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| author | Greg Kroah-Hartman <greg@kroah.com> | 2018-10-04 21:06:14 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-01 11:44:25 +0300 |
| commit | e2e3a814194c453ca8bac45f42f8c9f43a475ced (patch) | |
| tree | 1b07ae7554979caa2965f5b03b5738d98bddf8fe /drivers/tty | |
| parent | 3540460e924b3fd975c2a824d33776ed04ba445e (diff) | |
| download | linux-e2e3a814194c453ca8bac45f42f8c9f43a475ced.tar.xz | |
tty: wipe buffer if not echoing data
commit b97b3d9fb57860a60592859e332de7759fd54c2e upstream.
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 0475f9685a41..904fc9c37fde 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -154,17 +154,28 @@ 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; @@ -173,7 +184,9 @@ 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; } /** @@ -1962,11 +1975,12 @@ 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 && |