From: Kai Kang <kai.kang@...>

Backport patch to fix CVE-2021-3621.

CVE: CVE-2021-3621

Signed-off-by: Kai Kang <kai.kang@...>
---
.../sssd/files/CVE-2021-3621.patch | 291 ++++++++++++++++++
recipes-security/sssd/sssd_1.16.5.bb | 1 +
2 files changed, 292 insertions(+)
create mode 100644 recipes-security/sssd/files/CVE-2021-3621.patch

diff --git a/recipes-security/sssd/files/CVE-2021-3621.patch b/recipes-security/sssd/files/CVE-2021-3621.patch
new file mode 100644
index 0000000..3d2c707
--- /dev/null
+++ b/recipes-security/sssd/files/CVE-2021-3621.patch
@@ -0,0 +1,291 @@
+Backport patch to fix CVE-2021-3621.
+
+Upstream-Status: Backport [https://github.com/SSSD/sssd/commit/b4b3267]
+CVE: CVE-2021-3621
+
+Signed-off-by: Kai Kang <kai.kang@...>
+
+From b4b32677a886bc26d60ce0171505aa3ab0c82c8a Mon Sep 17 00:00:00 2001
+From: Alexey Tikhonov <atikhono@...>
+Date: Fri, 30 Jul 2021 19:05:31 +0200
+Subject: [PATCH] TOOLS: replace system() with execvp() to avoid execution of
+ user supplied command
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+:relnote: A flaw was found in SSSD, where the sssctl command was
+vulnerable to shell command injection via the logs-fetch and
+cache-expire subcommands. This flaw allows an attacker to trick
+the root user into running a specially crafted sssctl command,
+such as via sudo, to gain root access. The highest threat from this
+vulnerability is to confidentiality, integrity, as well as system
+availability.
+This patch fixes a flaw by replacing system() with execvp().
+
+:fixes: CVE-2021-3621
+
+Reviewed-by: Pavel Březina <pbrezina@...>
+---
+ src/tools/sssctl/sssctl.c | 40 +++++++++++++++++-------
+ src/tools/sssctl/sssctl.h | 2 +-
+ src/tools/sssctl/sssctl_data.c | 57 +++++++++++-----------------------
+ src/tools/sssctl/sssctl_logs.c | 31 ++++++++++++++----
+ 4 files changed, 73 insertions(+), 57 deletions(-)
+
+diff --git a/src/tools/sssctl/sssctl.c b/src/tools/sssctl/sssctl.c
+index afaa84bc0..403c89c35 100644
+--- a/src/tools/sssctl/sssctl.c
++++ b/src/tools/sssctl/sssctl.c
+@@ -97,22 +97,37 @@ sssctl_prompt(const char *message,
+ return SSSCTL_PROMPT_ERROR;
+ }
+
+-errno_t sssctl_run_command(const char *command)
++errno_t sssctl_run_command(const char *const argv[])
+ {
+ int ret;
++ int wstatus;
+
+- DEBUG(SSSDBG_TRACE_FUNC, "Running %s\n", command);
++ DEBUG(SSSDBG_TRACE_FUNC, "Running '%s'\n", argv[0]);
+
+- ret = system(command);
++ ret = fork();
+ if (ret == -1) {
+- DEBUG(SSSDBG_CRIT_FAILURE, "Unable to execute %s\n", command);
+ fprintf(stderr, _("Error while executing external command\n"));
+ return EFAULT;
+- } else if (WEXITSTATUS(ret) != 0) {
+- DEBUG(SSSDBG_CRIT_FAILURE, "Command %s failed with [%d]\n",
+- command, WEXITSTATUS(ret));
++ }
++
++ if (ret == 0) {
++ /* cast is safe - see
++ https://pubs.opengroup.org/onlinepubs/9699919799/functions/exec.html
++ "The statement about argv[] and envp[] being constants ... "
++ */
++ execvp(argv[0], discard_const_p(char * const, argv));
+ fprintf(stderr, _("Error while executing external command\n"));
+- return EIO;
++ _exit(1);
++ } else {
++ if (waitpid(ret, &wstatus, 0) == -1) {
++ fprintf(stderr,
++ _("Error while executing external command '%s'\n"), argv[0]);
++ return EFAULT;
++ } else if (WEXITSTATUS(wstatus) != 0) {
++ fprintf(stderr,
++ _("Command '%s' failed with [%d]\n"), argv[0], WEXITSTATUS(wstatus));
++ return EIO;
++ }
+ }
+
+ return EOK;
+@@ -132,11 +147,14 @@ static errno_t sssctl_manage_service(enum sssctl_svc_action action)
+ #elif defined(HAVE_SERVICE)
+ switch (action) {
+ case SSSCTL_SVC_START:
+- return sssctl_run_command(SERVICE_PATH" sssd start");
++ return sssctl_run_command(
++ (const char *[]){SERVICE_PATH, "sssd", "start", NULL});
+ case SSSCTL_SVC_STOP:
+- return sssctl_run_command(SERVICE_PATH" sssd stop");
++ return sssctl_run_command(
++ (const char *[]){SERVICE_PATH, "sssd", "stop", NULL});
+ case SSSCTL_SVC_RESTART:
+- return sssctl_run_command(SERVICE_PATH" sssd restart");
++ return sssctl_run_command(
++ (const char *[]){SERVICE_PATH, "sssd", "restart", NULL});
+ }
+ #endif
+
+diff --git a/src/tools/sssctl/sssctl.h b/src/tools/sssctl/sssctl.h
+index 70fc19eff..71f798b2a 100644
+--- a/src/tools/sssctl/sssctl.h
++++ b/src/tools/sssctl/sssctl.h
+@@ -42,7 +42,7 @@ enum sssctl_prompt_result
+ sssctl_prompt(const char *message,
+ enum sssctl_prompt_result defval);
+
+-errno_t sssctl_run_command(const char *command);
++errno_t sssctl_run_command(const char *const argv[]); /* argv[0] - command */
+ bool sssctl_start_sssd(bool force);
+ bool sssctl_stop_sssd(bool force);
+ bool sssctl_restart_sssd(bool force);
+diff --git a/src/tools/sssctl/sssctl_data.c b/src/tools/sssctl/sssctl_data.c
+index cc46cafbf..8a042664c 100644
+--- a/src/tools/sssctl/sssctl_data.c
++++ b/src/tools/sssctl/sssctl_data.c
+@@ -105,15 +105,15 @@ static errno_t sssctl_backup(bool force)
+ }
+ }
+
+- ret = sssctl_run_command("sss_override user-export "
+- SSS_BACKUP_USER_OVERRIDES);
++ ret = sssctl_run_command((const char *[]){"sss_override", "user-export",
++ SSS_BACKUP_USER_OVERRIDES, NULL});
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to export user overrides\n"));
+ return ret;
+ }
+
+- ret = sssctl_run_command("sss_override group-export "
+- SSS_BACKUP_GROUP_OVERRIDES);
++ ret = sssctl_run_command((const char *[]){"sss_override", "group-export",
++ SSS_BACKUP_GROUP_OVERRIDES, NULL});
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to export group overrides\n"));
+ return ret;
+@@ -158,8 +158,8 @@ static errno_t sssctl_restore(bool force_start, bool force_restart)
+ }
+
+ if (sssctl_backup_file_exists(SSS_BACKUP_USER_OVERRIDES)) {
+- ret = sssctl_run_command("sss_override user-import "
+- SSS_BACKUP_USER_OVERRIDES);
++ ret = sssctl_run_command((const char *[]){"sss_override", "user-import",
++ SSS_BACKUP_USER_OVERRIDES, NULL});
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to import user overrides\n"));
+ return ret;
+@@ -167,8 +167,8 @@ static errno_t sssctl_restore(bool force_start, bool force_restart)
+ }
+
+ if (sssctl_backup_file_exists(SSS_BACKUP_USER_OVERRIDES)) {
+- ret = sssctl_run_command("sss_override group-import "
+- SSS_BACKUP_GROUP_OVERRIDES);
++ ret = sssctl_run_command((const char *[]){"sss_override", "group-import",
++ SSS_BACKUP_GROUP_OVERRIDES, NULL});
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to import group overrides\n"));
+ return ret;
+@@ -296,40 +296,19 @@ errno_t sssctl_cache_expire(struct sss_cmdline *cmdline,
+ void *pvt)
+ {
+ errno_t ret;
+- char *cmd_args = NULL;
+- const char *cachecmd = SSS_CACHE;
+- char *cmd = NULL;
+- int i;
+-
+- if (cmdline->argc == 0) {
+- ret = sssctl_run_command(cachecmd);
+- goto done;
+- }
+
+- cmd_args = talloc_strdup(tool_ctx, "");
+- if (cmd_args == NULL) {
+- ret = ENOMEM;
+- goto done;
++ const char **args = talloc_array_size(tool_ctx,
++ sizeof(char *),
++ cmdline->argc + 2);
++ if (!args) {
++ return ENOMEM;
+ }
++ memcpy(&args[1], cmdline->argv, sizeof(char *) * cmdline->argc);
++ args[0] = SSS_CACHE;
++ args[cmdline->argc + 1] = NULL;
+
+- for (i = 0; i < cmdline->argc; i++) {
+- cmd_args = talloc_strdup_append(cmd_args, cmdline->argv[i]);
+- if (i != cmdline->argc - 1) {
+- cmd_args = talloc_strdup_append(cmd_args, " ");
+- }
+- }
+-
+- cmd = talloc_asprintf(tool_ctx, "%s %s", cachecmd, cmd_args);
+- if (cmd == NULL) {
+- ret = ENOMEM;
+- goto done;
+- }
+-
+- ret = sssctl_run_command(cmd);
+-
+-done:
+- talloc_free(cmd_args);
+- talloc_free(cmd);
++ ret = sssctl_run_command(args);
+
++ talloc_free(args);
+ return ret;
+ }
+diff --git a/src/tools/sssctl/sssctl_logs.c b/src/tools/sssctl/sssctl_logs.c
+index aca988c05..c85cc7a4b 100644
+--- a/src/tools/sssctl/sssctl_logs.c
++++ b/src/tools/sssctl/sssctl_logs.c
+@@ -32,6 +32,7 @@
+ #include <popt.h>
+ #include <stdio.h>
+ #include <signal.h>
++#include <glob.h>
+
+ #include "util/util.h"
+ #include "tools/common/sss_process.h"
+@@ -231,6 +232,7 @@ errno_t sssctl_logs_remove(struct sss_cmdline *cmdline,
+ {
+ struct sssctl_logs_opts opts = {0};
+ errno_t ret;
++ glob_t globbuf;
+
+ /* Parse command line. */
+ struct poptOption options[] = {
+@@ -254,8 +256,19 @@ errno_t sssctl_logs_remove(struct sss_cmdline *cmdline,
+
+ sss_signal(SIGHUP);
+ } else {
++ globbuf.gl_offs = 4;
++ ret = glob(LOG_PATH"/*.log", GLOB_ERR|GLOB_DOOFFS, NULL, &globbuf);
++ if (ret != 0) {
++ DEBUG(SSSDBG_CRIT_FAILURE, "Unable to expand log files list\n");
++ return ret;
++ }
++ globbuf.gl_pathv[0] = discard_const_p(char, "truncate");
++ globbuf.gl_pathv[2] = discard_const_p(char, "--size");
++ globbuf.gl_pathv[3] = discard_const_p(char, "0");
++
+ printf(_("Truncating log files...\n"));
+- ret = sssctl_run_command("truncate --size 0 " LOG_FILES);
++ ret = sssctl_run_command((const char * const*)globbuf.gl_pathv);
++ globfree(&globbuf);
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to truncate log files\n"));
+ return ret;
+@@ -270,8 +283,8 @@ errno_t sssctl_logs_fetch(struct sss_cmdline *cmdline,
+ void *pvt)
+ {
+ const char *file;
+- const char *cmd;
+ errno_t ret;
++ glob_t globbuf;
+
+ /* Parse command line. */
+ ret = sss_tool_popt_ex(cmdline, NULL, SSS_TOOL_OPT_OPTIONAL, NULL, NULL,
+@@ -281,13 +294,19 @@ errno_t sssctl_logs_fetch(struct sss_cmdline *cmdline,
+ return ret;
+ }
+
+- cmd = talloc_asprintf(tool_ctx, "tar -czf %s %s", file, LOG_FILES);
+- if (cmd == NULL) {
+- fprintf(stderr, _("Out of memory!"));
++ globbuf.gl_offs = 3;
++ ret = glob(LOG_PATH"/*.log", GLOB_ERR|GLOB_DOOFFS, NULL, &globbuf);
++ if (ret != 0) {
++ DEBUG(SSSDBG_CRIT_FAILURE, "Unable to expand log files list\n");
++ return ret;
+ }
++ globbuf.gl_pathv[0] = discard_const_p(char, "tar");
++ globbuf.gl_pathv[1] = discard_const_p(char, "-czf");
++ globbuf.gl_pathv[2] = discard_const_p(char, file);
+
+ printf(_("Archiving log files into %s...\n"), file);
+- ret = sssctl_run_command(cmd);
++ ret = sssctl_run_command((const char * const*)globbuf.gl_pathv);
++ globfree(&globbuf);
+ if (ret != EOK) {
+ fprintf(stderr, _("Unable to archive log files\n"));
+ return ret;
+--
+2.33.0
+
diff --git a/recipes-security/sssd/sssd_1.16.5.bb b/recipes-security/sssd/sssd_1.16.5.bb
index 9784ec7..02d0837 100644
--- a/recipes-security/sssd/sssd_1.16.5.bb
+++ b/recipes-security/sssd/sssd_1.16.5.bb
@@ -22,6 +22,7 @@ SRC_URI = "https://releases.pagure.org/SSSD/${BPN}/${BP}.tar.gz \
file://0001-build-Don-t-use-AC_CHECK_FILE-when-building-manpages.patch \
file://0001-nss-Collision-with-external-nss-symbol.patch \
file://0002-Provide-missing-defines-which-otherwise-are-availabl.patch \
+ file://CVE-2021-3621.patch \
"

SRC_URI[sha256sum] = "2e1a7bf036b583f686d35164f2d79bdf4857b98f51fe8b0d17aa0fa756e4d0c0"