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| author | Denys Vlasenko <vda.linux@googlemail.com> | 2017-04-13 12:57:04 +0200 |
|---|---|---|
| committer | Denys Vlasenko <vda.linux@googlemail.com> | 2017-04-13 12:57:04 +0200 |
| commit | 335681ca8e39144fa19814f7ba10d0fe760e4055 (patch) | |
| tree | 81c20a0be3daab564c842f510126037bf2331ab2 /loginutils | |
| parent | 517a82c5b6b5e279f3e96a6774445a2952ca312b (diff) | |
| download | busybox-w32-335681ca8e39144fa19814f7ba10d0fe760e4055.tar.gz busybox-w32-335681ca8e39144fa19814f7ba10d0fe760e4055.tar.bz2 busybox-w32-335681ca8e39144fa19814f7ba10d0fe760e4055.zip | |
su: FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY
When this feature is enabled, blank passwords are not accepted by su
unless the user is on a secure TTY defined in /etc/securetty. This
resembles the default PAM configuration of some Linux distros which
specify the nullok_secure option for pam_unix.so.
Based on patch by Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'loginutils')
| -rw-r--r-- | loginutils/su.c | 27 |
1 files changed, 22 insertions, 5 deletions
diff --git a/loginutils/su.c b/loginutils/su.c index d04b85fb1..f2cd799ae 100644 --- a/loginutils/su.c +++ b/loginutils/su.c | |||
| @@ -23,6 +23,11 @@ | |||
| 23 | //config: bool "If user's shell is not in /etc/shells, disallow -s PROG" | 23 | //config: bool "If user's shell is not in /etc/shells, disallow -s PROG" |
| 24 | //config: default y | 24 | //config: default y |
| 25 | //config: depends on SU | 25 | //config: depends on SU |
| 26 | //config: | ||
| 27 | //config:config FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY | ||
| 28 | //config: bool "Disallow blank passwords from TTYs other than specified in /etc/securetty" | ||
| 29 | //config: default n | ||
| 30 | //config: depends on SU | ||
| 26 | 31 | ||
| 27 | //applet:/* Needs to be run by root or be suid root - needs to change uid and gid: */ | 32 | //applet:/* Needs to be run by root or be suid root - needs to change uid and gid: */ |
| 28 | //applet:IF_SU(APPLET(su, BB_DIR_BIN, BB_SUID_REQUIRE)) | 33 | //applet:IF_SU(APPLET(su, BB_DIR_BIN, BB_SUID_REQUIRE)) |
| @@ -79,6 +84,7 @@ int su_main(int argc UNUSED_PARAM, char **argv) | |||
| 79 | char user_buf[64]; | 84 | char user_buf[64]; |
| 80 | #endif | 85 | #endif |
| 81 | const char *old_user; | 86 | const char *old_user; |
| 87 | int r; | ||
| 82 | 88 | ||
| 83 | /* Note: we don't use "'+': stop at first non-option" idiom here. | 89 | /* Note: we don't use "'+': stop at first non-option" idiom here. |
| 84 | * For su, "SCRIPT ARGS" or "-c CMD ARGS" do not stop option parsing: | 90 | * For su, "SCRIPT ARGS" or "-c CMD ARGS" do not stop option parsing: |
| @@ -99,6 +105,11 @@ int su_main(int argc UNUSED_PARAM, char **argv) | |||
| 99 | argv++; | 105 | argv++; |
| 100 | } | 106 | } |
| 101 | 107 | ||
| 108 | tty = xmalloc_ttyname(STDIN_FILENO); | ||
| 109 | if (!tty) | ||
| 110 | tty = "none"; | ||
| 111 | tty = skip_dev_pfx(tty); | ||
| 112 | |||
| 102 | if (ENABLE_FEATURE_SU_SYSLOG) { | 113 | if (ENABLE_FEATURE_SU_SYSLOG) { |
| 103 | /* The utmp entry (via getlogin) is probably the best way to | 114 | /* The utmp entry (via getlogin) is probably the best way to |
| 104 | * identify the user, especially if someone su's from a su-shell. | 115 | * identify the user, especially if someone su's from a su-shell. |
| @@ -112,20 +123,26 @@ int su_main(int argc UNUSED_PARAM, char **argv) | |||
| 112 | pw = getpwuid(cur_uid); | 123 | pw = getpwuid(cur_uid); |
| 113 | old_user = pw ? xstrdup(pw->pw_name) : ""; | 124 | old_user = pw ? xstrdup(pw->pw_name) : ""; |
| 114 | } | 125 | } |
| 115 | tty = xmalloc_ttyname(2); | ||
| 116 | if (!tty) { | ||
| 117 | tty = "none"; | ||
| 118 | } | ||
| 119 | openlog(applet_name, 0, LOG_AUTH); | 126 | openlog(applet_name, 0, LOG_AUTH); |
| 120 | } | 127 | } |
| 121 | 128 | ||
| 122 | pw = xgetpwnam(opt_username); | 129 | pw = xgetpwnam(opt_username); |
| 123 | 130 | ||
| 124 | if (cur_uid == 0 || ask_and_check_password(pw) > 0) { | 131 | r = 1; |
| 132 | if (cur_uid != 0) | ||
| 133 | r = ask_and_check_password(pw); | ||
| 134 | if (r > 0) { | ||
| 135 | if (ENABLE_FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY | ||
| 136 | && r == CHECKPASS_PW_HAS_EMPTY_PASSWORD | ||
| 137 | && !check_securetty(tty) | ||
| 138 | ) { | ||
| 139 | goto fail; | ||
| 140 | } | ||
| 125 | if (ENABLE_FEATURE_SU_SYSLOG) | 141 | if (ENABLE_FEATURE_SU_SYSLOG) |
| 126 | syslog(LOG_NOTICE, "%c %s %s:%s", | 142 | syslog(LOG_NOTICE, "%c %s %s:%s", |
| 127 | '+', tty, old_user, opt_username); | 143 | '+', tty, old_user, opt_username); |
| 128 | } else { | 144 | } else { |
| 145 | fail: | ||
| 129 | if (ENABLE_FEATURE_SU_SYSLOG) | 146 | if (ENABLE_FEATURE_SU_SYSLOG) |
| 130 | syslog(LOG_NOTICE, "%c %s %s:%s", | 147 | syslog(LOG_NOTICE, "%c %s %s:%s", |
| 131 | '-', tty, old_user, opt_username); | 148 | '-', tty, old_user, opt_username); |