diff options
| author | Greg KH <greg@kroah.com> | 2018-10-04 11:06:14 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-10-11 19:50:00 +0200 |
| commit | b97b3d9fb57860a60592859e332de7759fd54c2e (patch) | |
| tree | 79b21a2681fb9fee48b022d6072aa6500cf3de7d /drivers/tty | |
| parent | c9a8e5fce009e3c601a43c49ea9dbcb25d1ffac5 (diff) | |
| download | linux-b97b3d9fb57860a60592859e332de7759fd54c2e.tar.bz2 | |
tty: wipe buffer if not echoing data
If we are not echoing the data to userspace or the console is in icanon
mode, then perhaps it is a "secret" so we should wipe it once we are
done with it.
This mirrors the logic that the audit code has.
Reported-by: aszlig <aszlig@nix.build>
Tested-by: Milan Broz <gmazyland@gmail.com>
Tested-by: Daniel Zatovic <daniel.zatovic@gmail.com>
Tested-by: aszlig <aszlig@nix.build>
Cc: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
| -rw-r--r-- | drivers/tty/n_tty.c | 20 |
1 files changed, 17 insertions, 3 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 431742201709..3ad460219fd6 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -152,17 +152,28 @@ static inline unsigned char *echo_buf_addr(struct n_tty_data *ldata, size_t i) return &ldata->echo_buf[i & (N_TTY_BUF_SIZE - 1)]; } +/* If we are not echoing the data, perhaps this is a secret so erase it */ +static void zero_buffer(struct tty_struct *tty, u8 *buffer, int size) +{ + bool icanon = !!L_ICANON(tty); + bool no_echo = !L_ECHO(tty); + + if (icanon && no_echo) + memset(buffer, 0x00, size); +} + static int tty_copy_to_user(struct tty_struct *tty, void __user *to, size_t tail, size_t n) { struct n_tty_data *ldata = tty->disc_data; size_t size = N_TTY_BUF_SIZE - tail; - const void *from = read_buf_addr(ldata, tail); + void *from = read_buf_addr(ldata, tail); int uncopied; if (n > size) { tty_audit_add_data(tty, from, size); uncopied = copy_to_user(to, from, size); + zero_buffer(tty, from, size - uncopied); if (uncopied) return uncopied; to += size; @@ -171,7 +182,9 @@ static int tty_copy_to_user(struct tty_struct *tty, void __user *to, } tty_audit_add_data(tty, from, n); - return copy_to_user(to, from, n); + uncopied = copy_to_user(to, from, n); + zero_buffer(tty, from, n - uncopied); + return uncopied; } /** @@ -1960,11 +1973,12 @@ static int copy_from_read_buf(struct tty_struct *tty, n = min(head - ldata->read_tail, N_TTY_BUF_SIZE - tail); n = min(*nr, n); if (n) { - const unsigned char *from = read_buf_addr(ldata, tail); + unsigned char *from = read_buf_addr(ldata, tail); retval = copy_to_user(*b, from, n); n -= retval; is_eof = n == 1 && *from == EOF_CHAR(tty); tty_audit_add_data(tty, from, n); + zero_buffer(tty, from, n); smp_store_release(&ldata->read_tail, ldata->read_tail + n); /* Turn single EOF into zero-length read */ if (L_EXTPROC(tty) && ldata->icanon && is_eof && |