diff options
| -rw-r--r-- | include/unistd.h | 41 | ||||
| -rw-r--r-- | src/unistd/getpass.c | 193 |
2 files changed, 234 insertions, 0 deletions
diff --git a/include/unistd.h b/include/unistd.h index fb1a1c8..c45e425 100644 --- a/include/unistd.h +++ b/include/unistd.h @@ -1112,6 +1112,47 @@ int daemonise(const char*, int) #endif +/** + * Get password input from the terminal. + * + * The exact behaviour of this function depends on the implementations. + * However you can assume that, the controlling terminal (/dev/tty) is + * opened and used for input and output, and that echoing is disabled. + * You cannot assume that arbitrary lengths are supported. However, in + * this implementation, line editing is enabled and arbitrary lengths + * are supported. If the length of the input (excluding termination) is + * less than 8192 a statically allocated string is returned, otherwise + * a dynamically allocated string is returned. + * + * @etymology (Get) (pass)word from terminal! + * + * @param prompt Text to print at the beginning of the line. + * Used to tell the user what is expected of her. + * Must not be `NULL`. + * @return The entered line. You should override it with zeroes as + * soon as possible to avoid leaving cleartest passphrases + * visible in memory, or potentially stored to unencrypted + * swap. The returned string is statically allocated, do + * not deallocate it, unless you know that you are using + * slibc and the length of the string is at least 8192. + * `NULL` on error. If a statically allocated string is + * returned, it will be overwritten at the next call. + * + * @throws Any error specified for open(3). + * @throws Any error specified for malloc(3). + * @throws Any error specified for read(3). + * @throws Any error specified for tcgetattr(3). + * @throws Any error specified for tcsetattr(3). + * @throws Any error specified for tcdrain(3). + * + * @since Always. + */ +char* getpass(const char*) + __GCC_ONLY(__attribute__((__nonnull__, __warn_unused_result__))) + __deprecated("'getpass' has been deprecated without any " + "replacement. You could use libpassphrase instead. :)"); + + #endif diff --git a/src/unistd/getpass.c b/src/unistd/getpass.c new file mode 100644 index 0000000..5968d38 --- /dev/null +++ b/src/unistd/getpass.c @@ -0,0 +1,193 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include <unistd.h> +#include <fcntl.h> +#include <stdio.h> +#include <termios.h> +#include <string.h> +#include <strings.h> +#include <errno.h> +#include <slibc-alloca.h> + + +#define t(...) do { if (__VA_ARGS__) goto fail; } while (0) + + + +/** + * This function performs the actual password-reading + * part of `getpass`. It will read into a statically + * allocated buffer until that buffer is full (8196 bytes, + * including termination), and switch to a dynamically + * allocated buffer when the it [the statically allocated + * buffer] is full. + * + * @prarm fd File descriptor to the, already configured, + * controlling terminal. + * @return The entered line. You should override it with zeroes as + * soon as possible to avoid leaving cleartest passphrases + * visible in memory, or potentially stored to unencrypted + * swap. The returned string is statically allocated, and + * should not be deallocated, if the length of the string, + * is (strictly) less than 8196, otherwise it is dynamically + * allocated, and should be deallocated. + * + * @throws Any error specified for malloc(3). + * @throws Any error specified for read(3). + */ +static char* _getpass(int fd) +{ + static char pass_s[8196]; + char* pass_d = NULL; + size_t ptr_s = 0, ptr_d = 8196, size_d = (8196 << 1); + ssize_t got = 1; + void* new; + + /* Read into statically allocated buffer until it is full. */ + while (ptr_s < sizeof(pass_s) / sizeof(char)) + { + /* Read. */ + t (got = read(fd, pass_s + ptr_s, sizeof(pass_s) - ptr_s * sizeof(char)), got < 0); + ptr_s += (size_t)got; + /* End of line? */ + if ((got == 0) || (pass_s[ptr_s - 1] == '\n')) + { + pass_s[ptr_s - !!got] = '\0'; + return pass_s; + } + } + + /* Transfer input to dynamically allocated buffer. */ + t (pass_d = secure_realloc(pass_d, size_d * sizeof(char)), pass_d == NULL); + memcpy(pass_d, pass_s, sizeof(pass_s)), explicit_bzero(pass_s, sizeof(pass_s)); + + /* Read into dynamically allocated buffer. */ + for (;;) + { + /* Do we need to grow the buffer? */ + if (ptr_d + 1 == size_d) + { + t (new = secure_realloc(pass_d, (size_d <<= 1) * sizeof(char)), new == NULL); + pass_d = new; + } + /* Read. */ + t (got = read(fd, pass_d + ptr_d, (size_d - ptr_d - 1) * sizeof(char)), got < 0); + ptr_d += (size_t)got; + /* End of line? */ + if ((got == 0) || (pass_d[ptr_d - 1] == '\n')) + { + pass_d[ptr_d - !!got] = '\0'; + return pass_d; + } + } + + fail: + saved_errno = errno; + explicit_bzero(pass_s, sizeof(pass_s)); + secure_free(pass_d); + errno = saved_errno; + return NULL; +} + + +/** + * Get password input from the terminal. + * + * The exact behaviour of this function depends on the implementations. + * However you can assume that, the controlling terminal (/dev/tty) is + * opened and used for input and output, and that echoing is disabled. + * You cannot assume that arbitrary lengths are supported. However, in + * this implementation, line editing is enabled and arbitrary lengths + * are supported. If the length of the input (excluding termination) is + * less than 8192 a statically allocated string is returned, otherwise + * a dynamically allocated string is returned. + * + * @etymology (Get) (pass)word from terminal! + * + * @param prompt Text to print at the beginning of the line. + * Used to tell the user what is expected of her. + * Must not be `NULL`. + * @return The entered line. You should override it with zeroes as + * soon as possible to avoid leaving cleartest passphrases + * visible in memory, or potentially stored to unencrypted + * swap. The returned string is statically allocated, do + * not deallocate it, unless you know that you are using + * slibc and the length of the string is at least 8192. + * `NULL` on error. If a statically allocated string is + * returned, it will be overwritten at the next call. + * + * @throws Any error specified for open(3). + * @throws Any error specified for malloc(3). + * @throws Any error specified for read(3). + * @throws Any error specified for tcgetattr(3). + * @throws Any error specified for tcsetattr(3). + * @throws Any error specified for tcdrain(3). + * + * @since Always. + */ +char* getpass(const char* prompt) +{ + struct termios saved_stty, stty; + char* pass; + int fd = -1, stty_saved = 0, saved_errno; + + /* Open controlling terminal. */ + t (fd = open("/dev/tty", O_RDWR | O_NOCTTY | O_CLOEXEC), fd < 0); + + /* Configure terminal settings. */ + t (tcgetattr(fd, &stty)); + saved_stty = stty; + stty_saved = 1; + stty.c_lflag = (stty.c_lflag & (tcflag_t)~(ECHO | ISIG )) | (tcflag_t)ICANON; + stty.c_iflag = (stty.c_iflag & (tcflag_t)~(INLCR | IGNCR)) | (tcflag_t)ICRNL; + t (tcsetattr(fd, TCSAFLUSH, &stty)); + t (tcdrain(fd)); + + /* Prompt the user. */ + (void) dprintf(fd, "%s", prompt); + + /* Get password. */ + pass = _getpass(fd); + if (pass == NULL) + goto fail; + + /* Move cursor to next line. */ + (void) dprintf(fd, "\n"); + + /* Restore terminal settings. */ + (void) tcsetattr(fd, TCSAFLUSH, &saved_stty); + (void) tcdrain(fd); + + /* Close controlling terminal. */ + close(fd); + + return pass; + + fail: + saved_errno = errno; + if (fd >= 0) + close(fd); + if (stty_saved) + { + tcsetattr(fd, TCSAFLUSH, &saved_stty); + tcdrain(fd); + } + errno = saved_errno; + return NULL; +} + |