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tty: wipe buffer if not echoing data

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commit b97b3d9fb5 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>
This commit is contained in:
Greg Kroah-Hartman
2018-10-04 11:06:14 -07:00
committed by Greg Kroah-Hartman
parent d196147ecf
commit 2b7e9180b4
1 changed files with 17 additions and 2 deletions
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19
drivers/tty/n_tty.c
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@@ -165,15 +165,29 @@ static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
return put_user(x, ptr);
}
/* If we are not echoing the data, perhaps this is a secret so erase it */
static inline 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 inline int tty_copy_to_user(struct tty_struct *tty,
void __user *to,
const void *from,
void *from,
unsigned long n)
{
struct n_tty_data *ldata = tty->disc_data;
int retval;
tty_audit_add_data(tty, from, n, ldata->icanon);
return copy_to_user(to, from, n);
retval = copy_to_user(to, from, n);
if (!retval)
zero_buffer(tty, from, n);
return retval;
}
/**
@@ -2005,6 +2019,7 @@ static int copy_from_read_buf(struct tty_struct *tty,
is_eof = n == 1 && read_buf(ldata, tail) == EOF_CHAR(tty);
tty_audit_add_data(tty, read_buf_addr(ldata, tail), n,
ldata->icanon);
zero_buffer(tty, read_buf_addr(ldata, tail), 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 &&