxed process when its domain is +not scoped. If a process's domain is scoped, it can only connect to processes in +the same scoped domain. + +IPC scoping does not support Landlock rules, so if a domain is scoped, no rules +can be added to allow accessing to a resource outside of the scoped domain. + Truncating files ---------------- @@ -404,7 +426,7 @@ Access rights ------------- .. kernel-doc:: include/uapi/linux/landlock.h - :identifiers: fs_access net_access + :identifiers: fs_access net_access scope Creating a new ruleset ---------------------- @@ -541,6 +563,13 @@ earlier ABI. Starting with the Landlock ABI version 5, it is possible to restrict the use of :manpage:`ioctl(2)` using the new ``LANDLOCK_ACCESS_FS_IOCTL_DEV`` right. +Abstract Unix sockets Restriction (ABI < 6) +-------------------------------------------- + +With ABI version 6, it is possible to restrict connection to an abstract Unix socket +through ``LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET``, thanks to the ``scoped`` ruleset +attribute. + .. _kernel_support: Kernel support