Initial revision
This commit is contained in:
Jim Meyering
parent
07280902d9
commit
9678ebcd17
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@ -0,0 +1,519 @@
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/* su for GNU. Run a shell with substitute user and group IDs.
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Copyright (C) 1992 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* Run a shell with the real and effective UID and GID and groups
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of USER, default `root'.
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The shell run is taken from USER's password entry, /bin/sh if
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none is specified there. If the account has a password, su
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prompts for a password unless run by a user with real UID 0.
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Does not change the current directory.
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Sets `HOME' and `SHELL' from the password entry for USER, and if
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USER is not root, sets `USER' and `LOGNAME' to USER.
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The subshell is not a login shell.
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If one or more ARGs are given, they are passed as additional
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arguments to the subshell.
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Does not handle /bin/sh or other shells specially
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(setting argv[0] to "-su", passing -c only to certain shells, etc.).
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I don't see the point in doing that, and it's ugly.
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This program intentionally does not support a "wheel group" that
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restricts who can su to UID 0 accounts. RMS considers that to
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be fascist.
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Options:
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-, -l, --login Make the subshell a login shell.
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Unset all environment variables except
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TERM, HOME and SHELL (set as above), and USER
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and LOGNAME (set unconditionally as above), and
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set PATH to a default value.
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Change to USER's home directory.
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Prepend "-" to the shell's name.
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-c, --commmand=COMMAND
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Pass COMMAND to the subshell with a -c option
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instead of starting an interactive shell.
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-f, --fast Pass the -f option to the subshell.
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-m, -p, --preserve-environment
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Do not change HOME, USER, LOGNAME, SHELL.
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Run $SHELL instead of USER's shell from /etc/passwd
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unless not the superuser and USER's shell is
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restricted.
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Overridden by --login and --shell.
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-s, --shell=shell Run SHELL instead of USER's shell from /etc/passwd
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unless not the superuser and USER's shell is
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restricted.
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Compile-time options:
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-DSYSLOG_SUCCESS Log successful su's (by default, to root) with syslog.
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-DSYSLOG_FAILURE Log failed su's (by default, to root) with syslog.
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-DSYSLOG_NON_ROOT Log all su's, not just those to root (UID 0).
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Never logs attempted su's to nonexistent accounts.
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Written by David MacKenzie <djm@gnu.ai.mit.edu>. */
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#include <stdio.h>
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#include <getopt.h>
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#include <sys/types.h>
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#include <pwd.h>
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#include "system.h"
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#ifdef HAVE_SYSLOG_H
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#include <syslog.h>
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void log_su ();
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#else
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#ifdef SYSLOG_SUCCESS
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#undef SYSLOG_SUCCESS
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#endif
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#ifdef SYSLOG_FAILURE
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#undef SYSLOG_FAILURE
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#endif
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#ifdef SYSLOG_NON_ROOT
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#undef SYSLOG_NON_ROOT
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#endif
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#endif
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#ifdef _POSIX_VERSION
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#include <limits.h>
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#ifdef NGROUPS_MAX
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#undef NGROUPS_MAX
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#endif
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#define NGROUPS_MAX sysconf (_SC_NGROUPS_MAX)
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#else /* not _POSIX_VERSION */
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struct passwd *getpwuid ();
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struct group *getgrgid ();
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uid_t getuid ();
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#include <sys/param.h>
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#if !defined(NGROUPS_MAX) && defined(NGROUPS)
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#define NGROUPS_MAX NGROUPS
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#endif
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#endif /* not _POSIX_VERSION */
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#ifdef _POSIX_SOURCE
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#define endgrent()
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#define endpwent()
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#endif
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#ifdef HAVE_SHADOW_H
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#include <shadow.h>
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#endif
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/* The default PATH for simulated logins to non-superuser accounts. */
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#define DEFAULT_LOGIN_PATH ":/usr/ucb:/bin:/usr/bin"
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/* The default PATH for simulated logins to superuser accounts. */
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#define DEFAULT_ROOT_LOGIN_PATH "/usr/ucb:/bin:/usr/bin:/etc"
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/* The shell to run if none is given in the user's passwd entry. */
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#define DEFAULT_SHELL "/bin/sh"
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/* The user to become if none is specified. */
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#define DEFAULT_USER "root"
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char *crypt ();
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char *getpass ();
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char *getusershell ();
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void endusershell ();
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void setusershell ();
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char *basename ();
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char *concat ();
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char *xmalloc ();
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char *xrealloc ();
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int correct_password ();
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int elements ();
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int restricted_shell ();
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void change_identity ();
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void error ();
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void modify_environment ();
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void run_shell ();
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void usage ();
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void xputenv ();
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extern char **environ;
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/* The name this program was run with. */
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char *program_name;
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/* If nonzero, pass the `-f' option to the subshell. */
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int fast_startup;
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/* If nonzero, simulate a login instead of just starting a shell. */
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int simulate_login;
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/* If nonzero, change some environment vars to indicate the user su'd to. */
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int change_environment;
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struct option longopts[] =
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{
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{"command", 1, 0, 'c'},
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{"fast", 0, &fast_startup, 1},
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{"login", 0, &simulate_login, 1},
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{"preserve-environment", 0, &change_environment, 0},
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{"shell", 1, 0, 's'},
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{0, 0, 0, 0}
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};
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void
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main (argc, argv)
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int argc;
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char **argv;
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{
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int optc;
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char *new_user = DEFAULT_USER;
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char *command = 0;
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char **additional_args = 0;
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char *shell = 0;
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struct passwd *pw;
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program_name = argv[0];
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fast_startup = 0;
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simulate_login = 0;
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change_environment = 1;
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while ((optc = getopt_long (argc, argv, "c:flmps:", longopts, (int *) 0))
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!= EOF)
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{
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switch (optc)
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{
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case 0:
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break;
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case 'c':
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command = optarg;
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break;
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case 'f':
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fast_startup = 1;
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break;
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case 'l':
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simulate_login = 1;
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break;
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case 'm':
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case 'p':
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change_environment = 0;
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break;
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case 's':
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shell = optarg;
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break;
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default:
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usage ();
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}
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}
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if (optind < argc && !strcmp (argv[optind], "-"))
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{
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simulate_login = 1;
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++optind;
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}
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if (optind < argc)
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new_user = argv[optind++];
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if (optind < argc)
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additional_args = argv + optind;
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pw = getpwnam (new_user);
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if (pw == 0)
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error (1, 0, "user %s does not exist", new_user);
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endpwent ();
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if (!correct_password (pw))
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{
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#ifdef SYSLOG_FAILURE
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log_su (pw, 0);
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#endif
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error (1, 0, "incorrect password");
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}
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#ifdef SYSLOG_SUCCESS
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else
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{
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log_su (pw, 1);
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}
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#endif
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if (pw->pw_shell == 0 || pw->pw_shell[0] == 0)
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pw->pw_shell = DEFAULT_SHELL;
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if (shell == 0 && change_environment == 0)
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shell = getenv ("SHELL");
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if (shell != 0 && getuid () && restricted_shell (pw->pw_shell))
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{
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/* The user being su'd to has a nonstandard shell, and so is
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probably a uucp account or has restricted access. Don't
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compromise the account by allowing access with a standard
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shell. */
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error (0, 0, "using restricted shell %s", pw->pw_shell);
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shell = 0;
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}
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if (shell == 0)
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shell = pw->pw_shell;
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shell = strcpy (xmalloc (strlen (shell) + 1), shell);
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modify_environment (pw, shell);
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change_identity (pw);
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if (simulate_login && chdir (pw->pw_dir))
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error (0, errno, "warning: cannot change directory to %s", pw->pw_dir);
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run_shell (shell, command, additional_args);
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}
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/* Ask the user for a password.
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Return 1 if the user gives the correct password for entry PW,
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0 if not. Return 1 without asking for a password if run by UID 0
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or if PW has an empty password. */
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int
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correct_password (pw)
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struct passwd *pw;
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{
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char *unencrypted, *encrypted, *correct;
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#ifdef HAVE_SHADOW_H
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/* Shadow passwd stuff for SVR3 and maybe other systems. */
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struct spwd *sp = getspnam (pw->pw_name);
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endspent ();
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if (sp)
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correct = sp->sp_pwdp;
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else
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#endif
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correct = pw->pw_passwd;
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if (getuid () == 0 || correct == 0 || correct[0] == '\0')
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return 1;
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unencrypted = getpass ("Password:");
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encrypted = crypt (unencrypted, correct);
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bzero (unencrypted, strlen (unencrypted));
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return strcmp (encrypted, correct) == 0;
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}
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/* Update `environ' for the new shell based on PW, with SHELL being
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the value for the SHELL environment variable. */
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void
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modify_environment (pw, shell)
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struct passwd *pw;
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char *shell;
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{
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char *term;
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if (simulate_login)
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{
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/* Leave TERM unchanged. Set HOME, SHELL, USER, LOGNAME, PATH.
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Unset all other environment variables. */
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term = getenv ("TERM");
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environ = (char **) xmalloc (2 * sizeof (char *));
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environ[0] = 0;
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if (term)
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xputenv (concat ("TERM", "=", term));
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xputenv (concat ("HOME", "=", pw->pw_dir));
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xputenv (concat ("SHELL", "=", shell));
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xputenv (concat ("USER", "=", pw->pw_name));
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xputenv (concat ("LOGNAME", "=", pw->pw_name));
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xputenv (concat ("PATH", "=", pw->pw_uid
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? DEFAULT_LOGIN_PATH : DEFAULT_ROOT_LOGIN_PATH));
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}
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else
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{
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/* Set HOME, SHELL, and if not becoming a super-user,
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USER and LOGNAME. */
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if (change_environment)
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{
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xputenv (concat ("HOME", "=", pw->pw_dir));
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xputenv (concat ("SHELL", "=", shell));
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if (pw->pw_uid)
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{
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xputenv (concat ("USER", "=", pw->pw_name));
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xputenv (concat ("LOGNAME", "=", pw->pw_name));
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}
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}
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}
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}
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/* Become the user and group(s) specified by PW. */
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void
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change_identity (pw)
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struct passwd *pw;
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{
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#ifdef NGROUPS_MAX
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errno = 0;
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if (initgroups (pw->pw_name, pw->pw_gid) == -1)
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error (1, errno, "cannot set groups");
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endgrent ();
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#endif
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if (setgid (pw->pw_gid))
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error (1, errno, "cannot set group id");
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if (setuid (pw->pw_uid))
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error (1, errno, "cannot set user id");
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}
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/* Run SHELL, or DEFAULT_SHELL if SHELL is empty.
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If COMMAND is nonzero, pass it to the shell with the -c option.
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If ADDITIONAL_ARGS is nonzero, pass it to the shell as more
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arguments. */
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void
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run_shell (shell, command, additional_args)
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char *shell;
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char *command;
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char **additional_args;
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{
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char **args;
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int argno = 1;
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if (additional_args)
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args = (char **) xmalloc (sizeof (char *)
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* (10 + elements (additional_args)));
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else
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args = (char **) xmalloc (sizeof (char *) * 10);
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if (simulate_login)
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{
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args[0] = xmalloc (strlen (shell) + 2);
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args[0][0] = '-';
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strcpy (args[0] + 1, basename (shell));
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}
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else
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args[0] = basename (shell);
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if (fast_startup)
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args[argno++] = "-f";
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if (command)
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{
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args[argno++] = "-c";
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args[argno++] = command;
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}
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if (additional_args)
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for (; *additional_args; ++additional_args)
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args[argno++] = *additional_args;
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args[argno] = 0;
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execv (shell, args);
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error (1, errno, "cannot run %s", shell);
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}
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#if defined (SYSLOG_SUCCESS) || defined (SYSLOG_FAILURE)
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/* Log the fact that someone has run su to the user given by PW;
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if SUCCESSFUL is nonzero, they gave the correct password, etc. */
|
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void
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log_su (pw, successful)
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struct passwd *pw;
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int successful;
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{
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char *new_user, *old_user, *tty;
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|
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#ifndef SYSLOG_NON_ROOT
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if (pw->pw_uid)
|
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return;
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#endif
|
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new_user = pw->pw_name;
|
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/* The utmp entry (via getlogin) is probably the best way to identify
|
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the user, especially if someone su's from a su-shell. */
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old_user = getlogin ();
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if (old_user == 0)
|
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old_user = "";
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tty = ttyname (2);
|
||||
if (tty == 0)
|
||||
tty = "";
|
||||
/* 4.2BSD openlog doesn't have the third parameter. */
|
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openlog (basename (program_name), 0
|
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#ifdef LOG_AUTH
|
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, LOG_AUTH
|
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#endif
|
||||
);
|
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syslog (LOG_NOTICE,
|
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#ifdef SYSLOG_NON_ROOT
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"%s(to %s) %s on %s",
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#else
|
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"%s%s on %s",
|
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#endif
|
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successful ? "" : "FAILED SU ",
|
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#ifdef SYSLOG_NON_ROOT
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new_user,
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#endif
|
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old_user, tty);
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closelog ();
|
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}
|
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#endif
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/* Return 1 if SHELL is a restricted shell (one not returned by
|
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getusershell), else 0, meaning it is a standard shell. */
|
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|
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int
|
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restricted_shell (shell)
|
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char *shell;
|
||||
{
|
||||
char *line;
|
||||
|
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setusershell ();
|
||||
while (line = getusershell ())
|
||||
{
|
||||
if (*line != '#' && strcmp (line, shell) == 0)
|
||||
{
|
||||
endusershell ();
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||||
return 0;
|
||||
}
|
||||
}
|
||||
endusershell ();
|
||||
return 1;
|
||||
}
|
||||
|
||||
/* Return the number of elements in ARR, a null-terminated array. */
|
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|
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int
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elements (arr)
|
||||
char **arr;
|
||||
{
|
||||
int n = 0;
|
||||
|
||||
for (n = 0; *arr; ++arr)
|
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++n;
|
||||
return n;
|
||||
}
|
||||
|
||||
/* Add VAL to the environment, checking for out of memory errors. */
|
||||
|
||||
void
|
||||
xputenv (val)
|
||||
char *val;
|
||||
{
|
||||
if (putenv (val))
|
||||
error (1, 0, "virtual memory exhausted");
|
||||
}
|
||||
|
||||
/* Return a newly-allocated string whose contents concatenate
|
||||
those of S1, S2, S3. */
|
||||
|
||||
char *
|
||||
concat (s1, s2, s3)
|
||||
char *s1, *s2, *s3;
|
||||
{
|
||||
int len1 = strlen (s1), len2 = strlen (s2), len3 = strlen (s3);
|
||||
char *result = (char *) xmalloc (len1 + len2 + len3 + 1);
|
||||
|
||||
strcpy (result, s1);
|
||||
strcpy (result + len1, s2);
|
||||
strcpy (result + len1 + len2, s3);
|
||||
result[len1 + len2 + len3] = 0;
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
void
|
||||
usage ()
|
||||
{
|
||||
fprintf (stderr, "\
|
||||
Usage: %s [-flmp] [-c command] [-s shell] [--login] [--fast]\n\
|
||||
[--preserve-environment] [--command=command] [--shell=shell] [-]\n\
|
||||
[user [arg...]]\n", program_name);
|
||||
exit (1);
|
||||
}
|
||||
Loading…
Reference in New Issue