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  1. 14 Jul, 2023 30 commits
  3. 13 Jul, 2023 10 commits
    • Yafang Shao's avatar
      selftests/bpf: Add selftest for PTR_UNTRUSTED · 1cd0e771
      Yafang Shao authored 
      Add a new selftest to check the PTR_UNTRUSTED condition. Below is the
result,

 #160     ptr_untrusted:OK
Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-5-laoar.shao@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      1cd0e771
    • Yafang Shao's avatar
      bpf: Fix an error in verifying a field in a union · 33937607
      Yafang Shao authored 
      We are utilizing BPF LSM to monitor BPF operations within our container
environment. When we add support for raw_tracepoint, it hits below
error.

; (const void *)attr->raw_tracepoint.name);
27: (79) r3 = *(u64 *)(r2 +0)
access beyond the end of member map_type (mend:4) in struct (anon) with off 0 size 8

It can be reproduced with below BPF prog.

SEC("lsm/bpf")
int BPF_PROG(bpf_audit, int cmd, union bpf_attr *attr, unsigned int size)
{
	switch (cmd) {
	case BPF_RAW_TRACEPOINT_OPEN:
		bpf_printk("raw_tracepoint is %s", attr->raw_tracepoint.name);
		break;
	default:
		break;
	}
	return 0;
}

The reason is that when accessing a field in a union, such as bpf_attr,
if the field is located within a nested struct that is not the first
member of the union, it can result in incorrect field verification.

  union bpf_attr {
      struct {
          __u32 map_type; <<<< Actually it will find that field.
          __u32 key_size;
          __u32 value_size;
         ...
      };
      ...
      struct {
          __u64 name;    <<<< We want to verify this field.
          __u32 prog_fd;
      } raw_tracepoint;
  };

Considering the potential deep nesting levels, finding a perfect
solution to address this issue has proven challenging. Therefore, I
propose a solution where we simply skip the verification process if the
field in question is located within a union.

Fixes: 7e3617a7 ("bpf: Add array support to btf_struct_access")
Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-4-laoar.shao@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      33937607
    • Yafang Shao's avatar
      selftests/bpf: Add selftests for nested_trust · d2284d68
      Yafang Shao authored 
      Add selftests for nested_strust to check whehter PTR_UNTRUSTED is cleared
as expected, the result as follows:

 #141/1   nested_trust/test_read_cpumask:OK
 #141/2   nested_trust/test_skb_field:OK                    <<<<
 #141/3   nested_trust/test_invalid_nested_user_cpus:OK
 #141/4   nested_trust/test_invalid_nested_offset:OK
 #141/5   nested_trust/test_invalid_skb_field:OK            <<<<
 #141     nested_trust:OK

The #141/2 and #141/5 are newly added.
Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-3-laoar.shao@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      d2284d68
    • Yafang Shao's avatar
      bpf: Fix an error around PTR_UNTRUSTED · 7ce4dc3e
      Yafang Shao authored 
      Per discussion with Alexei, the PTR_UNTRUSTED flag should not been
cleared when we start to walk a new struct, because the struct in
question may be a struct nested in a union. We should also check and set
this flag before we walk its each member, in case itself is a union.
We will clear this flag if the field is BTF_TYPE_SAFE_RCU_OR_NULL.

Fixes: 6fcd486b ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: default avatarYafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20230713025642.27477-2-laoar.shao@gmail.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      7ce4dc3e
    • Alexei Starovoitov's avatar
      Merge branch 'bpf-x86-allow-function-arguments-up-to-12-for-tracing' · f892cac2
      Alexei Starovoitov authored 
      Menglong Dong says:

====================
bpf, x86: allow function arguments up to 12 for TRACING

From: Menglong Dong <imagedong@tencent.com>

For now, the BPF program of type BPF_PROG_TYPE_TRACING can only be used
on the kernel functions whose arguments count less than or equal to 6, if
not considering '> 8 bytes' struct argument. This is not friendly at all,
as too many functions have arguments count more than 6. According to the
current kernel version, below is a statistics of the function arguments
count:

argument count | function count
7              | 704
8              | 270
9              | 84
10             | 47
11             | 47
12             | 27
13             | 22
14             | 5
15             | 0
16             | 1

Therefore, let's enhance it by increasing the function arguments count
allowed in arch_prepare_bpf_trampoline(), for now, only x86_64.

In the 1st patch, we save/restore regs with BPF_DW size to make the code
in save_regs()/restore_regs() simpler.

In the 2nd patch, we make arch_prepare_bpf_trampoline() support to copy
function arguments in stack for x86 arch. Therefore, the maximum
arguments can be up to MAX_BPF_FUNC_ARGS for FENTRY, FEXIT and
MODIFY_RETURN. Meanwhile, we clean the potential garbage value when we
copy the arguments on-stack.

And the 3rd patch is for the testcases of the this series.

Changes since v9:
- fix the failed test cases of trampoline_count and get_func_args_test
  in the 3rd patch

Changes since v8:
- change the way to test fmod_ret in the 3rd patch

Changes since v7:
- split the testcases, and add fentry_many_args/fexit_many_args to
  DENYLIST.aarch64 in 3rd patch

Changes since v6:
- somit nits from commit message and comment in the 1st patch
- remove the inline in get_nr_regs() in the 1st patch
- rename some function and various in the 1st patch

Changes since v5:
- adjust the commit log of the 1st patch, avoiding confusing people that
  bugs exist in current code
- introduce get_nr_regs() to get the space that used to pass args on
  stack correct in the 2nd patch
- add testcases to tracing_struct.c instead of fentry_test.c and
  fexit_test.c

Changes since v4:
- consider the case of the struct in arguments can't be hold by regs
- add comment for some code
- add testcases for MODIFY_RETURN
- rebase to the latest

Changes since v3:
- try make the stack pointer 16-byte aligned. Not sure if I'm right :)
- introduce clean_garbage() to clean the grabage when argument count is 7
- use different data type in bpf_testmod_fentry_test{7,12}
- add testcase for grabage values in ctx

Changes since v2:
- keep MAX_BPF_FUNC_ARGS still
- clean garbage value in upper bytes in the 2nd patch
- move bpf_fentry_test{7,12} to bpf_testmod.c and rename them to
  bpf_testmod_fentry_test{7,12} meanwhile in the 3rd patch

Changes since v1:
- change the maximun function arguments to 14 from 12
- add testcases (Jiri Olsa)
- instead EMIT4 with EMIT3_off32 for "lea" to prevent overflow
====================

Link: https://lore.kernel.org/r/20230713040738.1789742-1-imagedong@tencent.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      f892cac2
    • Menglong Dong's avatar
      selftests/bpf: add testcase for TRACING with 6+ arguments · 5e9cf77d
      Menglong Dong authored 
      Add fentry_many_args.c and fexit_many_args.c to test the fentry/fexit
with 7/11 arguments. As this feature is not supported by arm64 yet, we
disable these testcases for arm64 in DENYLIST.aarch64. We can combine
them with fentry_test.c/fexit_test.c when arm64 is supported too.

Correspondingly, add bpf_testmod_fentry_test7() and
bpf_testmod_fentry_test11() to bpf_testmod.c

Meanwhile, add bpf_modify_return_test2() to test_run.c to test the
MODIFY_RETURN with 7 arguments.

Add bpf_testmod_test_struct_arg_7/bpf_testmod_test_struct_arg_7 in
bpf_testmod.c to test the struct in the arguments.

And the testcases passed on x86_64:

./test_progs -t fexit
Summary: 5/14 PASSED, 0 SKIPPED, 0 FAILED

./test_progs -t fentry
Summary: 3/2 PASSED, 0 SKIPPED, 0 FAILED

./test_progs -t modify_return
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED

./test_progs -t tracing_struct
Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED
Signed-off-by: default avatarMenglong Dong <imagedong@tencent.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230713040738.1789742-4-imagedong@tencent.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      5e9cf77d
    • Menglong Dong's avatar
      bpf, x86: allow function arguments up to 12 for TRACING · 473e3150
      Menglong Dong authored 
      For now, the BPF program of type BPF_PROG_TYPE_TRACING can only be used
on the kernel functions whose arguments count less than or equal to 6, if
not considering '> 8 bytes' struct argument. This is not friendly at all,
as too many functions have arguments count more than 6.

According to the current kernel version, below is a statistics of the
function arguments count:

argument count | function count
7              | 704
8              | 270
9              | 84
10             | 47
11             | 47
12             | 27
13             | 22
14             | 5
15             | 0
16             | 1

Therefore, let's enhance it by increasing the function arguments count
allowed in arch_prepare_bpf_trampoline(), for now, only x86_64.

For the case that we don't need to call origin function, which means
without BPF_TRAMP_F_CALL_ORIG, we need only copy the function arguments
that stored in the frame of the caller to current frame. The 7th and later
arguments are stored in "$rbp + 0x18", and they will be copied to the
stack area following where register values are saved.

For the case with BPF_TRAMP_F_CALL_ORIG, we need prepare the arguments
in stack before call origin function, which means we need alloc extra
"8 * (arg_count - 6)" memory in the top of the stack. Note, there should
not be any data be pushed to the stack before calling the origin function.
So 'rbx' value will be stored on a stack position higher than where stack
arguments are stored for BPF_TRAMP_F_CALL_ORIG.

According to the research of Yonghong, struct members should be all in
register or all on the stack. Meanwhile, the compiler will pass the
argument on regs if the remaining regs can hold the argument. Therefore,
we need save the arguments in order. Otherwise, disorder of the args can
happen. For example:

  struct foo_struct {
      long a;
      int b;
  };
  int foo(char, char, char, char, char, struct foo_struct,
          char);

the arg1-5,arg7 will be passed by regs, and arg6 will by stack. Therefore,
we should save/restore the arguments in the same order with the
declaration of foo(). And the args used as ctx in stack will be like this:

  reg_arg6   -- copy from regs
  stack_arg2 -- copy from stack
  stack_arg1
  reg_arg5   -- copy from regs
  reg_arg4
  reg_arg3
  reg_arg2
  reg_arg1

We use EMIT3_off32() or EMIT4() for "lea" and "sub". The range of the
imm in "lea" and "sub" is [-128, 127] if EMIT4() is used. Therefore,
we use EMIT3_off32() instead if the imm out of the range.

It works well for the FENTRY/FEXIT/MODIFY_RETURN.
Signed-off-by: default avatarMenglong Dong <imagedong@tencent.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230713040738.1789742-3-imagedong@tencent.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      473e3150
    • Menglong Dong's avatar
      bpf, x86: save/restore regs with BPF_DW size · 02a6dfa8
      Menglong Dong authored 
      As we already reserve 8 byte in the stack for each reg, it is ok to
store/restore the regs in BPF_DW size. This will make the code in
save_regs()/restore_regs() simpler.
Signed-off-by: default avatarMenglong Dong <imagedong@tencent.com>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20230713040738.1789742-2-imagedong@tencent.comSigned-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      02a6dfa8
    • Linus Torvalds's avatar
      Merge tag 'net-6.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net · b1983d42
      Linus Torvalds authored 
      Pull networking fixes from Paolo Abeni:
 "Including fixes from netfilter, wireless and ebpf.

  Current release - regressions:

   - netfilter: conntrack: gre: don't set assured flag for clash entries

   - wifi: iwlwifi: remove 'use_tfh' config to fix crash

  Previous releases - regressions:

   - ipv6: fix a potential refcount underflow for idev

   - icmp6: ifix null-ptr-deref of ip6_null_entry->rt6i_idev in
     icmp6_dev()

   - bpf: fix max stack depth check for async callbacks

   - eth: mlx5e:
      - check for NOT_READY flag state after locking
      - fix page_pool page fragment tracking for XDP

   - eth: igc:
      - fix tx hang issue when QBV gate is closed
      - fix corner cases for TSN offload

   - eth: octeontx2-af: Move validation of ptp pointer before its usage

   - eth: ena: fix shift-out-of-bounds in exponential backoff

  Previous releases - always broken:

   - core: prevent skb corruption on frag list segmentation

   - sched:
      - cls_fw: fix improper refcount update leads to use-after-free
      - sch_qfq: account for stab overhead in qfq_enqueue

   - netfilter:
      - report use refcount overflow
      - prevent OOB access in nft_byteorder_eval

   - wifi: mt7921e: fix init command fail with enabled device

   - eth: ocelot: fix oversize frame dropping for preemptible TCs

   - eth: fec: recycle pages for transmitted XDP frames"

* tag 'net-6.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (79 commits)
  selftests: tc-testing: add test for qfq with stab overhead
  net/sched: sch_qfq: account for stab overhead in qfq_enqueue
  selftests: tc-testing: add tests for qfq mtu sanity check
  net/sched: sch_qfq: reintroduce lmax bound check for MTU
  wifi: cfg80211: fix receiving mesh packets without RFC1042 header
  wifi: rtw89: debug: fix error code in rtw89_debug_priv_send_h2c_set()
  net: txgbe: fix eeprom calculation error
  net/sched: make psched_mtu() RTNL-less safe
  net: ena: fix shift-out-of-bounds in exponential backoff
  netdevsim: fix uninitialized data in nsim_dev_trap_fa_cookie_write()
  net/sched: flower: Ensure both minimum and maximum ports are specified
  MAINTAINERS: Add another mailing list for QUALCOMM ETHQOS ETHERNET DRIVER
  docs: netdev: update the URL of the status page
  wifi: iwlwifi: remove 'use_tfh' config to fix crash
  xdp: use trusted arguments in XDP hints kfuncs
  bpf: cpumap: Fix memory leak in cpu_map_update_elem
  wifi: airo: avoid uninitialized warning in airo_get_rate()
  octeontx2-pf: Add additional check for MCAM rules
  net: dsa: Removed unneeded of_node_put in felix_parse_ports_node
  net: fec: use netdev_err_once() instead of netdev_err()
  ...
      b1983d42
    • Linus Torvalds's avatar
      Merge tag 'trace-v6.5-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace · ebc27aac
      Linus Torvalds authored 
      Pull tracing fixes from Steven Rostedt:

 - Fix some missing-prototype warnings

 - Fix user events struct args (did not include size of struct)

   When creating a user event, the "struct" keyword is to denote that
   the size of the field will be passed in. But the parsing failed to
   handle this case.

 - Add selftest to struct sizes for user events

 - Fix sample code for direct trampolines.

   The sample code for direct trampolines attached to handle_mm_fault().
   But the prototype changed and the direct trampoline sample code was
   not updated. Direct trampolines needs to have the arguments correct
   otherwise it can fail or crash the system.

 - Remove unused ftrace_regs_caller_ret() prototype.

 - Quiet false positive of FORTIFY_SOURCE

   Due to backward compatibility, the structure used to save stack
   traces in the kernel had a fixed size of 8. This structure is
   exported to user space via the tracing format file. A change was made
   to allow more than 8 functions to be recorded, and user space now
   uses the size field to know how many functions are actually in the
   stack.

   But the structure still has size of 8 (even though it points into the
   ring buffer that has the required amount allocated to hold a full
   stack.

   This was fine until the fortifier noticed that the
   memcpy(&entry->caller, stack, size) was greater than the 8 functions
   and would complain at runtime about it.

   Hide this by using a pointer to the stack location on the ring buffer
   instead of using the address of the entry structure caller field.

 - Fix a deadloop in reading trace_pipe that was caused by a mismatch
   between ring_buffer_empty() returning false which then asked to read
   the data, but the read code uses rb_num_of_entries() that returned
   zero, and causing a infinite "retry".

 - Fix a warning caused by not using all pages allocated to store ftrace
   functions, where this can happen if the linker inserts a bunch of
   "NULL" entries, causing the accounting of how many pages needed to be
   off.

 - Fix histogram synthetic event crashing when the start event is
   removed and the end event is still using a variable from it

 - Fix memory leak in freeing iter->temp in tracing_release_pipe()

* tag 'trace-v6.5-rc1-3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Fix memory leak of iter->temp when reading trace_pipe
  tracing/histograms: Add histograms to hist_vars if they have referenced variables
  tracing: Stop FORTIFY_SOURCE complaining about stack trace caller
  ftrace: Fix possible warning on checking all pages used in ftrace_process_locs()
  ring-buffer: Fix deadloop issue on reading trace_pipe
  tracing: arm64: Avoid missing-prototype warnings
  selftests/user_events: Test struct size match cases
  tracing/user_events: Fix struct arg size match check
  x86/ftrace: Remove unsued extern declaration ftrace_regs_caller_ret()
  arm64: ftrace: Add direct call trampoline samples support
  samples: ftrace: Save required argument registers in sample trampolines
      ebc27aac
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