kernel/include/net/icmp.h, branch linux-4.14.y

net: icmp: pass zeroed opts from icmp{,v6}_ndo_send before sending

2021-03-03T17:22:57Z

commit ee576c47db60432c37e54b1e2b43a8ca6d3a8dca upstream. The icmp{,v6}_send functions make all sorts of use of skb->cb, casting it with IPCB or IP6CB, assuming the skb to have come directly from the inet layer. But when the packet comes from the ndo layer, especially when forwarded, there's no telling what might be in skb->cb at that point. As a result, the icmp sending code risks reading bogus memory contents, which can result in nasty stack overflows such as this one reported by a user: panic+0x108/0x2ea __stack_chk_fail+0x14/0x20 __icmp_send+0x5bd/0x5c0 icmp_ndo_send+0x148/0x160 In icmp_send, skb->cb is cast with IPCB and an ip_options struct is read from it. The optlen parameter there is of particular note, as it can induce writes beyond bounds. There are quite a few ways that can happen in __ip_options_echo. For example: // sptr/skb are attacker-controlled skb bytes sptr = skb_network_header(skb); // dptr/dopt points to stack memory allocated by __icmp_send dptr = dopt->__data; // sopt is the corrupt skb->cb in question if (sopt->rr) { optlen = sptr[sopt->rr+1]; // corrupt skb->cb + skb->data soffset = sptr[sopt->rr+2]; // corrupt skb->cb + skb->data // this now writes potentially attacker-controlled data, over // flowing the stack: memcpy(dptr, sptr+sopt->rr, optlen); } In the icmpv6_send case, the story is similar, but not as dire, as only IP6CB(skb)->iif and IP6CB(skb)->dsthao are used. The dsthao case is worse than the iif case, but it is passed to ipv6_find_tlv, which does a bit of bounds checking on the value. This is easy to simulate by doing a `memset(skb->cb, 0x41, sizeof(skb->cb));` before calling icmp{,v6}_ndo_send, and it's only by good fortune and the rarity of icmp sending from that context that we've avoided reports like this until now. For example, in KASAN: BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0xa0e/0x12b0 Write of size 38 at addr ffff888006f1f80e by task ping/89 CPU: 2 PID: 89 Comm: ping Not tainted 5.10.0-rc7-debug+ #5 Call Trace: dump_stack+0x9a/0xcc print_address_description.constprop.0+0x1a/0x160 __kasan_report.cold+0x20/0x38 kasan_report+0x32/0x40 check_memory_region+0x145/0x1a0 memcpy+0x39/0x60 __ip_options_echo+0xa0e/0x12b0 __icmp_send+0x744/0x1700 Actually, out of the 4 drivers that do this, only gtp zeroed the cb for the v4 case, while the rest did not. So this commit actually removes the gtp-specific zeroing, while putting the code where it belongs in the shared infrastructure of icmp{,v6}_ndo_send. This commit fixes the issue by passing an empty IPCB or IP6CB along to the functions that actually do the work. For the icmp_send, this was already trivial, thanks to __icmp_send providing the plumbing function. For icmpv6_send, this required a tiny bit of refactoring to make it behave like the v4 case, after which it was straight forward. Fixes: a2b78e9b2cac ("sunvnet: generate ICMP PTMUD messages for smaller port MTUs") Reported-by: SinYu Reviewed-by: Willem de Bruijn Link: https://lore.kernel.org/netdev/CAF=yD-LOF116aHub6RMe8vB8ZpnrrnoTdqhobEx+bvoA8AsP0w@mail.gmail.com/T/ Signed-off-by: Jason A. Donenfeld Link: https://lore.kernel.org/r/20210223131858.72082-1-Jason@zx2c4.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman

icmp: introduce helper for nat'd source address in network device context

2021-03-03T17:22:56Z

commit 0b41713b606694257b90d61ba7e2712d8457648b upstream. This introduces a helper function to be called only by network drivers that wraps calls to icmp[v6]_send in a conntrack transformation, in case NAT has been used. We don't want to pollute the non-driver path, though, so we introduce this as a helper to be called by places that actually make use of this, as suggested by Florian. Signed-off-by: Jason A. Donenfeld Cc: Florian Westphal Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: Add __icmp_send helper.

2019-03-13T21:03:09Z

[ Upstream commit 9ef6b42ad6fd7929dd1b6092cb02014e382c6a91 ] Add __icmp_send function having ip_options struct parameter Signed-off-by: Sergey Nazarov Reviewed-by: Paul Moore Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman

net: snmp: kill STATS_BH macros

2016-04-28T02:48:25Z

There is nothing related to BH in SNMP counters anymore, since linux-3.0. Rename helpers to use __ prefix instead of _BH prefix, for contexts where preemption is disabled. This more closely matches convention used to update percpu variables. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: icmp: rename ICMPMSGIN_INC_STATS_BH()

2016-04-28T02:48:23Z

Remove misleading _BH suffix. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: rename ICMP_INC_STATS_BH()

2016-04-28T02:48:22Z

Rename ICMP_INC_STATS_BH() to __ICMP_INC_STATS() Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

icmp.h: Remove extern from function prototypes

2013-09-20T18:49:33Z

There are a mix of function prototypes with and without extern in the kernel sources. Standardize on not using extern for function prototypes. Function prototypes don't need to be written with extern. extern is assumed by the compiler. Its use is as unnecessary as using auto to declare automatic/local variables in a block. Signed-off-by: Joe Perches Signed-off-by: David S. Miller

ipv4: fix error handling in icmp_protocol.

2013-02-22T20:10:18Z

Now we handle icmp errors in each transport protocol's err_handler, for icmp protocols, that is ping_err. Since this handler only care of those icmp errors triggered by echo request, errors triggered by echo reply(which sent by kernel) are sliently ignored. So wrap ping_err() with icmp_err() to deal with those icmp errors. Signed-off-by: Li Wei Signed-off-by: David S. Miller

net: cleanup unsigned to unsigned int

2012-04-15T16:44:40Z

Use of "unsigned int" is preferred to bare "unsigned" in net tree. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller

net: remove unused icmp_ioctl() definition.

2012-04-02T08:33:46Z

The patch removes unused icmp_ioctl() method definition in include/net/icmp.h. Signed-off-by: Rami Rosen Signed-off-by: David S. Miller