diff options
Diffstat (limited to 'modules/arch/unix/mod_privileges.c')
| -rw-r--r-- | modules/arch/unix/mod_privileges.c | 588 |
1 files changed, 588 insertions, 0 deletions
diff --git a/modules/arch/unix/mod_privileges.c b/modules/arch/unix/mod_privileges.c new file mode 100644 index 0000000..fede3d8 --- /dev/null +++ b/modules/arch/unix/mod_privileges.c @@ -0,0 +1,588 @@ +/* Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include <priv.h> +#include <sys/types.h> +#include <unistd.h> + +#include "httpd.h" +#include "http_config.h" +#include "http_protocol.h" +#include "http_log.h" +#include "mpm_common.h" +#include "ap_mpm.h" +#include "apr_strings.h" + +/* TODO - get rid of unixd dependency */ +#include "unixd.h" + +#define CFG_CHECK(x) if ((x) == -1) { \ + char msgbuf[128]; \ + apr_strerror(errno, msgbuf, sizeof(msgbuf)); \ + return apr_pstrdup(cmd->pool, msgbuf); \ +} +#define CR_CHECK(x, y) if (x == -1) \ + ap_log_error(APLOG_MARK, APLOG_CRIT, errno, 0, y \ + "Failed to initialise privileges") + +module AP_MODULE_DECLARE_DATA privileges_module; + +/* #define BIG_SECURITY_HOLE 1 */ + +typedef enum { PRIV_UNSET, PRIV_FAST, PRIV_SECURE, PRIV_SELECTIVE } priv_mode; + +typedef struct { + priv_set_t *priv; + priv_set_t *child_priv; + uid_t uid; + gid_t gid; + priv_mode mode; +} priv_cfg; + +typedef struct { + priv_mode mode; +} priv_dir_cfg; + +static priv_set_t *priv_setid; +static priv_set_t *priv_default = NULL; +static int dtrace_enabled = 0; + +static apr_status_t priv_cfg_cleanup(void *CFG) +{ + priv_cfg *cfg = CFG; + priv_freeset(cfg->priv); + priv_freeset(cfg->child_priv); + return APR_SUCCESS; +} +static void *privileges_merge_cfg(apr_pool_t *pool, void *BASE, void *ADD) +{ + /* inherit the mode if it's not set; the rest won't be inherited */ + priv_cfg *base = BASE; + priv_cfg *add = ADD; + priv_cfg *ret = apr_pmemdup(pool, add, sizeof(priv_cfg)); + ret->mode = (add->mode == PRIV_UNSET) ? base->mode : add->mode; + return ret; +} +static void *privileges_create_cfg(apr_pool_t *pool, server_rec *s) +{ + priv_cfg *cfg = apr_palloc(pool, sizeof(priv_cfg)); + + /* Start at basic privileges all round. */ + cfg->priv = priv_str_to_set("basic", ",", NULL); + cfg->child_priv = priv_str_to_set("basic", ",", NULL); + + /* By default, run in secure vhost mode. + * That means dropping basic privileges we don't usually need. + */ + CR_CHECK(priv_delset(cfg->priv, PRIV_FILE_LINK_ANY), APLOGNO(03160)); + CR_CHECK(priv_delset(cfg->priv, PRIV_PROC_INFO), APLOGNO(03161)); + CR_CHECK(priv_delset(cfg->priv, PRIV_PROC_SESSION), APLOGNO(03162)); + +/* Hmmm, should CGI default to secure too ? */ +/* + CR_CHECK(priv_delset(cfg->child_priv, PRIV_FILE_LINK_ANY), APLOGNO(03163)); + CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_INFO), APLOGNO(03164)); + CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_SESSION), APLOGNO(03165)); + CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_FORK), APLOGNO(03166)); + CR_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_EXEC), APLOGNO(03167)); +*/ + + /* we´ll use 0 for unset */ + cfg->uid = 0; + cfg->gid = 0; + cfg->mode = PRIV_UNSET; + apr_pool_cleanup_register(pool, cfg, priv_cfg_cleanup, + apr_pool_cleanup_null); + + /* top-level default_priv wants the top-level cfg */ + if (priv_default == NULL) { + priv_default = cfg->priv; + } + return cfg; +} +static void *privileges_create_dir_cfg(apr_pool_t *pool, char *dummy) +{ + priv_dir_cfg *cfg = apr_palloc(pool, sizeof(priv_dir_cfg)); + cfg->mode = PRIV_UNSET; + return cfg; +} +static void *privileges_merge_dir_cfg(apr_pool_t *pool, void *BASE, void *ADD) +{ + priv_dir_cfg *base = BASE; + priv_dir_cfg *add = ADD; + priv_dir_cfg *ret = apr_palloc(pool, sizeof(priv_dir_cfg)); + ret->mode = (add->mode == PRIV_UNSET) ? base->mode : add->mode; + return ret; +} + +static apr_status_t privileges_end_req(void *data) +{ + request_rec *r = data; + priv_cfg *cfg = ap_get_module_config(r->server->module_config, + &privileges_module); + priv_dir_cfg *dcfg = ap_get_module_config(r->per_dir_config, + &privileges_module); + + /* ugly hack: grab default uid and gid from unixd */ + extern unixd_config_rec ap_unixd_config; + + /* If we forked a child, we dropped privilege to revert, so + * all we can do now is exit + */ + if ((cfg->mode == PRIV_SECURE) || + ((cfg->mode == PRIV_SELECTIVE) && (dcfg->mode == PRIV_SECURE))) { + exit(0); + } + + /* if either user or group are not the default, restore them */ + if (cfg->uid || cfg->gid) { + if (setppriv(PRIV_ON, PRIV_EFFECTIVE, priv_setid) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02136) + "PRIV_ON failed restoring default user/group"); + } + if (cfg->uid && (setuid(ap_unixd_config.user_id) == -1)) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02137) + "Error restoring default userid"); + } + if (cfg->gid && (setgid(ap_unixd_config.group_id) == -1)) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02138) + "Error restoring default group"); + } + } + + /* restore default privileges */ + if (setppriv(PRIV_SET, PRIV_EFFECTIVE, priv_default) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02139) + "Error restoring default privileges"); + } + return APR_SUCCESS; +} +static int privileges_req(request_rec *r) +{ + /* secure mode: fork a process to handle the request */ + apr_proc_t proc; + apr_status_t rv; + int exitcode; + apr_exit_why_e exitwhy; + int fork_req; + priv_cfg *cfg = ap_get_module_config(r->server->module_config, + &privileges_module); + + void *breadcrumb = ap_get_module_config(r->request_config, + &privileges_module); + + if (!breadcrumb) { + /* first call: this is the vhost */ + fork_req = (cfg->mode == PRIV_SECURE); + + /* set breadcrumb */ + ap_set_module_config(r->request_config, &privileges_module, &cfg->mode); + + /* If we have per-dir config, defer doing anything */ + if ((cfg->mode == PRIV_SELECTIVE)) { + /* Defer dropping privileges 'til we have a directory + * context that'll tell us whether to fork. + */ + return DECLINED; + } + } + else { + /* second call is for per-directory. */ + priv_dir_cfg *dcfg; + if ((cfg->mode != PRIV_SELECTIVE)) { + /* Our fate was already determined for the vhost - + * nothing to do per-directory + */ + return DECLINED; + } + dcfg = ap_get_module_config(r->per_dir_config, &privileges_module); + fork_req = (dcfg->mode == PRIV_SECURE); + } + + if (fork_req) { + rv = apr_proc_fork(&proc, r->pool); + switch (rv) { + case APR_INPARENT: + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02140) + "parent waiting for child"); + /* FIXME - does the child need to run synchronously? + * esp. if we enable mod_privileges with threaded MPMs? + * We do need at least to ensure r outlives the child. + */ + rv = apr_proc_wait(&proc, &exitcode, &exitwhy, APR_WAIT); + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02141) "parent: child %s", + (rv == APR_CHILD_DONE) ? "done" : "notdone"); + + /* The child has taken responsibility for reading all input + * and sending all output. So we need to bow right out, + * and even abandon "normal" housekeeping. + */ + r->eos_sent = 1; + apr_table_unset(r->headers_in, "Content-Type"); + apr_table_unset(r->headers_in, "Content-Length"); + /* Testing with ab and 100k requests reveals no nasties + * so I infer we're not leaking anything like memory + * or file descriptors. That's nice! + */ + return DONE; + case APR_INCHILD: + ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r, APLOGNO(02142) "In child!"); + break; /* now we'll drop privileges in the child */ + default: + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02143) + "Failed to fork secure child process!"); + return HTTP_INTERNAL_SERVER_ERROR; + } + } + + /* OK, now drop privileges. */ + + /* cleanup should happen even if something fails part-way through here */ + apr_pool_cleanup_register(r->pool, r, privileges_end_req, + apr_pool_cleanup_null); + /* set user and group if configured */ + if (cfg->uid || cfg->gid) { + if (setppriv(PRIV_ON, PRIV_EFFECTIVE, priv_setid) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02144) + "No privilege to set user/group"); + } + /* if we should be able to set these but can't, it could be + * a serious security issue. Bail out rather than risk it! + */ + if (cfg->uid && (setuid(cfg->uid) == -1)) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02145) + "Error setting userid"); + return HTTP_INTERNAL_SERVER_ERROR; + } + if (cfg->gid && (setgid(cfg->gid) == -1)) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r, APLOGNO(02146) + "Error setting group"); + return HTTP_INTERNAL_SERVER_ERROR; + } + } + /* set vhost's privileges */ + if (setppriv(PRIV_SET, PRIV_EFFECTIVE, cfg->priv) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02147) + "Error setting effective privileges"); + return HTTP_INTERNAL_SERVER_ERROR; + } + + /* ... including those of any subprocesses */ + if (setppriv(PRIV_SET, PRIV_INHERITABLE, cfg->child_priv) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02148) + "Error setting inheritable privileges"); + return HTTP_INTERNAL_SERVER_ERROR; + } + if (setppriv(PRIV_SET, PRIV_LIMIT, cfg->child_priv) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02149) + "Error setting limit privileges"); + return HTTP_INTERNAL_SERVER_ERROR; + } + + /* If we're in a child process, drop down PPERM too */ + if (fork_req) { + if (setppriv(PRIV_SET, PRIV_PERMITTED, cfg->priv) == -1) { + ap_log_rerror(APLOG_MARK, APLOG_ERR, errno, r, APLOGNO(02150) + "Error setting permitted privileges"); + return HTTP_INTERNAL_SERVER_ERROR; + } + } + + return OK; +} +#define PDROP_CHECK(x) if (x == -1) { \ + ap_log_error(APLOG_MARK, APLOG_CRIT, errno, s, APLOGNO(02151) \ + "Error dropping privileges"); \ + return !OK; \ + } + +static int privileges_drop_first(apr_pool_t *pool, server_rec *s) +{ + /* We need to set privileges before mod_unixd, + * 'cos otherwise setuid will wipe our privilege to do so + */ + priv_cfg *spcfg; + server_rec *sp; + priv_set_t *ppriv = priv_allocset(); + + /* compute ppriv from the union of all the vhosts plus setid */ + priv_copyset(priv_setid, ppriv); + for (sp = s; sp != NULL; sp=sp->next) { + spcfg = ap_get_module_config(sp->module_config, &privileges_module); + priv_union(spcfg->priv, ppriv); + } + PDROP_CHECK(setppriv(PRIV_SET, PRIV_PERMITTED, ppriv)) + PDROP_CHECK(setppriv(PRIV_SET, PRIV_EFFECTIVE, ppriv)) + priv_freeset(ppriv); + + return OK; +} +static int privileges_drop_last(apr_pool_t *pool, server_rec *s) +{ + /* Our config stuff has set the privileges we need, so now + * we just set them to those of the parent server_rec + * + * This has to happen after mod_unixd, 'cos mod_unixd needs + * privileges we drop here. + */ + priv_cfg *cfg = ap_get_module_config(s->module_config, &privileges_module); + + /* defaults - the default vhost */ + PDROP_CHECK(setppriv(PRIV_SET, PRIV_LIMIT, cfg->child_priv)) + PDROP_CHECK(setppriv(PRIV_SET, PRIV_INHERITABLE, cfg->child_priv)) + PDROP_CHECK(setppriv(PRIV_SET, PRIV_EFFECTIVE, cfg->priv)) + + return OK; +} +static apr_status_t privileges_term(void *rec) +{ + priv_freeset(priv_setid); + return APR_SUCCESS; +} +static int privileges_postconf(apr_pool_t *pconf, apr_pool_t *plog, + apr_pool_t *ptemp, server_rec *s) +{ + priv_cfg *cfg; + server_rec *sp; + + /* if we have dtrace enabled, merge it into everything */ + if (dtrace_enabled) { + for (sp = s; sp != NULL; sp = sp->next) { + cfg = ap_get_module_config(sp->module_config, &privileges_module); + CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_KERNEL), APLOGNO(03168)); + CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_PROC), APLOGNO(03169)); + CR_CHECK(priv_addset(cfg->priv, PRIV_DTRACE_USER), APLOGNO(03170)); + CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_KERNEL), APLOGNO(03171)); + CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_PROC), APLOGNO(03172)); + CR_CHECK(priv_addset(cfg->child_priv, PRIV_DTRACE_USER), APLOGNO(03173)); + } + CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_KERNEL), APLOGNO(03174)); + CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_PROC), APLOGNO(03175)); + CR_CHECK(priv_addset(priv_default, PRIV_DTRACE_USER), APLOGNO(03176)); + } + + /* set up priv_setid for per-request use */ + priv_setid = priv_allocset(); + apr_pool_cleanup_register(pconf, NULL, privileges_term, + apr_pool_cleanup_null); + priv_emptyset(priv_setid); + if (priv_addset(priv_setid, PRIV_PROC_SETID) == -1) { + ap_log_perror(APLOG_MARK, APLOG_CRIT, errno, ptemp, APLOGNO(02152) + "priv_addset"); + return !OK; + } + return OK; +} +static int privileges_init(apr_pool_t *pconf, apr_pool_t *plog, + apr_pool_t *ptemp) +{ + /* refuse to work if the MPM is threaded */ + int threaded; + int rv = ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded); + if (rv != APR_SUCCESS) { + ap_log_perror(APLOG_MARK, APLOG_NOTICE, rv, ptemp, APLOGNO(02153) + "mod_privileges: unable to determine MPM characteristics." + " Please ensure you are using a non-threaded MPM " + "with this module."); + } + if (threaded) { + ap_log_perror(APLOG_MARK, APLOG_CRIT, rv, ptemp, APLOGNO(02154) + "mod_privileges is not compatible with a threaded MPM."); + return !OK; + } + return OK; +} +static void privileges_hooks(apr_pool_t *pool) +{ + ap_hook_post_read_request(privileges_req, NULL, NULL, + APR_HOOK_REALLY_FIRST); + ap_hook_header_parser(privileges_req, NULL, NULL, APR_HOOK_REALLY_FIRST); + ap_hook_drop_privileges(privileges_drop_first, NULL, NULL, APR_HOOK_FIRST); + ap_hook_drop_privileges(privileges_drop_last, NULL, NULL, APR_HOOK_LAST); + ap_hook_post_config(privileges_postconf, NULL, NULL, APR_HOOK_MIDDLE); + ap_hook_pre_config(privileges_init, NULL, NULL, APR_HOOK_FIRST); +} + +static const char *vhost_user(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + cfg->uid = ap_uname2id(arg); + if (cfg->uid == 0) { + return apr_pstrcat(cmd->pool, "Invalid userid for VHostUser: ", + arg, NULL); + } + return NULL; +} +static const char *vhost_group(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + cfg->gid = ap_gname2id(arg); + if (cfg->uid == 0) { + return apr_pstrcat(cmd->pool, "Invalid groupid for VHostGroup: ", + arg, NULL); + } + return NULL; +} +static const char *vhost_secure(cmd_parms *cmd, void *dir, int arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + if (!arg) { + /* add basic privileges, excluding those covered by cgimode */ + CFG_CHECK(priv_addset(cfg->priv, PRIV_FILE_LINK_ANY)); + CFG_CHECK(priv_addset(cfg->priv, PRIV_PROC_INFO)); + CFG_CHECK(priv_addset(cfg->priv, PRIV_PROC_SESSION)); + } + return NULL; +} +static const char *vhost_cgimode(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + if (!strcasecmp(arg, "on")) { + /* default - nothing to do */ + } + else if (!strcasecmp(arg, "off")) { + /* drop fork+exec privs */ + CFG_CHECK(priv_delset(cfg->priv, PRIV_PROC_FORK)); + CFG_CHECK(priv_delset(cfg->priv, PRIV_PROC_EXEC)); + } + else if (!strcasecmp(arg, "secure")) { + /* deny privileges to CGI procs */ + CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_FORK)); + CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_EXEC)); + CFG_CHECK(priv_delset(cfg->child_priv, PRIV_FILE_LINK_ANY)); + CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_INFO)); + CFG_CHECK(priv_delset(cfg->child_priv, PRIV_PROC_SESSION)); + } + else { + return "VHostCGIMode must be On, Off or Secure"; + } + + return NULL; +} +static const char *dtraceenable(cmd_parms *cmd, void *dir, int arg) +{ + const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY); + if (err != NULL) { + return err; + } + dtrace_enabled = arg; + return NULL; +} + +static const char *privs_mode(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_mode mode = PRIV_UNSET; + if (!strcasecmp(arg, "FAST")) { + mode = PRIV_FAST; + } + else if (!strcasecmp(arg, "SECURE")) { + mode = PRIV_SECURE; + } + else if (!strcasecmp(arg, "SELECTIVE")) { + mode = PRIV_SELECTIVE; + } + + if (cmd->path) { + /* In a directory context, set the per_dir_config */ + priv_dir_cfg *cfg = dir; + cfg->mode = mode; + if ((mode == PRIV_UNSET) || (mode == PRIV_SELECTIVE)) { + return "PrivilegesMode in a Directory context must be FAST or SECURE"; + } + } + else { + /* In a global or vhost context, set the server config */ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + cfg->mode = mode; + if (mode == PRIV_UNSET) { + return "PrivilegesMode must be FAST, SECURE or SELECTIVE"; + } + } + return NULL; +} + +#ifdef BIG_SECURITY_HOLE +static const char *vhost_privs(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + const char *priv = arg; + + if (*priv == '-') { + CFG_CHECK(priv_delset(cfg->priv, priv+1)); + } + else if (*priv == '+') { + CFG_CHECK(priv_addset(cfg->priv, priv+1)); + } + else { + priv_emptyset(cfg->priv); + CFG_CHECK(priv_addset(cfg->priv, priv)); + } + return NULL; +} +static const char *vhost_cgiprivs(cmd_parms *cmd, void *dir, const char *arg) +{ + priv_cfg *cfg = ap_get_module_config(cmd->server->module_config, + &privileges_module); + const char *priv = arg; + if (*priv == '-') { + CFG_CHECK(priv_delset(cfg->child_priv, priv+1)); + } + else if (*priv == '+') { + CFG_CHECK(priv_addset(cfg->child_priv, priv+1)); + } + else { + priv_emptyset(cfg->child_priv); + CFG_CHECK(priv_addset(cfg->child_priv, priv)); + } + return NULL; +} +#endif +static const command_rec privileges_cmds[] = { + AP_INIT_TAKE1("VHostUser", vhost_user, NULL, RSRC_CONF, + "Userid under which the virtualhost will run"), + AP_INIT_TAKE1("VHostGroup", vhost_group, NULL, RSRC_CONF, + "Group under which the virtualhost will run"), + AP_INIT_FLAG("VHostSecure", vhost_secure, NULL, RSRC_CONF, + "Run in enhanced security mode (default ON)"), + AP_INIT_TAKE1("VHostCGIMode", vhost_cgimode, NULL, RSRC_CONF, + "Enable fork+exec for this virtualhost (Off|Secure|On)"), + AP_INIT_FLAG("DTracePrivileges", dtraceenable, NULL, RSRC_CONF, + "Enable DTrace"), + AP_INIT_TAKE1("PrivilegesMode", privs_mode, NULL, RSRC_CONF|ACCESS_CONF, + "tradeoff performance vs security (fast or secure)"), +#ifdef BIG_SECURITY_HOLE + AP_INIT_ITERATE("VHostPrivs", vhost_privs, NULL, RSRC_CONF, + "Privileges available in the (virtual) server"), + AP_INIT_ITERATE("VHostCGIPrivs", vhost_cgiprivs, NULL, RSRC_CONF, + "Privileges available to external programs"), +#endif + {NULL} +}; +AP_DECLARE_MODULE(privileges) = { + STANDARD20_MODULE_STUFF, + privileges_create_dir_cfg, + privileges_merge_dir_cfg, + privileges_create_cfg, + privileges_merge_cfg, + privileges_cmds, + privileges_hooks +}; |