On 1/30/2024 12:29 AM, Ondrej Mosnacek wrote: > On Tue, Jan 30, 2024 at 4:01 AM Paul Moore <paul@xxxxxxxxxxxxxx> wrote: >> On Mon, Jan 29, 2024 at 6:25 PM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: >>> On 1/29/2024 3:02 PM, Paul Moore wrote: >>>> On Fri, Jan 26, 2024 at 1:45 PM Ondrej Mosnacek <omosnace@xxxxxxxxxx> wrote: >>>>> For these hooks the true "neutral" value is -EOPNOTSUPP, which is >>>>> currently what is returned when no LSM provides this hook and what LSMs >>>>> return when there is no security context set on the socket. Correct the >>>>> value in <linux/lsm_hooks.h> and adjust the dispatch functions in >>>>> security/security.c to avoid issues when the BPF LSM is enabled. >>>>> >>>>> Fixes: 98e828a0650f ("security: Refactor declaration of LSM hooks") >>>>> Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx> >>>>> --- >>>>> include/linux/lsm_hook_defs.h | 4 ++-- >>>>> security/security.c | 31 +++++++++++++++++++++++++++---- >>>>> 2 files changed, 29 insertions(+), 6 deletions(-) >>>>> >>>>> diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h >>>>> index 185924c56378..76458b6d53da 100644 >>>>> --- a/include/linux/lsm_hook_defs.h >>>>> +++ b/include/linux/lsm_hook_defs.h >>>>> @@ -315,9 +315,9 @@ LSM_HOOK(int, 0, socket_getsockopt, struct socket *sock, int level, int optname) >>>>> LSM_HOOK(int, 0, socket_setsockopt, struct socket *sock, int level, int optname) >>>>> LSM_HOOK(int, 0, socket_shutdown, struct socket *sock, int how) >>>>> LSM_HOOK(int, 0, socket_sock_rcv_skb, struct sock *sk, struct sk_buff *skb) >>>>> -LSM_HOOK(int, 0, socket_getpeersec_stream, struct socket *sock, >>>>> +LSM_HOOK(int, -ENOPROTOOPT, socket_getpeersec_stream, struct socket *sock, >>>>> sockptr_t optval, sockptr_t optlen, unsigned int len) >>>>> -LSM_HOOK(int, 0, socket_getpeersec_dgram, struct socket *sock, >>>>> +LSM_HOOK(int, -ENOPROTOOPT, socket_getpeersec_dgram, struct socket *sock, >>>>> struct sk_buff *skb, u32 *secid) >>>>> LSM_HOOK(int, 0, sk_alloc_security, struct sock *sk, int family, gfp_t priority) >>>>> LSM_HOOK(void, LSM_RET_VOID, sk_free_security, struct sock *sk) >>>>> diff --git a/security/security.c b/security/security.c >>>>> index 6196ccaba433..3aaad75c9ce8 100644 >>>>> --- a/security/security.c >>>>> +++ b/security/security.c >>>>> @@ -4624,8 +4624,20 @@ EXPORT_SYMBOL(security_sock_rcv_skb); >>>>> int security_socket_getpeersec_stream(struct socket *sock, sockptr_t optval, >>>>> sockptr_t optlen, unsigned int len) >>>>> { >>>>> - return call_int_hook(socket_getpeersec_stream, -ENOPROTOOPT, sock, >>>>> - optval, optlen, len); >>>>> + struct security_hook_list *hp; >>>>> + int rc; >>>>> + >>>>> + /* >>>>> + * Only one module will provide a security context. >>>>> + */ >>>>> + hlist_for_each_entry(hp, &security_hook_heads.socket_getpeersec_stream, >>>>> + list) { >>>>> + rc = hp->hook.socket_getpeersec_stream(sock, optval, optlen, >>>>> + len); >>>>> + if (rc != LSM_RET_DEFAULT(socket_getpeersec_stream)) >>>>> + return rc; >>>>> + } >>>>> + return LSM_RET_DEFAULT(socket_getpeersec_stream); >>>>> } >>>> I'm beginning to wonder if we shouldn't update call_int_hook() so that >>>> it works for LSM_RET_DEFAULT() instead of assuming a zero/0 return >>>> value. Thoughts? >>> call_int_hook() was intended to address the "normal" case, where all >>> hooks registered would be called and the first error, if any, would >>> result in an immediate failure return. Hooks that behaved in any other >>> manner were expected to be open coded. The point of using the macros >>> was to reduce so much code duplication. I really don't want to see >>> call_int_hook() evolve into something hard to work with, or that has >>> non-obvious side effects. I think we could probably integrate >>> LSM_RET_DEFAULT() safely, but I'm wary of hiding these abnormal cases >>> in the macro. >> Yes, I'm not talking about modifying call_int_hook() to handle >> something like security_vm_enough_memory_mm(), I'm just talking about >> updating it use LSM_RET_DEFAULT() instead of zero. >> >> While we are at it, we should probably get rid of the second parameter >> too, @IRC, and just use the assigned LSM_RET_DEFAULT(). That always >> struck me as a bug waiting to happen if/when those two fell out of >> sync. > You're reading my mind :) I already started writing a patch that does > exactly that after I posted the security_inode_getsecctx() patch. > While working on it I gradually found two more pre-existing issues, so > I wanted to post fixes for them before the refactor for better > backportability. I should be able to post the patch today. > > BTW, the IRC param removal means that a few of the existing > call_int_hook() calls have to be open-coded, but even then the patch > removes more LoC than it adds, so I think it's worth it. OK, I'm good with it. Getting rid of @IRC is the clincher.