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authorMiloslav Trmac <mitr@redhat.com>2007-07-15 23:40:56 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-07-16 09:05:47 -0700
commit522ed7767e800cff6c650ec64b0ee0677303119c (patch)
treef65ecb29f2cf885018d3557f840de3ef4be6ec64 /drivers/char/n_tty.c
parent4f27c00bf80f122513d3a5be16ed851573164534 (diff)
downloadlinux-linaro-stable-522ed7767e800cff6c650ec64b0ee0677303119c.tar.gz
Audit: add TTY input auditing
Add TTY input auditing, used to audit system administrator's actions. This is required by various security standards such as DCID 6/3 and PCI to provide non-repudiation of administrator's actions and to allow a review of past actions if the administrator seems to overstep their duties or if the system becomes misconfigured for unknown reasons. These requirements do not make it necessary to audit TTY output as well. Compared to an user-space keylogger, this approach records TTY input using the audit subsystem, correlated with other audit events, and it is completely transparent to the user-space application (e.g. the console ioctls still work). TTY input auditing works on a higher level than auditing all system calls within the session, which would produce an overwhelming amount of mostly useless audit events. Add an "audit_tty" attribute, inherited across fork (). Data read from TTYs by process with the attribute is sent to the audit subsystem by the kernel. The audit netlink interface is extended to allow modifying the audit_tty attribute, and to allow sending explanatory audit events from user-space (for example, a shell might send an event containing the final command, after the interactive command-line editing and history expansion is performed, which might be difficult to decipher from the TTY input alone). Because the "audit_tty" attribute is inherited across fork (), it would be set e.g. for sshd restarted within an audited session. To prevent this, the audit_tty attribute is cleared when a process with no open TTY file descriptors (e.g. after daemon startup) opens a TTY. See https://www.redhat.com/archives/linux-audit/2007-June/msg00000.html for a more detailed rationale document for an older version of this patch. [akpm@linux-foundation.org: build fix] Signed-off-by: Miloslav Trmac <mitr@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Paul Fulghum <paulkf@microgate.com> Cc: Casey Schaufler <casey@schaufler-ca.com> Cc: Steve Grubb <sgrubb@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/char/n_tty.c')
-rw-r--r--drivers/char/n_tty.c20
1 files changed, 16 insertions, 4 deletions
diff --git a/drivers/char/n_tty.c b/drivers/char/n_tty.c
index 371631f4bfb9..038056911934 100644
--- a/drivers/char/n_tty.c
+++ b/drivers/char/n_tty.c
@@ -45,6 +45,8 @@
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/bitops.h>
+#include <linux/audit.h>
+#include <linux/file.h>
#include <asm/uaccess.h>
#include <asm/system.h>
@@ -78,6 +80,13 @@ static inline void free_buf(unsigned char *buf)
free_page((unsigned long) buf);
}
+static inline int tty_put_user(struct tty_struct *tty, unsigned char x,
+ unsigned char __user *ptr)
+{
+ tty_audit_add_data(tty, &x, 1);
+ return put_user(x, ptr);
+}
+
/**
* n_tty_set__room - receive space
* @tty: terminal
@@ -1153,6 +1162,7 @@ static int copy_from_read_buf(struct tty_struct *tty,
if (n) {
retval = copy_to_user(*b, &tty->read_buf[tty->read_tail], n);
n -= retval;
+ tty_audit_add_data(tty, &tty->read_buf[tty->read_tail], n);
spin_lock_irqsave(&tty->read_lock, flags);
tty->read_tail = (tty->read_tail + n) & (N_TTY_BUF_SIZE-1);
tty->read_cnt -= n;
@@ -1279,7 +1289,7 @@ do_it_again:
break;
cs = tty->link->ctrl_status;
tty->link->ctrl_status = 0;
- if (put_user(cs, b++)) {
+ if (tty_put_user(tty, cs, b++)) {
retval = -EFAULT;
b--;
break;
@@ -1321,7 +1331,7 @@ do_it_again:
/* Deal with packet mode. */
if (tty->packet && b == buf) {
- if (put_user(TIOCPKT_DATA, b++)) {
+ if (tty_put_user(tty, TIOCPKT_DATA, b++)) {
retval = -EFAULT;
b--;
break;
@@ -1352,15 +1362,17 @@ do_it_again:
spin_unlock_irqrestore(&tty->read_lock, flags);
if (!eol || (c != __DISABLED_CHAR)) {
- if (put_user(c, b++)) {
+ if (tty_put_user(tty, c, b++)) {
retval = -EFAULT;
b--;
break;
}
nr--;
}
- if (eol)
+ if (eol) {
+ tty_audit_push(tty);
break;
+ }
}
if (retval)
break;