shadow/lib/prototypes.h
Alex Colomar 155c9421b9 libmisc: agetpass(), erase_pass(): Add functions for getting passwords safely
There are several issues with getpass(3).

Many implementations of it share the same issues that the infamous
gets(3).  In glibc it's not so terrible, since it's a wrapper
around getline(3).  But it still has an important bug:

If the password is long enough, getline(3) will realloc(3) memory,
and prefixes of the password will be laying around in some
deallocated memory.

See the getpass(3) manual page for more details, and especially
the commit that marked it as deprecated, which links to a long
discussion in the linux-man@ mailing list.

So, readpassphrase(3bsd) is preferrable, which is provided by
libbsd on GNU systems.  However, using readpassphrase(3) directly
is a bit verbose, so we can write our own wrapper with a simpler
interface similar to that of getpass(3).

One of the benefits of writing our own interface around
readpassphrase(3) is that we can hide there any checks that should
be done always and which would be error-prone to repeat every
time.  For example, check that there was no truncation in the
password.

Also, use malloc(3) to get the buffer, instead of using a global
buffer.  We're not using a multithreaded program (and it wouldn't
make sense to do so), but it's nice to know that the visibility of
our passwords is as limited as possible.

erase_pass() is a clean-up function that handles all clean-up
correctly, including zeroing the entire buffer, and then
free(3)ing the memory.  By using [[gnu::malloc(erase_pass)]], we
make sure that we don't leak the buffers in any case, since the
compiler will be able to enforce clean up.

Link: <https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/commit?id=7ca189099d73bde954eed2d7fc21732bcc8ddc6b>
Reported-by: Christian Göttsche <cgzones@googlemail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
2022-12-05 10:47:19 +01:00

508 lines
15 KiB
C

/*
* SPDX-FileCopyrightText: 1990 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 2000, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2003 - 2006, Tomasz Kłoczko
* SPDX-FileCopyrightText: 2007 - 2010, Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
/*
* prototypes.h
*
* prototypes of libmisc functions, and private lib functions.
*
* $Id$
*
*/
#ifndef _PROTOTYPES_H
#define _PROTOTYPES_H
#include <config.h>
#include <sys/stat.h>
#ifdef USE_UTMPX
#include <utmpx.h>
#else
#include <utmp.h>
#endif
#include <sys/types.h>
#include <pwd.h>
#include <grp.h>
#include <shadow.h>
#include <lastlog.h>
#include "defines.h"
#include "commonio.h"
/* addgrps.c */
#if defined (HAVE_SETGROUPS) && ! defined (USE_PAM)
extern int add_groups (const char *);
#endif
/* age.c */
extern void agecheck (/*@null@*/const struct spwd *);
extern int expire (const struct passwd *, /*@null@*/const struct spwd *);
/* agetpass.c */
extern void erase_pass(char *pass);
[[gnu::malloc(erase_pass)]]
extern char *agetpass(const char *prompt);
/* isexpired.c */
extern int isexpired (const struct passwd *, /*@null@*/const struct spwd *);
/* btrfs.c */
#ifdef WITH_BTRFS
extern int btrfs_create_subvolume(const char *path);
extern int btrfs_remove_subvolume(const char *path);
extern int btrfs_is_subvolume(const char *path);
extern int is_btrfs(const char *path);
#endif
/* basename() renamed to Basename() to avoid libc name space confusion */
/* basename.c */
extern /*@observer@*/const char *Basename (const char *str);
/* chowndir.c */
extern int chown_tree (const char *root,
uid_t old_uid, uid_t new_uid,
gid_t old_gid, gid_t new_gid);
/* chowntty.c */
extern void chown_tty (const struct passwd *);
/* cleanup.c */
typedef /*@null@*/void (*cleanup_function) (/*@null@*/void *arg);
void add_cleanup (/*@notnull@*/cleanup_function pcf, /*@null@*/void *arg);
void del_cleanup (/*@notnull@*/cleanup_function pcf);
void do_cleanups (void);
/* cleanup_group.c */
struct cleanup_info_mod {
char *audit_msg;
char *action;
/*@observer@*/const char *name;
};
void cleanup_report_add_group (void *group_name);
void cleanup_report_add_group_group (void *group_name);
#ifdef SHADOWGRP
void cleanup_report_add_group_gshadow (void *group_name);
#endif
void cleanup_report_del_group (void *group_name);
void cleanup_report_del_group_group (void *group_name);
#ifdef SHADOWGRP
void cleanup_report_del_group_gshadow (void *group_name);
#endif
void cleanup_report_mod_passwd (void *cleanup_info);
void cleanup_report_mod_group (void *cleanup_info);
void cleanup_report_mod_gshadow (void *cleanup_info);
void cleanup_unlock_group (/*@null@*/void *unused);
#ifdef SHADOWGRP
void cleanup_unlock_gshadow (/*@null@*/void *unused);
#endif
void cleanup_unlock_passwd (/*@null@*/void *unused);
/* console.c */
extern bool console (const char *);
/* copydir.c */
extern int copy_tree (const char *src_root, const char *dst_root,
bool copy_root,
bool reset_selinux,
uid_t old_uid, uid_t new_uid,
gid_t old_gid, gid_t new_gid);
/* date_to_str.c */
extern void date_to_str (size_t size, char buf[size], long date);
/* encrypt.c */
extern /*@exposed@*//*@null@*/char *pw_encrypt (const char *, const char *);
/* entry.c */
extern void pw_entry (const char *, struct passwd *);
/* env.c */
extern void addenv (const char *, /*@null@*/const char *);
extern void initenv (void);
extern void set_env (int, char *const *);
extern void sanitize_env (void);
/* fields.c */
extern void change_field (char *, size_t, const char *);
extern int valid_field (const char *, const char *);
/* find_new_gid.c */
extern int find_new_gid (bool sys_group,
gid_t *gid,
/*@null@*/gid_t const *preferred_gid);
/* find_new_uid.c */
extern int find_new_uid (bool sys_user,
uid_t *uid,
/*@null@*/uid_t const *preferred_uid);
#ifdef ENABLE_SUBIDS
/* find_new_sub_gids.c */
extern int find_new_sub_gids (gid_t *range_start, unsigned long *range_count);
/* find_new_sub_uids.c */
extern int find_new_sub_uids (uid_t *range_start, unsigned long *range_count);
#endif /* ENABLE_SUBIDS */
/* get_gid.c */
extern int get_gid (const char *gidstr, gid_t *gid);
/* getgr_nam_gid.c */
extern /*@only@*//*@null@*/struct group *getgr_nam_gid (/*@null@*/const char *grname);
/* getlong.c */
extern int getlong (const char *numstr, /*@out@*/long int *result);
/* get_pid.c */
extern int get_pid (const char *pidstr, pid_t *pid);
/* getrange */
extern int getrange (const char *range,
unsigned long *min, bool *has_min,
unsigned long *max, bool *has_max);
/* gettime.c */
extern time_t gettime (void);
/* get_uid.c */
extern int get_uid (const char *uidstr, uid_t *uid);
/* getulong.c */
extern int getulong (const char *numstr, /*@out@*/unsigned long int *result);
/* fputsx.c */
extern /*@null@*/char *fgetsx (/*@returned@*/ /*@out@*/char *, int, FILE *);
extern int fputsx (const char *, FILE *);
/* groupio.c */
extern void __gr_del_entry (const struct commonio_entry *ent);
extern /*@observer@*/const struct commonio_db *__gr_get_db (void);
extern /*@dependent@*/ /*@null@*/struct commonio_entry *__gr_get_head (void);
extern void __gr_set_changed (void);
/* groupmem.c */
extern /*@null@*/ /*@only@*/struct group *__gr_dup (const struct group *grent);
extern void gr_free_members (struct group *grent);
extern void gr_free (/*@out@*/ /*@only@*/struct group *grent);
extern bool gr_append_member (struct group *grp, char *member);
/* hushed.c */
extern bool hushed (const char *username);
/* audit_help.c */
#ifdef WITH_AUDIT
extern int audit_fd;
extern void audit_help_open (void);
/* Use AUDIT_NO_ID when a name is provided to audit_logger instead of an ID */
#define AUDIT_NO_ID ((unsigned int) -1)
typedef enum {
SHADOW_AUDIT_FAILURE = 0,
SHADOW_AUDIT_SUCCESS = 1} shadow_audit_result;
extern void audit_logger (int type, const char *pgname, const char *op,
const char *name, unsigned int id,
shadow_audit_result result);
void audit_logger_message (const char *message, shadow_audit_result result);
#endif
/* limits.c */
#ifndef USE_PAM
extern void setup_limits (const struct passwd *);
#endif
/* list.c */
extern /*@only@*/ /*@out@*/char **add_list (/*@returned@*/ /*@only@*/char **, const char *);
extern /*@only@*/ /*@out@*/char **del_list (/*@returned@*/ /*@only@*/char **, const char *);
extern /*@only@*/ /*@out@*/char **dup_list (char *const *);
extern bool is_on_list (char *const *list, const char *member);
extern /*@only@*/char **comma_to_list (const char *);
/* log.c */
extern void dolastlog (
struct lastlog *ll,
const struct passwd *pw,
/*@unique@*/const char *line,
/*@unique@*/const char *host);
/* login_nopam.c */
extern int login_access (const char *user, const char *from);
/* loginprompt.c */
extern void login_prompt (const char *, char *, int);
/* mail.c */
extern void mailcheck (void);
/* motd.c */
extern void motd (void);
/* myname.c */
extern /*@null@*//*@only@*/struct passwd *get_my_pwent (void);
/* nss.c */
#include <libsubid/subid.h>
extern void nss_init(const char *nsswitch_path);
extern bool nss_is_initialized(void);
struct subid_nss_ops {
/*
* nss_has_range: does a user own a given subid range
*
* @owner: username
* @start: first subid in queried range
* @count: number of subids in queried range
* @idtype: subuid or subgid
* @result: true if @owner has been allocated the subid range.
*
* returns success if the module was able to determine an answer (true or false),
* else an error status.
*/
enum subid_status (*has_range)(const char *owner, unsigned long start, unsigned long count, enum subid_type idtype, bool *result);
/*
* nss_list_owner_ranges: list the subid ranges delegated to a user.
*
* @owner - string representing username being queried
* @id_type - subuid or subgid
* @ranges - pointer to an array of struct subid_range, or NULL. The
* returned array must be freed by the caller.
* @count - pointer to an integer into which the number of returned ranges
* is written.
* returns success if the module was able to determine an answer,
* else an error status.
*/
enum subid_status (*list_owner_ranges)(const char *owner, enum subid_type id_type, struct subid_range **ranges, int *count);
/*
* nss_find_subid_owners: find uids who own a given subuid or subgid.
*
* @id - the delegated id (subuid or subgid) being queried
* @id_type - subuid or subgid
* @uids - pointer to an array of uids which will be allocated by
* nss_find_subid_owners()
* @count - number of uids found
*
* returns success if the module was able to determine an answer,
* else an error status.
*/
enum subid_status (*find_subid_owners)(unsigned long id, enum subid_type id_type, uid_t **uids, int *count);
/* The dlsym handle to close */
void *handle;
};
extern struct subid_nss_ops *get_subid_nss_handle(void);
/* pam_pass_non_interactive.c */
#ifdef USE_PAM
extern int do_pam_passwd_non_interactive (const char *pam_service,
const char *username,
const char* password);
#endif /* USE_PAM */
/* obscure.c */
#ifndef USE_PAM
extern bool obscure (const char *, const char *, const struct passwd *);
#endif
/* pam_pass.c */
#ifdef USE_PAM
extern void do_pam_passwd (const char *user, bool silent, bool change_expired);
#endif
/* port.c */
extern bool isttytime (const char *, const char *, time_t);
/* prefix_flag.c */
extern const char* process_prefix_flag (const char* short_opt, int argc, char **argv);
extern struct group *prefix_getgrnam(const char *name);
extern struct group *prefix_getgrgid(gid_t gid);
extern struct passwd *prefix_getpwuid(uid_t uid);
extern struct passwd *prefix_getpwnam(const char* name);
extern struct spwd *prefix_getspnam(const char* name);
extern struct group *prefix_getgr_nam_gid(const char *grname);
extern void prefix_setpwent(void);
extern struct passwd* prefix_getpwent(void);
extern void prefix_endpwent(void);
extern void prefix_setgrent(void);
extern struct group* prefix_getgrent(void);
extern void prefix_endgrent(void);
/* pwd2spwd.c */
#ifndef USE_PAM
extern struct spwd *pwd_to_spwd (const struct passwd *);
#endif
/* pwdcheck.c */
#ifndef USE_PAM
extern void passwd_check (const char *, const char *, const char *);
#endif
/* pwd_init.c */
extern void pwd_init (void);
/* pwio.c */
extern void __pw_del_entry (const struct commonio_entry *ent);
extern struct commonio_db *__pw_get_db (void);
extern /*@dependent@*/ /*@null@*/struct commonio_entry *__pw_get_head (void);
/* pwmem.c */
extern /*@null@*/ /*@only@*/struct passwd *__pw_dup (const struct passwd *pwent);
extern void pw_free (/*@out@*/ /*@only@*/struct passwd *pwent);
/* remove_tree.c */
extern int remove_tree (const char *root, bool remove_root);
/* rlogin.c */
extern int do_rlogin (const char *remote_host, char *name, size_t namelen,
char *term, size_t termlen);
/* root_flag.c */
extern void process_root_flag (const char* short_opt, int argc, char **argv);
/* salt.c */
extern /*@observer@*/const char *crypt_make_salt (/*@null@*//*@observer@*/const char *meth, /*@null@*/void *arg);
/* selinux.c */
#ifdef WITH_SELINUX
extern int set_selinux_file_context (const char *dst_name, mode_t mode);
extern void reset_selinux_handle (void);
extern int reset_selinux_file_context (void);
extern int check_selinux_permit (const char *perm_name);
#endif
/* semanage.c */
#ifdef WITH_SELINUX
extern int set_seuser(const char *login_name, const char *seuser_name);
extern int del_seuser(const char *login_name);
#endif
/* setugid.c */
extern int setup_groups (const struct passwd *info);
extern int change_uid (const struct passwd *info);
#if (defined HAVE_INITGROUPS) && (! defined USE_PAM)
extern int setup_uid_gid (const struct passwd *info, bool is_console);
#else
extern int setup_uid_gid (const struct passwd *info);
#endif
/* setup.c */
extern void setup (struct passwd *);
/* setupenv.c */
extern void setup_env (struct passwd *);
/* sgetgrent.c */
extern struct group *sgetgrent (const char *buf);
/* sgetpwent.c */
extern struct passwd *sgetpwent (const char *buf);
/* sgetspent.c */
#ifndef HAVE_SGETSPENT
extern struct spwd *sgetspent (const char *string);
#endif
/* sgroupio.c */
extern void __sgr_del_entry (const struct commonio_entry *ent);
extern /*@null@*/ /*@only@*/struct sgrp *__sgr_dup (const struct sgrp *sgent);
extern void sgr_free (/*@out@*/ /*@only@*/struct sgrp *sgent);
extern /*@dependent@*/ /*@null@*/struct commonio_entry *__sgr_get_head (void);
extern void __sgr_set_changed (void);
/* shadowio.c */
extern /*@dependent@*/ /*@null@*/struct commonio_entry *__spw_get_head (void);
extern void __spw_del_entry (const struct commonio_entry *ent);
/* shadowmem.c */
extern /*@null@*/ /*@only@*/struct spwd *__spw_dup (const struct spwd *spent);
extern void spw_free (/*@out@*/ /*@only@*/struct spwd *spent);
/* shell.c */
extern int shell (const char *file, /*@null@*/const char *arg, char *const envp[]);
/* spawn.c */
extern int run_command (const char *cmd, const char *argv[],
/*@null@*/const char *envp[], /*@out@*/int *status);
/* strtoday.c */
extern long strtoday (const char *);
/* suauth.c */
extern int check_su_auth (const char *actual_id,
const char *wanted_id,
bool su_to_root);
/* sulog.c */
extern void sulog (const char *tty,
bool success,
const char *oldname,
const char *name);
/* sub.c */
extern void subsystem (const struct passwd *);
/* ttytype.c */
extern void ttytype (const char *);
/* tz.c */
#ifndef USE_PAM
extern /*@observer@*/const char *tz (const char *);
#endif
/* ulimit.c */
extern int set_filesize_limit (int blocks);
/* user_busy.c */
extern int user_busy (const char *name, uid_t uid);
/* utmp.c */
#ifndef USE_UTMPX
extern /*@null@*/struct utmp *get_current_utmp (void);
extern struct utmp *prepare_utmp (const char *name,
const char *line,
const char *host,
/*@null@*/const struct utmp *ut);
extern int setutmp (struct utmp *ut);
#else
extern /*@null@*/struct utmpx *get_current_utmp (void);
extern struct utmpx *prepare_utmpx (const char *name,
const char *line,
const char *host,
/*@null@*/const struct utmpx *ut);
extern int setutmpx (struct utmpx *utx);
#endif /* USE_UTMPX */
/* valid.c */
extern bool valid (const char *, const struct passwd *);
/* xmalloc.c */
extern /*@maynotreturn@*/ /*@only@*//*@out@*//*@notnull@*/void *xmalloc (size_t size)
/*@ensures MaxSet(result) == (size - 1); @*/;
extern /*@maynotreturn@*/ /*@only@*//*@notnull@*/char *xstrdup (const char *);
/* xgetpwnam.c */
extern /*@null@*/ /*@only@*/struct passwd *xgetpwnam (const char *);
/* xgetpwuid.c */
extern /*@null@*/ /*@only@*/struct passwd *xgetpwuid (uid_t);
/* xgetgrnam.c */
extern /*@null@*/ /*@only@*/struct group *xgetgrnam (const char *);
/* xgetgrgid.c */
extern /*@null@*/ /*@only@*/struct group *xgetgrgid (gid_t);
/* xgetspnam.c */
extern /*@null@*/ /*@only@*/struct spwd *xgetspnam(const char *);
/* yesno.c */
extern bool yes_or_no (bool read_only);
#endif /* _PROTOTYPES_H */