Ondrej Mosnacek a28124e8ad selinux: fix race between old and new sidtab ... commit 9ad6e9cb39c66366bf7b9aece114aca277981a1f upstream. Since commit 1b8b31a2e6 ("selinux: convert policy read-write lock to RCU"), there is a small window during policy load where the new policy pointer has already been installed, but some threads may still be holding the old policy pointer in their read-side RCU critical sections. This means that there may be conflicting attempts to add a new SID entry to both tables via sidtab_context_to_sid(). See also (and the rest of the thread): https://lore.kernel.org/selinux/CAFqZXNvfux46_f8gnvVvRYMKoes24nwm2n3sPbMjrB8vKTW00g@mail.gmail.com/ Fix this by installing the new policy pointer under the old sidtab's spinlock along with marking the old sidtab as "frozen". Then, if an attempt to add new entry to a "frozen" sidtab is detected, make sidtab_context_to_sid() return -ESTALE to indicate that a new policy has been installed and that the caller will have to abort the policy transaction and try again after re-taking the policy pointer (which is guaranteed to be a newer policy). This requires adding a retry-on-ESTALE logic to all callers of sidtab_context_to_sid(), but fortunately these are easy to determine and aren't that many. This seems to be the simplest solution for this problem, even if it looks somewhat ugly. Note that other places in the kernel (e.g. do_mknodat() in fs/namei.c) use similar stale-retry patterns, so I think it's reasonable. Cc: stable@vger.kernel.org Fixes: 1b8b31a2e6 ("selinux: convert policy read-write lock to RCU") Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com> Signed-off-by: Paul Moore <paul@paul-moore.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2021-04-14 08:41:57 +02:00
..
include	selinux: fix variable scope issue in live sidtab conversion	2021-03-30 14:31:53 +02:00
ss	selinux: fix race between old and new sidtab	2021-04-14 08:41:57 +02:00
.gitignore
avc.c
hooks.c	selinux: fix inconsistency between inode_getxattr and inode_listsecurity	2021-03-04 11:38:28 +01:00
ibpkey.c	selinux: Fix error return code in sel_ib_pkey_sid_slow()	2020-11-12 20:16:09 -05:00
Kconfig
Makefile
netif.c
netlabel.c
netlink.c
netnode.c
netport.c
nlmsgtab.c
selinuxfs.c	selinux: fix variable scope issue in live sidtab conversion	2021-03-30 14:31:53 +02:00
status.c
xfrm.c