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7ed1df2e8061e296366ce77a7363ab09c4e73566
shadow/lib/tcbfuncs.c
Alejandro Colomar bddcd9b095 Remove superfluous casts 
-  Every non-const pointer converts automatically to void *.
-  Every pointer converts automatically to void *.
-  void * converts to any other pointer.
-  const void * converts to any other const pointer.
-  Integer variables convert to each other.

I changed the declaration of a few variables in order to allow removing
a cast.

However, I didn't attempt to edit casts inside comparisons, since they
are very delicate.  I also kept casts in variadic functions, since they
are necessary, and in allocation functions, because I have other plans
for them.

I also changed a few casts to int that are better as ptrdiff_t.

This change has triggered some warnings about const correctness issues,
which have also been fixed in this patch (see for example src/login.c).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-09 10:03:03 -06:00

605 lines
15 KiB
C
Raw Blame History

/*
* SPDX-FileCopyrightText: 2001 Rafal Wojtczuk, Solar Designer
* SPDX-License-Identifier: 0BSD
*/
#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"
#include "shadowlog_internal.h"
#define SHADOWTCB_HASH_BY 1000
#define SHADOWTCB_LOCK_SUFFIX ".lock"
static /*@null@*//*@only@*/char *stored_tcb_user = NULL;
shadowtcb_status shadowtcb_drop_priv (void)
{
if (!getdef_bool ("USE_TCB")) {
return SHADOWTCB_SUCCESS;
}
if (NULL != stored_tcb_user) {
if (tcb_drop_priv (stored_tcb_user) == 0) {
return SHADOWTCB_SUCCESS;
}
}
return SHADOWTCB_FAILURE;
}
shadowtcb_status shadowtcb_gain_priv (void)
{
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 (shadow_logfd, _("%s: out of memory\n"), shadow_progname); \
(void) fflush (shadow_logfd); \
} 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 (shadow_logfd,
_("%s: Cannot stat %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: %s is neither a directory, nor a symlink.\n"),
shadow_progname, path);
free (path);
return NULL;
}
ret = readlink (path, link, sizeof (link) - 1);
if (-1 == ret) {
fprintf (shadow_logfd,
_("%s: Cannot read symbolic link %s: %s\n"),
shadow_progname, path, strerror (errno));
free (path);
return NULL;
}
free (path);
if ((size_t)ret >= sizeof(link) - 1) {
link[sizeof(link) - 1] = '\0';
fprintf (shadow_logfd,
_("%s: Suspiciously long symlink: %s\n"),
shadow_progname, link);
return NULL;
}
link[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 (shadow_logfd,
_("%s: Cannot stat %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot create directory %s: %s\n"),
shadow_progname, dir, strerror (errno));
goto out_free_dir;
}
if (chown (dir, 0, st.st_gid) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change owner of %s: %s\n"),
shadow_progname, dir, strerror (errno));
goto out_free_dir;
}
if (chmod (dir, 0711) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: unlink: %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot remove directory %s: %s\n"),
shadow_progname, 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 (NULL == stored_tcb_user) {
return SHADOWTCB_FAILURE;
}
if (asprintf (&olddir, TCB_DIR "/%s", stored_tcb_user) == -1) {
goto out_free_nomem;
}
if (stat (olddir, &oldmode) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot stat %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot rename %s to %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot remove %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot create symbolic link %s: %s\n"),
shadow_progname, 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;
}
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 == stored_tcb_user) {
return SHADOWTCB_FAILURE;
}
if (NULL == user_newname) {
user_newname = stored_tcb_user;
}
if (move_dir (user_newname, user_newid) == SHADOWTCB_FAILURE) {
return SHADOWTCB_FAILURE;
}
if (-1 == user_newid) {
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 (shadow_logfd,
_("%s: Cannot stat %s: %s\n"),
shadow_progname, tcbdir, strerror (errno));
goto out_free;
}
if (chown (tcbdir, 0, 0) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change owners of %s: %s\n"),
shadow_progname, tcbdir, strerror (errno));
goto out_free;
}
if (chmod (tcbdir, 0700) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, tcbdir, strerror (errno));
goto out_free;
}
if (lstat (shadow, &filemode) != 0) {
if (errno != ENOENT) {
fprintf (shadow_logfd,
_("%s: Cannot lstat %s: %s\n"),
shadow_progname, shadow, strerror (errno));
goto out_free;
}
fprintf (shadow_logfd,
_("%s: Warning, user %s has no tcb shadow file.\n"),
shadow_progname, user_newname);
} else {
if (!S_ISREG (filemode.st_mode) ||
filemode.st_nlink != 1) {
fprintf (shadow_logfd,
_("%s: Emergency: %s's tcb shadow is not a "
"regular file with st_nlink=1.\n"
"The account is left locked.\n"),
shadow_progname, user_newname);
goto out_free;
}
if (chown (shadow, user_newid, filemode.st_gid) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change owner of %s: %s\n"),
shadow_progname, shadow, strerror (errno));
goto out_free;
}
if (chmod (shadow, filemode.st_mode & 07777) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot change owner of %s: %s\n"),
shadow_progname, tcbdir, strerror (errno));
goto out_free;
}
if (chmod (tcbdir, dirmode.st_mode & 07777) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: Cannot stat %s: %s\n"),
shadow_progname, 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 (shadow_logfd,
_("%s: mkdir: %s: %s\n"),
shadow_progname, dir, strerror (errno));
goto out_free;
}
fd = open (shadow, O_RDWR | O_CREAT | O_TRUNC, 0600);
if (fd < 0) {
fprintf (shadow_logfd,
_("%s: Cannot open %s: %s\n"),
shadow_progname, shadow, strerror (errno));
goto out_free;
}
close (fd);
if (chown (shadow, 0, authgid) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change owner of %s: %s\n"),
shadow_progname, shadow, strerror (errno));
goto out_free;
}
if (chmod (shadow, (mode_t) ((authgid == shadowgid) ? 0600 : 0640)) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, shadow, strerror (errno));
goto out_free;
}
if (chown (dir, 0, authgid) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change owner of %s: %s\n"),
shadow_progname, dir, strerror (errno));
goto out_free;
}
if (chmod (dir, (mode_t) ((authgid == shadowgid) ? 02700 : 02710)) != 0) {
fprintf (shadow_logfd,
_("%s: Cannot change mode of %s: %s\n"),
shadow_progname, 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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