linux/kernel/bpf, branch v4.19

xsk: do not call synchronize_net() under RCU read lock

2018-10-11T08:19:01Z

The XSKMAP update and delete functions called synchronize_net(), which can sleep. It is not allowed to sleep during an RCU read section. Instead we need to make sure that the sock sk_destruct (xsk_destruct) function is asynchronously called after an RCU grace period. Setting the SOCK_RCU_FREE flag for XDP sockets takes care of this. Fixes: fbfc504a24f5 ("bpf: introduce new bpf AF_XDP map type BPF_MAP_TYPE_XSKMAP") Reported-by: Eric Dumazet Signed-off-by: Björn Töpel Acked-by: Song Liu Signed-off-by: Daniel Borkmann

bpf: 32-bit RSH verification must truncate input before the ALU op

2018-10-05T16:41:45Z

When I wrote commit 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification"), I assumed that, in order to emulate 64-bit arithmetic with 32-bit logic, it is sufficient to just truncate the output to 32 bits; and so I just moved the register size coercion that used to be at the start of the function to the end of the function. That assumption is true for almost every op, but not for 32-bit right shifts, because those can propagate information towards the least significant bit. Fix it by always truncating inputs for 32-bit ops to 32 bits. Also get rid of the coerce_reg_to_size() after the ALU op, since that has no effect. Fixes: 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification") Acked-by: Daniel Borkmann Signed-off-by: Jann Horn Signed-off-by: Daniel Borkmann

bpf: don't accept cgroup local storage with zero value size

2018-10-02T12:42:23Z

Explicitly forbid creating cgroup local storage maps with zero value size, as it makes no sense and might even cause a panic. Reported-by: syzbot+18628320d3b14a5c459c@syzkaller.appspotmail.com Signed-off-by: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: Daniel Borkmann

bpf: harden flags check in cgroup_storage_update_elem()

2018-09-28T13:50:23Z

cgroup_storage_update_elem() shouldn't accept any flags argument values except BPF_ANY and BPF_EXIST to guarantee the backward compatibility, had a new flag value been added. Fixes: de9cbbaadba5 ("bpf: introduce cgroup storage maps") Signed-off-by: Roman Gushchin Reported-by: Daniel Borkmann Cc: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: sockmap, fix transition through disconnect without close

2018-09-22T00:46:41Z

It is possible (via shutdown()) for TCP socks to go trough TCP_CLOSE state via tcp_disconnect() without actually calling tcp_close which would then call our bpf_tcp_close() callback. Because of this a user could disconnect a socket then put it in a LISTEN state which would break our assumptions about sockets always being ESTABLISHED state. To resolve this rely on the unhash hook, which is called in the disconnect case, to remove the sock from the sockmap. Reported-by: Eric Dumazet Fixes: 1aa12bdf1bfb ("bpf: sockmap, add sock close() hook to remove socks") Signed-off-by: John Fastabend Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann

bpf: sockmap only allow ESTABLISHED sock state

2018-09-22T00:46:41Z

After this patch we only allow socks that are in ESTABLISHED state or are being added via a sock_ops event that is transitioning into an ESTABLISHED state. By allowing sock_ops events we allow users to manage sockmaps directly from sock ops programs. The two supported sock_ops ops are BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB and BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB. Similar to TLS ULP this ensures sk_user_data is correct. Reported-by: Eric Dumazet Fixes: 1aa12bdf1bfb ("bpf: sockmap, add sock close() hook to remove socks") Signed-off-by: John Fastabend Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann

bpf/verifier: disallow pointer subtraction

2018-09-12T21:30:02Z

Subtraction of pointers was accidentally allowed for unpriv programs by commit 82abbf8d2fc4. Revert that part of commit. Fixes: 82abbf8d2fc4 ("bpf: do not allow root to mangle valid pointers") Reported-by: Jann Horn Acked-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: btf: Fix end boundary calculation for type section

2018-09-12T20:00:23Z

The end boundary math for type section is incorrect in btf_check_all_metas(). It just happens that hdr->type_off is always 0 for now because there are only two sections (type and string) and string section must be at the end (ensured in btf_parse_str_sec). However, type_off may not be 0 if a new section would be added later. This patch fixes it. Fixes: f80442a4cd18 ("bpf: btf: Change how section is supported in btf_header") Reported-by: Dmitry Vyukov Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann

bpf: avoid misuse of psock when TCP_ULP_BPF collides with another ULP

2018-09-02T20:31:10Z

Currently we check sk_user_data is non NULL to determine if the sk exists in a map. However, this is not sufficient to ensure the psock or the ULP ops are not in use by another user, such as kcm or TLS. To avoid this when adding a sock to a map also verify it is of the correct ULP type. Additionally, when releasing a psock verify that it is the TCP_ULP_BPF type before releasing the ULP. The error case where we abort an update due to ULP collision can cause this error path. For example, __sock_map_ctx_update_elem() [...] err = tcp_set_ulp_id(sock, TCP_ULP_BPF) <- collides with TLS if (err) <- so err out here goto out_free [...] out_free: smap_release_sock() <- calling tcp_cleanup_ulp releases the TLS ULP incorrectly. Fixes: 2f857d04601a ("bpf: sockmap, remove STRPARSER map_flags and add multi-map support") Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann

bpf: sockmap, decrement copied count correctly in redirect error case

2018-08-28T07:01:06Z

Currently, when a redirect occurs in sockmap and an error occurs in the redirect call we unwind the scatterlist once in the error path of bpf_tcp_sendmsg_do_redirect() and then again in sendmsg(). Then in the error path of sendmsg we decrement the copied count by the send size. However, its possible we partially sent data before the error was generated. This can happen if do_tcp_sendpages() partially sends the scatterlist before encountering a memory pressure error. If this happens we need to decrement the copied value (the value tracking how many bytes were actually sent to TCP stack) by the number of remaining bytes _not_ the entire send size. Otherwise we risk confusing userspace. Also we don't need two calls to free the scatterlist one is good enough. So remove the one in bpf_tcp_sendmsg_do_redirect() and then properly reduce copied by the number of remaining bytes which may in fact be the entire send size if no bytes were sent. To do this use bool to indicate if free_start_sg() should do mem accounting or not. Signed-off-by: John Fastabend Signed-off-by: Daniel Borkmann