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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2006-12-08 05:36:04 -0500
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-08 11:28:38 -0500
commit24ec839c431eb79bb8f6abc00c4e1eb3b8c4d517 (patch)
tree2ff478b1925159eeac007913c2a8f19d5f5e6010 /security
parent562f9c574e0707f9159a729ea41faf53b221cd30 (diff)
[PATCH] tty: ->signal->tty locking
Fix the locking of signal->tty. Use ->sighand->siglock to protect ->signal->tty; this lock is already used by most other members of ->signal/->sighand. And unless we are 'current' or the tasklist_lock is held we need ->siglock to access ->signal anyway. (NOTE: sys_unshare() is broken wrt ->sighand locking rules) Note that tty_mutex is held over tty destruction, so while holding tty_mutex any tty pointer remains valid. Otherwise the lifetime of ttys are governed by their open file handles. This leaves some holes for tty access from signal->tty (or any other non file related tty access). It solves the tty SLAB scribbles we were seeing. (NOTE: the change from group_send_sig_info to __group_send_sig_info needs to be examined by someone familiar with the security framework, I think it is safe given the SEND_SIG_PRIV from other __group_send_sig_info invocations) [schwidefsky@de.ibm.com: 3270 fix] [akpm@osdl.org: various post-viro fixes] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Alan Cox <alan@redhat.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Prarit Bhargava <prarit@redhat.com> Cc: Chris Wright <chrisw@sous-sol.org> Cc: Roland McGrath <roland@redhat.com> Cc: Stephen Smalley <sds@tycho.nsa.gov> Cc: James Morris <jmorris@namei.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Jeff Dike <jdike@addtoit.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jan Kara <jack@ucw.cz> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/hooks.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 44e9cd470543..f5df8c70a9b5 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1695,9 +1695,10 @@ static inline void flush_unauthorized_files(struct files_struct * files)
1695 struct tty_struct *tty; 1695 struct tty_struct *tty;
1696 struct fdtable *fdt; 1696 struct fdtable *fdt;
1697 long j = -1; 1697 long j = -1;
1698 int drop_tty = 0;
1698 1699
1699 mutex_lock(&tty_mutex); 1700 mutex_lock(&tty_mutex);
1700 tty = current->signal->tty; 1701 tty = get_current_tty();
1701 if (tty) { 1702 if (tty) {
1702 file_list_lock(); 1703 file_list_lock();
1703 file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list); 1704 file = list_entry(tty->tty_files.next, typeof(*file), f_u.fu_list);
@@ -1710,12 +1711,14 @@ static inline void flush_unauthorized_files(struct files_struct * files)
1710 struct inode *inode = file->f_dentry->d_inode; 1711 struct inode *inode = file->f_dentry->d_inode;
1711 if (inode_has_perm(current, inode, 1712 if (inode_has_perm(current, inode,
1712 FILE__READ | FILE__WRITE, NULL)) { 1713 FILE__READ | FILE__WRITE, NULL)) {
1713 /* Reset controlling tty. */ 1714 drop_tty = 1;
1714 current->signal->tty = NULL;
1715 current->signal->tty_old_pgrp = 0;
1716 } 1715 }
1717 } 1716 }
1718 file_list_unlock(); 1717 file_list_unlock();
1718
1719 /* Reset controlling tty. */
1720 if (drop_tty)
1721 proc_set_tty(current, NULL);
1719 } 1722 }
1720 mutex_unlock(&tty_mutex); 1723 mutex_unlock(&tty_mutex);
1721 1724