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authorJiri Slaby <jslaby@suse.cz>2013-04-26 13:48:53 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-26 07:59:23 -0700
commit37b7f3c76595e23257f61bd80b223de8658617ee (patch)
tree7e9b3cd8a5c5b10d6ee32dc8b85c5d5211fd5eeb
parent91d80a84bbc8f28375cca7e65ec666577b4209ad (diff)
downloadlinux-37b7f3c76595e23257f61bd80b223de8658617ee.tar.gz
TTY: fix atime/mtime regression
In commit b0de59b5733d ("TTY: do not update atime/mtime on read/write") we removed timestamps from tty inodes to fix a security issue and waited if something breaks. Well, 'w', the utility to find out logged users and their inactivity time broke. It shows that users are inactive since the time they logged in. To revert to the old behaviour while still preventing attackers to guess the password length, we update the timestamps in one-minute intervals by this patch. Signed-off-by: Jiri Slaby <jslaby@suse.cz> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/tty/tty_io.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 05400acbc45..b0452688308 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -941,6 +941,14 @@ void start_tty(struct tty_struct *tty)
EXPORT_SYMBOL(start_tty);
+static void tty_update_time(struct timespec *time)
+{
+ unsigned long sec = get_seconds();
+ sec -= sec % 60;
+ if ((long)(sec - time->tv_sec) > 0)
+ time->tv_sec = sec;
+}
+
/**
* tty_read - read method for tty device files
* @file: pointer to tty file
@@ -960,10 +968,11 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
loff_t *ppos)
{
int i;
+ struct inode *inode = file_inode(file);
struct tty_struct *tty = file_tty(file);
struct tty_ldisc *ld;
- if (tty_paranoia_check(tty, file_inode(file), "tty_read"))
+ if (tty_paranoia_check(tty, inode, "tty_read"))
return -EIO;
if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
return -EIO;
@@ -977,6 +986,9 @@ static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
i = -EIO;
tty_ldisc_deref(ld);
+ if (i > 0)
+ tty_update_time(&inode->i_atime);
+
return i;
}
@@ -1077,8 +1089,10 @@ static inline ssize_t do_tty_write(
break;
cond_resched();
}
- if (written)
+ if (written) {
+ tty_update_time(&file_inode(file)->i_mtime);
ret = written;
+ }
out:
tty_write_unlock(tty);
return ret;