From f1a92e02faa2715777286acd07b8d0f465c5df37 Mon Sep 17 00:00:00 2001

From: Jes Sorensen <jsorensen@fb.com>

Date: Mon, 20 Apr 2020 11:11:25 -0400

Subject: [PATCH 27/33] plugins/fsverity: Install fsverity signatures

This plugin installs fsverity signatures for regular files, when a signature

is found in the RPM. It tries to enable them unconditionally, but fails

gracefully if fsverity isn't supported or enabled.

Signed-off-by: Jes Sorensen <jsorensen@fb.com>

---

 configure.ac        |  29 ++++++++

 macros.in           |   4 +

 plugins/Makefile.am |   7 ++

 plugins/fsverity.c  | 177 ++++++++++++++++++++++++++++++++++++++++++++

 4 files changed, 217 insertions(+)

 create mode 100644 plugins/fsverity.c

diff --git a/configure.ac b/configure.ac

index cc7144440..7d3c31831 100644

--- a/configure.ac

+++ b/configure.ac

@@ -1049,6 +1049,35 @@ AS_IF([test "$enable_plugins" != no],[

 ])

 AM_CONDITIONAL(IMA, [test "x$ac_cv_func_lsetxattr" = xyes])

+AS_IF([test "$enable_plugins" != no],[

+AC_CHECK_HEADERS([linux/fsverity.h],[FSVERITY_IOCTL="yes"])

+])

+AM_CONDITIONAL(FSVERITY_IOCTL,[test "x$FSVERITY_IOCTL" = xyes])

+

+#=================

+# Check for audit library.

+AC_ARG_WITH(audit,

+AS_HELP_STRING([--with-audit],[Linux audit plugin]),

+with_audit=$withval,

+with_audit=auto)

+

+WITH_AUDIT_LIB=

+AS_IF([test "$enable_plugins" != no],[

+  AS_IF([test "x$with_audit" != xno],[

+    AC_SEARCH_LIBS([audit_open],[audit],[

+      WITH_AUDIT_LIB="$ac_res"

+      AC_DEFINE(WITH_AUDIT, 1, [libaudit support])

+      with_audit=yes

+    ],[

+      if test "x$with_audit" != xauto; then

+        AC_MSG_ERROR([missing audit library])

+      fi

+    ])

+  ])

+])

+AC_SUBST(WITH_AUDIT_LIB)

+AM_CONDITIONAL(AUDIT,[test "$with_audit" = yes])

+

 user_with_uid0=$(awk -F: '$3==0 {print $1;exit}' /etc/passwd)

 group_with_gid0=$(awk -F: '$3==0 {print $1;exit}' /etc/group)

 AC_DEFINE_UNQUOTED([UID_0_USER],["$user_with_uid0"],[Get the user name having userid 0])

diff --git a/macros.in b/macros.in

index fe8862903..3c722146b 100644

--- a/macros.in

+++ b/macros.in

@@ -767,6 +767,9 @@ package or when debugging this package.\

 # performance for rotational disks)

 #%_flush_io	0

+# Set to 1 to have fsverity signatures written for %config files.

+#%_fsverity_sign_config_files	0

+

 #

 # Default output format string for rpm -qa

 #

@@ -1185,6 +1188,7 @@ package or when debugging this package.\

 %__transaction_syslog		%{__plugindir}/syslog.so

 %__transaction_ima		%{__plugindir}/ima.so

 %__transaction_fapolicyd	%{__plugindir}/fapolicyd.so

+%__transaction_fsverity		%{__plugindir}/fsverity.so

 %__transaction_prioreset	%{__plugindir}/prioreset.so

 #------------------------------------------------------------------------------

diff --git a/plugins/Makefile.am b/plugins/Makefile.am

index cbfb81e19..e51b71f62 100644

--- a/plugins/Makefile.am

+++ b/plugins/Makefile.am

@@ -48,3 +48,10 @@ fapolicyd_la_sources = fapolicyd.c

 fapolicyd_la_LIBADD = $(top_builddir)/lib/librpm.la $(top_builddir)/rpmio/librpmio.la

 plugins_LTLIBRARIES += fapolicyd.la

 endif

+

+if FSVERITY_IOCTL

+fsverity_la_sources = fsverity.c

+fsverity_la_LIBADD = $(top_builddir)/lib/librpm.la $(top_builddir)/rpmio/librpmio.la

+plugins_LTLIBRARIES += fsverity.la

+endif

+

diff --git a/plugins/fsverity.c b/plugins/fsverity.c

new file mode 100644

index 000000000..15ddcf33e

--- /dev/null

+++ b/plugins/fsverity.c

@@ -0,0 +1,177 @@

+/**

+ * Copyright (C) 2020 Facebook

+ *

+ * Author: Jes Sorensen <jsorensen@fb.com>

+ */

+

+#include "system.h"

+

+#include <errno.h>

+#include <fcntl.h>

+#include <sys/ioctl.h>

+#include <linux/fsverity.h>

+

+#include <rpm/rpmfi.h>

+#include <rpm/rpmte.h>

+#include <rpm/rpmfiles.h>

+#include <rpm/rpmtypes.h>

+#include <rpm/rpmlog.h>

+#include <rpmio/rpmstring.h>

+#include <rpmio/rpmmacro.h>

+

+#include "lib/rpmfs.h"

+#include "lib/rpmplugin.h"

+#include "lib/rpmte_internal.h"

+

+#include "sign/rpmsignverity.h"

+

+static int sign_config_files = 0;

+

+/*

+ * This unconditionally tries to apply the fsverity signature to a file,

+ * but fails gracefully if the file system doesn't support it or the

+ * verity feature flag isn't enabled in the file system (ext4).

+ */

+static rpmRC fsverity_fsm_file_prepare(rpmPlugin plugin, rpmfi fi,

+				       const char *path, const char *dest,

+				       mode_t file_mode, rpmFsmOp op)

+{

+    struct fsverity_enable_arg arg;

+    const unsigned char * signature = NULL;

+    size_t len;

+    int rc = RPMRC_OK;

+    int fd;

+    rpmFileAction action = XFO_ACTION(op);

+    char *buffer;

+

+    /* Ignore skipped files and unowned directories */

+    if (XFA_SKIPPING(action) || (op & FAF_UNOWNED)) {

+	rpmlog(RPMLOG_DEBUG, "fsverity skipping early: path %s dest %s\n",

+	       path, dest);

+	goto exit;

+    }

+

+    /*

+     * Do not install signatures for config files unless the

+     * user explicitly asks for it.

+     */

+    if (rpmfiFFlags(fi) & RPMFILE_CONFIG) {

+	if (!(rpmfiFMode(fi) & (S_IXUSR|S_IXGRP|S_IXOTH)) &&

+	    !sign_config_files) {

+	    rpmlog(RPMLOG_DEBUG, "fsverity skipping: path %s dest %s\n",

+		   path, dest);

+

+	    goto exit;

+	}

+    }

+

+    /*

+     * Right now fsverity doesn't deal with symlinks or directories, so do

+     * not try to install signatures for non regular files.

+     */

+    if (!S_ISREG(rpmfiFMode(fi))) {

+	rpmlog(RPMLOG_DEBUG, "fsverity skipping non regular: path %s dest %s\n",

+	       path, dest);

+	goto exit;

+    }

+

+    signature = rpmfiVSignature(fi, &len;;

+    if (!signature || !len) {

+	rpmlog(RPMLOG_DEBUG, "fsverity no signature for: path %s dest %s\n",

+	       path, dest);

+	goto exit;

+    }

+

+    memset(&arg, 0, sizeof(arg));

+    arg.version = 1;

+    arg.hash_algorithm = FS_VERITY_HASH_ALG_SHA256;

+    arg.block_size = RPM_FSVERITY_BLKSZ;

+    arg.sig_ptr = (uintptr_t)signature;

+    arg.sig_size = len;

+

+    buffer = pgpHexStr(signature, arg.sig_size);

+    rpmlog(RPMLOG_DEBUG, "applying signature: %s\n", buffer);

+    free(buffer);

+

+    fd = open(path, O_RDONLY);

+    if (fd < 0) {

+	rpmlog(RPMLOG_ERR, "failed to open path %s\n", path);

+	goto exit;

+    }

+

+    /*

+     * Enable fsverity on the file.

+     * fsverity not supported by file system (ENOTTY) and fsverity not

+     * enabled on file system are expected and not considered

+     * errors. Every other non-zero error code will result in the

+     * installation failing.

+     */

+    if (ioctl(fd, FS_IOC_ENABLE_VERITY, &arg) != 0) {

+	switch(errno) {

+	case EBADMSG:

+	    rpmlog(RPMLOG_DEBUG, "invalid or malformed fsverity signature for %s\n", path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case EEXIST:

+	    rpmlog(RPMLOG_DEBUG, "fsverity signature already enabled %s\n",

+		   path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case EINVAL:

+	    rpmlog(RPMLOG_DEBUG, "invalid arguments for ioctl %s\n", path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case EKEYREJECTED:

+	    rpmlog(RPMLOG_DEBUG, "signature doesn't match file %s\n", path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case EMSGSIZE:

+	    rpmlog(RPMLOG_DEBUG, "invalid signature size for %s\n", path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case ENOPKG:

+	    rpmlog(RPMLOG_DEBUG, "unsupported signature algoritm (%i) for %s\n",

+		   arg.hash_algorithm, path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case ETXTBSY:

+	    rpmlog(RPMLOG_DEBUG, "file is open by other process %s\n",

+		   path);

+	    rc = RPMRC_FAIL;

+	    break;

+	case ENOTTY:

+	    rpmlog(RPMLOG_DEBUG, "fsverity not supported by file system for %s\n",

+		   path);

+	    break;

+	case EOPNOTSUPP:

+	    rpmlog(RPMLOG_DEBUG, "fsverity not enabled on file system for %s\n",

+		   path);

+	    break;

+	default:

+	    rpmlog(RPMLOG_DEBUG, "failed to enable verity (errno %i) for %s\n",

+		   errno, path);

+	    rc = RPMRC_FAIL;

+	    break;

+	}

+    }

+

+    rpmlog(RPMLOG_DEBUG, "fsverity enabled signature for: path %s dest %s\n",

+	   path, dest);

+    close(fd);

+exit:

+    return rc;

+}

+

+static rpmRC fsverity_init(rpmPlugin plugin, rpmts ts)

+{

+    sign_config_files = rpmExpandNumeric("%{?_fsverity_sign_config_files}");

+

+    rpmlog(RPMLOG_DEBUG, "fsverity_init\n");

+

+    return RPMRC_OK;

+}

+

+struct rpmPluginHooks_s fsverity_hooks = {

+    .init = fsverity_init,

+    .fsm_file_prepare = fsverity_fsm_file_prepare,

+};

-- 

2.27.0