chantra / rpms / rpm

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From df089e178da0918dc74a8572a99324b0987bce30 Mon Sep 17 00:00:00 2001
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Message-Id: <df089e178da0918dc74a8572a99324b0987bce30.1554983206.git.pmatilai@redhat.com>
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In-Reply-To: <2ec0832287bd1443ebf336f8a98293f30bfa2036.1554983205.git.pmatilai@redhat.com>
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References: <2ec0832287bd1443ebf336f8a98293f30bfa2036.1554983205.git.pmatilai@redhat.com>
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From: Panu Matilainen <pmatilai@redhat.com>
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Date: Mon, 18 Mar 2019 15:56:34 +0200
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Subject: [PATCH 3/3] Verify packages before signing (RhBug:1646388)
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Permitting corrupted packages to be signed is bad business for everybody
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involved, this is something we should've always done. Besides being an
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actual security risk, it can lead to odd results with verification
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especially with the payload digest on signed packages.
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One point worth noting is that this means that pre 4.14-packages cannot
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be signed in FIPS mode now because there's no way to validate the package
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payload range due to MD5 being disabled. This seems like a feature and
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not a limitation, so disabler for the verify step intentionally left out.
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Optimally we'd verify the package on the same read that's passed
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to gpg but for simplicitys sake that's left as an future exercise,
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now we simply read the package twice.
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---
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 sign/rpmgensig.c   | 32 ++++++++++++++++++++++++++++++++
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 tests/rpmsigdig.at | 20 ++++++++++++++++++++
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 2 files changed, 52 insertions(+)
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diff --git a/sign/rpmgensig.c b/sign/rpmgensig.c
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index 2bcbab768..5be542001 100644
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--- a/sign/rpmgensig.c
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+++ b/sign/rpmgensig.c
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@@ -21,6 +21,7 @@
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 #include "lib/rpmlead.h"
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 #include "lib/signature.h"
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+#include "lib/rpmvs.h"
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 #include "sign/rpmsignfiles.h"
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 #include "debug.h"
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@@ -489,6 +490,31 @@ static rpmRC includeFileSignatures(Header *sigp, Header *hdrp)
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 #endif
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 }
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+static int msgCb(struct rpmsinfo_s *sinfo, void *cbdata)
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+{
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+    char **msg = cbdata;
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+    if (sinfo->rc && *msg == NULL)
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+	*msg = rpmsinfoMsg(sinfo);
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+    return (sinfo->rc != RPMRC_FAIL);
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+}
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+
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+/* Require valid digests on entire package for signing. */
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+static int checkPkg(FD_t fd, char **msg)
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+{
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+    int rc;
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+    struct rpmvs_s *vs = rpmvsCreate(RPMSIG_DIGEST_TYPE, 0, NULL);
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+    off_t offset = Ftell(fd);
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+
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+    Fseek(fd, 0, SEEK_SET);
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+    rc = rpmpkgRead(vs, fd, NULL, NULL, msg);
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+    if (!rc)
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+	rc = rpmvsVerify(vs, RPMSIG_DIGEST_TYPE, msgCb, msg);
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+    Fseek(fd, offset, SEEK_SET);
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+
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+    rpmvsFree(vs);
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+    return rc;
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+}
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+
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 /** \ingroup rpmcli
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  * Create/modify elements in signature header.
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  * @param rpm		path to package
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@@ -519,6 +545,12 @@ static int rpmSign(const char *rpm, int deleting, int signfiles)
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     if (manageFile(&fd, rpm, O_RDWR))
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 	goto exit;
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+    /* Ensure package is intact before attempting to sign */
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+    if ((rc = checkPkg(fd, &msg))) {
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+	rpmlog(RPMLOG_ERR, "not signing corrupt package %s: %s\n", rpm, msg);
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+	goto exit;
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+    }
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+
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     if ((rc = rpmLeadRead(fd, &msg)) != RPMRC_OK) {
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 	rpmlog(RPMLOG_ERR, "%s: %s\n", rpm, msg);
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 	goto exit;
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diff --git a/tests/rpmsigdig.at b/tests/rpmsigdig.at
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index 413c3d2c8..e93420306 100644
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--- a/tests/rpmsigdig.at
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+++ b/tests/rpmsigdig.at
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@@ -472,3 +472,23 @@ run rpmsign --key-id 1964C5FC --addsign "${RPMTEST}"/tmp/hello-2.0-1.x86_64-sign
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 [],
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 [])
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 AT_CLEANUP
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+
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+AT_SETUP([rpmsign --addsign <corrupted>])
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+AT_KEYWORDS([rpmsign signature])
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+AT_CHECK([
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+RPMDB_CLEAR
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+RPMDB_INIT
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+rm -rf "${TOPDIR}"
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+
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+pkg="hello-2.0-1.x86_64.rpm"
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+cp "${RPMTEST}"/data/RPMS/${pkg} "${RPMTEST}"/tmp/${pkg}
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+dd if=/dev/zero of="${RPMTEST}"/tmp/${pkg} \
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+   conv=notrunc bs=1 seek=333 count=4 2> /dev/null
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+run rpmsign --key-id 1964C5FC --addsign "${RPMTEST}/tmp/${pkg}"
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+],
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+[1],
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+[/home/pmatilai/repos/rpm/tests/testing/tmp/hello-2.0-1.x86_64.rpm:
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+],
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+[error: not signing corrupt package /home/pmatilai/repos/rpm/tests/testing/tmp/hello-2.0-1.x86_64.rpm: MD5 digest: BAD (Expected 007ca1d8b35cca02a1854ba301c5432e != 137ca1d8b35cca02a1854ba301c5432e)
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+])
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+AT_CLEANUP
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-- 
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2.20.1
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