linux.git/kernel/bpf/syscall.c, branch v5.0-rc2

Remove 'type' argument from access_ok() function

2019-01-04T02:57:57+00:00

Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument
of the user address range verification function since we got rid of the
old racy i386-only code to walk page tables by hand.

It existed because the original 80386 would not honor the write protect
bit when in kernel mode, so you had to do COW by hand before doing any
user access.  But we haven't supported that in a long time, and these
days the 'type' argument is a purely historical artifact.

A discussion about extending 'user_access_begin()' to do the range
checking resulted this patch, because there is no way we're going to
move the old VERIFY_xyz interface to that model.  And it's best done at
the end of the merge window when I've done most of my merges, so let's
just get this done once and for all.

This patch was mostly done with a sed-script, with manual fix-ups for
the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form.

There were a couple of notable cases:

 - csky still had the old "verify_area()" name as an alias.

 - the iter_iov code had magical hardcoded knowledge of the actual
   values of VERIFY_{READ,WRITE} (not that they mattered, since nothing
   really used it)

 - microblaze used the type argument for a debug printout

but other than those oddities this should be a total no-op patch.

I tried to fix up all architectures, did fairly extensive grepping for
access_ok() uses, and the changes are trivial, but I may have missed
something.  Any missed conversion should be trivially fixable, though.

Signed-off-by: Linus Torvalds

bpf: support raw tracepoints in modules

2018-12-18T22:08:12+00:00

Distributions build drivers as modules, including network and filesystem
drivers which export numerous tracepoints.  This enables
bpf(BPF_RAW_TRACEPOINT_OPEN) to attach to those tracepoints.

Signed-off-by: Matt Mullins 
Acked-by: Martin KaFai Lau 
Signed-off-by: Alexei Starovoitov

bpf: remove useless version check for prog load

2018-12-17T21:41:35+00:00

Existing libraries and tracing frameworks work around this kernel
version check by automatically deriving the kernel version from
uname(3) or similar such that the user does not need to do it
manually; these workarounds also make the version check useless
at the same time.

Moreover, most other BPF tracing types enabling bpf_probe_read()-like
functionality have /not/ adapted this check, and in general these
days it is well understood anyway that all the tracing programs are
not stable with regards to future kernels as kernel internal data
structures are subject to change from release to release.

Back at last netconf we discussed [0] and agreed to remove this
check from bpf_prog_load() and instead document it here in the uapi
header that there is no such guarantee for stable API for these
programs.

  [0] http://vger.kernel.org/netconf2018_files/DanielBorkmann_netconf2018.pdf

Signed-off-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Acked-by: Quentin Monnet 
Signed-off-by: Alexei Starovoitov

bpf: remove obsolete prog->aux sanitation in bpf_insn_prepare_dump

2018-12-13T20:42:44+00:00

This logic is not needed anymore since we got rid of the verifier
rewrite that was using prog->aux address in f6069b9aa993 ("bpf:
fix redirect to map under tail calls").

Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov

bpf: include sub program tags in bpf_prog_info

2018-12-13T11:22:28+00:00

Changes v2 -> v3:
1. remove check for bpf_dump_raw_ok().

Changes v1 -> v2:
1. Fix error path as Martin suggested.

This patch adds nr_prog_tags and prog_tags to bpf_prog_info. This is a
reliable way for user space to get tags of all sub programs. Before this
patch, user space need to find sub program tags via kallsyms.

This feature will be used in BPF introspection, where user space queries
information about BPF programs via sys_bpf.

Signed-off-by: Song Liu 
Acked-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann

bpf: Remove bpf_dump_raw_ok() check for func_info and line_info

2018-12-13T11:16:30+00:00

The func_info and line_info have the bpf insn offset but
they do not contain kernel address.  They will still be useful
for the userspace tool to annotate the xlated insn.

This patch removes the bpf_dump_raw_ok() guard for the
func_info and line_info during bpf_prog_get_info_by_fd().

The guard stays for jited_line_info which contains the kernel
address.

Although this bpf_dump_raw_ok() guard behavior has started since
the earlier func_info patch series, I marked the Fixes tag to the
latest line_info patch series which contains both func_info and
line_info and this patch is fixing for both of them.

Fixes: c454a46b5efd ("bpf: Add bpf_line_info support")
Signed-off-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann

bpf: pass struct btf pointer to the map_check_btf() callback

2018-12-12T23:33:33+00:00

If key_type or value_type are of non-trivial data types
(e.g. structure or typedef), it's not possible to check them without
the additional information, which can't be obtained without a pointer
to the btf structure.

So, let's pass btf pointer to the map_check_btf() callbacks.

Signed-off-by: Roman Gushchin 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Signed-off-by: Daniel Borkmann 
Signed-off-by: Alexei Starovoitov

bpf: rename _info_cnt to nr__info in bpf_prog_info

2018-12-10T22:51:45+00:00

In uapi bpf.h, currently we have the following fields in
the struct bpf_prog_info:
	__u32 func_info_cnt;
	__u32 line_info_cnt;
	__u32 jited_line_info_cnt;
The above field names "func_info_cnt" and "line_info_cnt"
also appear in union bpf_attr for program loading.

The original intention is to keep the names the same
between bpf_prog_info and bpf_attr
so it will imply what we returned to user space will be
the same as what the user space passed to the kernel.

Such a naming convention in bpf_prog_info is not consistent
with other fields like:
        __u32 nr_jited_ksyms;
        __u32 nr_jited_func_lens;

This patch made this adjustment so in bpf_prog_info
newly introduced *_info_cnt becomes nr_*_info.

Acked-by: Song Liu 
Acked-by: Martin KaFai Lau 
Signed-off-by: Yonghong Song 
Signed-off-by: Alexei Starovoitov

bpf: clean up bpf_prog_get_info_by_fd()

2018-12-10T22:48:42+00:00

info.nr_jited_ksyms and info.nr_jited_func_lens cannot be 0 in these two
statements, so we don't need to check them.

Signed-off-by: Song Liu 
Acked-by: Martin KaFai Lau 
Signed-off-by: Alexei Starovoitov

bpf: Add bpf_line_info support

2018-12-09T21:54:38+00:00

This patch adds bpf_line_info support.

It accepts an array of bpf_line_info objects during BPF_PROG_LOAD.
The "line_info", "line_info_cnt" and "line_info_rec_size" are added
to the "union bpf_attr".  The "line_info_rec_size" makes
bpf_line_info extensible in the future.

The new "check_btf_line()" ensures the userspace line_info is valid
for the kernel to use.

When the verifier is translating/patching the bpf_prog (through
"bpf_patch_insn_single()"), the line_infos' insn_off is also
adjusted by the newly added "bpf_adj_linfo()".

If the bpf_prog is jited, this patch also provides the jited addrs (in
aux->jited_linfo) for the corresponding line_info.insn_off.
"bpf_prog_fill_jited_linfo()" is added to fill the aux->jited_linfo.
It is currently called by the x86 jit.  Other jits can also use
"bpf_prog_fill_jited_linfo()" and it will be done in the followup patches.
In the future, if it deemed necessary, a particular jit could also provide
its own "bpf_prog_fill_jited_linfo()" implementation.

A few "*line_info*" fields are added to the bpf_prog_info such
that the user can get the xlated line_info back (i.e. the line_info
with its insn_off reflecting the translated prog).  The jited_line_info
is available if the prog is jited.  It is an array of __u64.
If the prog is not jited, jited_line_info_cnt is 0.

The verifier's verbose log with line_info will be done in
a follow up patch.

Signed-off-by: Martin KaFai Lau 
Acked-by: Yonghong Song 
Signed-off-by: Alexei Starovoitov