Date: Mon, 26 Mar 2012 12:18:15 +0000 (UTC) From: Jean-Sebastien Pedron <dumbbell@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r233507 - head/lib/libpam/modules/pam_exec Message-ID: <201203261218.q2QCIFUf032406@svn.freebsd.org>
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Author: dumbbell Date: Mon Mar 26 12:18:15 2012 New Revision: 233507 URL: http://svn.freebsd.org/changeset/base/233507 Log: Use program exit status as pam_exec return code (optional) pam_exec(8) now accepts a new option "return_prog_exit_status". When set, the program exit status is used as the pam_exec return code. It allows the program to tell why the step failed (eg. user unknown). However, if it exits with a code not allowed by the calling PAM service module function (see $PAM_SM_FUNC below), a warning is logged and PAM_SERVICE_ERR is returned. The following changes are related to this new feature but they apply no matter if the "return_prog_exit_status" option is set or not. The environment passed to the program is extended: o $PAM_SM_FUNC contains the name of the PAM service module function (eg. pam_sm_authenticate). o All valid PAM return codes' numerical values are available through variables named after the return code name. For instance, $PAM_SUCCESS, $PAM_USER_UNKNOWN or $PAM_PERM_DENIED. pam_exec return code better reflects what went on: o If the program exits with !0, the return code is now PAM_PERM_DENIED, not PAM_SYSTEM_ERR. o If the program fails because of a signal (WIFSIGNALED) or doesn't terminate normally (!WIFEXITED), the return code is now PAM_SERVICE_ERR, not PAM_SYSTEM_ERR. o If a syscall in pam_exec fails, the return code remains PAM_SYSTEM_ERR. waitpid(2) is called in a loop. If it returns because of EINTR, do it again. Before, it would return PAM_SYSTEM_ERR without waiting for the child to exit. Several log messages now include the PAM service module function name. The man page is updated accordingly. Reviewed by: gleb@, des@ Sponsored by: Yakaz (http://www.yakaz.com) MFC after: 2 weeks Modified: head/lib/libpam/modules/pam_exec/pam_exec.8 head/lib/libpam/modules/pam_exec/pam_exec.c Modified: head/lib/libpam/modules/pam_exec/pam_exec.8 ============================================================================== --- head/lib/libpam/modules/pam_exec/pam_exec.8 Mon Mar 26 11:48:47 2012 (r233506) +++ head/lib/libpam/modules/pam_exec/pam_exec.8 Mon Mar 26 12:18:15 2012 (r233507) @@ -32,7 +32,7 @@ .\" .\" $FreeBSD$ .\" -.Dd February 1, 2005 +.Dd February 8, 2012 .Dt PAM_EXEC 8 .Os .Sh NAME @@ -45,9 +45,25 @@ .Pa pam_exec .Op Ar arguments .Sh DESCRIPTION -The exec service module for PAM executes the program designated by its -first argument, with its remaining arguments as command-line -arguments. +The exec service module for PAM executes the program designated by +its first argument if no options are specified, with its remaining +arguments as command-line arguments. +If options are specified, the program and its arguments follow the last +option or +.Cm -- +if the program name conflicts with an option name. +.Pp +The following options may be passed before the program and its +arguments: +.Bl -tag -width ".Cm return_prog_exit_status" +.It Cm return_prog_exit_status +Use the program exit status as the return code of the pam_sm_* function. +It must be a valid return value for this function. +.It Cm -- +Stop options parsing; +program and its arguments follow. +.El +.Pp The child's environment is set to the current PAM environment list, as returned by .Xr pam_getenvlist 3 . @@ -56,13 +72,69 @@ variables: .Ev PAM_RHOST , .Ev PAM_RUSER , .Ev PAM_SERVICE , -.Ev PAM_TTY , +.Ev PAM_SM_FUNC , +.Ev PAM_TTY and .Ev PAM_USER . +.Pp +The +.Ev PAM_SM_FUNC +variable contains the name of the PAM service module function being +called. +It may be: +.Bl -dash -offset indent -compact +.It +pam_sm_acct_mgmt +.It +pam_sm_authenticate +.It +pam_sm_chauthtok +.It +pam_sm_close_session +.It +pam_sm_open_session +.It +pam_sm_setcred +.El +.Pp +If +.Cm return_prog_exit_status +is not set (default), the +.Ev PAM_SM_FUNC +function returns +.Er PAM_SUCCESS +if the program exit status is 0, +.Er PAM_PERM_DENIED +otherwise. +.Pp +If +.Cm return_prog_exit_status +is set, the program exit status is used. +It should be +.Er PAM_SUCCESS +or one of the error codes allowed by the calling +.Ev PAM_SM_FUNC +function. +The valid codes are documented in each function man page. +If the exit status is not a valid return code, +.Er PAM_SERVICE_ERR +is returned. +Each valid codes numerical value is available as an environment variable +(eg.\& +.Ev PAM_SUCESS , +.Ev PAM_USER_UNKNOWN , +etc). +This is useful in shell scripts for instance. .Sh SEE ALSO .Xr pam_get_item 3 , .Xr pam.conf 5 , -.Xr pam 8 +.Xr pam 8 , +.Xr pam_sm_acct_mgmt 8 , +.Xr pam_sm_authenticate 8 , +.Xr pam_sm_chauthtok 8, +.Xr pam_sm_close_session 8 , +.Xr pam_sm_open_session 8 , +.Xr pam_sm_setcred 8 . .Sh AUTHORS The .Nm Modified: head/lib/libpam/modules/pam_exec/pam_exec.c ============================================================================== --- head/lib/libpam/modules/pam_exec/pam_exec.c Mon Mar 26 11:48:47 2012 (r233506) +++ head/lib/libpam/modules/pam_exec/pam_exec.c Mon Mar 26 12:18:15 2012 (r233507) @@ -60,32 +60,71 @@ static struct { ENV_ITEM(PAM_RUSER), }; +#define PAM_RV_COUNT 24 + static int -_pam_exec(pam_handle_t *pamh __unused, int flags __unused, - int argc, const char *argv[]) +_pam_exec(pam_handle_t *pamh __unused, + const char *func, int flags __unused, int argc, const char *argv[]) { - int envlen, i, nitems, pam_err, status; - char *env, **envlist, **tmp; + int envlen, i, nitems, pam_err, status, return_prog_exit_status; + int nitems_rv; + char *env, **envlist, **tmp, *envstr; volatile int childerr; pid_t pid; - if (argc < 1) - return (PAM_SERVICE_ERR); - /* * XXX For additional credit, divert child's stdin/stdout/stderr * to the conversation function. */ /* - * Set up the child's environment list. It consists of the PAM - * environment, plus a few hand-picked PAM items. + * Parse options: + * return_prog_exit_status: + * use the program exit status as the return code of pam_exec + * --: + * stop options parsing; what follows is the command to execute + */ + return_prog_exit_status = 0; + for (i = 0; i < argc; ++i) { + if (strcmp(argv[i], "return_prog_exit_status") == 0) { + openpam_log(PAM_LOG_DEBUG, + "%s: Option \"return_prog_exit_status\" enabled", + func); + return_prog_exit_status = 1; + } else { + if (strcmp(argv[i], "--") == 0) { + argc--; + argv++; + } + + break; + } + } + + argc -= i; + argv += i; + + /* Check there's a program name left after parsing options. */ + if (argc < 1) { + openpam_log(PAM_LOG_ERROR, "%s: No program specified: aborting", + func); + return (PAM_SERVICE_ERR); + } + + /* + * Set up the child's environment list. It consists of the PAM + * environment, plus a few hand-picked PAM items, the pam_sm_* + * function name calling it and, if return_prog_exit_status is + * set, the valid return codes numerical values. */ envlist = pam_getenvlist(pamh); for (envlen = 0; envlist[envlen] != NULL; ++envlen) /* nothing */ ; nitems = sizeof(env_items) / sizeof(*env_items); - tmp = realloc(envlist, (envlen + nitems + 1) * sizeof(*envlist)); + /* Count PAM return values put in the environment. */ + nitems_rv = return_prog_exit_status ? PAM_RV_COUNT : 0; + tmp = realloc(envlist, (envlen + nitems + 1 + nitems_rv + 1) * + sizeof(*envlist)); if (tmp == NULL) { openpam_free_envlist(envlist); return (PAM_BUF_ERR); @@ -93,7 +132,6 @@ _pam_exec(pam_handle_t *pamh __unused, i envlist = tmp; for (i = 0; i < nitems; ++i) { const void *item; - char *envstr; pam_err = pam_get_item(pamh, env_items[i].item, &item); if (pam_err != PAM_SUCCESS || item == NULL) @@ -107,10 +145,59 @@ _pam_exec(pam_handle_t *pamh __unused, i envlist[envlen] = NULL; } + /* Add the pam_sm_* function name to the environment. */ + asprintf(&envstr, "PAM_SM_FUNC=%s", func); + if (envstr == NULL) { + openpam_free_envlist(envlist); + return (PAM_BUF_ERR); + } + envlist[envlen++] = envstr; + + /* Add the PAM return values to the environment. */ + if (return_prog_exit_status) { +#define ADD_PAM_RV_TO_ENV(name) \ + asprintf(&envstr, #name "=%d", name); \ + if (envstr == NULL) { \ + openpam_free_envlist(envlist); \ + return (PAM_BUF_ERR); \ + } \ + envlist[envlen++] = envstr + /* + * CAUTION: When adding/removing an item in the list + * below, be sure to update the value of PAM_RV_COUNT. + */ + ADD_PAM_RV_TO_ENV(PAM_ABORT); + ADD_PAM_RV_TO_ENV(PAM_ACCT_EXPIRED); + ADD_PAM_RV_TO_ENV(PAM_AUTHINFO_UNAVAIL); + ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_DISABLE_AGING); + ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_ERR); + ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_LOCK_BUSY); + ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_RECOVERY_ERR); + ADD_PAM_RV_TO_ENV(PAM_AUTH_ERR); + ADD_PAM_RV_TO_ENV(PAM_BUF_ERR); + ADD_PAM_RV_TO_ENV(PAM_CONV_ERR); + ADD_PAM_RV_TO_ENV(PAM_CRED_ERR); + ADD_PAM_RV_TO_ENV(PAM_CRED_EXPIRED); + ADD_PAM_RV_TO_ENV(PAM_CRED_INSUFFICIENT); + ADD_PAM_RV_TO_ENV(PAM_CRED_UNAVAIL); + ADD_PAM_RV_TO_ENV(PAM_IGNORE); + ADD_PAM_RV_TO_ENV(PAM_MAXTRIES); + ADD_PAM_RV_TO_ENV(PAM_NEW_AUTHTOK_REQD); + ADD_PAM_RV_TO_ENV(PAM_PERM_DENIED); + ADD_PAM_RV_TO_ENV(PAM_SERVICE_ERR); + ADD_PAM_RV_TO_ENV(PAM_SESSION_ERR); + ADD_PAM_RV_TO_ENV(PAM_SUCCESS); + ADD_PAM_RV_TO_ENV(PAM_SYSTEM_ERR); + ADD_PAM_RV_TO_ENV(PAM_TRY_AGAIN); + ADD_PAM_RV_TO_ENV(PAM_USER_UNKNOWN); + } + + envlist[envlen] = NULL; + /* * Fork and run the command. By using vfork() instead of fork(), * we can distinguish between an execve() failure and a non-zero - * exit code from the command. + * exit status from the command. */ childerr = 0; if ((pid = vfork()) == 0) { @@ -120,81 +207,246 @@ _pam_exec(pam_handle_t *pamh __unused, i } openpam_free_envlist(envlist); if (pid == -1) { - openpam_log(PAM_LOG_ERROR, "vfork(): %m"); + openpam_log(PAM_LOG_ERROR, "%s: vfork(): %m", func); return (PAM_SYSTEM_ERR); } - if (waitpid(pid, &status, 0) == -1) { - openpam_log(PAM_LOG_ERROR, "waitpid(): %m"); + while (waitpid(pid, &status, 0) == -1) { + if (errno == EINTR) + continue; + openpam_log(PAM_LOG_ERROR, "%s: waitpid(): %m", func); return (PAM_SYSTEM_ERR); } if (childerr != 0) { - openpam_log(PAM_LOG_ERROR, "execve(): %m"); + openpam_log(PAM_LOG_ERROR, "%s: execve(): %m", func); return (PAM_SYSTEM_ERR); } if (WIFSIGNALED(status)) { - openpam_log(PAM_LOG_ERROR, "%s caught signal %d%s", - argv[0], WTERMSIG(status), + openpam_log(PAM_LOG_ERROR, "%s: %s caught signal %d%s", + func, argv[0], WTERMSIG(status), WCOREDUMP(status) ? " (core dumped)" : ""); - return (PAM_SYSTEM_ERR); + return (PAM_SERVICE_ERR); } if (!WIFEXITED(status)) { - openpam_log(PAM_LOG_ERROR, "unknown status 0x%x", status); - return (PAM_SYSTEM_ERR); + openpam_log(PAM_LOG_ERROR, "%s: unknown status 0x%x", + func, status); + return (PAM_SERVICE_ERR); } - if (WEXITSTATUS(status) != 0) { - openpam_log(PAM_LOG_ERROR, "%s returned code %d", - argv[0], WEXITSTATUS(status)); - return (PAM_SYSTEM_ERR); + + if (return_prog_exit_status) { + openpam_log(PAM_LOG_DEBUG, + "%s: Use program exit status as return value: %d", + func, WEXITSTATUS(status)); + return (WEXITSTATUS(status)); + } else { + return (WEXITSTATUS(status) == 0 ? + PAM_SUCCESS : PAM_PERM_DENIED); } - return (PAM_SUCCESS); } PAM_EXTERN int pam_sm_authenticate(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; + + ret = _pam_exec(pamh, __func__, flags, argc, argv); - return (_pam_exec(pamh, flags, argc, argv)); + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_AUTHINFO_UNAVAIL: + case PAM_AUTH_ERR: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_CRED_INSUFFICIENT: + case PAM_IGNORE: + case PAM_MAXTRIES: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SYSTEM_ERR: + case PAM_USER_UNKNOWN: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } + + return (ret); } PAM_EXTERN int pam_sm_setcred(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; - return (_pam_exec(pamh, flags, argc, argv)); + ret = _pam_exec(pamh, __func__, flags, argc, argv); + + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_CRED_ERR: + case PAM_CRED_EXPIRED: + case PAM_CRED_UNAVAIL: + case PAM_IGNORE: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SYSTEM_ERR: + case PAM_USER_UNKNOWN: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } + + return (ret); } PAM_EXTERN int pam_sm_acct_mgmt(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; + + ret = _pam_exec(pamh, __func__, flags, argc, argv); - return (_pam_exec(pamh, flags, argc, argv)); + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_ACCT_EXPIRED: + case PAM_AUTH_ERR: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_IGNORE: + case PAM_NEW_AUTHTOK_REQD: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SYSTEM_ERR: + case PAM_USER_UNKNOWN: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } + + return (ret); } PAM_EXTERN int pam_sm_open_session(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; + + ret = _pam_exec(pamh, __func__, flags, argc, argv); - return (_pam_exec(pamh, flags, argc, argv)); + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_IGNORE: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SESSION_ERR: + case PAM_SYSTEM_ERR: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } + + return (ret); } PAM_EXTERN int pam_sm_close_session(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; + + ret = _pam_exec(pamh, __func__, flags, argc, argv); + + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_IGNORE: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SESSION_ERR: + case PAM_SYSTEM_ERR: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } - return (_pam_exec(pamh, flags, argc, argv)); + return (ret); } PAM_EXTERN int pam_sm_chauthtok(pam_handle_t *pamh, int flags, int argc, const char *argv[]) { + int ret; + + ret = _pam_exec(pamh, __func__, flags, argc, argv); + + /* + * We must check that the program returned a valid code for this + * function. + */ + switch (ret) { + case PAM_SUCCESS: + case PAM_ABORT: + case PAM_AUTHTOK_DISABLE_AGING: + case PAM_AUTHTOK_ERR: + case PAM_AUTHTOK_LOCK_BUSY: + case PAM_AUTHTOK_RECOVERY_ERR: + case PAM_BUF_ERR: + case PAM_CONV_ERR: + case PAM_IGNORE: + case PAM_PERM_DENIED: + case PAM_SERVICE_ERR: + case PAM_SYSTEM_ERR: + case PAM_TRY_AGAIN: + break; + default: + openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d", + argv[0], ret); + ret = PAM_SERVICE_ERR; + } - return (_pam_exec(pamh, flags, argc, argv)); + return (ret); } PAM_MODULE_ENTRY("pam_exec");
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