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appletlib.c: make it actally follow _BB_SUID_ALWAYS rules

Browse Source 
adduser: implement -S and code shrink / fix uid selection
*: sanitize getspnam_r use

   text    data     bss     dec     hex filename
 777042     974    9676  787692   c04ec busybox_old
 776883     974    9676  787533   c044d busybox_unstripped
This commit is contained in:
Denis Vlasenko 2007-10-29 19:25:45 +00:00
parent 5a28a25b9d
commit 15ca51e3e2
7 changed files with 121 additions and 153 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/usage.h
View File

@ -27,7 +27,7 @@
" -g GECOS GECOS field\n" \
" -s SHELL Login shell\n" \
" -G GROUP Add user to existing group\n" \
" -S Create a system user (ignored)\n" \
" -S Create a system user\n" \
" -D Do not assign a password\n" \
" -H Do not create home directory"

9
libbb/appletlib.c
View File

@ -459,10 +459,7 @@ static void check_suid(const struct bb_applet *applet)
if (sct->m_applet == applet)
goto found;
}
/* default: drop all privileges */
xsetgid(rgid);
xsetuid(ruid);
return;
goto check_need_suid;
found:
m = sct->m_mode;
if (sct->m_uid == ruid)
@ -505,13 +502,13 @@ static void check_suid(const struct bb_applet *applet)
}
}
#endif
check_need_suid:
#endif
if (applet->need_suid == _BB_SUID_ALWAYS) {
/* Real uid is not 0. If euid isn't 0 too, suid bit
* is most probably not set on our executable */
if (geteuid())
bb_error_msg_and_die("applet requires root privileges!");
bb_error_msg_and_die("must be suid to work properly");
} else if (applet->need_suid == _BB_SUID_NEVER) {
xsetgid(rgid); /* drop all privileges */
xsetuid(ruid);

15
libbb/correct_password.c
View File

@ -40,6 +40,11 @@ int correct_password(const struct passwd *pw)
{
char *unencrypted, *encrypted;
const char *correct;
#if ENABLE_FEATURE_SHADOWPASSWDS
/* Using _r function to avoid pulling in static buffers */
struct spwd spw;
char buffer[256];
#endif
/* fake salt. crypt() can choke otherwise. */
correct = "aa";
@ -50,11 +55,11 @@ int correct_password(const struct passwd *pw)
correct = pw->pw_passwd;
#if ENABLE_FEATURE_SHADOWPASSWDS
if ((correct[0] == 'x' || correct[0] == '*') && !correct[1]) {
/* Using _r function to avoid pulling in static buffers */
struct spwd spw;
struct spwd *result;
char buffer[256];
correct = (getspnam_r(pw->pw_name, &spw, buffer, sizeof(buffer), &result)) ? "aa" : spw.sp_pwdp;
/* getspnam_r may return 0 yet set result to NULL.
* At least glibc 2.4 does this. Be extra paranoid here. */
struct spwd *result = NULL;
int r = getspnam_r(pw->pw_name, &spw, buffer, sizeof(buffer), &result);
correct = (r || !result) ? "aa" : result->sp_pwdp;
}
#endif

2
loginutils/addgroup.c
View File

@ -56,7 +56,7 @@ static void new_group(char *group, gid_t gid)
/* add entry to group */
file = xfopen(bb_path_group_file, "a");
/* group:passwd:gid:userlist */
fprintf(file, "%s:x:%d:\n", group, gr.gr_gid);
fprintf(file, "%s:x:%u:\n", group, (unsigned)gr.gr_gid);
if (ENABLE_FEATURE_CLEAN_UP)
fclose(file);
#if ENABLE_FEATURE_SHADOWPASSWDS

202
loginutils/adduser.c
View File

@ -11,68 +11,47 @@
#include "libbb.h"
#define OPT_DONT_SET_PASS (1 << 4)
#define OPT_SYSTEM_ACCOUNT (1 << 5)
#define OPT_DONT_MAKE_HOME (1 << 6)
/* remix */
/* EDR recoded such that the uid may be passed in *p */
static int passwd_study(const char *filename, struct passwd *p)
/* recoded such that the uid may be passed in *p */
static void passwd_study(struct passwd *p)
{
enum { min = 500, max = 65000 };
FILE *passwd;
/* We are using reentrant fgetpwent_r() in order to avoid
* pulling in static buffers from libc (think static build here) */
char buffer[256];
struct passwd pw;
struct passwd *result;
int max;
passwd = xfopen(filename, "r");
if (getpwnam(p->pw_name))
bb_error_msg_and_die("login '%s' is in use", p->pw_name);
/* EDR if uid is out of bounds, set to min */
if ((p->pw_uid > max) || (p->pw_uid < min))
p->pw_uid = min;
/* stuff to do:
* make sure login isn't taken;
* find free uid and gid;
*/
while (!fgetpwent_r(passwd, &pw, buffer, sizeof(buffer), &result)) {
if (strcmp(pw.pw_name, p->pw_name) == 0) {
/* return 0; */
return 1;
}
if ((pw.pw_uid >= p->pw_uid) && (pw.pw_uid < max)
&& (pw.pw_uid >= min)) {
p->pw_uid = pw.pw_uid + 1;
}
if (option_mask32 & OPT_SYSTEM_ACCOUNT) {
p->pw_uid = 0;
max = 999;
} else {
p->pw_uid = 1000;
max = 64999;
}
if (p->pw_gid == 0) {
/* EDR check for an already existing gid */
while (getgrgid(p->pw_uid) != NULL)
/* check for a free uid (and maybe gid) */
while (getpwuid(p->pw_uid) || (!p->pw_gid && getgrgid(p->pw_uid)))
p->pw_uid++;
/* EDR also check for an existing group definition */
if (getgrnam(p->pw_name) != NULL)
return 3;
/* EDR create new gid always = uid */
if (!p->pw_gid) {
/* new gid = uid */
p->pw_gid = p->pw_uid;
if (getgrnam(p->pw_name))
bb_error_msg_and_die("group name '%s' is in use", p->pw_name);
}
/* EDR bounds check */
if ((p->pw_uid > max) || (p->pw_uid < min))
return 2;
/* return 1; */
return 0;
if (p->pw_uid > max)
bb_error_msg_and_die("no free uids left");
}
static void addgroup_wrapper(struct passwd *p)
{
char *cmd;
cmd = xasprintf("addgroup -g %d \"%s\"", p->pw_gid, p->pw_name);
cmd = xasprintf("addgroup -g %u '%s'", (unsigned)p->pw_gid, p->pw_name);
system(cmd);
free(cmd);
}
@ -84,85 +63,12 @@ static void passwd_wrapper(const char *login)
static const char prog[] ALIGN1 = "passwd";
BB_EXECLP(prog, prog, login, NULL);
bb_error_msg_and_die("failed to execute '%s', you must set the password for '%s' manually", prog, login);
}
/* putpwent(3) remix */
static int adduser(struct passwd *p)
{
FILE *file;
int addgroup = !p->pw_gid;
/* make sure everything is kosher and setup uid && gid */
file = xfopen(bb_path_passwd_file, "a");
fseek(file, 0, SEEK_END);
switch (passwd_study(bb_path_passwd_file, p)) {
case 1:
bb_error_msg_and_die("%s: login already in use", p->pw_name);
case 2:
bb_error_msg_and_die("illegal uid or no uids left");
case 3:
bb_error_msg_and_die("%s: group name already in use", p->pw_name);
}
/* add to passwd */
if (putpwent(p, file) == -1) {
bb_perror_nomsg_and_die();
}
/* Do fclose even if !ENABLE_FEATURE_CLEAN_UP.
* We will exec passwd, files must be flushed & closed before that! */
fclose(file);
#if ENABLE_FEATURE_SHADOWPASSWDS
/* add to shadow if necessary */
file = fopen_or_warn(bb_path_shadow_file, "a");
if (file) {
fseek(file, 0, SEEK_END);
fprintf(file, "%s:!:%ld:%d:%d:%d:::\n",
p->pw_name, /* username */
time(NULL) / 86400, /* sp->sp_lstchg */
0, /* sp->sp_min */
99999, /* sp->sp_max */
7); /* sp->sp_warn */
fclose(file);
}
#endif
/* add to group */
/* addgroup should be responsible for dealing w/ gshadow */
/* if using a pre-existing group, don't create one */
if (addgroup) addgroup_wrapper(p);
/* Clear the umask for this process so it doesn't
* screw up the permissions on the mkdir and chown. */
umask(0);
if (!(option_mask32 & OPT_DONT_MAKE_HOME)) {
/* Set the owner and group so it is owned by the new user,
then fix up the permissions to 2755. Can't do it before
since chown will clear the setgid bit */
if (mkdir(p->pw_dir, 0755)
|| chown(p->pw_dir, p->pw_uid, p->pw_gid)
|| chmod(p->pw_dir, 02755)) {
bb_simple_perror_msg(p->pw_dir);
}
}
if (!(option_mask32 & OPT_DONT_SET_PASS)) {
/* interactively set passwd */
passwd_wrapper(p->pw_name);
}
return 0;
bb_error_msg_and_die("cannot execute %s, you must set password manually", prog);
}
/*
* adduser will take a login_name as its first parameter.
*
* home
* shell
* gecos
*
* home, shell, gecos:
* can be customized via command-line parameters.
*/
int adduser_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
@ -170,6 +76,7 @@ int adduser_main(int argc, char **argv)
{
struct passwd pw;
const char *usegroup = NULL;
FILE *file;
/* got root? */
if (geteuid()) {
@ -185,16 +92,69 @@ int adduser_main(int argc, char **argv)
getopt32(argv, "h:g:s:G:DSH", &pw.pw_dir, &pw.pw_gecos, &pw.pw_shell, &usegroup);
argv += optind;
/* create a passwd struct */
/* fill in the passwd struct */
pw.pw_name = argv[0];
if (!pw.pw_dir) {
/* create string for $HOME if not specified already */
pw.pw_dir = xasprintf("/home/%s", argv[0]);
}
pw.pw_passwd = (char *)"x";
pw.pw_uid = 0;
pw.pw_gid = usegroup ? xgroup2gid(usegroup) : 0; /* exits on failure */
/* grand finale */
return adduser(&pw);
/* make sure everything is kosher and setup uid && maybe gid */
passwd_study(&pw);
/* add to passwd */
file = xfopen(bb_path_passwd_file, "a");
//fseek(file, 0, SEEK_END); /* paranoia, "a" should ensure that anyway */
if (putpwent(&pw, file) != 0) {
bb_perror_nomsg_and_die();
}
/* do fclose even if !ENABLE_FEATURE_CLEAN_UP.
* We will exec passwd, files must be flushed & closed before that! */
fclose(file);
#if ENABLE_FEATURE_SHADOWPASSWDS
/* add to shadow if necessary */
file = fopen_or_warn(bb_path_shadow_file, "a");
if (file) {
//fseek(file, 0, SEEK_END);
fprintf(file, "%s:!:%u:0:99999:7:::\n",
pw.pw_name, /* username */
(unsigned)(time(NULL) / 86400) /* sp->sp_lstchg */
/*0,*/ /* sp->sp_min */
/*99999,*/ /* sp->sp_max */
/*7*/ /* sp->sp_warn */
);
fclose(file);
}
#endif
/* add to group */
/* addgroup should be responsible for dealing w/ gshadow */
/* if using a pre-existing group, don't create one */
if (!usegroup)
addgroup_wrapper(&pw);
/* Clear the umask for this process so it doesn't
* screw up the permissions on the mkdir and chown. */
umask(0);
if (!(option_mask32 & OPT_DONT_MAKE_HOME)) {
/* Set the owner and group so it is owned by the new user,
then fix up the permissions to 2755. Can't do it before
since chown will clear the setgid bit */
if (mkdir(pw.pw_dir, 0755)
|| chown(pw.pw_dir, pw.pw_uid, pw.pw_gid)
|| chmod(pw.pw_dir, 02755) /* set setgid bit on homedir */
) {
bb_simple_perror_msg(pw.pw_dir);
}
}
if (!(option_mask32 & OPT_DONT_SET_PASS)) {
/* interactively set passwd */
passwd_wrapper(pw.pw_name);
}
return 0;
}

15
loginutils/passwd.c
View File

@ -93,11 +93,9 @@ int passwd_main(int argc, char **argv)
uid_t myuid;
struct rlimit rlimit_fsize;
char c;
#if ENABLE_FEATURE_SHADOWPASSWDS
/* Using _r function to avoid pulling in static buffers */
struct spwd spw;
struct spwd *result;
char buffer[256];
#endif
@ -128,16 +126,19 @@ int passwd_main(int argc, char **argv)
}
#if ENABLE_FEATURE_SHADOWPASSWDS
/* getspnam_r() can lie! Even if user isn't in shadow, it can
* return success (pwd field was seen set to "!" in this case) */
{
/* getspnam_r may return 0 yet set result to NULL.
* At least glibc 2.4 does this. Be extra paranoid here. */
struct spwd *result = NULL;
if (getspnam_r(pw->pw_name, &spw, buffer, sizeof(buffer), &result)
|| LONE_CHAR(spw.sp_pwdp, '!')) {
|| !result || strcmp(result->sp_namp, pw->pw_name) != 0) {
/* LOGMODE_BOTH */
bb_error_msg("no record of %s in %s, using %s",
name, bb_path_shadow_file,
bb_path_passwd_file);
} else {
pw->pw_passwd = spw.sp_pwdp;
pw->pw_passwd = result->sp_pwdp;
}
}
#endif
@ -161,7 +162,7 @@ int passwd_main(int argc, char **argv)
newp = xasprintf("!%s", pw->pw_passwd);
} else if (opt & OPT_unlock) {
if (c) goto skip; /* not '!' */
/* pw->pw_passwd pints to static storage,
/* pw->pw_passwd points to static storage,
* strdup'ing to avoid nasty surprizes */
newp = xstrdup(&pw->pw_passwd[1]);
} else if (opt & OPT_delete) {

11
loginutils/sulogin.c
View File

@ -44,7 +44,6 @@ int sulogin_main(int argc, char **argv)
/* Using _r function to avoid pulling in static buffers */
char buffer[256];
struct spwd spw;
struct spwd *result;
#endif
logmode = LOGMODE_BOTH;
@ -83,10 +82,16 @@ int sulogin_main(int argc, char **argv)
}
#if ENABLE_FEATURE_SHADOWPASSWDS
if (getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result)) {
{
/* getspnam_r may return 0 yet set result to NULL.
* At least glibc 2.4 does this. Be extra paranoid here. */
struct spwd *result = NULL;
int r = getspnam_r(pwd->pw_name, &spw, buffer, sizeof(buffer), &result);
if (r || !result) {
goto auth_error;
}
pwd->pw_passwd = spw.sp_pwdp;
pwd->pw_passwd = result->sp_pwdp;
}
#endif
while (1) {