From 44d37ad3602b3823764eeb0f6c1ee3ef6c4fb936 Mon Sep 17 00:00:00 2001 From: Jeff Vander Stoep Date: Wed, 21 Oct 2015 17:44:25 -0400 Subject: [PATCH] selinux: do not check open perm on ftruncate call Use the ATTR_FILE attribute to distinguish between truncate() and ftruncate() system calls. The two other cases where do_truncate is called with a filp (and therefore ATTR_FILE is set) are for coredump files and for open(O_TRUNC). In both of those cases the open permission has already been checked during file open and therefore does not need to be repeated. Commit 95dbf739313f ("SELinux: check OPEN on truncate calls") fixed a major issue where domains were allowed to truncate files without the open permission. However, it introduced a new bug where a domain with the write permission can no longer ftruncate files without the open permission, even when they receive an already open file. Signed-off-by: Jeff Vander Stoep Acked-by: Stephen Smalley Signed-off-by: Paul Moore --- security/selinux/hooks.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index e4369d86e588..7cd71cea0503 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2946,7 +2946,8 @@ static int selinux_inode_setattr(struct dentry *dentry, struct iattr *iattr) ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_TIMES_SET)) return dentry_has_perm(cred, dentry, FILE__SETATTR); - if (selinux_policycap_openperm && (ia_valid & ATTR_SIZE)) + if (selinux_policycap_openperm && (ia_valid & ATTR_SIZE) + && !(ia_valid & ATTR_FILE)) av |= FILE__OPEN; return dentry_has_perm(cred, dentry, av); -- 2.39.5