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sssd.30907
0040-TOOLS-replace-system-with-execvp-to-avoid-...
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File 0040-TOOLS-replace-system-with-execvp-to-avoid-execution-.patch of Package sssd.30907
From b4b32677a886bc26d60ce0171505aa3ab0c82c8a Mon Sep 17 00:00:00 2001 From: Alexey Tikhonov <atikhono@redhat.com> 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@redhat.com> --- 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; -- 2.32.0
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