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Commit 9d3cbde7 authored by Lennart Kramer's avatar Lennart Kramer
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send raw uid/gid to maxima process 

this no longer hardcodes the number of processes and is in preparation for
rootless operation
parent b40d2a91
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src/maxima_fork.c
+ 41
− 50
View file @ 9d3cbde7
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <pwd.h>
#include <signal.h>
#include <sys/resource.h>
......@@ -10,14 +8,9 @@
#include <sys/stat.h>
#include <sys/wait.h>
#include <fcntl.h>
#include <bsd/unistd.h>
#include <limits.h>
#include <grp.h>
// number of processes
#ifndef N_SLOT
#define N_SLOT 32
#endif
// maximum number of open file descriptors
#ifndef RNOFILE
......@@ -40,33 +33,6 @@ char filepath[FILEPATH_LEN];
// redirects input/output, creates temporary subdirectories
char *fork_new_process() {
fflush(stdout);
uid_t user_id[N_SLOT];
gid_t group_id[N_SLOT];
// cache and verify uids/gids on startup
for (int i = 1; i <= N_SLOT; i++) {
char username[16];
int len = snprintf(username, 15, "maxima-%d", i);
if (len < 0 || len > 15) {
dprintf(STDERR_FILENO, "Internal error getting user name\n");
return NULL;
}
struct passwd *userinfo = getpwnam(username);
if (!userinfo) {
dprintf(STDERR_FILENO, "Could not read user information for %s: %s\n",
username, strerror(errno));
return NULL;
}
uid_t uid = userinfo->pw_uid;
gid_t gid = userinfo->pw_gid;
if (uid == 0 || gid == 0) {
dprintf(STDERR_FILENO, "maxima-%d is root, quitting\n", i);
return NULL;
}
user_id[i - 1] = uid;
group_id[i - 1] = gid;
}
// send an S for Synchronization, so that
// the server process doesn't accidentally write into
......@@ -101,25 +67,39 @@ char *fork_new_process() {
for (;;) {
// can't flush enough
fflush(stdout);
int slot;
// the slot number and temp directory is sent to the process
// over stdin in the format "%d%s", where %s can contain anything
// the uid/gid and temp directory is sent to the process
// over stdin in the format "%d:%d%s", where %s can contain anything
// but newlines and musn't start with a number, which isn't a
// problem for absolute paths
if (scanf("%d", &slot) == EOF) {
if (errno != 0) {
perror("Error getting slot number from stdin");
char *input = fgets(filepath, FILEPATH_LEN, stdin);
if (!input) {
perror("Error getting input");
ret = NULL;
break;
}
char *cur;
long uid = strtol(input, &cur, 10);
if (cur == input) {
fprintf(stderr, "Invalid uid\n");
ret = NULL;
break;
}
if (*cur++ != ':') {
fprintf(stderr, "Invalid input\n");
ret = NULL;
break;
}
char *tempdir = fgets(filepath, FILEPATH_LEN, stdin);
if (!tempdir) {
perror("Error getting temp path name");
input = cur;
long gid = strtol(input, &cur, 10);
if (cur == input) {
fprintf(stderr, "Invalid gid\n");
ret = NULL;
break;
}
char *tempdir = cur;
// remove the last newline, if it exists
size_t last_char = strlen(tempdir) - 1;
if (tempdir[last_char] == '\n') {
......@@ -138,15 +118,19 @@ char *fork_new_process() {
continue;
}
// verify valid slot number
if (slot <= 0 || slot > N_SLOT) {
dprintf(STDERR_FILENO, "Invalid slot number: %d\n", slot);
// valididate uid and gid
if (uid <= 0 || uid > 0xffff) {
dprintf(STDERR_FILENO, "Invalid uid: %ld\n", uid);
ret = NULL;
break;
}
if (gid <= 0 || gid > 0xffff) {
dprintf(STDERR_FILENO, "Invalid gid: %ld\n", gid);
ret = NULL;
break;
}
uid_t uid = user_id[slot - 1];
gid_t gid = group_id[slot - 1];
// note: setgid should be executed before setuid when dropping from root
if (setgid(gid) == -1) {
perror("Could not set gid");
......@@ -168,6 +152,13 @@ char *fork_new_process() {
break;
}
// start new process group
if (setpgid(0, 0) == -1) {
perror("Could not set pgid");
ret = NULL;
break;
}
if (chdir(tempdir) == -1) {
perror("Could not chdir to temporary directory");
ret = NULL;
......
src/web/go.sum
+ 84
− 0
View file @ 9d3cbde7
This diff is collapsed.
src/web/web.go
+ 14
− 14
View file @ 9d3cbde7
......@@ -7,7 +7,7 @@ import (
"errors"
"fmt"
"io"
"io/ioutil"
"io/fs"
"log"
"net/http"
"os"
......@@ -156,12 +156,12 @@ func new_mother_proc(binpath string, libs []string) (*MotherProcess, error) {
func (p *MotherProcess) spawn_new(user *User) (*ChildProcess, float64, error) {
start := time.Now()
var result ChildProcess
var child ChildProcess
err := user.sync_execute_as(MAXIMA_SPAWN_TIMEOUT, func(err error) error {
if err != nil {
return err
}
tmp_dir, err := ioutil.TempDir(tmp_prefix, "maxima-plot-")
tmp_dir, err := os.MkdirTemp(tmp_prefix, "maxima-plot-")
if err != nil {
return fmt.Errorf("unable to create temp dir: %s", err)
}
......@@ -187,7 +187,7 @@ func (p *MotherProcess) spawn_new(user *User) (*ChildProcess, float64, error) {
return fmt.Errorf("could not create named pipe in temp folder: %s", err)
}
_, err = fmt.Fprintf(p.Input, "%d%s\n", user.Id, tmp_dir)
_, err = fmt.Fprintf(p.Input, "%d:%d%s\n", user.Uid, user.Gid, tmp_dir)
if err != nil {
return fmt.Errorf("unable to communicate with process: %s", err)
}
......@@ -204,10 +204,10 @@ func (p *MotherProcess) spawn_new(user *User) (*ChildProcess, float64, error) {
return fmt.Errorf("could not open temp dir inpipe: %s", err)
}
result.User = user
result.Input = in
result.Outfile = out
result.TempDir = tmp_dir
child.User = user
child.Input = in
child.Outfile = out
child.TempDir = tmp_dir
return nil
})
if err != nil {
......@@ -215,21 +215,21 @@ func (p *MotherProcess) spawn_new(user *User) (*ChildProcess, float64, error) {
}
debugf("Debug: Attempting to read from child")
err = result.Outfile.SetReadDeadline(time.Now().Add(MAXIMA_SPAWN_TIMEOUT))
err = child.Outfile.SetReadDeadline(time.Now().Add(MAXIMA_SPAWN_TIMEOUT))
if err != nil {
return nil, 0.0, fmt.Errorf("unable to set read deadline: %s", err)
}
bufout := bufio.NewReader(result.Outfile)
bufout := bufio.NewReader(child.Outfile)
_, err = fmt.Fscanf(bufout, "\nT")
if err != nil {
return nil, 0.0, fmt.Errorf("not able to find end marker: %s", err)
}
result.Output = bufout
child.Output = bufout
total := time.Since(start)
total_ms := float64(total.Microseconds()) / 1000
debugf("Debug: child took %s for startup", total)
return &result, total_ms, nil
return &child, total_ms, nil
}
type MaximaResponse struct {
......@@ -349,7 +349,7 @@ func (req *MaximaRequest) WriteResponseWithoutPlots(response MaximaResponse) {
req.Metrics.NumSuccess.Inc()
}
func (req *MaximaRequest) WriteResponseWithPlots(response MaximaResponse, output_dir string, plots_output []os.FileInfo) {
func (req *MaximaRequest) WriteResponseWithPlots(response MaximaResponse, output_dir string, plots_output []fs.DirEntry) {
debugf("Debug: output (%d) is zip, OUTPUT len %d", req.User.Id, response.Response.Len())
req.W.Header().Set("Content-Type", "application/zip;charset=UTF-8")
zipfile := zip.NewWriter(req.W)
......@@ -420,7 +420,7 @@ func (req *MaximaRequest) WriteResponse(response MaximaResponse) {
output_dir := filepath.Clean(filepath.Join(req.Proc.TempDir, "output")) + "/"
// if there are any files inside the output dir, we give back a zip file containing all output
// files and the command output inside a file named OUTPUT
plots_output, err := ioutil.ReadDir(output_dir)
plots_output, err := os.ReadDir(output_dir)
if err != nil {
// just return text if directory could not be read and assume no plots were generated
req.log_with_input("Warn: could not read temp directory of maxima process: %s", err)
......
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