From: Marc Fiuczynski <mef@cs.princeton.edu>
Date: Mon, 11 Oct 2004 15:35:18 +0000 (+0000)
Subject: Fixed version of vsh.c that no longer uses planetlab.c.
X-Git-Tag: after-util-vserver-0_30_208-revert~241
X-Git-Url: http://git.onelab.eu/?a=commitdiff_plain;h=e051f492b3d0b27ea6062972361ddc4d6d1ee69d;p=util-vserver.git
Fixed version of vsh.c that no longer uses planetlab.c.
Moreover, it parses the S_CAPS entry in /etc/vservers/<vserver>.conf for
the various CAP options. It does so with better error checking than the
prior version.
---
diff --git a/src/vsh.c b/src/vsh.c
index d932471..a834f2b 100644
--- a/src/vsh.c
+++ b/src/vsh.c
@@ -19,13 +19,499 @@
* 02111-1307, USA.
*/
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+#include "compat.h"
+
#include <stdio.h>
#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <pwd.h>
#include <string.h>
+#include <stdlib.h>
#include <errno.h>
+#include <pwd.h>
+#include <unistd.h>
+#include <syscall.h>
+#include <sys/syscall.h>
+#include <asm/unistd.h>
+#include <sys/mount.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <ctype.h>
+
+//--------------------------------------------------------------------
+#include "linuxcaps.h"
+#include "vserver.h"
+
+/* Null byte made explicit */
+#define NULLBYTE_SIZE 1
+
+/* Base for all vserver roots for chroot */
+#define VSERVER_ROOT_BASE "/vservers"
+
+/* Change to root:root (before entering new context) */
+static int setuidgid_root()
+{
+ if (setgid(0) < 0) {
+ fprintf(stderr, "setgid error\n");
+ return -1;
+ }
+ if (setuid(0) < 0) {
+ fprintf(stderr, "setuid error\n");
+ return -1;
+ }
+ return 0;
+}
+
+static void compute_new_root(char *base, char **root, uid_t uid)
+{
+ int root_len;
+ struct passwd *pwd;
+
+ if ((pwd = getpwuid(uid)) == NULL) {
+ perror("vserver: getpwuid error ");
+ exit(1);
+ }
+
+ root_len =
+ strlen(base) + strlen("/") +
+ strlen(pwd->pw_name) + NULLBYTE_SIZE;
+ (*root) = (char *)malloc(root_len);
+ if ((*root) == NULL) {
+ perror("vserver: malloc error ");
+ exit(1);
+ }
+
+ sprintf((*root), "%s/%s", base, pwd->pw_name);
+ (*root)[root_len - 1] = '\0';
+}
+
+/* Example: sandbox_root = /vservers/bnc, relpath = /proc/1 */
+static int sandbox_file_exists(char *sandbox_root, char *relpath)
+{
+ struct stat stat_buf;
+ char *file;
+ int len, exists = 0;
+
+ len = strlen(sandbox_root) + strlen(relpath) + NULLBYTE_SIZE;
+ if ((file = (char *)malloc(len)) == NULL) {
+ perror("vserver: malloc error ");
+ exit(1);
+ }
+ sprintf(file, "%s%s", sandbox_root, relpath);
+ file[len - 1] = '\0';
+ if (stat(file, &stat_buf) == 0) {
+ exists = 1;
+ }
+
+
+ free(file);
+ return exists;
+}
+
+static int proc_mounted(char *sandbox_root)
+{
+ return sandbox_file_exists(sandbox_root, "/proc/1");
+}
+
+static int devpts_mounted(char *sandbox_root)
+{
+ return sandbox_file_exists(sandbox_root, "/dev/pts/0");
+}
+
+static void mount_proc(char *sandbox_root,uid_t uid)
+{
+ char *source = "/proc";
+ char *target;
+ int len;
+
+ len = strlen(sandbox_root) + strlen("/") + strlen("proc") + NULLBYTE_SIZE;
+ if ((target = (char *)malloc(len)) == NULL) {
+ perror("vserver: malloc error ");
+ exit(1);
+ }
+
+ sprintf(target, "%s/proc", sandbox_root);
+ target[len - 1] = '\0';
+ if (!proc_mounted(sandbox_root))
+ mount(source, target, "proc", MS_BIND | MS_RDONLY, NULL);
+
+ free(target);
+}
+
+static void mount_devpts(char *sandbox_root)
+{
+ char *source = "/dev/pts";
+ char *target;
+ int len;
+
+ len = strlen(sandbox_root) + strlen("/") + strlen("dev/pts") + NULLBYTE_SIZE;
+ if ((target = (char *)malloc(len)) == NULL) {
+ perror("vserver: malloc error ");
+ exit(1);
+ }
+
+ sprintf(target, "%s/dev/pts", sandbox_root);
+ target[len - 1] = '\0';
+ if (!devpts_mounted(sandbox_root))
+ mount(source, target, "devpts", 0, NULL);
+
+ free(target);
+}
+
+static int sandbox_chroot(uid_t uid)
+{
+ char *sandbox_root = NULL;
+
+ compute_new_root(VSERVER_ROOT_BASE,&sandbox_root, uid);
+ mount_proc(sandbox_root,uid);
+ mount_devpts(sandbox_root);
+ if (chroot(sandbox_root) < 0) {
+ fprintf(stderr,"vserver: chroot error (%s): ",sandbox_root);
+ perror("");
+ exit(1);
+ }
+ if (chdir("/") < 0) {
+ perror("vserver: chdir error ");
+ exit(1);
+ }
+ return 0;
+}
+
+static struct {
+ const char *option;
+ int bit;
+}tbcap[]={
+ // The following capabilities are normally available
+ // to vservers administrator, but are place for
+ // completeness
+ {"CAP_CHOWN",CAP_CHOWN},
+ {"CAP_DAC_OVERRIDE",CAP_DAC_OVERRIDE},
+ {"CAP_DAC_READ_SEARCH",CAP_DAC_READ_SEARCH},
+ {"CAP_FOWNER",CAP_FOWNER},
+ {"CAP_FSETID",CAP_FSETID},
+ {"CAP_KILL",CAP_KILL},
+ {"CAP_SETGID",CAP_SETGID},
+ {"CAP_SETUID",CAP_SETUID},
+ {"CAP_SETPCAP",CAP_SETPCAP},
+ {"CAP_SYS_TTY_CONFIG",CAP_SYS_TTY_CONFIG},
+ {"CAP_LEASE",CAP_LEASE},
+ {"CAP_SYS_CHROOT",CAP_SYS_CHROOT},
+
+ // Those capabilities are not normally available
+ // to vservers because they are not needed and
+ // may represent a security risk
+ {"CAP_LINUX_IMMUTABLE",CAP_LINUX_IMMUTABLE},
+ {"CAP_NET_BIND_SERVICE",CAP_NET_BIND_SERVICE},
+ {"CAP_NET_BROADCAST",CAP_NET_BROADCAST},
+ {"CAP_NET_ADMIN", CAP_NET_ADMIN},
+ {"CAP_NET_RAW", CAP_NET_RAW},
+ {"CAP_IPC_LOCK", CAP_IPC_LOCK},
+ {"CAP_IPC_OWNER", CAP_IPC_OWNER},
+ {"CAP_SYS_MODULE",CAP_SYS_MODULE},
+ {"CAP_SYS_RAWIO", CAP_SYS_RAWIO},
+ {"CAP_SYS_PACCT", CAP_SYS_PACCT},
+ {"CAP_SYS_ADMIN", CAP_SYS_ADMIN},
+ {"CAP_SYS_BOOT", CAP_SYS_BOOT},
+ {"CAP_SYS_NICE", CAP_SYS_NICE},
+ {"CAP_SYS_RESOURCE",CAP_SYS_RESOURCE},
+ {"CAP_SYS_TIME", CAP_SYS_TIME},
+ {"CAP_MKNOD", CAP_MKNOD},
+#ifdef CAP_QUOTACTL
+ {"CAP_QUOTACTL", CAP_QUOTACTL},
+#endif
+ {NULL,0}
+};
+
+#define VSERVERCONF "/etc/vservers/"
+static unsigned get_remove_cap(char *name) {
+ FILE *fb;
+ unsigned remove_cap;
+
+ char *vserverconf;
+ int vserverconflen;
+
+ remove_cap = /* NOTE: keep in sync with chcontext.c */
+ (1<<CAP_LINUX_IMMUTABLE)|
+ (1<<CAP_NET_BROADCAST)|
+ (1<<CAP_NET_ADMIN)|
+ (1<<CAP_NET_RAW)|
+ (1<<CAP_IPC_LOCK)|
+ (1<<CAP_IPC_OWNER)|
+ (1<<CAP_SYS_MODULE)|
+ (1<<CAP_SYS_RAWIO)|
+ (1<<CAP_SYS_PACCT)|
+ (1<<CAP_SYS_ADMIN)|
+ (1<<CAP_SYS_BOOT)|
+ (1<<CAP_SYS_NICE)|
+ (1<<CAP_SYS_RESOURCE)|
+ (1<<CAP_SYS_TIME)|
+ (1<<CAP_MKNOD)|
+#ifdef CAP_QUOTACTL
+ (1<<CAP_QUOTACTL)|
+#endif
+#ifdef CAP_CONTEXT
+ (1<<CAP_CONTEXT)|
+#endif
+ 0
+ ;
+
+ /*
+ * find out which capabilities to put back in by reading the conf file
+ */
+
+ /* construct the pathname to the conf file */
+ vserverconflen = strlen(VSERVERCONF) + strlen(name) + strlen(".conf") + NULLBYTE_SIZE;
+ vserverconf = (char *)malloc(vserverconflen);
+ sprintf(vserverconf, "%s%s.conf", VSERVERCONF, name);
+
+ /* open the conf file for reading */
+ fb = fopen(vserverconf,"r");
+ if (fb != NULL) {
+ unsigned cap;
+ size_t index;
+ size_t len;
+ char buffer[1000], *p;
+
+ /* the conf file file exist */
+ while((p=fgets(buffer,sizeof(buffer)-1,fb))!=NULL) {
+
+ /* walk past leading spaces */
+ index = 0;
+ len = strnlen(buffer,sizeof(buffer)-1);
+ while(isspace((int)buffer[index])) {
+ if (index < len) {
+ index++;
+ } else {
+ goto out;
+ }
+ }
+
+ if (buffer[index] == '#') continue;
+
+ /* check if it is the S_CAPS */
+ if ((p=strstr(&buffer[index],"S_CAPS"))!=NULL) {
+ int j;
+ cap = 0;
+
+ /* what follows is a bunch of error
+ checking to parse the S_CAPS="..."
+ string */
+
+ /* adjust index into buffer */
+ index+= (p-&buffer[index])+strlen("S_CAPS");
+
+ /* skip over whitespace */
+ while(isspace((int)buffer[index])) {
+ if (index < len) {
+ index++;
+ } else {
+ /* parse error */
+ goto out;
+ }
+ }
+
+ /* expecting to see = sign */
+ if (buffer[index++]!='=') {
+ /* parse error */
+ goto out;
+ }
+
+ /* skip over whitespace */
+ while(isspace((int)buffer[index])) {
+ if (index < len) {
+ index++;
+ } else {
+ /* parse error */
+ goto out;
+ }
+ }
+
+ /* expecting to see the opening " */
+ if (buffer[index]!='"') {
+ /* parse error */
+ goto out;
+ }
+
+ /* check to see that we are still within bounds */
+ if (index < len) {
+ index++;
+ } else {
+ /* parse error */
+ goto out;
+ }
+
+ /* search for the closing " */
+ if((p=strstr(&buffer[index],"\""))==NULL) {
+ /* parse error */
+ goto out;
+ }
+
+ /* ok... we should now have a bunch of
+ CAP keys words within the quotes */
+
+ for (j=0; tbcap[j].option != NULL; j++){
+ if ((p=strstr(buffer,tbcap[j].option))!=NULL){
+ len = strlen(tbcap[j].option);
+ if (((isspace(*(p-1))) || (*(p-1)=='"')) &&
+ ((isspace(*(p+len))) || (*(p+len)=='"'))) {
+ cap |= (1<<tbcap[j].bit);
+ } else {
+ /* parse error */
+ goto out;
+ }
+ }
+ }
+ remove_cap &= ~cap;
+ break;
+ }
+ }
+ out:
+ /* close the conf file */
+ fclose(fb);
+ }
+ return remove_cap;
+}
+
+static int sandbox_processes(uid_t uid, unsigned remove_cap)
+{
+ int context;
+ int flags;
+
+ /* Unique context */
+ context = uid;
+
+ flags = 0;
+ flags |= 1; /* VX_INFO_LOCK -- cannot request a new vx_id */
+ /* flags |= 4; VX_INFO_NPROC -- limit number of procs in a context */
+
+ if (vc_new_s_context(context,remove_cap,flags) < 0) {
+ perror("vserver: new_s_context error ");
+ exit(1);
+ }
+ return 0;
+}
+
+
+void runas_slice_user(char *username)
+{
+ struct passwd *pwd;
+ char *home_env, *logname_env, *mail_env, *shell_env, *user_env;
+ int home_len, logname_len, mail_len, shell_len, user_len;
+ static char *envp[10];
+
+ if ((pwd = getpwnam(username)) == NULL) {
+ perror("vserver: getpwnam error ");
+ exit(1);
+ }
+
+ if (setgid(pwd->pw_gid) < 0) {
+ perror("vserver: setgid error ");
+ exit(1);
+ }
+
+ if (setuid(pwd->pw_uid) < 0) {
+ perror("vserver: setuid error ");
+ exit(1);
+ }
+
+ if (chdir(pwd->pw_dir) < 0) {
+ perror("vserver: chdir error ");
+ exit(1);
+ }
+
+ home_len = strlen("HOME=") + strlen(pwd->pw_dir) + NULLBYTE_SIZE;
+ logname_len = strlen("LOGNAME=") + strlen(username) + NULLBYTE_SIZE;
+ mail_len = strlen("MAIL=/var/spool/mail/") + strlen(username)
+ + NULLBYTE_SIZE;
+ shell_len = strlen("SHELL=") + strlen(pwd->pw_shell) + NULLBYTE_SIZE;
+ user_len = strlen("USER=") + strlen(username) + NULLBYTE_SIZE;
+
+ home_env = (char *)malloc(home_len);
+ logname_env = (char *)malloc(logname_len);
+ mail_env = (char *)malloc(mail_len);
+ shell_env = (char *)malloc(shell_len);
+ user_env = (char *)malloc(user_len);
+
+ if ((home_env == NULL) ||
+ (logname_env == NULL) ||
+ (mail_env == NULL) ||
+ (shell_env == NULL) ||
+ (user_env == NULL)) {
+ perror("vserver: malloc error ");
+ exit(1);
+ }
+
+ sprintf(home_env, "HOME=%s", pwd->pw_dir);
+ sprintf(logname_env, "LOGNAME=%s", username);
+ sprintf(mail_env, "MAIL=/var/spool/mail/%s", username);
+ sprintf(shell_env, "SHELL=%s", pwd->pw_shell);
+ sprintf(user_env, "USER=%s", username);
+
+ home_env[home_len - 1] = '\0';
+ logname_env[logname_len - 1] = '\0';
+ mail_env[mail_len - 1] = '\0';
+ shell_env[shell_len - 1] = '\0';
+ user_env[user_len - 1] = '\0';
+
+ envp[0] = home_env;
+ envp[1] = logname_env;
+ envp[2] = mail_env;
+ envp[3] = shell_env;
+ envp[4] = user_env;
+ envp[5] = 0;
+
+ if ((putenv(home_env) < 0) ||
+ (putenv(logname_env) < 0) ||
+ (putenv(mail_env) < 0) ||
+ (putenv(shell_env) < 0) ||
+ (putenv(user_env) < 0)) {
+ perror("vserver: putenv error ");
+ exit(1);
+ }
+}
+
+
+
+void slice_enter(char *context)
+{
+ struct passwd *pwd;
+ unsigned remove_cap;
+ uid_t uid;
+
+ if ((pwd = getpwnam(context)) == NULL) {
+ fprintf(stderr,"vserver: getpwname(%s) failed",context);
+ exit(2);
+ }
+
+ context = (char*)malloc(strlen(pwd->pw_name)+NULLBYTE_SIZE);
+ if (!context) {
+ perror("vserver: malloc failed");
+ exit(2);
+ }
+ strcpy(context,pwd->pw_name);
+
+ if (setuidgid_root() < 0) { /* For chroot, new_s_context */
+ fprintf(stderr,"vserver: Could not setuid/setguid to root:root\n");
+ exit(2);
+ }
+
+ remove_cap = get_remove_cap(context);
+
+ uid = pwd->pw_uid;
+ if (sandbox_chroot(uid) < 0) {
+ fprintf(stderr, "vserver: Could not chroot to vserver root\n");
+ exit(2);
+ }
+
+ if (sandbox_processes(uid, remove_cap) < 0) {
+ fprintf(stderr, "vserver: Could not sandbox processes in vserver\n");
+ exit(2);
+ }
+}
+
+//--------------------------------------------------------------------
#define DEFAULT_SHELL "/bin/sh"