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shadow/lib/tcbfuncs.c

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14 KiB
C
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/*
* Copyright (c) 2001 Rafal Wojtczuk, Solar Designer
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <tcb.h>
#include <unistd.h>
#include "config.h"
#include "defines.h"
#include "prototypes.h"
#include "getdef.h"
#include "shadowio.h"
#include "tcbfuncs.h"
#define SHADOWTCB_HASH_BY 1000
#define SHADOWTCB_LOCK_SUFFIX ".lock"
static /*@null@*//*@only@*/char *stored_tcb_user = NULL;
shadowtcb_status shadowtcb_drop_priv()
{
if (!getdef_bool("USE_TCB"))
return SHADOWTCB_SUCCESS;
if (stored_tcb_user)
return (tcb_drop_priv(stored_tcb_user) == 0) ? SHADOWTCB_SUCCESS : SHADOWTCB_FAILURE;
return SHADOWTCB_FAILURE;
}
shadowtcb_status shadowtcb_gain_priv()
{
if (!getdef_bool("USE_TCB"))
return SHADOWTCB_SUCCESS;
return (tcb_gain_priv() == 0) ? SHADOWTCB_SUCCESS : SHADOWTCB_FAILURE;
}
/* In case something goes wrong, we return immediately, not polluting the
* code with free(). All errors are fatal, so the application is expected
* to exit soon.
*/
#define OUT_OF_MEMORY do { \
fprintf(stderr, _("%s: out of memory\n"), Prog); \
(void) fflush(stderr); \
} while(false)
/* Returns user's tcb directory path relative to TCB_DIR. */
static /*@null@*/ char *shadowtcb_path_rel(const char *name, uid_t uid)
{
char *ret;
if (!getdef_bool("TCB_SYMLINKS") || uid < SHADOWTCB_HASH_BY) {
if (asprintf(&ret, "%s", name) == -1) {
OUT_OF_MEMORY;
return NULL;
}
} else if (uid < SHADOWTCB_HASH_BY * SHADOWTCB_HASH_BY) {
if (asprintf(&ret, ":%dK/%s", uid / SHADOWTCB_HASH_BY, name) == -1) {
OUT_OF_MEMORY;
return NULL;
}
} else {
if (asprintf(&ret, ":%dM/:%dK/%s",
uid / (SHADOWTCB_HASH_BY * SHADOWTCB_HASH_BY),
(uid % (SHADOWTCB_HASH_BY * SHADOWTCB_HASH_BY)) / SHADOWTCB_HASH_BY,
name) == -1) {
OUT_OF_MEMORY;
return NULL;
}
}
return ret;
}
static /*@null@*/ char *shadowtcb_path_rel_existing(const char *name)
{
char *path, *rval;
struct stat st;
char link[8192];
ssize_t ret;
if (asprintf(&path, TCB_DIR "/%s", name) == -1) {
OUT_OF_MEMORY;
return NULL;
}
if (lstat(path, &st) != 0) {
fprintf(stderr, _("%s: Cannot stat %s: %s\n"), Prog, path, strerror(errno));
free(path);
return NULL;
}
if (S_ISDIR(st.st_mode)) {
free(path);
rval = strdup(name);
if (NULL == rval) {
OUT_OF_MEMORY;
return NULL;
}
return rval;
}
if (!S_ISLNK(st.st_mode)) {
fprintf(stderr, _("%s: %s is neither a directory, nor a symlink.\n"), Prog, path);
free(path);
return NULL;
}
ret = readlink(path, link, sizeof(link) - 1);
if (ret == -1) {
fprintf(stderr, _("%s: Cannot read symbolic link %s: %s\n"), Prog, path, strerror(errno));
free(path);
return NULL;
}
free(path);
if ((size_t)ret >= sizeof(link) - 1) {
link[sizeof(link) - 1] = '\0';
fprintf(stderr, _("%s: Suspiciously long symlink: %s\n"), Prog, link);
return NULL;
}
link[(size_t)ret] = '\0';
rval = strdup(link);
if (NULL == rval) {
OUT_OF_MEMORY;
return NULL;
}
return rval;
}
static /*@null@*/ char *shadowtcb_path(const char *name, uid_t uid)
{
char *ret, *rel;
rel = shadowtcb_path_rel(name, uid);
if (NULL == rel)
return NULL;
if (asprintf(&ret, TCB_DIR "/%s", rel) == -1) {
OUT_OF_MEMORY;
free(rel);
return NULL;
}
free(rel);
return ret;
}
static /*@null@*/ char *shadowtcb_path_existing(const char *name)
{
char *ret, *rel;
rel = shadowtcb_path_rel_existing(name);
if (NULL == rel)
return NULL;
if (asprintf(&ret, TCB_DIR "/%s", rel) == -1) {
OUT_OF_MEMORY;
free(rel);
return NULL;
}
free(rel);
return ret;
}
static shadowtcb_status mkdir_leading(const char *name, uid_t uid)
{
char *ind, *dir, *ptr, *path = shadowtcb_path_rel(name, uid);
struct stat st;
if (NULL == path)
return SHADOWTCB_FAILURE;
ptr = path;
if (stat(TCB_DIR, &st) != 0) {
fprintf(stderr, _("%s: Cannot stat %s: %s\n"), Prog, TCB_DIR, strerror(errno));
goto out_free_path;
}
while ((ind = strchr(ptr, '/'))) {
*ind = '\0';
if (asprintf(&dir, TCB_DIR "/%s", path) == -1) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (mkdir(dir, 0700) != 0 && errno != EEXIST) {
fprintf(stderr, _("%s: Cannot create directory %s: %s\n"), Prog, dir, strerror(errno));
goto out_free_dir;
}
if (chown(dir, 0, st.st_gid) != 0) {
fprintf(stderr, _("%s: Cannot change owner of %s: %s\n"), Prog, dir, strerror(errno));
goto out_free_dir;
}
if (chmod(dir, 0711) != 0) {
fprintf(stderr, _("%s: Cannot change mode of %s: %s\n"), Prog, dir, strerror(errno));
goto out_free_dir;
}
free(dir);
*ind = '/';
ptr = ind + 1;
}
free(path);
return SHADOWTCB_SUCCESS;
out_free_dir:
free(dir);
out_free_path:
free(path);
return SHADOWTCB_FAILURE;
}
static shadowtcb_status unlink_suffs(const char *user)
{
static char *suffs[] = { "+", "-", SHADOWTCB_LOCK_SUFFIX };
char *tmp;
int i;
for (i = 0; i < 3; i++) {
if (asprintf(&tmp, TCB_FMT "%s", user, suffs[i]) == -1) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (unlink(tmp) != 0 && errno != ENOENT) {
fprintf(stderr, _("%s: unlink: %s: %s\n"), Prog, tmp, strerror(errno));
free(tmp);
return SHADOWTCB_FAILURE;
}
free(tmp);
}
return SHADOWTCB_SUCCESS;
}
/* path should be a relative existing tcb directory */
static shadowtcb_status rmdir_leading(char *path)
{
char *ind, *dir;
shadowtcb_status ret = SHADOWTCB_SUCCESS;
while ((ind = strrchr(path, '/'))) {
*ind = '\0';
if (asprintf(&dir, TCB_DIR "/%s", path) == -1) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (rmdir(dir) != 0) {
if (errno != ENOTEMPTY) {
fprintf(stderr, _("%s: Cannot remove directory %s: %s\n"), Prog, dir, strerror(errno));
ret = SHADOWTCB_FAILURE;
}
free(dir);
break;
}
free(dir);
}
return ret;
}
static shadowtcb_status move_dir(const char *user_newname, uid_t user_newid)
{
char *olddir = NULL, *newdir = NULL;
char *real_old_dir = NULL, *real_new_dir = NULL;
char *real_old_dir_rel = NULL, *real_new_dir_rel = NULL;
uid_t old_uid, the_newid;
struct stat oldmode;
shadowtcb_status ret = SHADOWTCB_FAILURE;
if (asprintf(&olddir, TCB_DIR "/%s", stored_tcb_user) == -1)
goto out_free_nomem;
if (stat(olddir, &oldmode) != 0) {
fprintf(stderr, _("%s: Cannot stat %s: %s\n"), Prog, olddir, strerror(errno));
goto out_free;
}
old_uid = oldmode.st_uid;
the_newid = (user_newid == -1) ? old_uid : user_newid;
real_old_dir = shadowtcb_path_existing(stored_tcb_user);
if (NULL == real_old_dir)
goto out_free;
real_new_dir = shadowtcb_path(user_newname, the_newid);
if (NULL == real_new_dir)
goto out_free;
if (strcmp(real_old_dir, real_new_dir) == 0) {
ret = SHADOWTCB_SUCCESS;
goto out_free;
}
real_old_dir_rel = shadowtcb_path_rel_existing(stored_tcb_user);
if (NULL == real_old_dir_rel)
goto out_free;
if (mkdir_leading(user_newname, the_newid) == SHADOWTCB_FAILURE)
goto out_free;
if (rename(real_old_dir, real_new_dir) != 0) {
fprintf(stderr, _("%s: Cannot rename %s to %s: %s\n"), Prog, real_old_dir, real_new_dir, strerror(errno));
goto out_free;
}
if (rmdir_leading(real_old_dir_rel) == SHADOWTCB_FAILURE)
goto out_free;
if (unlink(olddir) != 0 && errno != ENOENT) {
fprintf(stderr, _("%s: Cannot remove %s: %s\n"), Prog, olddir, strerror(errno));
goto out_free;
}
if (asprintf(&newdir, TCB_DIR "/%s", user_newname) == -1)
goto out_free_nomem;
real_new_dir_rel = shadowtcb_path_rel(user_newname, the_newid);
if (NULL == real_new_dir_rel)
goto out_free;
if ( (strcmp(real_new_dir, newdir) != 0)
&& (symlink(real_new_dir_rel, newdir) != 0)) {
fprintf(stderr, _("%s: Cannot create symbolic link %s: %s\n"), Prog, real_new_dir_rel, strerror(errno));
goto out_free;
}
ret = SHADOWTCB_SUCCESS;
goto out_free;
out_free_nomem:
OUT_OF_MEMORY;
out_free:
free(olddir);
free(newdir);
free(real_old_dir);
free(real_new_dir);
free(real_old_dir_rel);
free(real_new_dir_rel);
return ret;
}
shadowtcb_status shadowtcb_set_user(const char* name)
{
char *buf;
shadowtcb_status retval;
if (!getdef_bool("USE_TCB"))
return SHADOWTCB_SUCCESS;
if (NULL != stored_tcb_user)
free(stored_tcb_user);
stored_tcb_user = strdup(name);
if (NULL == stored_tcb_user) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (asprintf(&buf, TCB_FMT, name) == -1) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
retval = (spw_setdbname(buf) != 0) ? SHADOWTCB_SUCCESS : SHADOWTCB_FAILURE;
free(buf);
return retval;
}
/* tcb directory must be empty before shadowtcb_remove is called. */
shadowtcb_status shadowtcb_remove(const char *name)
{
shadowtcb_status ret = SHADOWTCB_SUCCESS;
char *path = shadowtcb_path_existing(name);
char *rel = shadowtcb_path_rel_existing(name);
if (NULL == path || NULL == rel || rmdir(path) != 0)
return SHADOWTCB_FAILURE;
if (rmdir_leading(rel) == SHADOWTCB_FAILURE)
return SHADOWTCB_FAILURE;
free(path);
free(rel);
if (asprintf(&path, TCB_DIR "/%s", name) == -1) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (unlink(path) != 0 && errno != ENOENT)
ret = SHADOWTCB_FAILURE;
free(path);
return ret;
}
shadowtcb_status shadowtcb_move(/*@NULL@*/const char *user_newname, uid_t user_newid)
{
struct stat dirmode, filemode;
char *tcbdir, *shadow;
shadowtcb_status ret = SHADOWTCB_FAILURE;
if (!getdef_bool("USE_TCB"))
return SHADOWTCB_SUCCESS;
if (NULL == user_newname)
user_newname = stored_tcb_user;
if (move_dir(user_newname, user_newid) == SHADOWTCB_FAILURE)
return SHADOWTCB_FAILURE;
if (user_newid == -1)
return SHADOWTCB_SUCCESS;
if ( (asprintf(&tcbdir, TCB_DIR "/%s", user_newname) == -1)
|| (asprintf(&shadow, TCB_FMT, user_newname) == -1)) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (stat(tcbdir, &dirmode) != 0) {
fprintf(stderr, _("%s: Cannot stat %s: %s\n"), Prog, tcbdir, strerror(errno));
goto out_free;
}
if (chown(tcbdir, 0, 0) != 0) {
fprintf(stderr, _("%s: Cannot change owners of %s: %s\n"), Prog, tcbdir, strerror(errno));
goto out_free;
}
if (chmod(tcbdir, 0700) != 0) {
fprintf(stderr, _("%s: Cannot change mode of %s: %s\n"), Prog, tcbdir, strerror(errno));
goto out_free;
}
if (lstat(shadow, &filemode) != 0) {
if (errno != ENOENT) {
fprintf(stderr, _("%s: Cannot lstat %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
fprintf(stderr,
_("%s: Warning, user %s has no tcb shadow file.\n"),
Prog, user_newname);
} else {
if (!S_ISREG(filemode.st_mode) ||
filemode.st_nlink != 1) {
fprintf(stderr,
_("%s: Emergency: %s's tcb shadow is not a regular file"
" with st_nlink=1.\n"
"The account is left locked.\n"),
Prog, user_newname);
goto out_free;
}
if (chown(shadow, user_newid, filemode.st_gid) != 0) {
fprintf(stderr, _("%s: Cannot change owner of %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
if (chmod(shadow, filemode.st_mode & 07777) != 0) {
fprintf(stderr, _("%s: Cannot change mode of %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
}
if (unlink_suffs(user_newname) == SHADOWTCB_FAILURE)
goto out_free;
if (chown(tcbdir, user_newid, dirmode.st_gid) != 0) {
fprintf(stderr, _("%s: Cannot change owner of %s: %s\n"), Prog, tcbdir, strerror(errno));
goto out_free;
}
ret = SHADOWTCB_SUCCESS;
out_free:
free(tcbdir);
free(shadow);
return ret;
}
shadowtcb_status shadowtcb_create(const char *name, uid_t uid)
{
char *dir, *shadow;
struct stat tcbdir_stat;
gid_t shadowgid, authgid;
struct group *gr;
int fd;
shadowtcb_status ret = SHADOWTCB_FAILURE;
if (!getdef_bool("USE_TCB"))
return SHADOWTCB_SUCCESS;
if (stat(TCB_DIR, &tcbdir_stat) != 0) {
fprintf(stderr, _("%s: Cannot stat %s: %s\n"), Prog, TCB_DIR, strerror(errno));
return SHADOWTCB_FAILURE;
}
shadowgid = tcbdir_stat.st_gid;
authgid = shadowgid;
if (getdef_bool("TCB_AUTH_GROUP")) {
gr = getgrnam("auth");
if (NULL != gr) {
authgid = gr->gr_gid;
}
}
if ( (asprintf(&dir, TCB_DIR "/%s", name) == -1)
|| (asprintf(&shadow, TCB_FMT, name) == -1)) {
OUT_OF_MEMORY;
return SHADOWTCB_FAILURE;
}
if (mkdir(dir, 0700) != 0) {
fprintf(stderr, _("%s: mkdir: %s: %s\n"), Prog, dir, strerror(errno));
goto out_free;
return 0;
}
fd = open(shadow, O_RDWR | O_CREAT | O_TRUNC, 0600);
if (fd < 0) {
fprintf(stderr, _("%s: Cannot open %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
close(fd);
if (chown(shadow, 0, authgid) != 0) {
fprintf(stderr, _("%s: Cannot change owner of %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
if (chmod(shadow, authgid == shadowgid ? 0600 : 0640) != 0) {
fprintf(stderr, _("%s: Cannot change mode of %s: %s\n"), Prog, shadow, strerror(errno));
goto out_free;
}
if (chown(dir, 0, authgid) != 0) {
fprintf(stderr, _("%s: Cannot change owner of %s: %s\n"), Prog, dir, strerror(errno));
goto out_free;
}
if (chmod(dir, authgid == shadowgid ? 02700 : 02710) != 0) {
fprintf(stderr, _("%s: Cannot change mode of %s: %s\n"), Prog, dir, strerror(errno));
goto out_free;
}
if ( (shadowtcb_set_user(name) == SHADOWTCB_FAILURE)
|| (shadowtcb_move(NULL, uid) == SHADOWTCB_FAILURE))
goto out_free;
ret = SHADOWTCB_SUCCESS;
out_free:
free(dir);
free(shadow);
return ret;
}
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