| Message ID | 17208ec89e09ed7223ffd2302abfa3475255c384.1492769294.git.sd@queasysnail.net |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Fri, Apr 21, 2017 at 12:14:51PM +0200, Sabrina Dubroca wrote: > When CONFIG_XFRM_SUB_POLICY=y, xfrm_dst stores a copy of the flowi for > that dst. Unfortunately, the code that allocates and fills this copy > doesn't care about what type of flowi (flowi, flowi4, flowi6) gets > passed. In multiple code paths (from raw_sendmsg, from TCP when > replying to a FIN, in vxlan, geneve, and gre), the flowi that gets > passed to xfrm is actually an on-stack flowi4, so we end up reading > memory on the stack past the end of the flowi4 struct. > > Since xfrm_dst->origin isn't used anywhere, just get rid of it. > xfrm_dst->partner isn't used either, so get rid of that too. > > Fixes: ca116922afa8 ("xfrm: Eliminate "fl" and "pol" args to xfrm_bundle_ok().") The commit you refer to here doesn't seem to have caused this bug. Thanks,
2017-04-21, 19:06:44 +0800, Herbert Xu wrote: > On Fri, Apr 21, 2017 at 12:14:51PM +0200, Sabrina Dubroca wrote: > > When CONFIG_XFRM_SUB_POLICY=y, xfrm_dst stores a copy of the flowi for > > that dst. Unfortunately, the code that allocates and fills this copy > > doesn't care about what type of flowi (flowi, flowi4, flowi6) gets > > passed. In multiple code paths (from raw_sendmsg, from TCP when > > replying to a FIN, in vxlan, geneve, and gre), the flowi that gets > > passed to xfrm is actually an on-stack flowi4, so we end up reading > > memory on the stack past the end of the flowi4 struct. > > > > Since xfrm_dst->origin isn't used anywhere, just get rid of it. > > xfrm_dst->partner isn't used either, so get rid of that too. > > > > Fixes: ca116922afa8 ("xfrm: Eliminate "fl" and "pol" args to xfrm_bundle_ok().") > > The commit you refer to here doesn't seem to have caused this bug. You're right. I had a note about that but it got lost. The bug (ignoring what flavor of flowi is passed) is older than that (from the introduction of subpolicies, I suspect, but I would have to dig more into the history), but this commit removed the last uses of origin/partner. Looking into raw_sendmsg(), this code may have been safe before 9d6ec938019c ("ipv4: Use flowi4 in public route lookup interfaces."), since full flowi were used. If we want a fix for kernels that don't have ca116922afa8, we would probably need to take the size of the flowi* struct depending on the address family passed to xfrm_resolve_and_create_bundle(). I'm not sure how to proceed here, any advice? Thanks,
On Fri, Apr 21, 2017 at 02:05:31PM +0200, Sabrina Dubroca wrote: > > You're right. I had a note about that but it got lost. The bug > (ignoring what flavor of flowi is passed) is older than that (from the > introduction of subpolicies, I suspect, but I would have to dig more > into the history), but this commit removed the last uses of > origin/partner. > > Looking into raw_sendmsg(), this code may have been safe before > 9d6ec938019c ("ipv4: Use flowi4 in public route lookup interfaces."), > since full flowi were used. > > If we want a fix for kernels that don't have ca116922afa8, we would > probably need to take the size of the flowi* struct depending on the > address family passed to xfrm_resolve_and_create_bundle(). > > > I'm not sure how to proceed here, any advice? I think the Fixes header should simply refer to the commit that introduced the bug. You're instead using it as a hint for how to backport the patch. That is beyond the scope of the Fixes header. So if the bug started with 9d6ec938019c then just use that in your Fixes header. If you want to help the backporter with more information then you can put ca116922afa8 in the body of the commit description. Cheers,
diff --git a/include/net/xfrm.h b/include/net/xfrm.h index 14d82bf16692..85bc8e7ade2e 100644 --- a/include/net/xfrm.h +++ b/include/net/xfrm.h @@ -945,10 +945,6 @@ struct xfrm_dst { struct flow_cache_object flo; struct xfrm_policy *pols[XFRM_POLICY_TYPE_MAX]; int num_pols, num_xfrms; -#ifdef CONFIG_XFRM_SUB_POLICY - struct flowi *origin; - struct xfrm_selector *partner; -#endif u32 xfrm_genid; u32 policy_genid; u32 route_mtu_cached; @@ -964,12 +960,6 @@ static inline void xfrm_dst_destroy(struct xfrm_dst *xdst) dst_release(xdst->route); if (likely(xdst->u.dst.xfrm)) xfrm_state_put(xdst->u.dst.xfrm); -#ifdef CONFIG_XFRM_SUB_POLICY - kfree(xdst->origin); - xdst->origin = NULL; - kfree(xdst->partner); - xdst->partner = NULL; -#endif } #endif diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index 236cbbc0ab9c..56fba8f073f5 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1793,43 +1793,6 @@ static struct dst_entry *xfrm_bundle_create(struct xfrm_policy *policy, goto out; } -#ifdef CONFIG_XFRM_SUB_POLICY -static int xfrm_dst_alloc_copy(void **target, const void *src, int size) -{ - if (!*target) { - *target = kmalloc(size, GFP_ATOMIC); - if (!*target) - return -ENOMEM; - } - - memcpy(*target, src, size); - return 0; -} -#endif - -static int xfrm_dst_update_parent(struct dst_entry *dst, - const struct xfrm_selector *sel) -{ -#ifdef CONFIG_XFRM_SUB_POLICY - struct xfrm_dst *xdst = (struct xfrm_dst *)dst; - return xfrm_dst_alloc_copy((void **)&(xdst->partner), - sel, sizeof(*sel)); -#else - return 0; -#endif -} - -static int xfrm_dst_update_origin(struct dst_entry *dst, - const struct flowi *fl) -{ -#ifdef CONFIG_XFRM_SUB_POLICY - struct xfrm_dst *xdst = (struct xfrm_dst *)dst; - return xfrm_dst_alloc_copy((void **)&(xdst->origin), fl, sizeof(*fl)); -#else - return 0; -#endif -} - static int xfrm_expand_policies(const struct flowi *fl, u16 family, struct xfrm_policy **pols, int *num_pols, int *num_xfrms) @@ -1901,16 +1864,6 @@ xfrm_resolve_and_create_bundle(struct xfrm_policy **pols, int num_pols, xdst = (struct xfrm_dst *)dst; xdst->num_xfrms = err; - if (num_pols > 1) - err = xfrm_dst_update_parent(dst, &pols[1]->selector); - else - err = xfrm_dst_update_origin(dst, fl); - if (unlikely(err)) { - dst_free(dst); - XFRM_INC_STATS(net, LINUX_MIB_XFRMOUTBUNDLECHECKERROR); - return ERR_PTR(err); - } - xdst->num_pols = num_pols; memcpy(xdst->pols, pols, sizeof(struct xfrm_policy *) * num_pols); xdst->policy_genid = atomic_read(&pols[0]->genid);
When CONFIG_XFRM_SUB_POLICY=y, xfrm_dst stores a copy of the flowi for that dst. Unfortunately, the code that allocates and fills this copy doesn't care about what type of flowi (flowi, flowi4, flowi6) gets passed. In multiple code paths (from raw_sendmsg, from TCP when replying to a FIN, in vxlan, geneve, and gre), the flowi that gets passed to xfrm is actually an on-stack flowi4, so we end up reading memory on the stack past the end of the flowi4 struct. Since xfrm_dst->origin isn't used anywhere, just get rid of it. xfrm_dst->partner isn't used either, so get rid of that too. Fixes: ca116922afa8 ("xfrm: Eliminate "fl" and "pol" args to xfrm_bundle_ok().") Signed-off-by: Sabrina Dubroca <sd@queasysnail.net> --- include/net/xfrm.h | 10 ---------- net/xfrm/xfrm_policy.c | 47 ----------------------------------------------- 2 files changed, 57 deletions(-)