From patchwork Tue Mar 26 18:27:40 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 10871955 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 480801669 for ; Tue, 26 Mar 2019 18:29:11 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3427628E3C for ; Tue, 26 Mar 2019 18:29:11 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2860628E3F; Tue, 26 Mar 2019 18:29:11 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-14.5 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_HI,USER_IN_DEF_DKIM_WL autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 0AE8828E3C for ; Tue, 26 Mar 2019 18:29:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732900AbfCZS3F (ORCPT ); Tue, 26 Mar 2019 14:29:05 -0400 Received: from mail-qk1-f202.google.com ([209.85.222.202]:53249 "EHLO mail-qk1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732888AbfCZS24 (ORCPT ); Tue, 26 Mar 2019 14:28:56 -0400 Received: by mail-qk1-f202.google.com with SMTP id z123so12364059qka.20 for ; Tue, 26 Mar 2019 11:28:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=ahwCRT59PUZ2OMjvkc7Um/co/AqhkFAUQugbjFE3pQg=; b=R2jr48bzMerg1oMgmmmSMR8HlYXKL/FiNAnxSWmcCueCQBGJw2kMfBP1Nz952fYkw0 zBz5k5I+oWx5YpGuyN8UqSbN973STVZEUATKECDMUb5svS2fWjQvt7fJEWLHBIMpvKQR C/P22YtQMfpusPgycXDw6S5EOrM2LaVN/i1Atun13qW8SO8k1BgLeiM3rFsUS6J6EN4j A/RsDbmdC/nSF42Vgk+LeCcwJDHXkWuek2Ou5bla/HgqZtwODBp8cVGYwB1D49tefdjL mYL23awC4c+Nv8UwxlbIZPdnFQlQjWNjHk/xls8WLrxuEqzUlYy5VSWjSF4rcy2Ulwku nLwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=ahwCRT59PUZ2OMjvkc7Um/co/AqhkFAUQugbjFE3pQg=; b=Eir/yo7ipU21qaeMAGcuFEV3yPsBNGh9tfcC8kN8aXjISSzPqtFAVbf5Z0RbKyW0pq WA8JznXl8NLZmCzU8+0rI6brfI8tH2vO9VdX5rvSyMxW9VGD9rpiMlJMDepnPvp480l7 pLMg0fcRUoCm0dmtvsnHhiarMm/qCwe8OZTg9sblMvlTqRTcfaeRAxC+9htPslGcK85z MeKHyAoNyym3X7N5gks9AuN7TUa8RVXp+53BMFwUc1T8AZBKS5TqiZb2mtCdLAst4aVJ f4047Q7v+bDF2vXhnxi/8nsJZc7DAZtgSbYB4XmxIEcAMsfVuuv+MhX6We8o+TJ/Q0yl xeOw== X-Gm-Message-State: APjAAAUiyqDbP93oHU7wqese4+dIXgNMbTLpsVYaEWaDMlJAgSpp9LKP CCqqVCT/URbZF5/U38Nt4Xpp/Dzk3rwqdnQS+VjWfQ== X-Google-Smtp-Source: APXvYqy+PZO657NT2rtW8JWUD/4TRR5zbeRGjli9Y62NtWOMN/t8xuRoQeqW8HHqnCrtjXRhw6Wm22riuwZjNviQj7ZjFg== X-Received: by 2002:a0c:ad4a:: with SMTP id v10mr26132549qvc.232.1553624935093; Tue, 26 Mar 2019 11:28:55 -0700 (PDT) Date: Tue, 26 Mar 2019 11:27:40 -0700 In-Reply-To: <20190326182742.16950-1-matthewgarrett@google.com> Message-Id: <20190326182742.16950-25-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190326182742.16950-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e-goog Subject: [PATCH V31 24/25] lockdown: Print current->comm in restriction messages From: Matthew Garrett To: jmorris@namei.org Cc: linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, dhowells@redhat.com, linux-api@vger.kernel.org, luto@kernel.org, Matthew Garrett Sender: owner-linux-security-module@vger.kernel.org Precedence: bulk List-ID: X-Virus-Scanned: ClamAV using ClamSMTP From: David Howells Print the content of current->comm in messages generated by lockdown to indicate a restriction that was hit. This makes it a bit easier to find out what caused the message. The message now patterned something like: Lockdown: : is restricted; see man kernel_lockdown.7 Signed-off-by: David Howells Signed-off-by: Matthew Garrett --- include/linux/ima.h | 9 ++++++ kernel/kexec_file.c | 7 +++- security/integrity/ima/ima.h | 2 ++ security/integrity/ima/ima_main.c | 2 +- security/integrity/ima/ima_policy.c | 50 +++++++++++++++++++++++++++++ security/lock_down.c | 4 +-- 6 files changed, 70 insertions(+), 4 deletions(-) diff --git a/include/linux/ima.h b/include/linux/ima.h index b5e16b8c50b7..05921227d700 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -127,4 +127,13 @@ static inline int ima_inode_removexattr(struct dentry *dentry, return 0; } #endif /* CONFIG_IMA_APPRAISE */ + +#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING) +extern bool ima_appraise_signature(enum kernel_read_file_id func); +#else +static inline bool ima_appraise_kexec_signature(enum kernel_read_file_id func) +{ + return false; +} +#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */ #endif /* _LINUX_IMA_H */ diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index a1cc37c8b43b..7599039623a7 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -240,7 +240,12 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, ret = 0; - if (kernel_is_locked_down(reason, LOCKDOWN_INTEGRITY)) { + /* If IMA is guaranteed to appraise a signature on the kexec + * image, permit it even if the kernel is otherwise locked + * down. + */ + if (!ima_appraise_signature(READING_KEXEC_IMAGE) && + kernel_is_locked_down(reason, LOCKDOWN_INTEGRITY)) { ret = -EPERM; goto out; } diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index cc12f3449a72..fe03cc6f1ca4 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -115,6 +115,8 @@ struct ima_kexec_hdr { u64 count; }; +extern const int read_idmap[]; + #ifdef CONFIG_HAVE_IMA_KEXEC void ima_load_kexec_buffer(void); #else diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 4ffac4f5c647..106f06dee9d1 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -442,7 +442,7 @@ int ima_read_file(struct file *file, enum kernel_read_file_id read_id) return 0; } -static const int read_idmap[READING_MAX_ID] = { +const int read_idmap[READING_MAX_ID] = { [READING_FIRMWARE] = FIRMWARE_CHECK, [READING_FIRMWARE_PREALLOC_BUFFER] = FIRMWARE_CHECK, [READING_MODULE] = MODULE_CHECK, diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 122797023bdb..f8f1cdb74a4f 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1341,3 +1341,53 @@ int ima_policy_show(struct seq_file *m, void *v) return 0; } #endif /* CONFIG_IMA_READ_POLICY */ + +#if defined(CONFIG_IMA_APPRAISE) && defined(CONFIG_INTEGRITY_TRUSTED_KEYRING) +/* + * ima_appraise_signature: whether IMA will appraise a given function using + * an IMA digital signature. This is restricted to cases where the kernel + * has a set of built-in trusted keys in order to avoid an attacker simply + * loading additional keys. + */ +bool ima_appraise_signature(enum kernel_read_file_id id) +{ + struct ima_rule_entry *entry; + bool found = false; + enum ima_hooks func; + + if (id >= READING_MAX_ID) + return false; + + func = read_idmap[id] ?: FILE_CHECK; + + rcu_read_lock(); + list_for_each_entry_rcu(entry, ima_rules, list) { + if (entry->action != APPRAISE) + continue; + + /* + * A generic entry will match, but otherwise require that it + * match the func we're looking for + */ + if (entry->func && entry->func != func) + continue; + + /* + * We require this to be a digital signature, not a raw IMA + * hash. + */ + if (entry->flags & IMA_DIGSIG_REQUIRED) + found = true; + + /* + * We've found a rule that matches, so break now even if it + * didn't require a digital signature - a later rule that does + * won't override it, so would be a false positive. + */ + break; + } + + rcu_read_unlock(); + return found; +} +#endif /* CONFIG_IMA_APPRAISE && CONFIG_INTEGRITY_TRUSTED_KEYRING */ diff --git a/security/lock_down.c b/security/lock_down.c index 0f9ef4c30aa8..6bcffd0bb200 100644 --- a/security/lock_down.c +++ b/security/lock_down.c @@ -70,8 +70,8 @@ bool __kernel_is_locked_down(const char *what, enum lockdown_level level, bool first) { if ((kernel_locked_down >= level) && what && first) - pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n", - what); + pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n", + current->comm, what); return (kernel_locked_down >= level); } EXPORT_SYMBOL(__kernel_is_locked_down);