[PATCH AUTOSEL 5.15 03/46] bpftool: Clear errno after libcap's checks

[PATCH AUTOSEL 5.15 03/46] bpftool: Clear errno after libcap's checks

[Sasha Levin]

From: Quentin Monnet <quentin@isovalent.com>

[ Upstream commit cea558855c39b7f1f02ff50dcf701ca6596bc964 ]

When bpftool is linked against libcap, the library runs a "constructor"
function to compute the number of capabilities of the running kernel
[0], at the beginning of the execution of the program. As part of this,
it performs multiple calls to prctl(). Some of these may fail, and set
errno to a non-zero value:

    # strace -e prctl ./bpftool version
    prctl(PR_CAPBSET_READ, CAP_MAC_OVERRIDE) = 1
    prctl(PR_CAPBSET_READ, 0x30 /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, CAP_CHECKPOINT_RESTORE) = 1
    prctl(PR_CAPBSET_READ, 0x2c /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, 0x2a /* CAP_??? */) = -1 EINVAL (Invalid argument)
    prctl(PR_CAPBSET_READ, 0x29 /* CAP_??? */) = -1 EINVAL (Invalid argument)
    ** fprintf added at the top of main(): we have errno == 1
    ./bpftool v7.0.0
    using libbpf v1.0
    features: libbfd, libbpf_strict, skeletons
    +++ exited with 0 +++

This has been addressed in libcap 2.63 [1], but until this version is
available everywhere, we can fix it on bpftool side.

Let's clean errno at the beginning of the main() function, to make sure
that these checks do not interfere with the batch mode, where we error
out if errno is set after a bpftool command.

  [0] https://git.kernel.org/pub/scm/libs/libcap/libcap.git/tree/libcap/cap_alloc.c?h=libcap-2.65#n20
  [1] https://git.kernel.org/pub/scm/libs/libcap/libcap.git/commit/?id=f25a1b7e69f7b33e6afb58b3e38f3450b7d2d9a0

Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220815162205.45043-1-quentin@isovalent.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/bpf/bpftool/main.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index d27ec4f852bb..b70c023f3a57 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -404,6 +404,16 @@ int main(int argc, char **argv)
 
 	setlinebuf(stdout);
 
+#ifdef USE_LIBCAP
+	/* Libcap < 2.63 hooks before main() to compute the number of
+	 * capabilities of the running kernel, and doing so it calls prctl()
+	 * which may fail and set errno to non-zero.
+	 * Let's reset errno to make sure this does not interfere with the
+	 * batch mode.
+	 */
+	errno = 0;
+#endif
+
 	last_do_help = do_help;
 	pretty_output = false;
 	json_output = false;
-- 
2.35.1

[PATCH AUTOSEL 5.15 43/46] net: If sock is dead don't access sock's sk_wq in sk_stream_wait_memory

[Sasha Levin]

From: Liu Jian <liujian56@huawei.com>

[ Upstream commit 3f8ef65af927db247418d4e1db49164d7a158fc5 ]

Fixes the below NULL pointer dereference:

  [...]
  [   14.471200] Call Trace:
  [   14.471562]  <TASK>
  [   14.471882]  lock_acquire+0x245/0x2e0
  [   14.472416]  ? remove_wait_queue+0x12/0x50
  [   14.473014]  ? _raw_spin_lock_irqsave+0x17/0x50
  [   14.473681]  _raw_spin_lock_irqsave+0x3d/0x50
  [   14.474318]  ? remove_wait_queue+0x12/0x50
  [   14.474907]  remove_wait_queue+0x12/0x50
  [   14.475480]  sk_stream_wait_memory+0x20d/0x340
  [   14.476127]  ? do_wait_intr_irq+0x80/0x80
  [   14.476704]  do_tcp_sendpages+0x287/0x600
  [   14.477283]  tcp_bpf_push+0xab/0x260
  [   14.477817]  tcp_bpf_sendmsg_redir+0x297/0x500
  [   14.478461]  ? __local_bh_enable_ip+0x77/0xe0
  [   14.479096]  tcp_bpf_send_verdict+0x105/0x470
  [   14.479729]  tcp_bpf_sendmsg+0x318/0x4f0
  [   14.480311]  sock_sendmsg+0x2d/0x40
  [   14.480822]  ____sys_sendmsg+0x1b4/0x1c0
  [   14.481390]  ? copy_msghdr_from_user+0x62/0x80
  [   14.482048]  ___sys_sendmsg+0x78/0xb0
  [   14.482580]  ? vmf_insert_pfn_prot+0x91/0x150
  [   14.483215]  ? __do_fault+0x2a/0x1a0
  [   14.483738]  ? do_fault+0x15e/0x5d0
  [   14.484246]  ? __handle_mm_fault+0x56b/0x1040
  [   14.484874]  ? lock_is_held_type+0xdf/0x130
  [   14.485474]  ? find_held_lock+0x2d/0x90
  [   14.486046]  ? __sys_sendmsg+0x41/0x70
  [   14.486587]  __sys_sendmsg+0x41/0x70
  [   14.487105]  ? intel_pmu_drain_pebs_core+0x350/0x350
  [   14.487822]  do_syscall_64+0x34/0x80
  [   14.488345]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
  [...]

The test scenario has the following flow:

thread1                               thread2
-----------                           ---------------
 tcp_bpf_sendmsg
  tcp_bpf_send_verdict
   tcp_bpf_sendmsg_redir              sock_close
    tcp_bpf_push_locked                 __sock_release
     tcp_bpf_push                         //inet_release
      do_tcp_sendpages                    sock->ops->release
       sk_stream_wait_memory          	   // tcp_close
          sk_wait_event                      sk->sk_prot->close
           release_sock(__sk);
            ***
                                                lock_sock(sk);
                                                  __tcp_close
                                                    sock_orphan(sk)
                                                      sk->sk_wq  = NULL
                                                release_sock
            ****
           lock_sock(__sk);
          remove_wait_queue(sk_sleep(sk), &wait);
             sk_sleep(sk)
             //NULL pointer dereference
             &rcu_dereference_raw(sk->sk_wq)->wait

While waiting for memory in thread1, the socket is released with its wait
queue because thread2 has closed it. This caused by tcp_bpf_send_verdict
didn't increase the f_count of psock->sk_redir->sk_socket->file in thread1.

We should check if SOCK_DEAD flag is set on wakeup in sk_stream_wait_memory
before accessing the wait queue.

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Liu Jian <liujian56@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Cc: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20220823133755.314697-2-liujian56@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/core/stream.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/core/stream.c b/net/core/stream.c
index a166a32b411f..a61130504827 100644
--- a/net/core/stream.c
+++ b/net/core/stream.c
@@ -159,7 +159,8 @@ int sk_stream_wait_memory(struct sock *sk, long *timeo_p)
 		*timeo_p = current_timeo;
 	}
 out:
-	remove_wait_queue(sk_sleep(sk), &wait);
+	if (!sock_flag(sk, SOCK_DEAD))
+		remove_wait_queue(sk_sleep(sk), &wait);
 	return err;
 
 do_error:
-- 
2.35.1

[PATCH AUTOSEL 5.15 45/46] libbpf: Fix overrun in netlink attribute iteration

[Sasha Levin]

From: Xin Liu <liuxin350@huawei.com>

[ Upstream commit 51e05a8cf8eb34da7473823b7f236a77adfef0b4 ]

I accidentally found that a change in commit 1045b03e07d8 ("netlink: fix
overrun in attribute iteration") was not synchronized to the function
`nla_ok` in tools/lib/bpf/nlattr.c, I think it is necessary to modify,
this patch will do it.

Signed-off-by: Xin Liu <liuxin350@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220930090708.62394-1-liuxin350@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 tools/lib/bpf/nlattr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/nlattr.c b/tools/lib/bpf/nlattr.c
index f57e77a6e40f..3900d052ed19 100644
--- a/tools/lib/bpf/nlattr.c
+++ b/tools/lib/bpf/nlattr.c
@@ -32,7 +32,7 @@ static struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
 
 static int nla_ok(const struct nlattr *nla, int remaining)
 {
-	return remaining >= sizeof(*nla) &&
+	return remaining >= (int)sizeof(*nla) &&
 	       nla->nla_len >= sizeof(*nla) &&
 	       nla->nla_len <= remaining;
 }
-- 
2.35.1