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Tue, 08 Apr 2025 11:02:55 -0400 X-MC-Unique: zKsBN8XdOHuLvUodn1doSg-1 X-Mimecast-MFC-AGG-ID: zKsBN8XdOHuLvUodn1doSg_1744124561 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 93592187BE12; Tue, 8 Apr 2025 15:02:34 +0000 (UTC) Received: from localhost (unknown [10.72.112.61]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 17FFD1956094; Tue, 8 Apr 2025 15:02:31 +0000 (UTC) Date: Tue, 8 Apr 2025 23:02:27 +0800 From: Baoquan He To: Mimi Zohar Cc: steven chen , stefanb@linux.ibm.com, roberto.sassu@huaweicloud.com, roberto.sassu@huawei.com, eric.snowberg@oracle.com, ebiederm@xmission.com, paul@paul-moore.com, code@tyhicks.com, bauermann@kolabnow.com, linux-integrity@vger.kernel.org, kexec@lists.infradead.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com, nramas@linux.microsoft.com, James.Bottomley@hansenpartnership.com, vgoyal@redhat.com, dyoung@redhat.com Subject: Re: [PATCH v11 2/9] ima: define and call ima_alloc_kexec_file_buf() Message-ID: References: <20250402124725.5601-1-chenste@linux.microsoft.com> <20250402124725.5601-3-chenste@linux.microsoft.com> <36e244edd96a51f0749d54811c9567f954680a39.camel@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250408_080301_952984_ED47053D X-CRM114-Status: GOOD ( 45.04 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 04/08/25 at 08:23am, Mimi Zohar wrote: > On Tue, 2025-04-08 at 16:18 +0800, Baoquan He wrote: > > On 04/08/25 at 01:03am, Mimi Zohar wrote: > > > On Tue, 2025-04-08 at 12:39 +0800, Baoquan He wrote: > > > > On 04/08/25 at 12:07am, Mimi Zohar wrote: > > > > > On Wed, 2025-04-02 at 05:47 -0700, steven chen wrote: > > > > > > In the current implementation, the ima_dump_measurement_list() API is > > > > > > called during the kexec "load" phase, where a buffer is allocated and > > > > > > the measurement records are copied. Due to this, new events added after > > > > > > kexec load but before kexec execute are not carried over to the new kernel > > > > > > during kexec operation > > > > > > > > > > Repeating this here is unnecessary. > > > > > > > > > > > > To allow the buffer allocation and population to be separated into distinct > > > > > > steps, make the function local seq_file "ima_kexec_file" to a file variable. > > > > > > > > > > This change was already made in [PATCH v11 1/9] ima: rename variable the > > > > > set_file "file" to "ima_kexec_file". Please remove. > > > > > > > > > > > > > > > > > Carrying the IMA measurement list across kexec requires allocating a > > > > > > buffer and copying the measurement records. Separate allocating the > > > > > > buffer and copying the measurement records into separate functions in > > > > > > order to allocate the buffer at kexec 'load' and copy the measurements > > > > > > at kexec 'execute'. > > > > > > > > > > > > Signed-off-by: Tushar Sugandhi > > > > > > Signed-off-by: steven chen > > > > > > --- > > > > > > security/integrity/ima/ima_kexec.c | 46 +++++++++++++++++++++++------- > > > > > > 1 file changed, 35 insertions(+), 11 deletions(-) > > > > > > > > > > > > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > > > > > > index 650beb74346c..b12ac3619b8f 100644 > > > > > > --- a/security/integrity/ima/ima_kexec.c > > > > > > +++ b/security/integrity/ima/ima_kexec.c > > > > > > @@ -15,26 +15,46 @@ > > > > > > #include "ima.h" > > > > > > > > > > > > #ifdef CONFIG_IMA_KEXEC > > > > > > +static struct seq_file ima_kexec_file; > > > > > > + > > > > > > +static void ima_free_kexec_file_buf(struct seq_file *sf) > > > > > > +{ > > > > > > + vfree(sf->buf); > > > > > > + sf->buf = NULL; > > > > > > + sf->size = 0; > > > > > > + sf->read_pos = 0; > > > > > > + sf->count = 0; > > > > > > +} > > > > > > + > > > > > > +static int ima_alloc_kexec_file_buf(size_t segment_size) > > > > > > +{ > > > > > > + ima_free_kexec_file_buf(&ima_kexec_file); > > > > > > > > > > After moving the vfree() here at this stage in the patch set, the IMA > > > > > measurement list fails to verify when doing two consecutive "kexec -s -l" > > > > > with/without a "kexec -s -u" in between. Only after "ima: kexec: move IMA log > > > > > copy from kexec load to execute" the IMA measurement list verifies properly with > > > > > the vfree() here. > > > > > > > > I also noticed this, patch 7 will remedy this. Put patch 7 just after > > > > this patch or squash it into this patch? > > > > > > > > [PATCH v11 7/9] ima: verify if the segment size has changed > > > > > > I'm glad you noticed this too! I've been staring at it for a while, not knowing > > > what to do. > > > > > > "ima: verify if the segment size has changed" is new to v11. It was originally > > > part of this patch. My comment on v10 was: > > > > > > The call to ima_reset_kexec_file() in ima_add_kexec_buffer() resets > > > ima_kexec_file.buf() hiding the fact that the above test always fails and falls > > > through. As a result, 'buf' is always being re-allocated. > > > > > > and > > > > > > Instead of adding and then removing the ima_reset_kexec_file() call from > > > ima_add_kexec_buffer(), defer adding the segment size test to when it is > > > actually possible for the segment size to change. Please make the segment size > > > test as a separate patch. > > > > > > ima_reset_kexec_file() will then only be called by ima_free_kexec_file_buf(). > > > Inline the ima_reset_kexec_file() code in ima_free_kexec_file_buf(). > > > > Thanks for deliberating on this and the details sharing, Mimi. > > > > It could be fine if we add note in patch 2 log to mention the possible > > failure. With my understanding, commit/patch bisectable means it won't > > break compiling and block the testing. The failure you are concerned > > about is not a blocker, right? And people won't back port partial > > patches of this series. > > > > Nore sure if there's another better way we can take or detour. > > Right, doing two consecutive kexec loads in a row is not common and won't block > testing. Patch readability is more important, in this case, at least to me. > I'm fine with your suggestion. That's great, thanks for confirming.