diff options
Diffstat (limited to 'src/transports/pipe.c')
| -rw-r--r-- | src/transports/pipe.c | 1145 |
1 files changed, 1145 insertions, 0 deletions
diff --git a/src/transports/pipe.c b/src/transports/pipe.c new file mode 100644 index 0000000..27422bd --- /dev/null +++ b/src/transports/pipe.c @@ -0,0 +1,1145 @@ +/************************************************* +* Exim - an Internet mail transport agent * +*************************************************/ + +/* Copyright (c) University of Cambridge 1995 - 2018 */ +/* Copyright (c) The Exim maintainers 2020 */ +/* See the file NOTICE for conditions of use and distribution. */ + + +#include "../exim.h" +#include "pipe.h" + +#ifdef HAVE_SETCLASSRESOURCES +#include <login_cap.h> +#endif + + + +/* Options specific to the pipe transport. They must be in alphabetic +order (note that "_" comes before the lower case letters). Those starting +with "*" are not settable by the user but are used by the option-reading +software for alternative value types. Some options are stored in the transport +instance block so as to be publicly visible; these are flagged with opt_public. +*/ +#define LOFF(field) OPT_OFF(pipe_transport_options_block, field) + +optionlist pipe_transport_options[] = { + { "allow_commands", opt_stringptr, LOFF(allow_commands) }, + { "batch_id", opt_stringptr | opt_public, + OPT_OFF(transport_instance, batch_id) }, + { "batch_max", opt_int | opt_public, + OPT_OFF(transport_instance, batch_max) }, + { "check_string", opt_stringptr, LOFF(check_string) }, + { "command", opt_stringptr, LOFF(cmd) }, + { "environment", opt_stringptr, LOFF(environment) }, + { "escape_string", opt_stringptr, LOFF(escape_string) }, + { "force_command", opt_bool, LOFF(force_command) }, + { "freeze_exec_fail", opt_bool, LOFF(freeze_exec_fail) }, + { "freeze_signal", opt_bool, LOFF(freeze_signal) }, + { "ignore_status", opt_bool, LOFF(ignore_status) }, + { "log_defer_output", opt_bool | opt_public, + OPT_OFF(transport_instance, log_defer_output) }, + { "log_fail_output", opt_bool | opt_public, + OPT_OFF(transport_instance, log_fail_output) }, + { "log_output", opt_bool | opt_public, + OPT_OFF(transport_instance, log_output) }, + { "max_output", opt_mkint, LOFF(max_output) }, + { "message_prefix", opt_stringptr, LOFF(message_prefix) }, + { "message_suffix", opt_stringptr, LOFF(message_suffix) }, + { "path", opt_stringptr, LOFF(path) }, + { "permit_coredump", opt_bool, LOFF(permit_coredump) }, + { "pipe_as_creator", opt_bool | opt_public, + OPT_OFF(transport_instance, deliver_as_creator) }, + { "restrict_to_path", opt_bool, LOFF(restrict_to_path) }, + { "return_fail_output",opt_bool | opt_public, + OPT_OFF(transport_instance, return_fail_output) }, + { "return_output", opt_bool | opt_public, + OPT_OFF(transport_instance, return_output) }, + { "temp_errors", opt_stringptr, LOFF(temp_errors) }, + { "timeout", opt_time, LOFF(timeout) }, + { "timeout_defer", opt_bool, LOFF(timeout_defer) }, + { "umask", opt_octint, LOFF(umask) }, + { "use_bsmtp", opt_bool, LOFF(use_bsmtp) }, + #ifdef HAVE_SETCLASSRESOURCES + { "use_classresources", opt_bool, LOFF(use_classresources) }, + #endif + { "use_crlf", opt_bool, LOFF(use_crlf) }, + { "use_shell", opt_bool, LOFF(use_shell) }, +}; + +/* Size of the options list. An extern variable has to be used so that its +address can appear in the tables drtables.c. */ + +int pipe_transport_options_count = + sizeof(pipe_transport_options)/sizeof(optionlist); + + +#ifdef MACRO_PREDEF + +/* Dummy values */ +pipe_transport_options_block pipe_transport_option_defaults = {0}; +void pipe_transport_init(transport_instance *tblock) {} +BOOL pipe_transport_entry(transport_instance *tblock, address_item *addr) {return FALSE;} + +#else /*!MACRO_PREDEF*/ + + +/* Default private options block for the pipe transport. */ + +pipe_transport_options_block pipe_transport_option_defaults = { + NULL, /* cmd */ + NULL, /* allow_commands */ + NULL, /* environment */ + US"/bin:/usr/bin", /* path */ + NULL, /* message_prefix (reset in init if not bsmtp) */ + NULL, /* message_suffix (ditto) */ + US mac_expanded_string(EX_TEMPFAIL) ":" /* temp_errors */ + mac_expanded_string(EX_CANTCREAT), + NULL, /* check_string */ + NULL, /* escape_string */ + 022, /* umask */ + 20480, /* max_output */ + 60*60, /* timeout */ + 0, /* options */ + FALSE, /* force_command */ + FALSE, /* freeze_exec_fail */ + FALSE, /* freeze_signal */ + FALSE, /* ignore_status */ + FALSE, /* permit_coredump */ + FALSE, /* restrict_to_path */ + FALSE, /* timeout_defer */ + FALSE, /* use_shell */ + FALSE, /* use_bsmtp */ + FALSE, /* use_classresources */ + FALSE /* use_crlf */ +}; + + + +/************************************************* +* Setup entry point * +*************************************************/ + +/* Called for each delivery in the privileged state, just before the uid/gid +are changed and the main entry point is called. In a system that supports the +login_cap facilities, this function is used to set the class resource limits +for the user. It may also re-enable coredumps. + +Arguments: + tblock points to the transport instance + addrlist addresses about to be delivered (not used) + dummy not used (doesn't pass back data) + uid the uid that will be set (not used) + gid the gid that will be set (not used) + errmsg where to put an error message + +Returns: OK, FAIL, or DEFER +*/ + +static int +pipe_transport_setup(transport_instance *tblock, address_item *addrlist, + transport_feedback *dummy, uid_t uid, gid_t gid, uschar **errmsg) +{ +pipe_transport_options_block *ob = + (pipe_transport_options_block *)(tblock->options_block); + +addrlist = addrlist; /* Keep compiler happy */ +dummy = dummy; +uid = uid; +gid = gid; +errmsg = errmsg; +ob = ob; + +#ifdef HAVE_SETCLASSRESOURCES +if (ob->use_classresources) + { + struct passwd *pw = getpwuid(uid); + if (pw != NULL) + { + login_cap_t *lc = login_getpwclass(pw); + if (lc != NULL) + { + setclassresources(lc); + login_close(lc); + } + } + } +#endif + +#ifdef RLIMIT_CORE +if (ob->permit_coredump) + { + struct rlimit rl; + rl.rlim_cur = RLIM_INFINITY; + rl.rlim_max = RLIM_INFINITY; + if (setrlimit(RLIMIT_CORE, &rl) < 0) + { +#ifdef SETRLIMIT_NOT_SUPPORTED + if (errno != ENOSYS && errno != ENOTSUP) +#endif + log_write(0, LOG_MAIN, + "delivery setrlimit(RLIMIT_CORE, RLIM_INFINITY) failed: %s", + strerror(errno)); + } + } +#endif + +return OK; +} + + + +/************************************************* +* Initialization entry point * +*************************************************/ + +/* Called for each instance, after its options have been read, to +enable consistency checks to be done, or anything else that needs +to be set up. */ + +void +pipe_transport_init(transport_instance *tblock) +{ +pipe_transport_options_block *ob = + (pipe_transport_options_block *)(tblock->options_block); + +/* Set up the setup entry point, to be called in the privileged state */ + +tblock->setup = pipe_transport_setup; + +/* If pipe_as_creator is set, then uid/gid should not be set. */ + +if (tblock->deliver_as_creator && (tblock->uid_set || tblock->gid_set || + tblock->expand_uid != NULL || tblock->expand_gid != NULL)) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "both pipe_as_creator and an explicit uid/gid are set for the %s " + "transport", tblock->name); + +/* If a fixed uid field is set, then a gid field must also be set. */ + +if (tblock->uid_set && !tblock->gid_set && tblock->expand_gid == NULL) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "user set without group for the %s transport", tblock->name); + +/* Temp_errors must consist only of digits and colons, but there can be +spaces round the colons, so allow them too. */ + +if (ob->temp_errors != NULL && Ustrcmp(ob->temp_errors, "*") != 0) + { + size_t p = Ustrspn(ob->temp_errors, "0123456789: "); + if (ob->temp_errors[p] != 0) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "temp_errors must be a list of numbers or an asterisk for the %s " + "transport", tblock->name); + } + +/* Only one of return_output/return_fail_output or log_output/log_fail_output +should be set. */ + +if (tblock->return_output && tblock->return_fail_output) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "both return_output and return_fail_output set for %s transport", + tblock->name); + +if (tblock->log_output && tblock->log_fail_output) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "both log_output and log_fail_output set for the %s transport", + tblock->name); + +/* If batch SMTP is set, force the check and escape strings, and arrange that +headers are also escaped. */ + +if (ob->use_bsmtp) + { + ob->check_string = US"."; + ob->escape_string = US".."; + ob->options |= topt_escape_headers; + } + +/* If not batch SMTP, and message_prefix or message_suffix are unset, insert +default values for them. */ + +else + { + if (ob->message_prefix == NULL) ob->message_prefix = + US"From ${if def:return_path{$return_path}{MAILER-DAEMON}} ${tod_bsdinbox}\n"; + if (ob->message_suffix == NULL) ob->message_suffix = US"\n"; + } + +/* The restrict_to_path and use_shell options are incompatible */ + +if (ob->restrict_to_path && ob->use_shell) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "both restrict_to_path and use_shell set for %s transport", + tblock->name); + +/* The allow_commands and use_shell options are incompatible */ + +if (ob->allow_commands && ob->use_shell) + log_write(0, LOG_PANIC_DIE|LOG_CONFIG, + "both allow_commands and use_shell set for %s transport", + tblock->name); + +/* Set up the bitwise options for transport_write_message from the various +driver options. Only one of body_only and headers_only can be set. */ + +ob->options |= + (tblock->body_only? topt_no_headers : 0) | + (tblock->headers_only? topt_no_body : 0) | + (tblock->return_path_add? topt_add_return_path : 0) | + (tblock->delivery_date_add? topt_add_delivery_date : 0) | + (tblock->envelope_to_add? topt_add_envelope_to : 0) | + (ob->use_crlf? topt_use_crlf : 0); +} + + + +/************************************************* +* Set up direct (non-shell) command * +*************************************************/ + +/* This function is called when a command line is to be parsed by the transport +and executed directly, without the use of /bin/sh. + +Arguments: + argvptr pointer to anchor for argv vector + cmd points to the command string + expand_arguments true if expansion is to occur + expand_fail error if expansion fails + addr chain of addresses + tname the transport name + ob the transport options block + +Returns: TRUE if all went well; otherwise an error will be + set in the first address and FALSE returned +*/ + +static BOOL +set_up_direct_command(const uschar ***argvptr, uschar *cmd, + BOOL expand_arguments, int expand_fail, address_item *addr, uschar *tname, + pipe_transport_options_block *ob) +{ +BOOL permitted = FALSE; +const uschar **argv; + +/* Set up "transport <name>" to be put in any error messages, and then +call the common function for creating an argument list and expanding +the items if necessary. If it fails, this function fails (error information +is in the addresses). */ + +if (!transport_set_up_command(argvptr, cmd, expand_arguments, expand_fail, + addr, string_sprintf("%.50s transport", tname), NULL)) + return FALSE; + +/* Point to the set-up arguments. */ + +argv = *argvptr; + +/* If allow_commands is set, see if the command is in the permitted list. */ + +if (ob->allow_commands) + { + int sep = 0; + const uschar *s; + uschar *p; + + if (!(s = expand_string(ob->allow_commands))) + { + addr->transport_return = DEFER; + addr->message = string_sprintf("failed to expand string \"%s\" " + "for %s transport: %s", ob->allow_commands, tname, expand_string_message); + return FALSE; + } + + while ((p = string_nextinlist(&s, &sep, NULL, 0))) + if (Ustrcmp(p, argv[0]) == 0) { permitted = TRUE; break; } + } + +/* If permitted is TRUE it means the command was found in the allowed list, and +no further checks are done. If permitted = FALSE, it either means +allow_commands wasn't set, or that the command didn't match anything in the +list. In both cases, if restrict_to_path is set, we fail if the command +contains any slashes, but if restrict_to_path is not set, we must fail the +command only if allow_commands is set. */ + +if (!permitted) + { + if (ob->restrict_to_path) + { + if (Ustrchr(argv[0], '/') != NULL) + { + addr->transport_return = FAIL; + addr->message = string_sprintf("\"/\" found in \"%s\" (command for %s " + "transport) - failed for security reasons", cmd, tname); + return FALSE; + } + } + + else if (ob->allow_commands) + { + addr->transport_return = FAIL; + addr->message = string_sprintf("\"%s\" command not permitted by %s " + "transport", argv[0], tname); + return FALSE; + } + } + +/* If the command is not an absolute path, search the PATH directories +for it. */ + +if (argv[0][0] != '/') + { + int sep = 0; + uschar *p; + const uschar *listptr = expand_string(ob->path); + + while ((p = string_nextinlist(&listptr, &sep, NULL, 0))) + { + struct stat statbuf; + sprintf(CS big_buffer, "%.256s/%.256s", p, argv[0]); + if (Ustat(big_buffer, &statbuf) == 0) + { + argv[0] = string_copy(big_buffer); + break; + } + } + if (!p) + { + addr->transport_return = FAIL; + addr->message = string_sprintf("\"%s\" command not found for %s transport", + argv[0], tname); + return FALSE; + } + } + +return TRUE; +} + + +/************************************************* +* Set up shell command * +*************************************************/ + +/* This function is called when a command line is to be passed to /bin/sh +without parsing inside the transport. + +Arguments: + argvptr pointer to anchor for argv vector + cmd points to the command string + expand_arguments true if expansion is to occur + expand_fail error if expansion fails + addr chain of addresses + tname the transport name + +Returns: TRUE if all went well; otherwise an error will be + set in the first address and FALSE returned +*/ + +static BOOL +set_up_shell_command(const uschar ***argvptr, uschar *cmd, + BOOL expand_arguments, int expand_fail, address_item *addr, uschar *tname) +{ +const uschar **argv; + +*argvptr = argv = store_get((4)*sizeof(uschar *), FALSE); + +argv[0] = US"/bin/sh"; +argv[1] = US"-c"; + +/* We have to take special action to handle the special "variable" called +$pipe_addresses, which is not recognized by the normal expansion function. */ + +if (expand_arguments) + { + uschar * p = Ustrstr(cmd, "pipe_addresses"); + gstring * g = NULL; + + DEBUG(D_transport) + debug_printf("shell pipe command before expansion:\n %s\n", cmd); + + /* Allow $recipients in the expansion iff it comes from a system filter */ + + f.enable_dollar_recipients = addr && addr->parent && + Ustrcmp(addr->parent->address, "system-filter") == 0; + + if (p != NULL && ( + (p > cmd && p[-1] == '$') || + (p > cmd + 1 && p[-2] == '$' && p[-1] == '{' && p[14] == '}'))) + { + uschar *q = p + 14; + + if (p[-1] == '{') { q++; p--; } + + g = string_get(Ustrlen(cmd) + 64); + g = string_catn(g, cmd, p - cmd - 1); + + for (address_item * ad = addr; ad; ad = ad->next) + { + /*XXX string_append_listele() ? */ + if (ad != addr) g = string_catn(g, US" ", 1); + g = string_cat(g, ad->address); + } + + g = string_cat(g, q); + argv[2] = (cmd = string_from_gstring(g)) ? expand_string(cmd) : NULL; + } + else + argv[2] = expand_string(cmd); + + f.enable_dollar_recipients = FALSE; + + if (!argv[2]) + { + addr->transport_return = f.search_find_defer ? DEFER : expand_fail; + addr->message = string_sprintf("Expansion of command \"%s\" " + "in %s transport failed: %s", + cmd, tname, expand_string_message); + return FALSE; + } + + DEBUG(D_transport) + debug_printf("shell pipe command after expansion:\n %s\n", argv[2]); + } +else + { + DEBUG(D_transport) + debug_printf("shell pipe command (no expansion):\n %s\n", cmd); + argv[2] = cmd; + } + +argv[3] = US 0; +return TRUE; +} + + + + +/************************************************* +* Main entry point * +*************************************************/ + +/* See local README for interface details. This transport always returns FALSE, +indicating that the status in the first address is the status for all addresses +in a batch. */ + +BOOL +pipe_transport_entry( + transport_instance *tblock, /* data for this instantiation */ + address_item *addr) /* address(es) we are working on */ +{ +pid_t pid, outpid; +int fd_in, fd_out, rc; +int envcount = 0; +int envsep = 0; +int expand_fail; +pipe_transport_options_block *ob = + (pipe_transport_options_block *)(tblock->options_block); +int timeout = ob->timeout; +BOOL written_ok = FALSE; +BOOL expand_arguments; +const uschar **argv; +uschar *envp[50]; +const uschar *envlist = ob->environment; +uschar *cmd, *ss; +uschar *eol = ob->use_crlf ? US"\r\n" : US"\n"; +transport_ctx tctx = { + .tblock = tblock, + .addr = addr, + .check_string = ob->check_string, + .escape_string = ob->escape_string, + ob->options | topt_not_socket /* set at initialization time */ +}; + +DEBUG(D_transport) debug_printf("%s transport entered\n", tblock->name); + +/* Set up for the good case */ + +addr->transport_return = OK; +addr->basic_errno = 0; + +/* Pipes are not accepted as general addresses, but they can be generated from +.forward files or alias files. In those cases, the pfr flag is set, and the +command to be obeyed is pointed to by addr->local_part; it starts with the pipe +symbol. In other cases, the command is supplied as one of the pipe transport's +options. */ + +if (testflag(addr, af_pfr) && addr->local_part[0] == '|') + if (ob->force_command) + { + /* Enables expansion of $address_pipe into separate arguments */ + setflag(addr, af_force_command); + cmd = ob->cmd; + expand_arguments = TRUE; + expand_fail = PANIC; + } + else + { + cmd = addr->local_part + 1; + while (isspace(*cmd)) cmd++; + expand_arguments = testflag(addr, af_expand_pipe); + expand_fail = FAIL; + } +else + { + cmd = ob->cmd; + expand_arguments = TRUE; + expand_fail = PANIC; + } + +/* If no command has been supplied, we are in trouble. + * We also check for an empty string since it may be + * coming from addr->local_part[0] == '|' + */ + +if (!cmd || !*cmd) + { + addr->transport_return = DEFER; + addr->message = string_sprintf("no command specified for %s transport", + tblock->name); + return FALSE; + } +if (is_tainted(cmd)) + { + addr->message = string_sprintf("Tainted '%s' (command " + "for %s transport) not permitted", cmd, tblock->name); + addr->transport_return = PANIC; + return FALSE; + } + +/* When a pipe is set up by a filter file, there may be values for $thisaddress +and numerical the variables in existence. These are passed in +addr->pipe_expandn for use here. */ + +if (expand_arguments && addr->pipe_expandn) + { + uschar **ss = addr->pipe_expandn; + expand_nmax = -1; + if (*ss) filter_thisaddress = *ss++; + while (*ss) + { + expand_nstring[++expand_nmax] = *ss; + expand_nlength[expand_nmax] = Ustrlen(*ss++); + } + } + +/* The default way of processing the command is to split it up into arguments +here, and run it directly. This offers some security advantages. However, there +are installations that want by default to run commands under /bin/sh always, so +there is an option to do that. */ + +if (ob->use_shell) + { + if (!set_up_shell_command(&argv, cmd, expand_arguments, expand_fail, addr, + tblock->name)) return FALSE; + } +else if (!set_up_direct_command(&argv, cmd, expand_arguments, expand_fail, addr, + tblock->name, ob)) return FALSE; + +expand_nmax = -1; /* Reset */ +filter_thisaddress = NULL; + +/* Set up the environment for the command. */ + +envp[envcount++] = string_sprintf("LOCAL_PART=%s", deliver_localpart); +envp[envcount++] = string_sprintf("LOGNAME=%s", deliver_localpart); +envp[envcount++] = string_sprintf("USER=%s", deliver_localpart); +envp[envcount++] = string_sprintf("LOCAL_PART_PREFIX=%#s", + deliver_localpart_prefix); +envp[envcount++] = string_sprintf("LOCAL_PART_SUFFIX=%#s", + deliver_localpart_suffix); +envp[envcount++] = string_sprintf("DOMAIN=%s", deliver_domain); +envp[envcount++] = string_sprintf("HOME=%#s", deliver_home); +envp[envcount++] = string_sprintf("MESSAGE_ID=%s", message_id); +envp[envcount++] = string_sprintf("PATH=%s", expand_string(ob->path)); +envp[envcount++] = string_sprintf("RECIPIENT=%#s%#s%#s@%#s", + deliver_localpart_prefix, deliver_localpart, deliver_localpart_suffix, + deliver_domain); +envp[envcount++] = string_sprintf("QUALIFY_DOMAIN=%s", qualify_domain_sender); +envp[envcount++] = string_sprintf("SENDER=%s", sender_address); +envp[envcount++] = US"SHELL=/bin/sh"; + +if (addr->host_list != NULL) + envp[envcount++] = string_sprintf("HOST=%s", addr->host_list->name); + +if (f.timestamps_utc) envp[envcount++] = US"TZ=UTC"; +else if (timezone_string != NULL && timezone_string[0] != 0) + envp[envcount++] = string_sprintf("TZ=%s", timezone_string); + +/* Add any requested items */ + +if (envlist) + if (!(envlist = expand_cstring(envlist))) + { + addr->transport_return = DEFER; + addr->message = string_sprintf("failed to expand string \"%s\" " + "for %s transport: %s", ob->environment, tblock->name, + expand_string_message); + return FALSE; + } + +while ((ss = string_nextinlist(&envlist, &envsep, NULL, 0))) + { + if (envcount > nelem(envp) - 2) + { + addr->transport_return = DEFER; + addr->basic_errno = E2BIG; + addr->message = string_sprintf("too many environment settings for " + "%s transport", tblock->name); + return FALSE; + } + envp[envcount++] = string_copy(ss); + } + +envp[envcount] = NULL; + +/* If the -N option is set, can't do any more. */ + +if (f.dont_deliver) + { + DEBUG(D_transport) + debug_printf("*** delivery by %s transport bypassed by -N option", + tblock->name); + return FALSE; + } + + +/* Handling the output from the pipe is tricky. If a file for catching this +output is provided, we could in theory just hand that fd over to the process, +but this isn't very safe because it might loop and carry on writing for +ever (which is exactly what happened in early versions of Exim). Therefore we +use the standard child_open() function, which creates pipes. We can then read +our end of the output pipe and count the number of bytes that come through, +chopping the sub-process if it exceeds some limit. + +However, this means we want to run a sub-process with both its input and output +attached to pipes. We can't handle that easily from a single parent process +using straightforward code such as the transport_write_message() function +because the subprocess might not be reading its input because it is trying to +write to a full output pipe. The complication of redesigning the world to +handle this is too great - simpler just to run another process to do the +reading of the output pipe. */ + + +/* As this is a local transport, we are already running with the required +uid/gid and current directory. Request that the new process be a process group +leader, so we can kill it and all its children on a timeout. */ + +if ((pid = child_open(USS argv, envp, ob->umask, &fd_in, &fd_out, TRUE, + US"pipe-tpt-cmd")) < 0) + { + addr->transport_return = DEFER; + addr->message = string_sprintf( + "Failed to create child process for %s transport: %s", tblock->name, + strerror(errno)); + return FALSE; + } +tctx.u.fd = fd_in; + +/* Now fork a process to handle the output that comes down the pipe. */ + +if ((outpid = exim_fork(US"pipe-tpt-output")) < 0) + { + addr->basic_errno = errno; + addr->transport_return = DEFER; + addr->message = string_sprintf( + "Failed to create process for handling output in %s transport", + tblock->name); + (void)close(fd_in); + (void)close(fd_out); + return FALSE; + } + +/* This is the code for the output-handling subprocess. Read from the pipe +in chunks, and write to the return file if one is provided. Keep track of +the number of bytes handled. If the limit is exceeded, try to kill the +subprocess group, and in any case close the pipe and exit, which should cause +the subprocess to fail. */ + +if (outpid == 0) + { + int count = 0; + (void)close(fd_in); + set_process_info("reading output from |%s", cmd); + while ((rc = read(fd_out, big_buffer, big_buffer_size)) > 0) + { + if (addr->return_file >= 0) + if(write(addr->return_file, big_buffer, rc) != rc) + DEBUG(D_transport) debug_printf("Problem writing to return_file\n"); + count += rc; + if (count > ob->max_output) + { + DEBUG(D_transport) debug_printf("Too much output from pipe - killed\n"); + if (addr->return_file >= 0) + { + uschar *message = US"\n\n*** Too much output - remainder discarded ***\n"; + rc = Ustrlen(message); + if(write(addr->return_file, message, rc) != rc) + DEBUG(D_transport) debug_printf("Problem writing to return_file\n"); + } + killpg(pid, SIGKILL); + break; + } + } + (void)close(fd_out); + _exit(0); + } + +(void)close(fd_out); /* Not used in this process */ + + +/* Carrying on now with the main parent process. Attempt to write the message +to it down the pipe. It is a fallacy to think that you can detect write errors +when the sub-process fails to read the pipe. The parent process may complete +writing and close the pipe before the sub-process completes. We could sleep a +bit here to let the sub-process get going, but it may still not complete. So we +ignore all writing errors. (When in the test harness, we do do a short sleep so +any debugging output is likely to be in the same order.) */ + +testharness_pause_ms(500); + +DEBUG(D_transport) debug_printf("Writing message to pipe\n"); + +/* Arrange to time out writes if there is a timeout set. */ + +if (timeout > 0) + { + sigalrm_seen = FALSE; + transport_write_timeout = timeout; + } + +/* Reset the counter of bytes written */ + +transport_count = 0; + +/* First write any configured prefix information */ + +if (ob->message_prefix) + { + uschar *prefix = expand_string(ob->message_prefix); + if (!prefix) + { + addr->transport_return = f.search_find_defer? DEFER : PANIC; + addr->message = string_sprintf("Expansion of \"%s\" (prefix for %s " + "transport) failed: %s", ob->message_prefix, tblock->name, + expand_string_message); + return FALSE; + } + if (!transport_write_block(&tctx, prefix, Ustrlen(prefix), FALSE)) + goto END_WRITE; + } + +/* If the use_bsmtp option is set, we need to write SMTP prefix information. +The various different values for batching are handled outside; if there is more +than one address available here, all must be included. Force SMTP dot-handling. +*/ + +if (ob->use_bsmtp) + { + if (!transport_write_string(fd_in, "MAIL FROM:<%s>%s", return_path, eol)) + goto END_WRITE; + + for (address_item * a = addr; a; a = a->next) + if (!transport_write_string(fd_in, + "RCPT TO:<%s>%s", + transport_rcpt_address(a, tblock->rcpt_include_affixes), + eol)) + goto END_WRITE; + + if (!transport_write_string(fd_in, "DATA%s", eol)) goto END_WRITE; + } + +/* Now the actual message */ + +if (!transport_write_message(&tctx, 0)) + goto END_WRITE; + +/* Now any configured suffix */ + +if (ob->message_suffix) + { + uschar *suffix = expand_string(ob->message_suffix); + if (!suffix) + { + addr->transport_return = f.search_find_defer? DEFER : PANIC; + addr->message = string_sprintf("Expansion of \"%s\" (suffix for %s " + "transport) failed: %s", ob->message_suffix, tblock->name, + expand_string_message); + return FALSE; + } + if (!transport_write_block(&tctx, suffix, Ustrlen(suffix), FALSE)) + goto END_WRITE; + } + +/* If local_smtp, write the terminating dot. */ + +if (ob->use_bsmtp && !transport_write_string(fd_in, ".%s", eol)) + goto END_WRITE; + +/* Flag all writing completed successfully. */ + +written_ok = TRUE; + +/* Come here if there are errors during writing. */ + +END_WRITE: + +/* OK, the writing is now all done. Close the pipe. */ + +(void) close(fd_in); + +/* Handle errors during writing. For timeouts, set the timeout for waiting for +the child process to 1 second. If the process at the far end of the pipe died +without reading all of it, we expect an EPIPE error, which should be ignored. +We used also to ignore WRITEINCOMPLETE but the writing function is now cleverer +at handling OS where the death of a pipe doesn't give EPIPE immediately. See +comments therein. */ + +if (!written_ok) + { + if (errno == ETIMEDOUT) + { + addr->message = string_sprintf("%stimeout while writing to pipe", + f.transport_filter_timed_out ? "transport filter " : ""); + addr->transport_return = ob->timeout_defer? DEFER : FAIL; + timeout = 1; + } + else if (errno == EPIPE) + { + debug_printf("transport error EPIPE ignored\n"); + } + else + { + addr->transport_return = PANIC; + addr->basic_errno = errno; + if (errno == ERRNO_CHHEADER_FAIL) + addr->message = + string_sprintf("Failed to expand headers_add or headers_remove: %s", + expand_string_message); + else if (errno == ERRNO_FILTER_FAIL) + addr->message = string_sprintf("Transport filter process failed (%d)%s", + addr->more_errno, + (addr->more_errno == EX_EXECFAILED)? ": unable to execute command" : ""); + else if (errno == ERRNO_WRITEINCOMPLETE) + addr->message = US"Failed repeatedly to write data"; + else + addr->message = string_sprintf("Error %d", errno); + return FALSE; + } + } + +/* Wait for the child process to complete and take action if the returned +status is nonzero. The timeout will be just 1 second if any of the writes +above timed out. */ + +if ((rc = child_close(pid, timeout)) != 0) + { + uschar * tmsg = addr->message + ? string_sprintf(" (preceded by %s)", addr->message) : US""; + + /* The process did not complete in time; kill its process group and fail + the delivery. It appears to be necessary to kill the output process too, as + otherwise it hangs on for some time if the actual pipe process is sleeping. + (At least, that's what I observed on Solaris 2.5.1.) Since we are failing + the delivery, that shouldn't cause any problem. */ + + if (rc == -256) + { + killpg(pid, SIGKILL); + kill(outpid, SIGKILL); + addr->transport_return = ob->timeout_defer? DEFER : FAIL; + addr->message = string_sprintf("pipe delivery process timed out%s", tmsg); + } + + /* Wait() failed. */ + + else if (rc == -257) + { + addr->transport_return = PANIC; + addr->message = string_sprintf("Wait() failed for child process of %s " + "transport: %s%s", tblock->name, strerror(errno), tmsg); + } + + /* Since the transport_filter timed out we assume it has sent the child process + a malformed or incomplete data stream. Kill off the child process + and prevent checking its exit status as it will has probably exited in error. + This prevents the transport_filter timeout message from getting overwritten + by the exit error which is not the cause of the problem. */ + + else if (f.transport_filter_timed_out) + { + killpg(pid, SIGKILL); + kill(outpid, SIGKILL); + } + + /* Either the process completed, but yielded a non-zero (necessarily + positive) status, or the process was terminated by a signal (rc will contain + the negation of the signal number). Treat killing by signal as failure unless + status is being ignored. By default, the message is bounced back, unless + freeze_signal is set, in which case it is frozen instead. */ + + else if (rc < 0) + { + if (ob->freeze_signal) + { + addr->transport_return = DEFER; + addr->special_action = SPECIAL_FREEZE; + addr->message = string_sprintf("Child process of %s transport (running " + "command \"%s\") was terminated by signal %d (%s)%s", tblock->name, cmd, + -rc, os_strsignal(-rc), tmsg); + } + else if (!ob->ignore_status) + { + addr->transport_return = FAIL; + addr->message = string_sprintf("Child process of %s transport (running " + "command \"%s\") was terminated by signal %d (%s)%s", tblock->name, cmd, + -rc, os_strsignal(-rc), tmsg); + } + } + + /* For positive values (process terminated with non-zero status), we need a + status code to request deferral. A number of systems contain the following + line in sysexits.h: + + #define EX_TEMPFAIL 75 + + with the description + + EX_TEMPFAIL -- temporary failure, indicating something that + is not really an error. In sendmail, this means + that a mailer (e.g.) could not create a connection, + and the request should be reattempted later. + + Based on this, we use exit code EX_TEMPFAIL as a default to mean "defer" when + not ignoring the returned status. However, there is now an option that + contains a list of temporary codes, with TEMPFAIL and CANTCREAT as defaults. + + Another case that needs special treatment is if execve() failed (typically + the command that was given is a non-existent path). By default this is + treated as just another failure, but if freeze_exec_fail is set, the reaction + is to freeze the message rather than bounce the address. Exim used to signal + this failure with EX_UNAVAILABLE, which is defined in many systems as + + #define EX_UNAVAILABLE 69 + + with the description + + EX_UNAVAILABLE -- A service is unavailable. This can occur + if a support program or file does not exist. This + can also be used as a catchall message when something + you wanted to do doesn't work, but you don't know why. + + However, this can be confused with a command that actually returns 69 because + something *it* wanted is unavailable. At release 4.21, Exim was changed to + use return code 127 instead, because this is what the shell returns when it + is unable to exec a command. We define it as EX_EXECFAILED, and use it in + child.c to signal execve() failure and other unexpected failures such as + setuid() not working - though that won't be the case here because we aren't + changing uid. */ + + else + { + /* Always handle execve() failure specially if requested to */ + + if (ob->freeze_exec_fail && rc == EX_EXECFAILED) + { + addr->transport_return = DEFER; + addr->special_action = SPECIAL_FREEZE; + addr->message = string_sprintf("pipe process failed to exec \"%s\"%s", + cmd, tmsg); + } + + /* Otherwise take action only if not ignoring status */ + + else if (!ob->ignore_status) + { + uschar *ss; + gstring * g; + + /* If temp_errors is "*" all codes are temporary. Initialization checks + that it's either "*" or a list of numbers. If not "*", scan the list of + temporary failure codes; if any match, the result is DEFER. */ + + if (ob->temp_errors[0] == '*') + addr->transport_return = DEFER; + + else + { + const uschar *s = ob->temp_errors; + uschar *p; + int sep = 0; + + addr->transport_return = FAIL; + while ((p = string_nextinlist(&s,&sep,NULL,0))) + if (rc == Uatoi(p)) { addr->transport_return = DEFER; break; } + } + + /* Ensure the message contains the expanded command and arguments. This + doesn't have to be brilliantly efficient - it is an error situation. */ + + addr->message = string_sprintf("Child process of %s transport returned " + "%d", tblock->name, rc); + g = string_cat(NULL, addr->message); + + /* If the return code is > 128, it often means that a shell command + was terminated by a signal. */ + + ss = (rc > 128)? + string_sprintf("(could mean shell command ended by signal %d (%s))", + rc-128, os_strsignal(rc-128)) : + US os_strexit(rc); + + if (*ss) + { + g = string_catn(g, US" ", 1); + g = string_cat (g, ss); + } + + /* Now add the command and arguments */ + + g = string_catn(g, US" from command:", 14); + + for (int i = 0; i < sizeof(argv)/sizeof(int *) && argv[i] != NULL; i++) + { + BOOL quote = FALSE; + g = string_catn(g, US" ", 1); + if (Ustrpbrk(argv[i], " \t") != NULL) + { + quote = TRUE; + g = string_catn(g, US"\"", 1); + } + g = string_cat(g, argv[i]); + if (quote) + g = string_catn(g, US"\"", 1); + } + + /* Add previous filter timeout message, if present. */ + + if (*tmsg) + g = string_cat(g, tmsg); + + addr->message = string_from_gstring(g); + } + } + } + +/* Ensure all subprocesses (in particular, the output handling process) +are complete before we pass this point. */ + +while (wait(&rc) >= 0); + +DEBUG(D_transport) debug_printf("%s transport yielded %d\n", tblock->name, + addr->transport_return); + +/* If there has been a problem, the message in addr->message contains details +of the pipe command. We don't want to expose these to the world, so we set up +something bland to return to the sender. */ + +if (addr->transport_return != OK) + addr->user_message = US"local delivery failed"; + +return FALSE; +} + +#endif /*!MACRO_PREDEF*/ +/* End of transport/pipe.c */ |