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[209.132.180.67]) by mx.google.com with ESMTP id q29si17142479pfi.98.2019.03.26.11.29.57; Tue, 26 Mar 2019 11:30:12 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=R2jr48bz; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732910AbfCZS3A (ORCPT + 99 others); Tue, 26 Mar 2019 14:29:00 -0400 Received: from mail-qk1-f202.google.com ([209.85.222.202]:43024 "EHLO mail-qk1-f202.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732891AbfCZS24 (ORCPT ); Tue, 26 Mar 2019 14:28:56 -0400 Received: by mail-qk1-f202.google.com with SMTP id m8so12378314qka.10 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=MQ+5c2I8Oy4oK6CvFPpZv0oky5p6vwU3hdnc9JnwKnGKoXYGjWyO6S/QzkwK/Jo91V ZGl8iClxxtOeRlJML1ka0QoWCpFXl2YOyyB7A7T7gP3t8YpMCgnY8CvimLA5VMmuLVy9 ReJ80XAyUkt5yE2IMdmaD298mwidDkpHAJcbqVqgMevJLX2t3A4nyBg4bSPNvumXMZUl +tfjKi2wbf+OY0tMH6oIzhVOFdorXVKnifrR15TcBXmJk+0oEMyMKzTF0bs7QneRspPM JFhSQy4SAfXvZJIyabDEwxX2Wk+TOuh00C043PdlN4hIyWN6eiCVXGhfnSCojEU5ZOhT MqlQ== X-Gm-Message-State: APjAAAVLYRU1rA6iRTPvvH0SAaa2dSCWzpqQJ+V3/2mAA8bWxf3LIjNo zl8hPck2P+2/9Kk6EsFtyRJmY4fDkAq9mJzsyy4D3g== 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 Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); -- 2.21.0.392.gf8f6787159e-goog