lighttpd1.4/src/mod_userdir.c

#include "base.h"
#include "log.h"
#include "buffer.h"

#include "response.h"

#include "plugin.h"

#include <sys/types.h>

#include <stdlib.h>
#include <string.h>

#ifdef HAVE_PWD_H
# include <pwd.h>
#endif

/* plugin config for all request/connections */
typedef struct {
	array *exclude_user;
	array *include_user;
	buffer *path;
	buffer *basepath;
	unsigned short letterhomes;
	unsigned short active;
} plugin_config;

typedef struct {
	PLUGIN_DATA;

	buffer *username;
	buffer *temp_path;

	plugin_config **config_storage;

	plugin_config conf;
} plugin_data;

/* init the plugin data */
INIT_FUNC(mod_userdir_init) {
	plugin_data *p;

	p = calloc(1, sizeof(*p));

	p->username = buffer_init();
	p->temp_path = buffer_init();

	return p;
}

/* detroy the plugin data */
FREE_FUNC(mod_userdir_free) {
	plugin_data *p = p_d;

	if (!p) return HANDLER_GO_ON;

	if (p->config_storage) {
		size_t i;

		for (i = 0; i < srv->config_context->used; i++) {
			plugin_config *s = p->config_storage[i];

			if (NULL == s) continue;

			array_free(s->include_user);
			array_free(s->exclude_user);
			buffer_free(s->path);
			buffer_free(s->basepath);

			free(s);
		}
		free(p->config_storage);
	}

	buffer_free(p->username);
	buffer_free(p->temp_path);

	free(p);

	return HANDLER_GO_ON;
}

/* handle plugin config and check values */

SETDEFAULTS_FUNC(mod_userdir_set_defaults) {
	plugin_data *p = p_d;
	size_t i;

	config_values_t cv[] = {
		{ "userdir.path",               NULL, T_CONFIG_STRING, T_CONFIG_SCOPE_CONNECTION },       /* 0 */
		{ "userdir.exclude-user",       NULL, T_CONFIG_ARRAY,  T_CONFIG_SCOPE_CONNECTION },       /* 1 */
		{ "userdir.include-user",       NULL, T_CONFIG_ARRAY,  T_CONFIG_SCOPE_CONNECTION },       /* 2 */
		{ "userdir.basepath",           NULL, T_CONFIG_STRING, T_CONFIG_SCOPE_CONNECTION },       /* 3 */
		{ "userdir.letterhomes",        NULL, T_CONFIG_BOOLEAN,T_CONFIG_SCOPE_CONNECTION },       /* 4 */
		{ "userdir.active",             NULL, T_CONFIG_BOOLEAN,T_CONFIG_SCOPE_CONNECTION },       /* 5 */
		{ NULL,                         NULL, T_CONFIG_UNSET,  T_CONFIG_SCOPE_UNSET }
	};

	if (!p) return HANDLER_ERROR;

	p->config_storage = calloc(1, srv->config_context->used * sizeof(plugin_config *));

	for (i = 0; i < srv->config_context->used; i++) {
		data_config const* config = (data_config const*)srv->config_context->data[i];
		plugin_config *s;

		s = calloc(1, sizeof(plugin_config));
		s->exclude_user = array_init();
		s->include_user = array_init();
		s->path = buffer_init();
		s->basepath = buffer_init();
		s->letterhomes = 0;
		/* enabled by default for backward compatibility; if userdir.path isn't set userdir is disabled too,
		 * but you can't disable it by setting it to an empty string. */
		s->active = 1;

		cv[0].destination = s->path;
		cv[1].destination = s->exclude_user;
		cv[2].destination = s->include_user;
		cv[3].destination = s->basepath;
		cv[4].destination = &(s->letterhomes);
		cv[5].destination = &(s->active);

		p->config_storage[i] = s;

		if (0 != config_insert_values_global(srv, config->value, cv, i == 0 ? T_CONFIG_SCOPE_SERVER : T_CONFIG_SCOPE_CONNECTION)) {
			return HANDLER_ERROR;
		}
	}

	return HANDLER_GO_ON;
}

#define PATCH(x) \
	p->conf.x = s->x;
static int mod_userdir_patch_connection(server *srv, connection *con, plugin_data *p) {
	size_t i, j;
	plugin_config *s = p->config_storage[0];

	PATCH(path);
	PATCH(exclude_user);
	PATCH(include_user);
	PATCH(basepath);
	PATCH(letterhomes);
	PATCH(active);

	/* skip the first, the global context */
	for (i = 1; i < srv->config_context->used; i++) {
		data_config *dc = (data_config *)srv->config_context->data[i];
		s = p->config_storage[i];

		/* condition didn't match */
		if (!config_check_cond(srv, con, dc)) continue;

		/* merge config */
		for (j = 0; j < dc->value->used; j++) {
			data_unset *du = dc->value->data[j];

			if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.path"))) {
				PATCH(path);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.exclude-user"))) {
				PATCH(exclude_user);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.include-user"))) {
				PATCH(include_user);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.basepath"))) {
				PATCH(basepath);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.letterhomes"))) {
				PATCH(letterhomes);
			} else if (buffer_is_equal_string(du->key, CONST_STR_LEN("userdir.active"))) {
				PATCH(active);
			}
		}
	}

	return 0;
}
#undef PATCH

URIHANDLER_FUNC(mod_userdir_docroot_handler) {
	plugin_data *p = p_d;
	size_t k;
	char *rel_url;
#ifdef HAVE_PWD_H
	struct passwd *pwd = NULL;
#endif

	if (buffer_is_empty(con->uri.path)) return HANDLER_GO_ON;

	mod_userdir_patch_connection(srv, con, p);

	/* enforce the userdir.path to be set in the config, ugly fix for #1587;
	 * should be replaced with a clean .enabled option in 1.5
	 */
	if (!p->conf.active || buffer_is_empty(p->conf.path)) return HANDLER_GO_ON;

	/* /~user/foo.html -> /home/user/public_html/foo.html */

	if (con->uri.path->ptr[0] != '/' ||
	    con->uri.path->ptr[1] != '~') return HANDLER_GO_ON;

	if (NULL == (rel_url = strchr(con->uri.path->ptr + 2, '/'))) {
		/* / is missing -> redirect to .../ as we are a user - DIRECTORY ! :) */
		http_response_redirect_to_directory(srv, con);

		return HANDLER_FINISHED;
	}

	/* /~/ is a empty username, catch it directly */
	if (0 == rel_url - (con->uri.path->ptr + 2)) {
		return HANDLER_GO_ON;
	}

	buffer_copy_string_len(p->username, con->uri.path->ptr + 2, rel_url - (con->uri.path->ptr + 2));

	if (buffer_string_is_empty(p->conf.basepath)
#ifdef HAVE_PWD_H
	    && NULL == (pwd = getpwnam(p->username->ptr))
#endif
	    ) {
		/* user not found */
		return HANDLER_GO_ON;
	}


	for (k = 0; k < p->conf.exclude_user->used; k++) {
		data_string *ds = (data_string *)p->conf.exclude_user->data[k];

		if (buffer_is_equal(ds->value, p->username)) {
			/* user in exclude list */
			return HANDLER_GO_ON;
		}
	}

	if (p->conf.include_user->used) {
		int found_user = 0;
		for (k = 0; k < p->conf.include_user->used; k++) {
			data_string *ds = (data_string *)p->conf.include_user->data[k];

			if (buffer_is_equal(ds->value, p->username)) {
				/* user in include list */
				found_user = 1;
				break;
			}
		}

		if (!found_user) return HANDLER_GO_ON;
	}

	/* we build the physical path */

	if (buffer_string_is_empty(p->conf.basepath)) {
#ifdef HAVE_PWD_H
		buffer_copy_string(p->temp_path, pwd->pw_dir);
#endif
	} else {
		char *cp;
		/* check if the username is valid
		 * a request for /~../ should lead to a directory traversal
		 * limiting to [-_a-z0-9.] should fix it */

		for (cp = p->username->ptr; *cp; cp++) {
			char c = *cp;

			if (!(c == '-' ||
			      c == '_' ||
			      c == '.' ||
			      (c >= 'a' && c <= 'z') ||
			      (c >= 'A' && c <= 'Z') ||
			      (c >= '0' && c <= '9'))) {

				return HANDLER_GO_ON;
			}
		}
		if (con->conf.force_lowercase_filenames) {
			buffer_to_lower(p->username);
		}

		buffer_copy_buffer(p->temp_path, p->conf.basepath);
		buffer_append_slash(p->temp_path);
		if (p->conf.letterhomes) {
			buffer_append_string_len(p->temp_path, p->username->ptr, 1);
			buffer_append_slash(p->temp_path);
		}
		buffer_append_string_buffer(p->temp_path, p->username);
	}
	buffer_append_slash(p->temp_path);
	buffer_append_string_buffer(p->temp_path, p->conf.path);

	if (buffer_string_is_empty(p->conf.basepath)) {
		struct stat st;
		int ret;

		ret = stat(p->temp_path->ptr, &st);
		if (ret < 0 || S_ISDIR(st.st_mode) != 1) {
			return HANDLER_GO_ON;
		}
	}

	buffer_copy_buffer(con->physical.basedir, p->temp_path);

	/* the physical rel_path is basically the same as uri.path;
	 * but it is converted to lowercase in case of force_lowercase_filenames and some special handling
	 * for trailing '.', ' ' and '/' on windows
	 * we assume that no docroot/physical handler changed this
	 * (docroot should only set the docroot/server name, phyiscal should only change the phyiscal.path;
	 *  the exception mod_secure_download doesn't work with userdir anyway)
	 */
	buffer_append_slash(p->temp_path);
	/* if no second '/' is found, we assume that it was stripped from the uri.path for the special handling
	 * on windows.
	 * we do not care about the trailing slash here on windows, as we already ensured it is a directory
	 *
	 * TODO: what to do with trailing dots in usernames on windows? they may result in the same directory
	 *       as a username without them.
	 */
	if (NULL != (rel_url = strchr(con->physical.rel_path->ptr + 2, '/'))) {
		buffer_append_string(p->temp_path, rel_url + 1); /* skip the / */
	}
	buffer_copy_buffer(con->physical.path, p->temp_path);

	buffer_reset(p->temp_path);

	return HANDLER_GO_ON;
}

/* this function is called at dlopen() time and inits the callbacks */

int mod_userdir_plugin_init(plugin *p);
int mod_userdir_plugin_init(plugin *p) {
	p->version     = LIGHTTPD_VERSION_ID;
	p->name        = buffer_init_string("userdir");

	p->init           = mod_userdir_init;
	p->handle_physical = mod_userdir_docroot_handler;
	p->set_defaults   = mod_userdir_set_defaults;
	p->cleanup        = mod_userdir_free;

	p->data        = NULL;

	return 0;
}