From patchwork Wed Aug 14 06:22:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Tahera Fahimi X-Patchwork-Id: 13762873 Received: from mail-pj1-f46.google.com (mail-pj1-f46.google.com [209.85.216.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AC75613B2A8; Wed, 14 Aug 2024 06:23:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.46 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723616585; cv=none; b=SKmQ2AiLsGdrdwcR2gujVKc1xwb+nOdlVcLgysil0rpvoD5K1VBdnCfcuatV3oY6QsIvhL6CKMor2yFESI2Fx+IzSM1HmPvgPyunxxa8xFPQsD9jXba1UQggQ/46k1lfgGKggJizlxodPqJCPnl9RXiVvV4H1pvIH3WeU5LKCSc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723616585; c=relaxed/simple; bh=kg/8idxdUWZ97chH/ydatb40FE1TQIX2TYlnPM93mr0=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=N5WvTOIJcusu6zu9Og7ZtPsBad1q3GQTMFJHsKzIBbJdArLsBxWCH9pg7cJEUxEFMI/dWVUP56juvEEFQPxVvSwVpaOifIn44eKpnAXT2t3ZdyjC7939s8NEKQ+NoKctdNRMrrgcCpMYI9McOEQO9y1nW2sKh6Ad/wfbG3xL1E8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=P10pBHHB; arc=none smtp.client-ip=209.85.216.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="P10pBHHB" Received: by mail-pj1-f46.google.com with SMTP id 98e67ed59e1d1-2cb5e0b020eso4875735a91.2; Tue, 13 Aug 2024 23:23:03 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1723616583; x=1724221383; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=JSbos34GZP1MBxqk5DevnuLIKX/BhuXlgd9OTZVY/rQ=; b=P10pBHHB/09I1rkpdVKSNSFczbS/luJ0cmye/WZW0xdwYWj7RaAB43CbMnU1691oFA QtFfMjixGCU37m80cDoVAMDjJlbsT5lT/u1gcYMp1LRtUIJFlI79RrGqWGl4nDOYVOB4 ntlZm0QlhREz+c1CcnlZjHdUhrU+kR5/FV6eBoJ7Ie6u+QUlEes5uKEb3oeMydl5R1+L YRoSlmfQzA+F5ovX4Us75naXWIz51e+SUeF203mqArwu2nFEOlAcNNnu+5HUlYT3AFwW 7luYMNgSff6AuZdsm2NMQ6fIspCtek+Kf3+dG9m6E+NCBlg5CMVRCkgLlizSDLEiIhZ3 6Bgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1723616583; x=1724221383; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=JSbos34GZP1MBxqk5DevnuLIKX/BhuXlgd9OTZVY/rQ=; b=ByILouvPYcdhfR6W38Nf0mRhh3ieEamFiFwHJ03QMzi4Uxut29gx6J2j7m+G+S3kCr ymYRThVLV3kSJfuaoix1ZHfDlMibELPW0YPwq7+uMLZiEOiRvWC3LhJcHodfpIgui85U O06xDG5Df4uCk4QSRU6e1gnkm+SyEqmcfIiwWlgDz388frrO1K3LELJFw1IxWWET8KGU /ahUArRekxCJU2fIdPDuN5Ssr+C5o3iof5/przCKh6SGZBH1LvyN3Qvv3qeDzEIwN5sv RBec+Jf6/sXP8x9qbXtb+BGZsX5OsFWlbwWN9Hj8zsrKMyPuq8SiGTsCRCFNIAALmB+k XOTQ== X-Forwarded-Encrypted: i=1; AJvYcCUYCq5rO8M2zf78hsL06L3YW/e6JhR2GJrn8F/kmlzNxIsneo1eLidnlGq3NlaNZtPmK2jyCssTl6enGjkaWwOJNBwmc0Pcdgvj/n7soHb6r//cSG4tN0C2nIqeSwVRNpSGqYFWlKCy9nxfRfhy+GfySR10c9KdFqHAE71HZyYdVaGfH52+e/RJeZle X-Gm-Message-State: AOJu0YznLdZ6nQ41pb75DtiOUy3ak+1+qfddvHQMnwPZbRm3axNboeR/ qsAU4qUDNAl7zAx5h30xyHgUR6Y6lynLfzVfcZVtDC7b5WK+N83S X-Google-Smtp-Source: AGHT+IF6HPZG22dVWfrD6tAfo2bx5IXCLTB3G2YTykE19Ncv2smJjp42YPHsxmMGgakJZ99PScYcRQ== X-Received: by 2002:a17:90b:17c2:b0:2ca:5a46:cbc8 with SMTP id 98e67ed59e1d1-2d3aab50abdmr2081710a91.26.1723616582727; Tue, 13 Aug 2024 23:23:02 -0700 (PDT) Received: from tahera-OptiPlex-5000.uc.ucalgary.ca ([136.159.49.123]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-2d3ac7f2120sm728811a91.31.2024.08.13.23.23.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Aug 2024 23:23:02 -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 v9 4/5] sample/Landlock: Support abstract unix socket restriction Date: Wed, 14 Aug 2024 00:22:22 -0600 Message-Id: <60861c67dab1e1e8cf05ec6bfd9e5ac75d09b63a.1723615689.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 --- v9: - Add a restrict approach on input of LL_SCOPED, so it only allows zero or one "a" to be the input. 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 | 58 +++++++++++++++++++++++++++++++++--- 1 file changed, 54 insertions(+), 4 deletions(-) diff --git a/samples/landlock/sandboxer.c b/samples/landlock/sandboxer.c index e8223c3e781a..bec201eb96f7 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 +187,40 @@ 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 abstract_scoping = false; + 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 && !abstract_scoping) { + abstract_scoping = true; + 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 +245,7 @@ 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 +260,15 @@ 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 +289,18 @@ 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]); fprintf(stderr, "This sandboxer can use Landlock features " "up to ABI version %d.\n", @@ -327,6 +368,10 @@ int main(const int argc, char *const argv[], char *const *const envp) /* Removes LANDLOCK_ACCESS_FS_IOCTL_DEV for ABI < 5 */ ruleset_attr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_IOCTL_DEV; + __attribute__((fallthrough)); + case 5: + /* Removes LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET for ABI < 6 */ + ruleset_attr.scoped &= ~LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET; fprintf(stderr, "Hint: You should update the running kernel " "to leverage Landlock features " @@ -358,6 +403,11 @@ int main(const int argc, char *const argv[], char *const *const envp) ~LANDLOCK_ACCESS_NET_CONNECT_TCP; } + if (abi >= 6 && !check_ruleset_scope(ENV_SCOPED_NAME, &ruleset_attr)) { + perror("Unsupported IPC scoping requested"); + return 1; + } + ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0); if (ruleset_fd < 0) {