From patchwork Thu Jul 7 22:32:25 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12910333 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 824EEC433EF for ; Thu, 7 Jul 2022 22:32:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237017AbiGGWcu (ORCPT ); Thu, 7 Jul 2022 18:32:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236968AbiGGWck (ORCPT ); Thu, 7 Jul 2022 18:32:40 -0400 Received: from mail-oi1-x22f.google.com (mail-oi1-x22f.google.com [IPv6:2607:f8b0:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D812565D7F for ; Thu, 7 Jul 2022 15:32:38 -0700 (PDT) Received: by mail-oi1-x22f.google.com with SMTP id l81so25049223oif.9 for ; Thu, 07 Jul 2022 15:32:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=2ze62Gr6yFI9YlZaCLh0XPJZ5QPI4eIkzUPPZ4mag1A=; b=Hjz2P6X2I1Fth6pZf+hGpgOQm1DMiy9L3g2o/gJ5yJGZFPSgpQkF362RzMHiiUskYa ngBdGQovMO2B3pfO+EpXtaDC79YUJJvDLqDr+oJrNm3GwsaNflwgOG6TSCmAD/tuwdsE o8CjTO+CykD3nVVlWp1MldRIv8CUqJ0r/ok6w= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=2ze62Gr6yFI9YlZaCLh0XPJZ5QPI4eIkzUPPZ4mag1A=; b=uyh548hjZ4vGegYgTwIWqOfVA8OKe7W54EG6zbJv3NYiUlWpc+nNXL8cRVAh9lKEBA 4a3b9IQ4tMsZoWYu1SEvXbMdTf4dWQq14UxJZKaZwOz0Zfn7Pcv9fPMdwiHTnSriUXsh zc9yryFsCUN7svOku3fl0z5QTQnJo3y+eIpdEFONEmmfGccFd+aXP36IS5lf2Y1auY8e U8B9ROXzTw3arQb3GciRR0W6Ty+TtaZ0Xf+/OpX1LFf+MFjwJKKJuewy6EiawQqAzy+z 2J8c0z7IvJwseGllm8cgc68OsINhDIOlntINbKElR8R5Ch1ClabF9hqGDDjV6Sx2ii/9 ZS/A== X-Gm-Message-State: AJIora/jJ/Cx75bwXJCwaE1mUFfj3/qYSzefdYPc0jxgo1eJzfcpPwd6 +Fvm+MZPKhJQUX2M98/XW+zx1A== X-Google-Smtp-Source: AGRyM1spTnHtSiohzejr09iqgEQq6SB21VULSXN2tn7SabY+Ll4UuXdWDcBCQ14/WEJipjBZIcHNCQ== X-Received: by 2002:a54:4393:0:b0:335:cdb9:16a9 with SMTP id u19-20020a544393000000b00335cdb916a9mr157809oiv.112.1657233158219; Thu, 07 Jul 2022 15:32:38 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id i16-20020a05683033f000b00616b835f5e7sm16246222otu.43.2022.07.07.15.32.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Jul 2022 15:32:37 -0700 (PDT) From: Frederick Lawler To: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com, paul@paul-moore.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com, ebiederm@xmission.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, Frederick Lawler Subject: [PATCH v2 1/4] security, lsm: Introduce security_create_user_ns() Date: Thu, 7 Jul 2022 17:32:25 -0500 Message-Id: <20220707223228.1940249-2-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220707223228.1940249-1-fred@cloudflare.com> References: <20220707223228.1940249-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Preventing user namespace (privileged or otherwise) creation comes in a few of forms in order of granularity: 1. /proc/sys/user/max_user_namespaces sysctl 2. OS specific patch(es) 3. CONFIG_USER_NS To block a task based on its attributes, the LSM hook cred_prepare is a good candidate for use because it provides more granular control, and it is called before create_user_ns(): cred = prepare_creds() security_prepare_creds() call_int_hook(cred_prepare, ... if (cred) create_user_ns(cred) Since security_prepare_creds() is meant for LSMs to copy and prepare credentials, access control is an unintended use of the hook. Therefore introduce a new function security_create_user_ns() with an accompanying create_user_ns LSM hook. This hook takes the prepared creds for LSM authors to write policy against. On success, the new namespace is applied to credentials, otherwise an error is returned. Signed-off-by: Frederick Lawler --- Changes since v1: - Changed commit wording - Moved execution to be after id mapping check - Changed signature to only accept a const struct cred * --- include/linux/lsm_hook_defs.h | 1 + include/linux/lsm_hooks.h | 4 ++++ include/linux/security.h | 6 ++++++ kernel/user_namespace.c | 5 +++++ security/security.c | 5 +++++ 5 files changed, 21 insertions(+) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index eafa1d2489fd..3eabd6b10776 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -223,6 +223,7 @@ LSM_HOOK(int, -ENOSYS, task_prctl, int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5) LSM_HOOK(void, LSM_RET_VOID, task_to_inode, struct task_struct *p, struct inode *inode) +LSM_HOOK(int, 0, create_user_ns, const struct cred *cred) LSM_HOOK(int, 0, ipc_permission, struct kern_ipc_perm *ipcp, short flag) LSM_HOOK(void, LSM_RET_VOID, ipc_getsecid, struct kern_ipc_perm *ipcp, u32 *secid) diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 91c8146649f5..07f833da0bbf 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -799,6 +799,10 @@ * security attributes, e.g. for /proc/pid inodes. * @p contains the task_struct for the task. * @inode contains the inode structure for the inode. + * @create_user_ns: + * Check permission prior to creating a new user namespace. + * @cred points to prepared creds. + * Return 0 if successful, otherwise < 0 error code. * * Security hooks for Netlink messaging. * diff --git a/include/linux/security.h b/include/linux/security.h index 7fc4e9f49f54..a195bf33246a 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -435,6 +435,7 @@ int security_task_kill(struct task_struct *p, struct kernel_siginfo *info, int security_task_prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5); void security_task_to_inode(struct task_struct *p, struct inode *inode); +int security_create_user_ns(const struct cred *cred); int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag); void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid); int security_msg_msg_alloc(struct msg_msg *msg); @@ -1185,6 +1186,11 @@ static inline int security_task_prctl(int option, unsigned long arg2, static inline void security_task_to_inode(struct task_struct *p, struct inode *inode) { } +static inline int security_create_user_ns(const struct cred *cred) +{ + return 0; +} + static inline int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag) { diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 5481ba44a8d6..3f464bbda0e9 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -9,6 +9,7 @@ #include #include #include +#include #include #include #include @@ -113,6 +114,10 @@ int create_user_ns(struct cred *new) !kgid_has_mapping(parent_ns, group)) goto fail_dec; + ret = security_create_user_ns(new); + if (ret < 0) + goto fail_dec; + ret = -ENOMEM; ns = kmem_cache_zalloc(user_ns_cachep, GFP_KERNEL); if (!ns) diff --git a/security/security.c b/security/security.c index 188b8f782220..c700dbdc14fe 100644 --- a/security/security.c +++ b/security/security.c @@ -1903,6 +1903,11 @@ void security_task_to_inode(struct task_struct *p, struct inode *inode) call_void_hook(task_to_inode, p, inode); } +int security_create_user_ns(const struct cred *cred) +{ + return call_int_hook(create_user_ns, 0, cred); +} + int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag) { return call_int_hook(ipc_permission, 0, ipcp, flag); From patchwork Thu Jul 7 22:32:26 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12910335 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37A3ACCA488 for ; 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Thu, 07 Jul 2022 15:32:39 -0700 (PDT) From: Frederick Lawler To: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com, paul@paul-moore.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com, ebiederm@xmission.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, Frederick Lawler Subject: [PATCH v2 2/4] bpf-lsm: Make bpf_lsm_create_user_ns() sleepable Date: Thu, 7 Jul 2022 17:32:26 -0500 Message-Id: <20220707223228.1940249-3-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220707223228.1940249-1-fred@cloudflare.com> References: <20220707223228.1940249-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Users may want to audit calls to security_create_user_ns() and access user space memory. Also create_user_ns() runs without pagefault_disabled(). Therefore, make bpf_lsm_create_user_ns() sleepable for mandatory access control policies. Signed-off-by: Frederick Lawler --- Changes since v1: - None --- kernel/bpf/bpf_lsm.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/bpf/bpf_lsm.c b/kernel/bpf/bpf_lsm.c index c1351df9f7ee..75853965e7b0 100644 --- a/kernel/bpf/bpf_lsm.c +++ b/kernel/bpf/bpf_lsm.c @@ -250,6 +250,7 @@ BTF_ID(func, bpf_lsm_task_getsecid_obj) BTF_ID(func, bpf_lsm_task_prctl) BTF_ID(func, bpf_lsm_task_setscheduler) BTF_ID(func, bpf_lsm_task_to_inode) +BTF_ID(func, bpf_lsm_create_user_ns) BTF_SET_END(sleepable_lsm_hooks) bool bpf_lsm_is_sleepable_hook(u32 btf_id) From patchwork Thu Jul 7 22:32:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12910334 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 221E0CCA483 for ; Thu, 7 Jul 2022 22:32:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237072AbiGGWcw (ORCPT ); Thu, 7 Jul 2022 18:32:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237025AbiGGWcv (ORCPT ); Thu, 7 Jul 2022 18:32:51 -0400 Received: from mail-oi1-x22f.google.com (mail-oi1-x22f.google.com [IPv6:2607:f8b0:4864:20::22f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D238067593 for ; Thu, 7 Jul 2022 15:32:42 -0700 (PDT) Received: by mail-oi1-x22f.google.com with SMTP id l81so25049366oif.9 for ; Thu, 07 Jul 2022 15:32:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=j5md+eRaroN3b4x5GXk8vDK0Yn23IzIrTWAe3e+Lx7Q=; b=aNBBpDIdjJ8tvtO8GaBiWmkh9oQhGcb6KAdgM/0e35zl+mr2r/xgzUWjFkfNmJOaEm Jvhr+t6gmYTNnCQMTKv+oMfi4pLA4Ogl9NJlch8V8tQGl16wtwfJpFXSaYcVKfYfcrMM jMLEPkI/8F3wR7TAumcOZqojwn71aRJyKEYgU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=j5md+eRaroN3b4x5GXk8vDK0Yn23IzIrTWAe3e+Lx7Q=; b=fzYox3jcS1HnKtH69ovrfaIJbWiyazz+X9qeV3aG3ISmVp/E3Nkdh7UKuYziSo1OJA lXQLxgmGKDJblq1jLBRTdA07POIjI85MUouyR1ameTsIPqzFvhYywfKg9lNLXRZCYfNF SPM6TIlqQOfYxlFazSN1+Ha4AX4Bwbmtj22WzWr36F9kjid6qmZ/hx6FJvmlAif3urTs fMtA2+PDb6kCo0EWriHCV3gmxetR5YddsLVJGHENrUo6uGGWp0ROuL/Bgf1+PenlgI5T +tl9504/xKakUdGMOLqy/4Xb+nDro0Dik7q1Eyb8LtoF+OSGQI4XKu5Em9u6wy2yQoPc +/MA== X-Gm-Message-State: AJIora9zFo7cLIqs4fNGxkE8zHrsWHAdhig+yRdQ8XFGD/+C0UUrO7mi 5W4v8sLs8OyzPSFbq378tiYY7A== X-Google-Smtp-Source: AGRyM1srNOFm7S5tg87SqlO14myBHyfKEwvfh+AVIicT3RMtZrigLBMXO3g8hWk7379whlu6136QGw== X-Received: by 2002:a05:6808:20a7:b0:337:a9f9:24fb with SMTP id s39-20020a05680820a700b00337a9f924fbmr157852oiw.220.1657233162560; Thu, 07 Jul 2022 15:32:42 -0700 (PDT) Received: from localhost.localdomain ([184.4.90.121]) by smtp.gmail.com with ESMTPSA id i16-20020a05683033f000b00616b835f5e7sm16246222otu.43.2022.07.07.15.32.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Jul 2022 15:32:41 -0700 (PDT) From: Frederick Lawler To: kpsingh@kernel.org, revest@chromium.org, jackmanb@chromium.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com, songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, jmorris@namei.org, serge@hallyn.com, paul@paul-moore.com, stephen.smalley.work@gmail.com, eparis@parisplace.org, shuah@kernel.org, brauner@kernel.org, casey@schaufler-ca.com, ebiederm@xmission.com, bpf@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, kernel-team@cloudflare.com, Frederick Lawler Subject: [PATCH v2 3/4] selftests/bpf: Add tests verifying bpf lsm create_user_ns hook Date: Thu, 7 Jul 2022 17:32:27 -0500 Message-Id: <20220707223228.1940249-4-fred@cloudflare.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220707223228.1940249-1-fred@cloudflare.com> References: <20220707223228.1940249-1-fred@cloudflare.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org The LSM hook create_user_ns was introduced to provide LSM's an opportunity to block or allow unprivileged user namespace creation. This test serves two purposes: it provides a test eBPF implementation, and tests the hook successfully blocks or allows user namespace creation. This tests 4 cases: 1. Unattached bpf program does not block unpriv user namespace creation. 2. Attached bpf program allows user namespace creation given CAP_SYS_ADMIN privileges. 3. Attached bpf program denies user namespace creation for a user without CAP_SYS_ADMIN. 4. The sleepable implementation loads Signed-off-by: Frederick Lawler --- The generic deny_namespace file name is used for future namespace expansion. I didn't want to limit these files to just the create_user_ns hook. Changes since v1: - Introduce this patch --- .../selftests/bpf/prog_tests/deny_namespace.c | 88 +++++++++++++++++++ .../selftests/bpf/progs/test_deny_namespace.c | 39 ++++++++ 2 files changed, 127 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/deny_namespace.c create mode 100644 tools/testing/selftests/bpf/progs/test_deny_namespace.c diff --git a/tools/testing/selftests/bpf/prog_tests/deny_namespace.c b/tools/testing/selftests/bpf/prog_tests/deny_namespace.c new file mode 100644 index 000000000000..a1fb07038dd5 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/deny_namespace.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include +#include "test_deny_namespace.skel.h" +#include +#include "cap_helpers.h" + +#define STACK_SIZE (1024 * 1024) +static char child_stack[STACK_SIZE]; + +int clone_callback(void *arg) +{ + return 0; +} + +static int create_new_user_ns(void) +{ + int status; + pid_t cpid; + + cpid = clone(clone_callback, child_stack + STACK_SIZE, + CLONE_NEWUSER | SIGCHLD, NULL); + + if (cpid == -1) + return errno; + + if (cpid == 0) + return 0; + + waitpid(cpid, &status, 0); + if (WIFEXITED(status)) + return WEXITSTATUS(status); + + return -1; +} + +static void test_create_user_ns_bpf(void) +{ + __u32 cap_mask = 1ULL << CAP_SYS_ADMIN; + __u64 old_caps = 0; + + ASSERT_OK(create_new_user_ns(), "priv new user ns"); + + cap_disable_effective(cap_mask, &old_caps); + + ASSERT_EQ(create_new_user_ns(), EPERM, "unpriv new user ns"); + + if (cap_mask & old_caps) + cap_enable_effective(cap_mask, NULL); +} + +static void test_unpriv_create_user_ns_no_bpf(void) +{ + __u32 cap_mask = 1ULL << CAP_SYS_ADMIN; + __u64 old_caps = 0; + + cap_disable_effective(cap_mask, &old_caps); + + ASSERT_OK(create_new_user_ns(), "no-bpf unpriv new user ns"); + + if (cap_mask & old_caps) + cap_enable_effective(cap_mask, NULL); +} + +void test_deny_namespace(void) +{ + struct test_deny_namespace *skel = NULL; + int err; + + if (test__start_subtest("unpriv_create_user_ns_no_bpf")) + test_unpriv_create_user_ns_no_bpf(); + + skel = test_deny_namespace__open_and_load(); + if (!ASSERT_OK_PTR(skel, "skel load")) + goto close_prog; + + err = test_deny_namespace__attach(skel); + if (!ASSERT_OK(err, "attach")) + goto close_prog; + + if (test__start_subtest("create_user_ns_bpf")) + test_create_user_ns_bpf(); + + test_deny_namespace__detach(skel); + +close_prog: + test_deny_namespace__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/test_deny_namespace.c b/tools/testing/selftests/bpf/progs/test_deny_namespace.c new file mode 100644 index 000000000000..eedede891431 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_deny_namespace.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +struct kernel_cap_struct { + __u32 cap[_LINUX_CAPABILITY_U32S_3]; +} __attribute__((preserve_access_index)); + +struct cred { + struct kernel_cap_struct cap_effective; +} __attribute__((preserve_access_index)); + +char _license[] SEC("license") = "GPL"; + +SEC("lsm/create_user_ns") +int BPF_PROG(test_create_user_ns, const struct cred *cred, int ret) +{ + struct kernel_cap_struct caps = cred->cap_effective; + int cap_index = CAP_TO_INDEX(CAP_SYS_ADMIN); + __u32 cap_mask = CAP_TO_MASK(CAP_SYS_ADMIN); + + if (ret) + return 0; + + ret = -EPERM; + if (caps.cap[cap_index] & cap_mask) + return 0; + + return -EPERM; +} + +SEC("lsm.s/create_user_ns") +int BPF_PROG(test_sleepable_create_user_ns, const struct cred *cred, int ret) +{ + return 0; +} From patchwork Thu Jul 7 22:32:28 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Frederick Lawler X-Patchwork-Id: 12910336 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D919BCCA479 for ; Thu, 7 Jul 2022 22:33:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237076AbiGGWdT (ORCPT ); Thu, 7 Jul 2022 18:33:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60370 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237077AbiGGWcw (ORCPT ); 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This patch implements a new namespace { userns_create } access control permission to restrict which domains allow or deny user namespace creation. This is necessary for system administrators to quickly protect their systems while waiting for vulnerability patches to be applied. This permission can be used in the following way: allow domA_t domB_t : namespace { userns_create }; Signed-off-by: Frederick Lawler --- Changes since v1: - Introduce this patch --- security/selinux/hooks.c | 9 +++++++++ security/selinux/include/classmap.h | 2 ++ 2 files changed, 11 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index beceb89f68d9..73fbcb434fe0 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4227,6 +4227,14 @@ static void selinux_task_to_inode(struct task_struct *p, spin_unlock(&isec->lock); } +static int selinux_userns_create(const struct cred *cred) +{ + u32 sid = current_sid(); + + return avc_has_perm(&selinux_state, sid, sid, SECCLASS_NAMESPACE, + NAMESPACE__USERNS_CREATE, NULL); +} + /* Returns error only if unable to parse addresses */ static int selinux_parse_skb_ipv4(struct sk_buff *skb, struct common_audit_data *ad, u8 *proto) @@ -7117,6 +7125,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(task_movememory, selinux_task_movememory), LSM_HOOK_INIT(task_kill, selinux_task_kill), LSM_HOOK_INIT(task_to_inode, selinux_task_to_inode), + LSM_HOOK_INIT(create_user_ns, selinux_userns_create), LSM_HOOK_INIT(ipc_permission, selinux_ipc_permission), LSM_HOOK_INIT(ipc_getsecid, selinux_ipc_getsecid), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index ff757ae5f253..9943e85c6b3e 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -254,6 +254,8 @@ const struct security_class_mapping secclass_map[] = { { COMMON_FILE_PERMS, NULL } }, { "io_uring", { "override_creds", "sqpoll", NULL } }, + { "namespace", + { "userns_create", NULL } }, { NULL } };