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Add simple cgi support +:

* read file byte after byte
* format code (syslog + err)
* move functions in utils.c
master
prx 5 months ago
parent
commit
470e47a018
  1. 9
      Makefile
  2. 2
      README.md
  3. 184
      main.c
  4. 7
      opts.h
  5. 14
      tests/test.sh
  6. 9
      tests/var/gemini/cgi-bin/test.cgi
  7. 9
      tests/var/gemini/cgi-bin/who.cgi
  8. 78
      utils.c
  9. 6
      utils.h
  10. 17
      vger.8

9
Makefile

@ -2,13 +2,18 @@ PREFIX?=/usr/local/
CFLAGS += -pedantic -Wall -Wextra -Wmissing-prototypes \
-Wstrict-prototypes -Wwrite-strings
.SUFFIXES: .c .o
.c.o:
${CC} ${CFLAGS} -c $<
all: vger
clean:
rm -f vger *.core *.o
vger: main.o mimes.o opts.h
${CC} -o vger main.o mimes.o
vger: main.o mimes.o utils.o opts.h
${CC} ${CFLAGS} -o $@ main.o mimes.o utils.o
install: vger
install -o root -g wheel vger ${PREFIX}/bin/

2
README.md

@ -55,7 +55,7 @@ without a `-d` parameter.
- `-u username`: enable chroot to the data directory and drop privileges to `username`.
- `-m MIME` : use MIME as default instead of "application/octet-stream".
- `-i` : Enable auto index if no "index.gmi" file is found in a directory.
- `-c CGI_PATH` : Exec CGI_PATH instead of serving it.
# How to configure Vger using relayd and inetd

184
main.c

@ -1,9 +1,11 @@
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <pwd.h>
#include <stdarg.h>
@ -15,6 +17,7 @@
#include "mimes.h"
#include "opts.h"
#include "utils.h"
#define GEMINI_PART 9
#define GEMINI_REQUEST_MAX 1024 /* see https://gemini.circumlunar.space/docs/specification.html */
@ -22,45 +25,11 @@
void autoindex(const char *);
void cgi(const char *cgicmd);
void display_file(const char *);
void status(const int, const char *);
void status_redirect(const int, const char *);
void drop_privileges(const char *, const char *);
void eunveil(const char *, const char *);
size_t estrlcat(char *, const char *, size_t);
size_t estrlcpy(char *, const char *, size_t);
void
eunveil(const char *path, const char *permissions)
{
if (unveil(path, permissions) == -1) {
syslog(LOG_DAEMON, "unveil on %s failed", path);
err(1, "unveil");
}
}
size_t
estrlcpy(char *dst, const char *src, size_t dstsize)
{
size_t n = 0;
n = strlcpy(dst, src, dstsize);
if (n >= dstsize) {
err(1, "strlcyp failed for %s = %s", dst, src);
}
return n;
}
size_t
estrlcat(char *dst, const char *src, size_t dstsize)
{
size_t size;
if ((size = strlcat(dst, src, dstsize)) >= dstsize)
err(1, "strlcat on %s + %s", dst, src);
return size;
}
void
drop_privileges(const char *user, const char *path)
@ -76,31 +45,26 @@ drop_privileges(const char *user, const char *path)
/* is root? */
if (getuid() != 0) {
syslog(LOG_DAEMON, "chroot requires program to be run as root");
errx(1, "chroot requires root user");
errlog("chroot requires program to be run as root");
}
/* search user uid from name */
if ((pw = getpwnam(user)) == NULL) {
syslog(LOG_DAEMON, "the user %s can't be found on the system", user);
err(1, "finding user");
errlog("the user %s can't be found on the system", user);
}
/* chroot worked? */
if (chroot(path) != 0) {
syslog(LOG_DAEMON, "the chroot_dir %s can't be used for chroot", path);
err(1, "chroot");
errlog("the chroot_dir %s can't be used for chroot", path);
}
chrooted = 1;
if (chdir("/") == -1) {
syslog(LOG_DAEMON, "failed to chdir(\"/\")");
err(1, "chdir");
errlog("failed to chdir(\"/\")");
}
/* drop privileges */
if (setgroups(1, &pw->pw_gid) ||
setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) ||
setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid)) {
syslog(LOG_DAEMON, "dropping privileges to user %s (uid=%i) failed",
errlog("dropping privileges to user %s (uid=%i) failed",
user, pw->pw_uid);
err(1, "Can't drop privileges");
}
}
#ifdef __OpenBSD__
@ -112,13 +76,20 @@ drop_privileges(const char *user, const char *path)
} else {
eunveil(path, "r");
}
if (strlen(cgibin) > 0) {
char cgifullpath[PATH_MAX] = {'\0'};
estrlcpy(cgifullpath, path, sizeof(cgifullpath));
estrlcat(cgifullpath, cgibin, sizeof(cgifullpath));
eunveil(cgifullpath, "rx");
}
/*
* prevent system calls other parsing queryfor fread file and
* write to stdio
*/
if (pledge("stdio rpath", NULL) == -1) {
syslog(LOG_DAEMON, "pledge call failed");
err(1, "pledge");
if (strlen(cgibin) > 0) {
epledge("stdio rpath exec proc", NULL);
} else {
epledge("stdio rpath", NULL);
}
#endif
}
@ -168,8 +139,8 @@ display_file(const char *uri)
if (fp[strlen(fp) -1 ] != '/') {
/* no ending "/", redirect to "path/" */
char new_uri[PATH_MAX] = {'\0'};
estrlcpy(new_uri, uri, sizeof(fp));
estrlcat(new_uri, "/", sizeof(fp));
estrlcpy(new_uri, uri, sizeof(new_uri));
estrlcat(new_uri, "/", sizeof(new_uri));
status_redirect(31, new_uri);
return;
@ -199,8 +170,8 @@ display_file(const char *uri)
status(20, file_mime);
/* read the file and write it to stdout */
while ((nread = fread(buffer, sizeof(char), sizeof(buffer), fd)) != 0)
fwrite(buffer, sizeof(char), nread, stdout);
while ((nread = fread(buffer, 1, sizeof(buffer), fd)) != 0)
fwrite(buffer, 1, nread, stdout);
goto closefd;
syslog(LOG_DAEMON, "path served %s", fp);
@ -257,6 +228,59 @@ autoindex(const char *path)
closedir(fd);
}
void
cgi(const char *cgicmd)
{
int pipedes[2] = {0};
pid_t pid;
if (pipe(pipedes) != 0) {
err(1, "pipe failed");
}
pid = fork();
if (pid < 0) {
close(pipedes[0]);
close(pipedes[1]);
err(1, "fork failed");
}
if (pid > 0) { /* parent */
char buf[3];
size_t nread = 0;
FILE *output = NULL;
close(pipedes[1]); /* make sure entry is closed so fread() gets EOF */
/* use fread/fwrite because are buffered */
output = fdopen(pipedes[0], "r");
if (output == NULL) {
err(1, "fdopen failed");
}
/* read pipe output */
while ((nread = fread(buf, 1, sizeof(buf), output)) != 0) {
fwrite(buf, 1, nread, stdout);
}
close(pipedes[0]);
fclose(output);
wait(NULL); /* wait for child to terminate */
exit(0);
} else if (pid == 0) { /* child */
dup2(pipedes[1], STDOUT_FILENO); /* set pipe output equal to stdout */
close(pipedes[1]); /* no need this file descriptor : it is now stdout */
execlp(cgicmd, cgicmd, NULL);
/* if execlp is ok, this will never be reached */
status(42, "text/plain");
errlog("error when trying to execlp %s", cgicmd);
}
}
int
main(int argc, char **argv)
{
@ -268,7 +292,7 @@ main(int argc, char **argv)
int option = 0;
char *pos = NULL;
while ((option = getopt(argc, argv, ":d:l:m:u:vi")) != -1) {
while ((option = getopt(argc, argv, ":d:l:m:u:c:vi")) != -1) {
switch (option) {
case 'd':
estrlcpy(chroot_dir, optarg, sizeof(chroot_dir));
@ -283,6 +307,9 @@ main(int argc, char **argv)
case 'u':
estrlcpy(user, optarg, sizeof(user));
break;
case 'c':
estrlcpy(cgibin, optarg, sizeof(cgibin));
break;
case 'v':
virtualhost = 1;
break;
@ -303,8 +330,7 @@ main(int argc, char **argv)
*/
if (fgets(request, GEMINI_REQUEST_MAX, stdin) == NULL) {
status(59, "request is too long (1024 max)");
syslog(LOG_DAEMON, "request is too long (1024 max): %s", request);
exit(1);
errlog("request is too long (1024 max): %s", request);
}
/* remove \r\n at the end of string */
@ -318,9 +344,8 @@ main(int argc, char **argv)
*/
if (strncmp(request, "gemini://", GEMINI_PART) != 0) {
/* error code url malformed */
syslog(LOG_DAEMON, "request «%s» doesn't match gemini://",
errlog("request «%s» doesn't match gemini://",
request);
exit(1);
}
syslog(LOG_DAEMON, "request %s", request);
@ -364,8 +389,47 @@ main(int argc, char **argv)
estrlcpy(uri, new_uri, sizeof(uri));
}
/* open file and send it to stdout */
display_file(uri);
/* check if uri is cgibin */
if ((strlen(cgibin) > 0) &&
(strncmp(uri, cgibin, strlen(cgibin)) == 0)
) {
char cgipath[PATH_MAX] = {'\0'};
estrlcpy(cgipath, chroot_dir, sizeof(cgipath));
estrlcat(cgipath, uri, sizeof(cgipath));
/* set env variables for CGI */
/* see https://lists.orbitalfox.eu/archives/gemini/2020/000315.html */
esetenv("GATEWAY_INTERFACE", "CGI/1.1", 1);
esetenv("SERVER_PROTOCOL", "GEMINI", 1);
esetenv("SERVER_SOFTWARE", "vger/1", 1);
/* look for "?" to set query */
pos = strchr(cgipath, '?');
if (pos != NULL) {
char query[PATH_MAX] = {'\0'};
estrlcpy(query, pos+1, sizeof(query));
esetenv("QUERY_STRING", query, 1);
pos[0] = '\0';
}
/* look for an extension to find PATH_INFO */
pos = strrchr(cgipath, '.');
if (pos != NULL) {
/* found a dot */
pos = strchr(pos, '/');
if (pos != NULL) {
setenv("PATH_INFO", pos, 1);
pos[0] = '\0'; /* keep only script name */
}
}
esetenv("SCRIPT_NAME", cgipath, 1);
esetenv("SERVER_NAME", hostname, 1);
cgi(cgipath);
} else {
//TODO: percent decoding here
/* open file and send it to stdout */
display_file(uri);
}
return (0);
}

7
opts.h

@ -6,7 +6,8 @@
#define DEFAULT_AUTOIDX 0
/* longest is 56 so 64 should be enough */
static char default_mime[64] = DEFAULT_MIME;
static char default_mime[64] = DEFAULT_MIME;
static char chroot_dir[PATH_MAX] = DEFAULT_CHROOT;
static char lang[16] = DEFAULT_LANG;
static unsigned int doautoidx = DEFAULT_AUTOIDX;
static char lang[16] = DEFAULT_LANG;
static unsigned int doautoidx = DEFAULT_AUTOIDX;
static char cgibin[PATH_MAX] = {'\0'};

14
tests/test.sh

@ -72,7 +72,19 @@ if ! [ $OUT = "874f5e1af67eff6b93bedf8ac8033066" ] ; then echo "error" ; exit 1
# auto index in directory
OUT=$(printf "gemini://host.name/autoidx/\r\n" | ../vger -d var/gemini/ -i | tee /dev/stderr | $MD5)
if ! [ $OUT = "770a987b8f5cf7169e6bc3c6563e1570" ] ; then echo "error" ; exit 1 ; fi
if ! [ $OUT = "9cb7ef77cbcd74dadafdbff47d864152" ] ; then echo "error" ; exit 1 ; fi
# cgi simple script
OUT=$(printf "gemini://host.name/cgi-bin/test.cgi\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | $MD5)
if ! [ $OUT = "ed3552892cf7edac4f81178467f6c48a" ] ; then echo "error" ; exit 1 ; fi
# cgi with use of variables
OUT=$(printf "gemini://host.name/cgi-bin/who.cgi?user=jean-mi\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | $MD5)
if ! [ $OUT = "06f710962d6504b19cdfe77f5fcff29e" ] ; then echo "error" ; exit 1 ; fi
# cgi with error
OUT=$(printf "gemini://host.name/cgi-bin/nope\r\n" | ../vger -d var/gemini/ -c /cgi-bin | tee /dev/stderr | $MD5)
if ! [ $OUT = "babaa82d5b2bd4e8d21ab412e060c890" ] ; then echo "error" ; exit 1 ; fi
# must fail only on OpenBSD !
# try to escape from unveil

9
tests/var/gemini/cgi-bin/test.cgi

@ -0,0 +1,9 @@
#!/bin/sh
echo "20 cgi_test"
echo "env vars:"
echo $GATEWAY_INTERFACE
echo $SERVER_SOFTWARE
echo $PATH_INFO
echo $QUERY_STRING

9
tests/var/gemini/cgi-bin/who.cgi

@ -0,0 +1,9 @@
#!/bin/sh
echo "20 cgi_test"
u=""
if [ -n "${QUERY_STRING}" ]; then
u="$(printf "%s" "${QUERY_STRING}" | cut -d'=' -f2)" #yeah, it's awful..
fi
echo "hello $u"

78
utils.c

@ -0,0 +1,78 @@
#include <err.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include "utils.h"
void
eunveil(const char *path, const char *permissions)
{
if (unveil(path, permissions) == -1) {
syslog(LOG_DAEMON, "unveil on %s failed", path);
err(1, "unveil on %s failed", path);
}
}
void
epledge(const char *promises, const char *execpromises)
{
if (pledge(promises, execpromises) == -1) {
syslog(LOG_DAEMON, "pledge failed for: %s", promises);
err(1, "pledge failed for: %s", promises);
}
}
size_t
estrlcpy(char *dst, const char *src, size_t dstsize)
{
size_t n = 0;
n = strlcpy(dst, src, dstsize);
if (n >= dstsize) {
err(1, "strlcyp failed for %s = %s", dst, src);
}
return n;
}
size_t
estrlcat(char *dst, const char *src, size_t dstsize)
{
size_t size;
if ((size = strlcat(dst, src, dstsize)) >= dstsize)
err(1, "strlcat on %s + %s", dst, src);
return size;
}
int
esetenv(const char *name, const char *value, int overwrite)
{
int ret = 0;
ret = setenv(name, value, overwrite);
if (ret != 0) {
err(1, "setenv %s:%s", name, value);
}
return ret;
}
void
errlog(const char *format, ...)
{
char e[1024] = {'\0'};
va_list ap;
va_start(ap, format);
vsnprintf(e, sizeof(e), format, ap);
va_end(ap);
syslog(LOG_DAEMON, "%s", e);
err(1, "%s", e);
}

6
utils.h

@ -0,0 +1,6 @@
void epledge(const char *, const char *);
void errlog(const char *format, ...);
void eunveil(const char *, const char *);
int esetenv(const char *, const char *, int);
size_t estrlcat(char *, const char *, size_t);
size_t estrlcpy(char *, const char *, size_t);

17
vger.8

@ -9,6 +9,7 @@
.Op Fl l Ar lang
.Op Fl v
.Op Fl i
.Op Fl c Ar cgi_path
.Op Fl d Ar path
.Op Fl u Ar username
.Op Fl m Ar mimetype
@ -40,6 +41,22 @@ Enable virtualhost support, the hostname in the query will be considered as a di
As example, for request gemini://hostname.example/file.gmi
.Nm
will read the file /var/gemini/hostname.example/file.gmi
.It Op Fl c
Enable CGI support.
.Ar cgi_path
will be executed as a cgi script. This path is relative to the served capsule. As example, for a request gemini://hostname.example/cgi-bin/hello.cgi, one must set:
.Bd -literal -offset indent
vger -c /cgi-bin/hello.cgi
.Ed
.Pp
In this case,
.Xr pledge 2
promises are set to "stdio proc exec"
and an additional
.Xr unveil 2
permission on the cgi script is set to "rx".
.Pp
Be very careful on how you write your CGI, it can read outside the chroot.
.It Op Fl m Ar mimetype
Use
.Ar mimetype

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