335681ca8
Denys Vlasenko
2017-04-13
Subject
su: FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY
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Architecture & Compiler Flags
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Build Log
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Commit Diff GitHub →
include/libbb.h+1 -0
| @@ -1486,6 +1486,7 @@ int check_securetty(const char *short_tty) FAST_FUNC; | |
| #else | |
| static ALWAYS_INLINE int check_securetty(const char *short_tty UNUSED_PARAM) { return 1; } | |
| #endif | |
| + | #define CHECKPASS_PW_HAS_EMPTY_PASSWORD 2 |
| int check_password(const struct passwd *pw, const char *plaintext) FAST_FUNC; | |
| int ask_and_check_password_extended(const struct passwd *pw, int timeout, const char *prompt) FAST_FUNC; | |
| int ask_and_check_password(const struct passwd *pw) FAST_FUNC; | |
libbb/correct_password.c+2 -2
| @@ -88,7 +88,7 @@ int FAST_FUNC check_password(const struct passwd *pw, const char *plaintext) | |
| /* Ask the user for a password. | |
| - | * Return 1 without asking if PW has an empty password. |
| + | * Return CHECKPASS_PW_HAS_EMPTY_PASSWORD without asking if PW has an empty password. |
| * Return -1 on EOF, error while reading input, or timeout. | |
| * Return 1 if the user gives the correct password for entry PW, | |
| * 0 if not. | |
| @@ -105,7 +105,7 @@ int FAST_FUNC ask_and_check_password_extended(const struct passwd *pw, | |
| pw_pass = get_passwd(pw, buffer); | |
| if (!pw_pass[0]) /* empty password field? */ | |
| - | return 1; |
| + | return CHECKPASS_PW_HAS_EMPTY_PASSWORD; |
| plaintext = bb_ask(STDIN_FILENO, timeout, prompt); | |
| if (!plaintext) { | |
loginutils/su.c+22 -5
| @@ -23,6 +23,11 @@ | |
| //config: bool "If user's shell is not in /etc/shells, disallow -s PROG" | |
| //config: default y | |
| //config: depends on SU | |
| + | //config: |
| + | //config:config FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY |
| + | //config: bool "Disallow blank passwords from TTYs other than specified in /etc/securetty" |
| + | //config: default n |
| + | //config: depends on SU |
| //applet:/* Needs to be run by root or be suid root - needs to change uid and gid: */ | |
| //applet:IF_SU(APPLET(su, BB_DIR_BIN, BB_SUID_REQUIRE)) | |
| @@ -79,6 +84,7 @@ int su_main(int argc UNUSED_PARAM, char **argv) | |
| char user_buf[64]; | |
| #endif | |
| const char *old_user; | |
| + | int r; |
| /* Note: we don't use "'+': stop at first non-option" idiom here. | |
| * 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) | |
| argv++; | |
| } | |
| + | tty = xmalloc_ttyname(STDIN_FILENO); |
| + | if (!tty) |
| + | tty = "none"; |
| + | tty = skip_dev_pfx(tty); |
| + | |
| if (ENABLE_FEATURE_SU_SYSLOG) { | |
| /* The utmp entry (via getlogin) is probably the best way to | |
| * 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) | |
| pw = getpwuid(cur_uid); | |
| old_user = pw ? xstrdup(pw->pw_name) : ""; | |
| } | |
| - | tty = xmalloc_ttyname(2); |
| - | if (!tty) { |
| - | tty = "none"; |
| - | } |
| openlog(applet_name, 0, LOG_AUTH); | |
| } | |
| pw = xgetpwnam(opt_username); | |
| - | if (cur_uid == 0 || ask_and_check_password(pw) > 0) { |
| + | r = 1; |
| + | if (cur_uid != 0) |
| + | r = ask_and_check_password(pw); |
| + | if (r > 0) { |
| + | if (ENABLE_FEATURE_SU_BLANK_PW_NEEDS_SECURE_TTY |
| + | && r == CHECKPASS_PW_HAS_EMPTY_PASSWORD |
| + | && !check_securetty(tty) |
| + | ) { |
| + | goto fail; |
| + | } |
| if (ENABLE_FEATURE_SU_SYSLOG) | |
| syslog(LOG_NOTICE, "%c %s %s:%s", | |
| '+', tty, old_user, opt_username); | |
| } else { | |
| + | fail: |
| if (ENABLE_FEATURE_SU_SYSLOG) | |
| syslog(LOG_NOTICE, "%c %s %s:%s", | |
| '-', tty, old_user, opt_username); | |