76 lines
2.8 KiB
Diff
76 lines
2.8 KiB
Diff
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From patchwork Fri Apr 13 15:27:52 2018
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Content-Type: text/plain; charset="utf-8"
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MIME-Version: 1.0
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Content-Transfer-Encoding: 7bit
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Subject: lockdown: fix coordination of kernel module signature verification
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From: Mimi Zohar <zohar@linux.vnet.ibm.com>
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X-Patchwork-Id: 10340277
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Message-Id: <1523633272.3272.30.camel@linux.vnet.ibm.com>
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To: David Howells <dhowells@redhat.com>
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Cc: Luca Boccassi <bluca@debian.org>,
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"Bruno E. O. Meneguele" <bmeneg@redhat.com>,
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linux-integrity <linux-integrity@vger.kernel.org>,
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linux-security-module <linux-security-module@vger.kernel.org>,
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linux-kernel <linux-kernel@vger.kernel.org>
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Date: Fri, 13 Apr 2018 11:27:52 -0400
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If both IMA-appraisal and sig_enforce are enabled, then both signatures
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are currently required. If the IMA-appraisal signature verification
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fails, it could rely on the appended signature verification; but with the
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lockdown patch set, the appended signature verification assumes that if
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IMA-appraisal is enabled, it has verified the signature. Basically each
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signature verification method would be relying on the other to verify the
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kernel module signature.
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This patch addresses the problem of requiring both kernel module signature
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verification methods, when both are enabled, by verifying just the
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appended signature.
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Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
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Acked-by: Bruno E. O. Meneguele <bmeneg@redhat.com>
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---
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kernel/module.c | 4 +---
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security/integrity/ima/ima_main.c | 7 ++++++-
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2 files changed, 7 insertions(+), 4 deletions(-)
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diff --git a/kernel/module.c b/kernel/module.c
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index 9c1709a05037..60861eb7bc4d 100644
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--- a/kernel/module.c
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+++ b/kernel/module.c
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@@ -2803,9 +2803,7 @@ static int module_sig_check(struct load_info *info, int flags,
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if (sig_enforce) {
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pr_notice("%s is rejected\n", reason);
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return -EKEYREJECTED;
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- }
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-
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- if (can_do_ima_check && is_ima_appraise_enabled())
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+ } else if (can_do_ima_check && is_ima_appraise_enabled())
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return 0;
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if (kernel_is_locked_down(reason))
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return -EPERM;
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diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
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index 754ece08e1c6..2155b1f316a4 100644
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--- a/security/integrity/ima/ima_main.c
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+++ b/security/integrity/ima/ima_main.c
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@@ -480,6 +480,7 @@ static int read_idmap[READING_MAX_ID] = {
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int ima_post_read_file(struct file *file, void *buf, loff_t size,
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enum kernel_read_file_id read_id)
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{
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+ bool sig_enforce = is_module_sig_enforced();
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enum ima_hooks func;
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u32 secid;
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@@ -490,7 +491,11 @@ int ima_post_read_file(struct file *file, void *buf, loff_t size,
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return 0;
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}
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- if (!file && read_id == READING_MODULE) /* MODULE_SIG_FORCE enabled */
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+ /*
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+ * If both IMA-appraisal and appended signature verification are
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+ * enabled, rely on the appended signature verification.
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+ */
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+ if (sig_enforce && read_id == READING_MODULE)
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return 0;
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/* permit signed certs */
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