From 037b0b86ecf5646f8eae777d8b52ff8b401692ec Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 16 Aug 2018 21:49:06 +0200 Subject: tcp, ulp: add alias for all ulp modules Lets not turn the TCP ULP lookup into an arbitrary module loader as we only intend to load ULP modules through this mechanism, not other unrelated kernel modules: [root@bar]# cat foo.c #include #include #include #include int main(void) { int sock = socket(PF_INET, SOCK_STREAM, 0); setsockopt(sock, IPPROTO_TCP, TCP_ULP, "sctp", sizeof("sctp")); return 0; } [root@bar]# gcc foo.c -O2 -Wall [root@bar]# lsmod | grep sctp [root@bar]# ./a.out [root@bar]# lsmod | grep sctp sctp 1077248 4 libcrc32c 16384 3 nf_conntrack,nf_nat,sctp [root@bar]# Fix it by adding module alias to TCP ULP modules, so probing module via request_module() will be limited to tcp-ulp-[name]. The existing modules like kTLS will load fine given tcp-ulp-tls alias, but others will fail to load: [root@bar]# lsmod | grep sctp [root@bar]# ./a.out [root@bar]# lsmod | grep sctp [root@bar]# Sockmap is not affected from this since it's either built-in or not. Fixes: 734942cc4ea6 ("tcp: ULP infrastructure") Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Acked-by: Song Liu Signed-off-by: Alexei Starovoitov --- include/net/tcp.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/net/tcp.h b/include/net/tcp.h index d196901c9dba..770917d0caa7 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -2065,6 +2065,10 @@ int tcp_set_ulp_id(struct sock *sk, const int ulp); void tcp_get_available_ulp(char *buf, size_t len); void tcp_cleanup_ulp(struct sock *sk); +#define MODULE_ALIAS_TCP_ULP(name) \ + __MODULE_INFO(alias, alias_userspace, name); \ + __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name) + /* Call BPF_SOCK_OPS program that returns an int. If the return value * is < 0, then the BPF op failed (for example if the loaded BPF * program does not support the chosen operation or there is no BPF -- cgit v1.2.3 From f6069b9aa9934ede26f41ac0781fce241279ad43 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 17 Aug 2018 23:26:14 +0200 Subject: bpf: fix redirect to map under tail calls Commits 109980b894e9 ("bpf: don't select potentially stale ri->map from buggy xdp progs") and 7c3001313396 ("bpf: fix ri->map_owner pointer on bpf_prog_realloc") tried to mitigate that buggy programs using bpf_redirect_map() helper call do not leave stale maps behind. Idea was to add a map_owner cookie into the per CPU struct redirect_info which was set to prog->aux by the prog making the helper call as a proof that the map is not stale since the prog is implicitly holding a reference to it. This owner cookie could later on get compared with the program calling into BPF whether they match and therefore the redirect could proceed with processing the map safely. In (obvious) hindsight, this approach breaks down when tail calls are involved since the original caller's prog->aux pointer does not have to match the one from one of the progs out of the tail call chain, and therefore the xdp buffer will be dropped instead of redirected. A way around that would be to fix the issue differently (which also allows to remove related work in fast path at the same time): once the life-time of a redirect map has come to its end we use it's map free callback where we need to wait on synchronize_rcu() for current outstanding xdp buffers and remove such a map pointer from the redirect info if found to be present. At that time no program is using this map anymore so we simply invalidate the map pointers to NULL iff they previously pointed to that instance while making sure that the redirect path only reads out the map once. Fixes: 97f91a7cf04f ("bpf: add bpf_redirect_map helper routine") Fixes: 109980b894e9 ("bpf: don't select potentially stale ri->map from buggy xdp progs") Reported-by: Sebastiano Miano Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Signed-off-by: Alexei Starovoitov --- include/linux/filter.h | 3 ++- include/trace/events/xdp.h | 5 ++--- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'include') diff --git a/include/linux/filter.h b/include/linux/filter.h index 5d565c50bcb2..6791a0ac0139 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -543,7 +543,6 @@ struct bpf_redirect_info { u32 flags; struct bpf_map *map; struct bpf_map *map_to_flush; - unsigned long map_owner; u32 kern_flags; }; @@ -781,6 +780,8 @@ static inline bool bpf_dump_raw_ok(void) struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, const struct bpf_insn *patch, u32 len); +void bpf_clear_redirect_map(struct bpf_map *map); + static inline bool xdp_return_frame_no_direct(void) { struct bpf_redirect_info *ri = this_cpu_ptr(&bpf_redirect_info); diff --git a/include/trace/events/xdp.h b/include/trace/events/xdp.h index 1ecf4c67fcf7..e95cb86b65cf 100644 --- a/include/trace/events/xdp.h +++ b/include/trace/events/xdp.h @@ -147,9 +147,8 @@ struct _bpf_dtab_netdev { #define devmap_ifindex(fwd, map) \ (!fwd ? 0 : \ - (!map ? 0 : \ - ((map->map_type == BPF_MAP_TYPE_DEVMAP) ? \ - ((struct _bpf_dtab_netdev *)fwd)->dev->ifindex : 0))) + ((map->map_type == BPF_MAP_TYPE_DEVMAP) ? \ + ((struct _bpf_dtab_netdev *)fwd)->dev->ifindex : 0)) #define _trace_xdp_redirect_map(dev, xdp, fwd, map, idx) \ trace_xdp_redirect_map(dev, xdp, devmap_ifindex(fwd, map), \ -- cgit v1.2.3