[ Upstream commit f30d4968e9aee737e174fc97942af46cfb49b484 ]
Below is a simplified case from a report in bcc [0]:
r4 = 20
*(u32 *)(r10 -4) = r4
*(u32 *)(r10 -8) = r4 /* r4 state is tracked */
r4 = *(u64 *)(r10 -8) /* Read more than the tracked 32bit scalar.
* verifier rejects as 'corrupted spill memory'.
*/
After commit 354e8f1970f8 ("bpf: Support <8-byte scalar spill and refill"),
the 8-byte aligned 32bit spill is also tracked by the verifier and the
register state is stored.
However, if 8 bytes are read from the stack instead of the tracked 4 byte
scalar, then verifier currently rejects the program as "corrupted spill
memory". This patch fixes this case by allowing it to read but marks the
register as unknown.
Also note that, if the prog is trying to corrupt/leak an earlier spilled
pointer by spilling another <8 bytes register on top, this has already
been rejected in the check_stack_write_fixed_off().
[0] https://github.com/iovisor/bcc/pull/3683
Fixes: 354e8f1970f8 ("bpf: Support <8-byte scalar spill and refill")
Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Reported-by: Yonghong Song <yhs@gmail.com>
Change-Id: I438e93ccc5cb9824bd86dbf33374e5dcb2bf53cb
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Hengqi Chen <hengqi.chen@gmail.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211102064535.316018-1-kafai@fb.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 71f656a50176915d6813751188b5758daa8d012b ]
Register range information is copied in several places. The intent is
to transfer range/id information from one register/stack spill to
another. Currently this is done using direct register assignment, e.g.:
static void find_equal_scalars(..., struct bpf_reg_state *known_reg)
{
...
struct bpf_reg_state *reg;
...
*reg = *known_reg;
...
}
However, such assignments also copy the following bpf_reg_state fields:
struct bpf_reg_state {
...
struct bpf_reg_state *parent;
...
enum bpf_reg_liveness live;
...
};
Copying of these fields is accidental and incorrect, as could be
demonstrated by the following example:
0: call ktime_get_ns()
1: r6 = r0
2: call ktime_get_ns()
3: r7 = r0
4: if r0 > r6 goto +1 ; r0 & r6 are unbound thus generated
; branch states are identical
5: *(u64 *)(r10 - 8) = 0xdeadbeef ; 64-bit write to fp[-8]
--- checkpoint ---
6: r1 = 42 ; r1 marked as written
7: *(u8 *)(r10 - 8) = r1 ; 8-bit write, fp[-8] parent & live
; overwritten
8: r2 = *(u64 *)(r10 - 8)
9: r0 = 0
10: exit
This example is unsafe because 64-bit write to fp[-8] at (5) is
conditional, thus not all bytes of fp[-8] are guaranteed to be set
when it is read at (8). However, currently the example passes
verification.
First, the execution path 1-10 is examined by verifier.
Suppose that a new checkpoint is created by is_state_visited() at (6).
After checkpoint creation:
- r1.parent points to checkpoint.r1,
- fp[-8].parent points to checkpoint.fp[-8].
At (6) the r1.live is set to REG_LIVE_WRITTEN.
At (7) the fp[-8].parent is set to r1.parent and fp[-8].live is set to
REG_LIVE_WRITTEN, because of the following code called in
check_stack_write_fixed_off():
static void save_register_state(struct bpf_func_state *state,
int spi, struct bpf_reg_state *reg,
int size)
{
...
state->stack[spi].spilled_ptr = *reg; // <--- parent & live copied
if (size == BPF_REG_SIZE)
state->stack[spi].spilled_ptr.live |= REG_LIVE_WRITTEN;
...
}
Note the intent to mark stack spill as written only if 8 bytes are
spilled to a slot, however this intent is spoiled by a 'live' field copy.
At (8) the checkpoint.fp[-8] should be marked as REG_LIVE_READ but
this does not happen:
- fp[-8] in a current state is already marked as REG_LIVE_WRITTEN;
- fp[-8].parent points to checkpoint.r1, parentage chain is used by
mark_reg_read() to mark checkpoint states.
At (10) the verification is finished for path 1-10 and jump 4-6 is
examined. The checkpoint.fp[-8] never gets REG_LIVE_READ mark and this
spill is pruned from the cached states by clean_live_states(). Hence
verifier state obtained via path 1-4,6 is deemed identical to one
obtained via path 1-6 and program marked as safe.
Note: the example should be executed with BPF_F_TEST_STATE_FREQ flag
set to force creation of intermediate verifier states.
This commit revisits the locations where bpf_reg_state instances are
copied and replaces the direct copies with a call to a function
copy_register_state(dst, src) that preserves 'parent' and 'live'
fields of the 'dst'.
Fixes: 679c782de1 ("bpf/verifier: per-register parent pointers")
Change-Id: I35e95201f36d82169507e3f849c69740f6cb0917
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230106142214.1040390-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 354e8f1970f821d4952458f77b1ab6c3eb24d530 ]
The verifier currently does not save the reg state when
spilling <8byte bounded scalar to the stack. The bpf program
will be incorrectly rejected when this scalar is refilled to
the reg and then used to offset into a packet header.
The later patch has a simplified bpf prog from a real use case
to demonstrate this case. The current work around is
to reparse the packet again such that this offset scalar
is close to where the packet data will be accessed to
avoid the spill. Thus, the header is parsed twice.
The llvm patch [1] will align the <8bytes spill to
the 8-byte stack address. This can simplify the verifier
support by avoiding to store multiple reg states for
each 8 byte stack slot.
This patch changes the verifier to save the reg state when
spilling <8bytes scalar to the stack. This reg state saving
is limited to spill aligned to the 8-byte stack address.
The current refill logic has already called coerce_reg_to_size(),
so coerce_reg_to_size() is not called on state->stack[spi].spilled_ptr
during spill.
When refilling in check_stack_read_fixed_off(), it checks
the refill size is the same as the number of bytes marked with
STACK_SPILL before restoring the reg state. When restoring
the reg state to state->regs[dst_regno], it needs
to avoid the state->regs[dst_regno].subreg_def being
over written because it has been marked by the check_reg_arg()
earlier [check_mem_access() is called after check_reg_arg() in
do_check()]. Reordering check_mem_access() and check_reg_arg()
will need a lot of changes in test_verifier's tests because
of the difference in verifier's error message. Thus, the
patch here is to save the state->regs[dst_regno].subreg_def
first in check_stack_read_fixed_off().
There are cases that the verifier needs to scrub the spilled slot
from STACK_SPILL to STACK_MISC. After this patch the spill is not always
in 8 bytes now, so it can no longer assume the other 7 bytes are always
marked as STACK_SPILL. In particular, the scrub needs to avoid marking
an uninitialized byte from STACK_INVALID to STACK_MISC. Otherwise, the
verifier will incorrectly accept bpf program reading uninitialized bytes
from the stack. A new helper scrub_spilled_slot() is created for this
purpose.
[1]: https://reviews.llvm.org/D109073
Change-Id: I856947f7a3dd1ed4d8a85d36f6c443733f096740
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210922004941.625398-1-kafai@fb.com
Stable-dep-of: 71f656a50176 ("bpf: Fix to preserve reg parent/live fields when copying range info")
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 345e004d023343d38088fdfea39688aa11e06ccf upstream.
Commit 354e8f1970f8 ("bpf: Support <8-byte scalar spill and refill")
introduced support in the verifier to track <8B spill/fills of scalars.
The backtracking logic for the precision bit was however skipping
spill/fills of less than 8B. That could cause state pruning to consider
two states equivalent when they shouldn't be.
As an example, consider the following bytecode snippet:
0: r7 = r1
1: call bpf_get_prandom_u32
2: r6 = 2
3: if r0 == 0 goto pc+1
4: r6 = 3
...
8: [state pruning point]
...
/* u32 spill/fill */
10: *(u32 *)(r10 - 8) = r6
11: r8 = *(u32 *)(r10 - 8)
12: r0 = 0
13: if r8 == 3 goto pc+1
14: r0 = 1
15: exit
The verifier first walks the path with R6=3. Given the support for <8B
spill/fills, at instruction 13, it knows the condition is true and skips
instruction 14. At that point, the backtracking logic kicks in but stops
at the fill instruction since it only propagates the precision bit for
8B spill/fill. When the verifier then walks the path with R6=2, it will
consider it safe at instruction 8 because R6 is not marked as needing
precision. Instruction 14 is thus never walked and is then incorrectly
removed as 'dead code'.
It's also possible to lead the verifier to accept e.g. an out-of-bound
memory access instead of causing an incorrect dead code elimination.
This regression was found via Cilium's bpf-next CI where it was causing
a conntrack map update to be silently skipped because the code had been
removed by the verifier.
This commit fixes it by enabling support for <8B spill/fills in the
bactracking logic. In case of a <8B spill/fill, the full 8B stack slot
will be marked as needing precision. Then, in __mark_chain_precision,
any tracked register spilled in a marked slot will itself be marked as
needing precision, regardless of the spill size. This logic makes two
assumptions: (1) only 8B-aligned spill/fill are tracked and (2) spilled
registers are only tracked if the spill and fill sizes are equal. Commit
ef979017b837 ("bpf: selftest: Add verifier tests for <8-byte scalar
spill and refill") covers the first assumption and the next commit in
this patchset covers the second.
Fixes: 354e8f1970f8 ("bpf: Support <8-byte scalar spill and refill")
Change-Id: I124b6d516ef7cfbc4d6ce16c5f72c8cfa22e61a9
Signed-off-by: Paul Chaignon <paul@isovalent.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 114039b342014680911c35bd6b72624180fd669a ]
To avoid potentially breaking existing users.
Both mac/no-mac cases have to be amended; mac_header >= network_header
is not enough (verified with a new test, see next patch).
Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Change-Id: I470a3f592f33f59523b741c44322c6a601cde1af
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221121180340.1983627-1-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 529409ea92d590659be487ba0839710329bd8074 ]
When equivalent completed state is found and it has additional precision
restrictions, BPF verifier propagates precision to
currently-being-verified state chain (i.e., including parent states) so
that if some of the states in the chain are not yet completed, necessary
precision restrictions are enforced.
Unfortunately, right now this happens only for the last frame (deepest
active subprogram's frame), not all the frames. This can lead to
incorrect matching of states due to missing precision marker. Currently
this doesn't seem possible as BPF verifier forces everything to precise
when validated BPF program has any subprograms. But with the next patch
lifting this restriction, this becomes problematic.
In fact, without this fix, we'll start getting failure in one of the
existing test_verifier test cases:
#906/p precise: cross frame pruning FAIL
Unexpected success to load!
verification time 48 usec
stack depth 0+0
processed 26 insns (limit 1000000) max_states_per_insn 3 total_states 17 peak_states 17 mark_read 8
This patch adds precision propagation across all frames.
Fixes: a3ce685dd0 ("bpf: fix precision tracking")
Change-Id: Ib77ae0c7eda8768dd8fd7d90ef4dd2a1124503da
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221104163649.121784-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 27113c59b6d0a587b29ae72d4ff3f832f58b0651 ]
Every 8 bytes of the stack is tracked by a bpf_stack_state.
Within each bpf_stack_state, there is a 'u8 slot_type[8]' to track
the type of each byte. Verifier tests slot_type[0] == STACK_SPILL
to decide if the spilled reg state is saved. Verifier currently only
saves the reg state if the whole 8 bytes are spilled to the stack,
so checking the slot_type[7] is the same as checking slot_type[0].
The later patch will allow verifier to save the bounded scalar
reg also for <8 bytes spill. There is a llvm patch [1] to ensure
the <8 bytes spill will be 8-byte aligned, so checking
slot_type[7] instead of slot_type[0] is required.
While at it, this patch refactors the slot_type[0] == STACK_SPILL
test into a new function is_spilled_reg() and change the
slot_type[0] check to slot_type[7] check in there also.
[1] https://reviews.llvm.org/D109073
Change-Id: I312e7cb205323ee857f91398239ddc3306074ff5
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210922004934.624194-1-kafai@fb.com
Stable-dep-of: 529409ea92d5 ("bpf: propagate precision across all frames, not just the last one")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f5e477a861e4a20d8a1c5f7a245f3a3c3c376b03 ]
For the case where allow_ptr_leaks is false, code is checking whether
slot type is STACK_INVALID and STACK_SPILL and rejecting other cases.
This is a consequence of incorrectly checking for register type instead
of the slot type (NOT_INIT and SCALAR_VALUE respectively). Fix the
check.
Fixes: 01f810ace9ed ("bpf: Allow variable-offset stack access")
Change-Id: Iec16dc4a0e7c1d6a7da77b1321e52f545c9c66a2
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20221103191013.1236066-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 836e49e103dfeeff670c934b7d563cbd982fce87 ]
bpf_selem_alloc function is used by inode_storage, sk_storage and
task_storage maps to set map value, for these map types, there may
be a spin lock in the map value, so if we use memcpy to copy the whole
map value from user, the spin lock field may be initialized incorrectly.
Since the spin lock field is zeroed by kzalloc, call copy_map_value
instead of memcpy to skip copying the spin lock field to fix it.
Fixes: 6ac99e8f23 ("bpf: Introduce bpf sk local storage")
Change-Id: Ic39bf3fc0cda0d57550d08efc4998916b3bc5e4d
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Link: https://lore.kernel.org/r/20221114134720.1057939-2-xukuohai@huawei.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 4b45cd81f737d79d0fbfc0d320a1e518e7f0bbf0 ]
pcpu_freelist_populate() initializes nr_elems / num_possible_cpus() + 1
free nodes for some CPUs, and then possibly one CPU with fewer nodes,
followed by remaining cpus with 0 nodes. For example, when nr_elems == 256
and num_possible_cpus() == 32, CPU 0~27 each gets 9 free nodes, CPU 28 gets
4 free nodes, CPU 29~31 get 0 free nodes, while in fact each CPU should get
8 nodes equally.
This patch initializes nr_elems / num_possible_cpus() free nodes for each
CPU firstly, then allocates the remaining free nodes by one for each CPU
until no free nodes left.
Fixes: e19494edab ("bpf: introduce percpu_freelist")
Change-Id: I8258a28678a5b7c457adfcd72ffc90e1e902f19a
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221110122128.105214-1-xukuohai@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit f1db20814af532f85e091231223e5e4818e8464b ]
Some helper functions will allocate memory. To avoid memory leaks, the
verifier requires the eBPF program to release these memories by calling
the corresponding helper functions.
When a resource is released, all pointer registers corresponding to the
resource should be invalidated. The verifier use release_references() to
do this job, by apply __mark_reg_unknown() to each relevant register.
It will give these registers the type of SCALAR_VALUE. A register that
will contain a pointer value at runtime, but of type SCALAR_VALUE, which
may allow the unprivileged user to get a kernel pointer by storing this
register into a map.
Using __mark_reg_not_init() while NOT allow_ptr_leaks can mitigate this
problem.
Fixes: fd978bf7fd ("bpf: Add reference tracking to verifier")
Change-Id: Id3f595cc190ca23f99d456fe34608d4854aa6934
Signed-off-by: Youlin Li <liulin063@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20221103093440.3161-1-liulin063@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b239da34203f49c40b5d656220c39647c3ff0b3c ]
For a lot of use cases in future patches, we will want to modify the
state of registers part of some same 'group' (e.g. same ref_obj_id). It
won't just be limited to releasing reference state, but setting a type
flag dynamically based on certain actions, etc.
Hence, we need a way to easily pass a callback to the function that
iterates over all registers in current bpf_verifier_state in all frames
upto (and including) the curframe.
While in C++ we would be able to easily use a lambda to pass state and
the callback together, sadly we aren't using C++ in the kernel. The next
best thing to avoid defining a function for each case seems like
statement expressions in GNU C. The kernel already uses them heavily,
hence they can passed to the macro in the style of a lambda. The
statement expression will then be substituted in the for loop bodies.
Variables __state and __reg are set to current bpf_func_state and reg
for each invocation of the expression inside the passed in verifier
state.
Then, convert mark_ptr_or_null_regs, clear_all_pkt_pointers,
release_reference, find_good_pkt_pointers, find_equal_scalars to
use bpf_for_each_reg_in_vstate.
Change-Id: I51184c648c5f6ae2836ff5fed4a28949bfb868d4
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220904204145.3089-16-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Stable-dep-of: f1db20814af5 ("bpf: Fix wrong reg type conversion in release_reference()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 6d94e741a8ff818e5518da8257f5ca0aaed1f269 ]
This patch adds the verifier support to recognize inlined branch conditions.
The LLVM knows that the branch evaluates to the same value, but the verifier
couldn't track it. Hence causing valid programs to be rejected.
The potential LLVM workaround: https://reviews.llvm.org/D87428
can have undesired side effects, since LLVM doesn't know that
skb->data/data_end are being compared. LLVM has to introduce extra boolean
variable and use inline_asm trick to force easier for the verifier assembly.
Instead teach the verifier to recognize that
r1 = skb->data;
r1 += 10;
r2 = skb->data_end;
if (r1 > r2) {
here r1 points beyond packet_end and
subsequent
if (r1 > r2) // always evaluates to "true".
}
Change-Id: I20dce0c55f3d3f685b5b392b2d853064505639fa
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20201111031213.25109-2-alexei.starovoitov@gmail.com
Stable-dep-of: f1db20814af5 ("bpf: Fix wrong reg type conversion in release_reference()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a657182a5c5150cdfacb6640aad1d2712571a409 upstream.
Hsin-Wei reported a KASAN splat triggered by their BPF runtime fuzzer which
is based on a customized syzkaller:
BUG: KASAN: slab-out-of-bounds in bpf_int_jit_compile+0x1257/0x13f0
Read of size 8 at addr ffff888004e90b58 by task syz-executor.0/1489
CPU: 1 PID: 1489 Comm: syz-executor.0 Not tainted 5.19.0 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x9c/0xc9
print_address_description.constprop.0+0x1f/0x1f0
? bpf_int_jit_compile+0x1257/0x13f0
kasan_report.cold+0xeb/0x197
? kvmalloc_node+0x170/0x200
? bpf_int_jit_compile+0x1257/0x13f0
bpf_int_jit_compile+0x1257/0x13f0
? arch_prepare_bpf_dispatcher+0xd0/0xd0
? rcu_read_lock_sched_held+0x43/0x70
bpf_prog_select_runtime+0x3e8/0x640
? bpf_obj_name_cpy+0x149/0x1b0
bpf_prog_load+0x102f/0x2220
? __bpf_prog_put.constprop.0+0x220/0x220
? find_held_lock+0x2c/0x110
? __might_fault+0xd6/0x180
? lock_downgrade+0x6e0/0x6e0
? lock_is_held_type+0xa6/0x120
? __might_fault+0x147/0x180
__sys_bpf+0x137b/0x6070
? bpf_perf_link_attach+0x530/0x530
? new_sync_read+0x600/0x600
? __fget_files+0x255/0x450
? lock_downgrade+0x6e0/0x6e0
? fput+0x30/0x1a0
? ksys_write+0x1a8/0x260
__x64_sys_bpf+0x7a/0xc0
? syscall_enter_from_user_mode+0x21/0x70
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f917c4e2c2d
The problem here is that a range of tnum_range(0, map->max_entries - 1) has
limited ability to represent the concrete tight range with the tnum as the
set of resulting states from value + mask can result in a superset of the
actual intended range, and as such a tnum_in(range, reg->var_off) check may
yield true when it shouldn't, for example tnum_range(0, 2) would result in
00XX -> v = 0000, m = 0011 such that the intended set of {0, 1, 2} is here
represented by a less precise superset of {0, 1, 2, 3}. As the register is
known const scalar, really just use the concrete reg->var_off.value for the
upper index check.
Fixes: d2e4c1e6c294 ("bpf: Constant map key tracking for prog array pokes")
Reported-by: Hsin-Wei Hung <hsinweih@uci.edu>
Change-Id: I03425b3777961f3ed6e48319d4acaea69e4ec014
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Shung-Hsi Yu <shung-hsi.yu@suse.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/r/984b37f9fdf7ac36831d2137415a4a915744c1b6.1661462653.git.daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4c46091ee985ae84c60c5e95055d779fcd291d87 upstream.
Syzbot found a Use After Free bug in compute_effective_progs().
The reproducer creates a number of BPF links, and causes a fault
injected alloc to fail, while calling bpf_link_detach on them.
Link detach triggers the link to be freed by bpf_link_free(),
which calls __cgroup_bpf_detach() and update_effective_progs().
If the memory allocation in this function fails, the function restores
the pointer to the bpf_cgroup_link on the cgroup list, but the memory
gets freed just after it returns. After this, every subsequent call to
update_effective_progs() causes this already deallocated pointer to be
dereferenced in prog_list_length(), and triggers KASAN UAF error.
To fix this issue don't preserve the pointer to the prog or link in the
list, but remove it and replace it with a dummy prog without shrinking
the table. The subsequent call to __cgroup_bpf_detach() or
__cgroup_bpf_detach() will correct it.
Fixes: af6eea57437a ("bpf: Implement bpf_link-based cgroup BPF program attachment")
Reported-by: <syzbot+f264bffdfbd5614f3bb2@syzkaller.appspotmail.com>
Change-Id: I7093d2421a29cc76fb0ca9e3e76313364f1e76ff
Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://syzkaller.appspot.com/bug?id=8ebf179a95c2a2670f7cf1ba62429ec044369db4
Link: https://lore.kernel.org/bpf/20220517180420.87954-1-tadeusz.struk@linaro.org
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ef1e93d2eeb58a1f08c37b22a2314b94bc045f15 upstream.
bpf_iter_attach_map() acquires a map uref, and the uref may be released
before or in the middle of iterating map elements. For example, the uref
could be released in bpf_iter_detach_map() as part of
bpf_link_release(), or could be released in bpf_map_put_with_uref() as
part of bpf_map_release().
So acquiring an extra map uref in bpf_iter_init_hash_map() and
releasing it in bpf_iter_fini_hash_map().
Fixes: d6c4503cc296 ("bpf: Implement bpf iterator for hash maps")
Change-Id: I924b7aba5cd7ca4a00ca45c044a540d74348ea72
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220810080538.1845898-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f76fa6b338055054f80c72b29c97fb95c1becadc upstream.
bpf_iter_attach_map() acquires a map uref, and the uref may be released
before or in the middle of iterating map elements. For example, the uref
could be released in bpf_iter_detach_map() as part of
bpf_link_release(), or could be released in bpf_map_put_with_uref() as
part of bpf_map_release().
Alternative fix is acquiring an extra bpf_link reference just like
a pinned map iterator does, but it introduces unnecessary dependency
on bpf_link instead of bpf_map.
So choose another fix: acquiring an extra map uref in .init_seq_private
for array map iterator.
Fixes: d3cc2ab546ad ("bpf: Implement bpf iterator for array maps")
Change-Id: I9e850c66f9dfd6d88db5644fb6fe26cc640d1d77
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220810080538.1845898-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 607b9cc92bd7208338d714a22b8082fe83bcb177 upstream.
Share the timing / signal interruption logic between different
implementations of PROG_TEST_RUN. There is a change in behaviour
as well. We check the loop exit condition before checking for
pending signals. This resolves an edge case where a signal
arrives during the last iteration. Instead of aborting with
EINTR we return the successful result to user space.
Change-Id: I93b9e54b8c563c3d0055dd8bd18e03c5de6e9c60
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210303101816.36774-2-lmb@cloudflare.com
[dtcccc: fix conflicts in bpf_test_run()]
Signed-off-by: Tianchen Ding <dtcccc@linux.alibaba.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3844d153a41adea718202c10ae91dc96b37453b5 upstream.
Kuee reported a corner case where the tnum becomes constant after the call
to __reg_bound_offset(), but the register's bounds are not, that is, its
min bounds are still not equal to the register's max bounds.
This in turn allows to leak pointers through turning a pointer register as
is into an unknown scalar via adjust_ptr_min_max_vals().
Before:
func#0 @0
0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0))
1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0))
2: (87) r3 = -r3 ; R3_w=scalar()
3: (87) r3 = -r3 ; R3_w=scalar()
4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881)
5: (75) if r3 s>= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)
6: (95) exit
from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
7: (d5) if r3 s<= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)
8: (95) exit
from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
9: (07) r3 += -32767 ; R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)) <--- [*]
10: (95) exit
What can be seen here is that R3=scalar(umin=32767,umax=32768,var_off=(0x7fff;
0x8000)) after the operation R3 += -32767 results in a 'malformed' constant, that
is, R3_w=scalar(imm=0,umax=1,var_off=(0x0; 0x0)). Intersecting with var_off has
not been done at that point via __update_reg_bounds(), which would have improved
the umax to be equal to umin.
Refactor the tnum <> min/max bounds information flow into a reg_bounds_sync()
helper and use it consistently everywhere. After the fix, bounds have been
corrected to R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) and thus the register
is regarded as a 'proper' constant scalar of 0.
After:
func#0 @0
0: R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
0: (b7) r0 = 1 ; R0_w=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0))
1: (b7) r3 = 0 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0))
2: (87) r3 = -r3 ; R3_w=scalar()
3: (87) r3 = -r3 ; R3_w=scalar()
4: (47) r3 |= 32767 ; R3_w=scalar(smin=-9223372036854743041,umin=32767,var_off=(0x7fff; 0xffffffffffff8000),s32_min=-2147450881)
5: (75) if r3 s>= 0x0 goto pc+1 ; R3_w=scalar(umin=9223372036854808575,var_off=(0x8000000000007fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)
6: (95) exit
from 5 to 7: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
7: (d5) if r3 s<= 0x8000 goto pc+1 ; R3=scalar(umin=32769,umax=9223372036854775807,var_off=(0x7fff; 0x7fffffffffff8000),s32_min=-2147450881,u32_min=32767)
8: (95) exit
from 7 to 9: R0=scalar(imm=1,umin=1,umax=1,var_off=(0x1; 0x0)) R1=ctx(off=0,imm=0,umax=0,var_off=(0x0; 0x0)) R3=scalar(umin=32767,umax=32768,var_off=(0x7fff; 0x8000)) R10=fp(off=0,imm=0,umax=0,var_off=(0x0; 0x0))
9: (07) r3 += -32767 ; R3_w=scalar(imm=0,umax=0,var_off=(0x0; 0x0)) <--- [*]
10: (95) exit
Fixes: b03c9f9fdc ("bpf/verifier: track signed and unsigned min/max values")
Reported-by: Kuee K1r0a <liulin063@gmail.com>
Change-Id: I5eefec7c85e8ad0b7d2b8782b8d25b6ca3ed5571
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220701124727.11153-2-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit a12ca6277eca6aeeccf66e840c23a2b520e24c8f upstream.
Kuee reported a quirk in the jmp32's jeq/jne simulation, namely that the
register value does not match expectations for the fall-through path. For
example:
Before fix:
0: R1=ctx(off=0,imm=0) R10=fp0
0: (b7) r2 = 0 ; R2_w=P0
1: (b7) r6 = 563 ; R6_w=P563
2: (87) r2 = -r2 ; R2_w=Pscalar()
3: (87) r2 = -r2 ; R2_w=Pscalar()
4: (4c) w2 |= w6 ; R2_w=Pscalar(umin=563,umax=4294967295,var_off=(0x233; 0xfffffdcc),s32_min=-2147483085) R6_w=P563
5: (56) if w2 != 0x8 goto pc+1 ; R2_w=P571 <--- [*]
6: (95) exit
R0 !read_ok
After fix:
0: R1=ctx(off=0,imm=0) R10=fp0
0: (b7) r2 = 0 ; R2_w=P0
1: (b7) r6 = 563 ; R6_w=P563
2: (87) r2 = -r2 ; R2_w=Pscalar()
3: (87) r2 = -r2 ; R2_w=Pscalar()
4: (4c) w2 |= w6 ; R2_w=Pscalar(umin=563,umax=4294967295,var_off=(0x233; 0xfffffdcc),s32_min=-2147483085) R6_w=P563
5: (56) if w2 != 0x8 goto pc+1 ; R2_w=P8 <--- [*]
6: (95) exit
R0 !read_ok
As can be seen on line 5 for the branch fall-through path in R2 [*] is that
given condition w2 != 0x8 is false, verifier should conclude that r2 = 8 as
upper 32 bit are known to be zero. However, verifier incorrectly concludes
that r2 = 571 which is far off.
The problem is it only marks false{true}_reg as known in the switch for JE/NE
case, but at the end of the function, it uses {false,true}_{64,32}off to
update {false,true}_reg->var_off and they still hold the prior value of
{false,true}_reg->var_off before it got marked as known. The subsequent
__reg_combine_32_into_64() then propagates this old var_off and derives new
bounds. The information between min/max bounds on {false,true}_reg from
setting the register to known const combined with the {false,true}_reg->var_off
based on the old information then derives wrong register data.
Fix it by detangling the BPF_JEQ/BPF_JNE cases and updating relevant
{false,true}_{64,32}off tnums along with the register marking to known
constant.
Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Kuee K1r0a <liulin063@gmail.com>
Change-Id: I19d33ae22be6d614e856e362b6cb896393245955
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20220701124727.11153-1-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit caff1fa4118cec4dfd4336521ebd22a6408a1e3e ]
I think there is something wrong with BPF_PROBE_MEM in ___bpf_prog_run()
in big-endian machine. Let's make a test and see what will happen if we
want to load a 'u16' with BPF_PROBE_MEM.
Let's make the src value '0x0001', the value of dest register will become
0x0001000000000000, as the value will be loaded to the first 2 byte of
DST with following code:
bpf_probe_read_kernel(&DST, SIZE, (const void *)(long) (SRC + insn->off));
Obviously, the value in DST is not correct. In fact, we can compare
BPF_PROBE_MEM with LDX_MEM_H:
DST = *(SIZE *)(unsigned long) (SRC + insn->off);
If the memory load is done by LDX_MEM_H, the value in DST will be 0x1 now.
And I think this error results in the test case 'test_bpf_sk_storage_map'
failing:
test_bpf_sk_storage_map:PASS:bpf_iter_bpf_sk_storage_map__open_and_load 0 nsec
test_bpf_sk_storage_map:PASS:socket 0 nsec
test_bpf_sk_storage_map:PASS:map_update 0 nsec
test_bpf_sk_storage_map:PASS:socket 0 nsec
test_bpf_sk_storage_map:PASS:map_update 0 nsec
test_bpf_sk_storage_map:PASS:socket 0 nsec
test_bpf_sk_storage_map:PASS:map_update 0 nsec
test_bpf_sk_storage_map:PASS:attach_iter 0 nsec
test_bpf_sk_storage_map:PASS:create_iter 0 nsec
test_bpf_sk_storage_map:PASS:read 0 nsec
test_bpf_sk_storage_map:FAIL:ipv6_sk_count got 0 expected 3
$10/26 bpf_iter/bpf_sk_storage_map:FAIL
The code of the test case is simply, it will load sk->sk_family to the
register with BPF_PROBE_MEM and check if it is AF_INET6. With this patch,
now the test case 'bpf_iter' can pass:
$10 bpf_iter:OK
Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
Change-Id: I937aa243cbace36a63279aecbc9292e2a84bef94
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20220524021228.533216-1-imagedong@tencent.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a2aa95b71c9bbec793b5c5fa50f0a80d882b3e8d upstream.
The cnt value in the 'cnt >= BPF_MAX_TRAMP_PROGS' check does not
include BPF_TRAMP_MODIFY_RETURN bpf programs, so the number of
the attached BPF_TRAMP_MODIFY_RETURN bpf programs in a trampoline
can exceed BPF_MAX_TRAMP_PROGS.
When this happens, the assignment '*progs++ = aux->prog' in
bpf_trampoline_get_progs() will cause progs array overflow as the
progs field in the bpf_tramp_progs struct can only hold at most
BPF_MAX_TRAMP_PROGS bpf programs.
Fixes: 88fd9e5352fe ("bpf: Refactor trampoline update code")
Change-Id: I9b779dae2f1f20eda315e1c18a5e1195c798969c
Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
Link: https://lore.kernel.org/r/20220430130803.210624-1-ytcoode@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit ee2a098851bfbe8bcdd964c0121f4246f00ff41e upstream.
Let's say that the caller has storage for num_elem stack frames. Then,
the BPF stack helper functions walk the stack for only num_elem frames.
This means that if skip > 0, one keeps only 'num_elem - skip' frames.
This is because it sets init_nr in the perf_callchain_entry to the end
of the buffer to save num_elem entries only. I believe it was because
the perf callchain code unwound the stack frames until it reached the
global max size (sysctl_perf_event_max_stack).
However it now has perf_callchain_entry_ctx.max_stack to limit the
iteration locally. This simplifies the code to handle init_nr in the
BPF callstack entries and removes the confusion with the perf_event's
__PERF_SAMPLE_CALLCHAIN_EARLY which sets init_nr to 0.
Also change the comment on bpf_get_stack() in the header file to be
more explicit what the return value means.
Fixes: c195651e56 ("bpf: add bpf_get_stack helper")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/30a7b5d5-6726-1cc2-eaee-8da2828a9a9c@oracle.com
Link: https://lore.kernel.org/bpf/20220314182042.71025-1-namhyung@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Based-on-patch-by: Eugene Loh <eugene.loh@oracle.com>
Change-Id: I65ccfdf6e3a9a4f77362cc4c72d80fedaeabf232
commit 75134f16e7dd0007aa474b281935c5f42e79f2c8 upstream.
syzbot reported various soft lockups caused by bpf batch operations.
INFO: task kworker/1:1:27 blocked for more than 140 seconds.
INFO: task hung in rcu_barrier
Nothing prevents batch ops to process huge amount of data,
we need to add schedule points in them.
Note that maybe_wait_bpf_programs(map) calls from
generic_map_delete_batch() can be factorized by moving
the call after the loop.
This will be done later in -next tree once we get this fix merged,
unless there is strong opinion doing this optimization sooner.
Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops")
Fixes: cb4d03ab499d ("bpf: Add generic support for lookup batch op")
Reported-by: syzbot <syzkaller@googlegroups.com>
Change-Id: I11ed1b3c8662ad2e2212ff61a09525c6c5fae83b
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Brian Vazquez <brianvv@google.com>
Link: https://lore.kernel.org/bpf/20220217181902.808742-1-eric.dumazet@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 4a11678f683814df82fca9018d964771e02d7e6d upstream.
If bpf_msg_push_data() is called with len 0 (as it happens during
selftests/bpf/test_sockmap), we do not need to do anything and can
return early.
Calling bpf_msg_push_data() with len 0 previously lead to a wrong ENOMEM
error: we later called get_order(copy + len); if len was 0, copy + len
was also often 0 and get_order() returned some undefined value (at the
moment 52). alloc_pages() caught that and failed, but then bpf_msg_push_data()
returned ENOMEM. This was wrong because we are most probably not out of
memory and actually do not need any additional memory.
Fixes: 6fff607e2f ("bpf: sk_msg program helper bpf_msg_push_data")
Change-Id: I299047dfbb9a4d2d86faebd3d5263d98100b4810
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/df69012695c7094ccb1943ca02b4920db3537466.1644421921.git.fmaurer@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b293dcc473d22a62dc6d78de2b15e4f49515db56 upstream.
After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages
after mapping"), non-VM_ALLOC mappings will be marked as accessible
in __get_vm_area_node() when KASAN is enabled. But now the flag for
ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access
after vmap() returns. Because the ringbuf area is created by mapping
allocated pages, so use VM_MAP instead.
After the change, info in /proc/vmallocinfo also changes from
[start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user
to
[start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com
Change-Id: I0225e3b0b85c2b3b0a79ae5aa81c1fcb88be44df
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220202060158.6260-1-houtao1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b992f01e66150fc5e90be4a96f5eb8e634c8249e upstream.
task_pt_regs() can return NULL on powerpc for kernel threads. This is
then used in __bpf_get_stack() to check for user mode, resulting in a
kernel oops. Guard against this by checking return value of
task_pt_regs() before trying to obtain the call chain.
Fixes: fa28dcb82a38f8 ("bpf: Introduce helper bpf_get_task_stack()")
Cc: stable@vger.kernel.org # v5.9+
Change-Id: Idb50b19f47069482dcdff02ebf32d99b99597ff8
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/d5ef83c361cc255494afd15ff1b4fb02a36e1dcf.1641468127.git.naveen.n.rao@linux.vnet.ibm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e60b0d12a95dcf16a63225cead4541567f5cb517 ]
If we ever get to a point again where we convert a bogus looking <ptr>_or_null
typed register containing a non-zero fixed or variable offset, then lets not
reset these bounds to zero since they are not and also don't promote the register
to a <ptr> type, but instead leave it as <ptr>_or_null. Converting to a unknown
register could be an avenue as well, but then if we run into this case it would
allow to leak a kernel pointer this way.
Fixes: f1174f77b5 ("bpf/verifier: rework value tracking")
Change-Id: I72ea1e72c525de5db16fa124e80d2e0b30fe3463
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 866de407444398bc8140ea70de1dba5f91cc34ac ]
BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.
Fixes: 8580ac9404f6 ("bpf: Process in-kernel BTF")
Change-Id: I26a2c4d57b427200d718b7a3d246f7556be2cfb3
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20211203053001.740945-1-houtao1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit c5a2d43e998a821701029f23e25b62f9188e93ff ]
Make BTF log size limit to be the same as the verifier log size limit.
Otherwise tools that progressively increase log size and use the same log
for BTF loading and program loading will be hitting hard to debug EINVAL.
Change-Id: I71d6b2d7cdc393b9d3ef7665a20dd075e721452c
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211201181040.23337-7-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ no upstream commit given implicitly fixed through the larger refactoring
in c25b2ae136039ffa820c26138ed4a5e5f3ab3841 ]
While auditing some other code, I noticed missing checks inside the pointer
arithmetic simulation, more specifically, adjust_ptr_min_max_vals(). Several
*_OR_NULL types are not rejected whereas they are _required_ to be rejected
given the expectation is that they get promoted into a 'real' pointer type
for the success case, that is, after an explicit != NULL check.
One case which stands out and is accessible from unprivileged (iff enabled
given disabled by default) is BPF ring buffer. From crafting a PoC, the NULL
check can be bypassed through an offset, and its id marking will then lead
to promotion of mem_or_null to a mem type.
bpf_ringbuf_reserve() helper can trigger this case through passing of reserved
flags, for example.
func#0 @0
0: R1=ctx(id=0,off=0,imm=0) R10=fp0
0: (7a) *(u64 *)(r10 -8) = 0
1: R1=ctx(id=0,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm
1: (18) r1 = 0x0
3: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm
3: (b7) r2 = 8
4: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R10=fp0 fp-8_w=mmmmmmmm
4: (b7) r3 = 0
5: R1_w=map_ptr(id=0,off=0,ks=0,vs=0,imm=0) R2_w=invP8 R3_w=invP0 R10=fp0 fp-8_w=mmmmmmmm
5: (85) call bpf_ringbuf_reserve#131
6: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
6: (bf) r6 = r0
7: R0_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
7: (07) r0 += 1
8: R0_w=mem_or_null(id=2,ref_obj_id=2,off=1,imm=0) R6_w=mem_or_null(id=2,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
8: (15) if r0 == 0x0 goto pc+4
R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
9: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
9: (62) *(u32 *)(r6 +0) = 0
R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
10: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
10: (bf) r1 = r6
11: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
11: (b7) r2 = 0
12: R0_w=mem(id=0,ref_obj_id=0,off=0,imm=0) R1_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R2_w=invP0 R6_w=mem(id=0,ref_obj_id=2,off=0,imm=0) R10=fp0 fp-8_w=mmmmmmmm refs=2
12: (85) call bpf_ringbuf_submit#132
13: R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm
13: (b7) r0 = 0
14: R0_w=invP0 R6=invP(id=0) R10=fp0 fp-8=mmmmmmmm
14: (95) exit
from 8 to 13: safe
processed 15 insns (limit 1000000) max_states_per_insn 0 total_states 1 peak_states 1 mark_read 0
OK
All three commits, that is b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support"),
457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it"), and the
afbf21dce668 ("bpf: Support readonly/readwrite buffers in verifier") suffer the same
cause and their *_OR_NULL type pendants must be rejected in adjust_ptr_min_max_vals().
Make the test more robust by reusing reg_type_may_be_null() helper such that we catch
all *_OR_NULL types we have today and in future.
Note that pointer arithmetic on PTR_TO_BTF_ID, PTR_TO_RDONLY_BUF, and PTR_TO_RDWR_BUF
is generally allowed.
Fixes: b121b341e598 ("bpf: Add PTR_TO_BTF_ID_OR_NULL support")
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Fixes: afbf21dce668 ("bpf: Support readonly/readwrite buffers in verifier")
Change-Id: Ia2d389517c8c158cac751548523c6012d1fde591
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit e572ff80f05c33cd0cb4860f864f5c9c044280b6 upstream.
Make the bounds propagation in __reg_assign_32_into_64() slightly more
robust and readable by aligning it similarly as we did back in the
__reg_combine_64_into_32() counterpart. Meaning, only propagate or
pessimize them as a smin/smax pair.
Change-Id: Iffb93f6b1a29084d280714c3adc48da81062025c
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 3cf2b61eb06765e27fec6799292d9fb46d0b7e60 upstream.
For the case where both s32_{min,max}_value bounds are positive, the
__reg_assign_32_into_64() directly propagates them to their 64 bit
counterparts, otherwise it pessimises them into [0,u32_max] universe and
tries to refine them later on by learning through the tnum as per comment
in mentioned function. However, that does not always happen, for example,
in mov32 operation we call zext_32_to_64(dst_reg) which invokes the
__reg_assign_32_into_64() as is without subsequent bounds update as
elsewhere thus no refinement based on tnum takes place.
Thus, not calling into the __update_reg_bounds() / __reg_deduce_bounds() /
__reg_bound_offset() triplet as we do, for example, in case of ALU ops via
adjust_scalar_min_max_vals(), will lead to more pessimistic bounds when
dumping the full register state:
Before fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=0,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Technically, the smin_value=0 and smax_value=4294967295 bounds are not
incorrect, but given the register is still a constant, they break assumptions
about const scalars that smin_value == smax_value and umin_value == umax_value.
After fix:
0: (b4) w0 = -1
1: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
1: (bc) w0 = w0
2: R0_w=invP4294967295
(id=0,imm=ffffffff,
smin_value=4294967295,smax_value=4294967295,
umin_value=4294967295,umax_value=4294967295,
var_off=(0xffffffff; 0x0),
s32_min_value=-1,s32_max_value=-1,
u32_min_value=-1,u32_max_value=-1)
Without the smin_value == smax_value and umin_value == umax_value invariant
being intact for const scalars, it is possible to leak out kernel pointers
from unprivileged user space if the latter is enabled. For example, when such
registers are involved in pointer arithmtics, then adjust_ptr_min_max_vals()
will taint the destination register into an unknown scalar, and the latter
can be exported and stored e.g. into a BPF map value.
Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Kuee K1r0a <liulin063@gmail.com>
Change-Id: I3e8ab235147192bc842635ad00956f1f06abaf0b
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f45b2974cc0ae959a4c503a071e38a56bd64372f upstream.
The arch_prepare_bpf_dispatcher function does not have a prototype, and
yields the following warning when W=1 is enabled for the kernel build.
>> arch/x86/net/bpf_jit_comp.c:2188:5: warning: no previous \
prototype for 'arch_prepare_bpf_dispatcher' [-Wmissing-prototypes]
2188 | int arch_prepare_bpf_dispatcher(void *image, s64 *funcs, \
int num_funcs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Remove the warning by adding a function declaration to include/linux/bpf.h.
Fixes: 75ccbef6369e ("bpf: Introduce BPF dispatcher")
Reported-by: kernel test robot <lkp@intel.com>
Change-Id: I2e0649f828d2e76e186b8abdf700c7b310b91323
Signed-off-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211117125708.769168-1-bjorn@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 353050be4c19e102178ccc05988101887c25ae53 upstream.
Commit a23740ec43ba ("bpf: Track contents of read-only maps as scalars") is
checking whether maps are read-only both from BPF program side and user space
side, and then, given their content is constant, reading out their data via
map->ops->map_direct_value_addr() which is then subsequently used as known
scalar value for the register, that is, it is marked as __mark_reg_known()
with the read value at verification time. Before a23740ec43ba, the register
content was marked as an unknown scalar so the verifier could not make any
assumptions about the map content.
The current implementation however is prone to a TOCTOU race, meaning, the
value read as known scalar for the register is not guaranteed to be exactly
the same at a later point when the program is executed, and as such, the
prior made assumptions of the verifier with regards to the program will be
invalid which can cause issues such as OOB access, etc.
While the BPF_F_RDONLY_PROG map flag is always fixed and required to be
specified at map creation time, the map->frozen property is initially set to
false for the map given the map value needs to be populated, e.g. for global
data sections. Once complete, the loader "freezes" the map from user space
such that no subsequent updates/deletes are possible anymore. For the rest
of the lifetime of the map, this freeze one-time trigger cannot be undone
anymore after a successful BPF_MAP_FREEZE cmd return. Meaning, any new BPF_*
cmd calls which would update/delete map entries will be rejected with -EPERM
since map_get_sys_perms() removes the FMODE_CAN_WRITE permission. This also
means that pending update/delete map entries must still complete before this
guarantee is given. This corner case is not an issue for loaders since they
create and prepare such program private map in successive steps.
However, a malicious user is able to trigger this TOCTOU race in two different
ways: i) via userfaultfd, and ii) via batched updates. For i) userfaultfd is
used to expand the competition interval, so that map_update_elem() can modify
the contents of the map after map_freeze() and bpf_prog_load() were executed.
This works, because userfaultfd halts the parallel thread which triggered a
map_update_elem() at the time where we copy key/value from the user buffer and
this already passed the FMODE_CAN_WRITE capability test given at that time the
map was not "frozen". Then, the main thread performs the map_freeze() and
bpf_prog_load(), and once that had completed successfully, the other thread
is woken up to complete the pending map_update_elem() which then changes the
map content. For ii) the idea of the batched update is similar, meaning, when
there are a large number of updates to be processed, it can increase the
competition interval between the two. It is therefore possible in practice to
modify the contents of the map after executing map_freeze() and bpf_prog_load().
One way to fix both i) and ii) at the same time is to expand the use of the
map's map->writecnt. The latter was introduced in fc9702273e2e ("bpf: Add mmap()
support for BPF_MAP_TYPE_ARRAY") and further refined in 1f6cb19be2e2 ("bpf:
Prevent re-mmap()'ing BPF map as writable for initially r/o mapping") with
the rationale to make a writable mmap()'ing of a map mutually exclusive with
read-only freezing. The counter indicates writable mmap() mappings and then
prevents/fails the freeze operation. Its semantics can be expanded beyond
just mmap() by generally indicating ongoing write phases. This would essentially
span any parallel regular and batched flavor of update/delete operation and
then also have map_freeze() fail with -EBUSY. For the check_mem_access() in
the verifier we expand upon the bpf_map_is_rdonly() check ensuring that all
last pending writes have completed via bpf_map_write_active() test. Once the
map->frozen is set and bpf_map_write_active() indicates a map->writecnt of 0
only then we are really guaranteed to use the map's data as known constants.
For map->frozen being set and pending writes in process of still being completed
we fall back to marking that register as unknown scalar so we don't end up
making assumptions about it. With this, both TOCTOU reproducers from i) and
ii) are fixed.
Note that the map->writecnt has been converted into a atomic64 in the fix in
order to avoid a double freeze_mutex mutex_{un,}lock() pair when updating
map->writecnt in the various map update/delete BPF_* cmd flavors. Spanning
the freeze_mutex over entire map update/delete operations in syscall side
would not be possible due to then causing everything to be serialized.
Similarly, something like synchronize_rcu() after setting map->frozen to wait
for update/deletes to complete is not possible either since it would also
have to span the user copy which can sleep. On the libbpf side, this won't
break d66562fba1ce ("libbpf: Add BPF object skeleton support") as the
anonymous mmap()-ed "map initialization image" is remapped as a BPF map-backed
mmap()-ed memory where for .rodata it's non-writable.
Fixes: a23740ec43ba ("bpf: Track contents of read-only maps as scalars")
Reported-by: w1tcher.bupt@gmail.com
Change-Id: I1fa51c61da044bf676798c9e55717da032545fe7
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
[fix conflict to call bpf_map_write_active_dec() in err_put block.
fix conflict to insert new functions after find_and_alloc_map().]
Reference: CVE-2021-4001
Signed-off-by: Masami Ichikawa(CIP) <masami.ichikawa@cybertrust.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 388e2c0b978339dee9b0a81a2e546f8979e021e2 ]
Similar to unsigned bounds propagation fix signed bounds.
The 'Fixes' tag is a hint. There is no security bug here.
The verifier was too conservative.
Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Change-Id: Ie2c18816b7e2a8eb73c330f56f690ed5019e0572
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-2-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit b9979db8340154526d9ab38a1883d6f6ba9b6d47 ]
Before this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0xffffffff))
After this fix:
166: (b5) if r2 <= 0x1 goto pc+22
from 166 to 189: R2=invP(id=1,umax_value=1,var_off=(0x0; 0x1))
While processing BPF_JLE the reg_set_min_max() would set true_reg->umax_value = 1
and call __reg_combine_64_into_32(true_reg).
Without the fix it would not pass the condition:
if (__reg64_bound_u32(reg->umin_value) && __reg64_bound_u32(reg->umax_value))
since umin_value == 0 at this point.
Before commit 10bf4e83167c the umin was incorrectly ingored.
The commit 10bf4e83167c fixed the correctness issue, but pessimized
propagation of 64-bit min max into 32-bit min max and corresponding var_off.
Fixes: 10bf4e83167c ("bpf: Fix propagation of 32 bit unsigned bounds from 64 bit bounds")
Change-Id: I3687ccc00a02b1177414ae042636695817a94037
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20211101222153.78759-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit fda7a38714f40b635f5502ec4855602c6b33dad2 upstream.
1. The ufd in generic_map_update_batch() should be read from batch.map_fd;
2. A call to fdget() should be followed by a symmetric call to fdput().
Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops")
Change-Id: I765bf0a26423c9597719c0984c2b7659f7a98993
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211019032934.1210517-1-xukuohai@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 54713c85f536048e685258f880bf298a74c3620d upstream.
Lorenzo noticed that the code testing for program type compatibility of
tail call maps is potentially racy in that two threads could encounter a
map with an unset type simultaneously and both return true even though they
are inserting incompatible programs.
The race window is quite small, but artificially enlarging it by adding a
usleep_range() inside the check in bpf_prog_array_compatible() makes it
trivial to trigger from userspace with a program that does, essentially:
map_fd = bpf_create_map(BPF_MAP_TYPE_PROG_ARRAY, 4, 4, 2, 0);
pid = fork();
if (pid) {
key = 0;
value = xdp_fd;
} else {
key = 1;
value = tc_fd;
}
err = bpf_map_update_elem(map_fd, &key, &value, 0);
While the race window is small, it has potentially serious ramifications in
that triggering it would allow a BPF program to tail call to a program of a
different type. So let's get rid of it by protecting the update with a
spinlock. The commit in the Fixes tag is the last commit that touches the
code in question.
v2:
- Use a spinlock instead of an atomic variable and cmpxchg() (Alexei)
v3:
- Put lock and the members it protects into an embedded 'owner' struct (Daniel)
Fixes: 3324b584b6 ("ebpf: misc core cleanup")
Reported-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Change-Id: I1e1a4d140d37bd81ca7818d084253883c6b41566
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211026110019.363464-1-toke@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 435b08ec0094ac1e128afe6cfd0d9311a8c617a7 upstream.
BPF test infra has some hacks in place which kzalloc() a socket and perform
minimum init via sock_net_set() and sock_init_data(). As a result, the sk's
skcd->cgroup is NULL since it didn't go through proper initialization as it
would have been the case from sk_alloc(). Rather than re-adding a NULL test
in sock_cgroup_ptr() just for this, use sk_{alloc,free}() pair for the test
socket. The latter also allows to get rid of the bpf_sk_storage_free() special
case.
Fixes: 8520e224f547 ("bpf, cgroups: Fix cgroup v2 fallback on v1/v2 mixed mode")
Fixes: b7a1848e83 ("bpf: add BPF_PROG_TEST_RUN support for flow dissector")
Fixes: 2cb494a36c ("bpf: add tests for direct packet access from CGROUP_SKB")
Reported-by: syzbot+664b58e9a40fbb2cec71@syzkaller.appspotmail.com
Reported-by: syzbot+33f36d0754d4c5c0e102@syzkaller.appspotmail.com
Change-Id: I49f99b5cdad56fd451d678c3d3e5881f2bfc223b
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: syzbot+664b58e9a40fbb2cec71@syzkaller.appspotmail.com
Tested-by: syzbot+33f36d0754d4c5c0e102@syzkaller.appspotmail.com
Link: https://lore.kernel.org/bpf/20210927123921.21535-2-daniel@iogearbox.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 8a98ae12fbefdb583a7696de719a1d57e5e940a2 ]
When introducing CAP_BPF, bpf_jit_charge_modmem() was not changed to treat
programs with CAP_BPF as privileged for the purpose of JIT memory allocation.
This means that a program without CAP_BPF can block a program with CAP_BPF
from loading a program.
Fix this by checking bpf_capable() in bpf_jit_charge_modmem().
Fixes: 2c78ee898d8f ("bpf: Implement CAP_BPF")
Change-Id: Ib74e2d6447ebda1e0601464258ee1faf81b5c9dc
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210922111153.19843-1-lmb@cloudflare.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 356ed64991c6847a0c4f2e8fa3b1133f7a14f1fc ]
Currently if a function ptr in struct_ops has a return value, its
caller will get a random return value from it, because the return
value of related BPF_PROG_TYPE_STRUCT_OPS prog is just dropped.
So adding a new flag BPF_TRAMP_F_RET_FENTRY_RET to tell bpf trampoline
to save and return the return value of struct_ops prog if ret_size of
the function ptr is greater than 0. Also restricting the flag to be
used alone.
Fixes: 85d33df357b6 ("bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS")
Change-Id: I3a671829c2417973d61f86e4b894f738eb29143b
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210914023351.3664499-1-houtao1@huawei.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit e21aa341785c679dd409c8cb71f864c00fe6c463 ]
The fexit/fmod_ret programs can be attached to kernel functions that can sleep.
The synchronize_rcu_tasks() will not wait for such tasks to complete.
In such case the trampoline image will be freed and when the task
wakes up the return IP will point to freed memory causing the crash.
Solve this by adding percpu_ref_get/put for the duration of trampoline
and separate trampoline vs its image life times.
The "half page" optimization has to be removed, since
first_half->second_half->first_half transition cannot be guaranteed to
complete in deterministic time. Every trampoline update becomes a new image.
The image with fmod_ret or fexit progs will be freed via percpu_ref_kill and
call_rcu_tasks. Together they will wait for the original function and
trampoline asm to complete. The trampoline is patched from nop to jmp to skip
fexit progs. They are freed independently from the trampoline. The image with
fentry progs only will be freed via call_rcu_tasks_trace+call_rcu_tasks which
will wait for both sleepable and non-sleepable progs to complete.
Fixes: fec56f5890d9 ("bpf: Introduce BPF trampoline")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Change-Id: I7aa259dccaf8ea9bfca5d7ae2acab623dd090b67
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU
Link: https://lore.kernel.org/bpf/20210316210007.38949-1-alexei.starovoitov@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit a2baf4e8bb0f306fbed7b5e6197c02896a638ab5 upstream.
Commit b910eaaaa4b8 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage()
helper") fixed a bug for bpf_get_local_storage() helper so different tasks
won't mess up with each other's percpu local storage.
The percpu data contains 8 slots so it can hold up to 8 contexts (same or
different tasks), for 8 different program runs, at the same time. This in
general is sufficient. But our internal testing showed the following warning
multiple times:
[...]
warning: WARNING: CPU: 13 PID: 41661 at include/linux/bpf-cgroup.h:193
__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
RIP: 0010:__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
<IRQ>
tcp_call_bpf.constprop.99+0x93/0xc0
tcp_conn_request+0x41e/0xa50
? tcp_rcv_state_process+0x203/0xe00
tcp_rcv_state_process+0x203/0xe00
? sk_filter_trim_cap+0xbc/0x210
? tcp_v6_inbound_md5_hash.constprop.41+0x44/0x160
tcp_v6_do_rcv+0x181/0x3e0
tcp_v6_rcv+0xc65/0xcb0
ip6_protocol_deliver_rcu+0xbd/0x450
ip6_input_finish+0x11/0x20
ip6_input+0xb5/0xc0
ip6_sublist_rcv_finish+0x37/0x50
ip6_sublist_rcv+0x1dc/0x270
ipv6_list_rcv+0x113/0x140
__netif_receive_skb_list_core+0x1a0/0x210
netif_receive_skb_list_internal+0x186/0x2a0
gro_normal_list.part.170+0x19/0x40
napi_complete_done+0x65/0x150
mlx5e_napi_poll+0x1ae/0x680
__napi_poll+0x25/0x120
net_rx_action+0x11e/0x280
__do_softirq+0xbb/0x271
irq_exit_rcu+0x97/0xa0
common_interrupt+0x7f/0xa0
</IRQ>
asm_common_interrupt+0x1e/0x40
RIP: 0010:bpf_prog_1835a9241238291a_tw_egress+0x5/0xbac
? __cgroup_bpf_run_filter_skb+0x378/0x4e0
? do_softirq+0x34/0x70
? ip6_finish_output2+0x266/0x590
? ip6_finish_output+0x66/0xa0
? ip6_output+0x6c/0x130
? ip6_xmit+0x279/0x550
? ip6_dst_check+0x61/0xd0
[...]
Using drgn [0] to dump the percpu buffer contents showed that on this CPU
slot 0 is still available, but slots 1-7 are occupied and those tasks in
slots 1-7 mostly don't exist any more. So we might have issues in
bpf_cgroup_storage_unset().
Further debugging confirmed that there is a bug in bpf_cgroup_storage_unset().
Currently, it tries to unset "current" slot with searching from the start.
So the following sequence is possible:
1. A task is running and claims slot 0
2. Running BPF program is done, and it checked slot 0 has the "task"
and ready to reset it to NULL (not yet).
3. An interrupt happens, another BPF program runs and it claims slot 1
with the *same* task.
4. The unset() in interrupt context releases slot 0 since it matches "task".
5. Interrupt is done, the task in process context reset slot 0.
At the end, slot 1 is not reset and the same process can continue to occupy
slots 2-7 and finally, when the above step 1-5 is repeated again, step 3 BPF
program won't be able to claim an empty slot and a warning will be issued.
To fix the issue, for unset() function, we should traverse from the last slot
to the first. This way, the above issue can be avoided.
The same reverse traversal should also be done in bpf_get_local_storage() helper
itself. Otherwise, incorrect local storage may be returned to BPF program.
[0] https://github.com/osandov/drgn
Fixes: b910eaaaa4b8 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper")
Change-Id: I070f8a97cfab559ea0747565e998b7d468ae1b51
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210810010413.1976277-1-yhs@fb.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit b910eaaaa4b89976ef02e5d6448f3f73dc671d91 upstream.
Jiri Olsa reported a bug ([1]) in kernel where cgroup local
storage pointer may be NULL in bpf_get_local_storage() helper.
There are two issues uncovered by this bug:
(1). kprobe or tracepoint prog incorrectly sets cgroup local storage
before prog run,
(2). due to change from preempt_disable to migrate_disable,
preemption is possible and percpu storage might be overwritten
by other tasks.
This issue (1) is fixed in [2]. This patch tried to address issue (2).
The following shows how things can go wrong:
task 1: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 2: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 1: run bpf program
task 1 will effectively use the percpu local storage setting by task 2
which will be either NULL or incorrect ones.
Instead of just one common local storage per cpu, this patch fixed
the issue by permitting 8 local storages per cpu and each local
storage is identified by a task_struct pointer. This way, we
allow at most 8 nested preemption between bpf_cgroup_storage_set()
and bpf_cgroup_storage_unset(). The percpu local storage slot
is released (calling bpf_cgroup_storage_unset()) by the same task
after bpf program finished running.
bpf_test_run() is also fixed to use the new bpf_cgroup_storage_set()
interface.
The patch is tested on top of [2] with reproducer in [1].
Without this patch, kernel will emit error in 2-3 minutes.
With this patch, after one hour, still no error.
[1] https://lore.kernel.org/bpf/CAKH8qBuXCfUz=w8L+Fj74OaUpbosO29niYwTki7e3Ag044_aww@mail.gmail.com/T
[2] https://lore.kernel.org/bpf/20210309185028.3763817-1-yhs@fb.com
Change-Id: I68adb9aeb2df2c6c49d11f5f948791ac602ebbbf
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20210323055146.3334476-1-yhs@fb.com
Cc: <stable@vger.kernel.org> # 5.10.x
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 5b029a32cfe4600f5e10e36b41778506b90fd4de upstream.
Commit 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support
for it") extended check_map_func_compatibility() by enforcing map -> helper
function match, but not helper -> map type match.
Due to this all of the bpf_ringbuf_*() helper functions could be used with
a wrong map type such as array or hash map, leading to invalid access due
to type confusion.
Also, both BPF_FUNC_ringbuf_{submit,discard} have ARG_PTR_TO_ALLOC_MEM as
argument and not a BPF map. Therefore, their check_map_func_compatibility()
presence is incorrect since it's only for map type checking.
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: Ryota Shiga (Flatt Security)
Change-Id: I6a2ae33012eecfa8df042a0600559b5fdf473cfd
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit c4eb1f403243fc7bbb7de644db8587c03de36da6 ]
In __htab_map_lookup_and_delete_batch(), hash buckets are iterated
over to count the number of elements in each bucket (bucket_size).
If bucket_size is large enough, the multiplication to calculate
kvmalloc() size could overflow, resulting in out-of-bounds write
as reported by KASAN:
[...]
[ 104.986052] BUG: KASAN: vmalloc-out-of-bounds in __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.986489] Write of size 4194224 at addr ffffc9010503be70 by task crash/112
[ 104.986889]
[ 104.987193] CPU: 0 PID: 112 Comm: crash Not tainted 5.14.0-rc4 #13
[ 104.987552] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 104.988104] Call Trace:
[ 104.988410] dump_stack_lvl+0x34/0x44
[ 104.988706] print_address_description.constprop.0+0x21/0x140
[ 104.988991] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989327] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989622] kasan_report.cold+0x7f/0x11b
[ 104.989881] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990239] kasan_check_range+0x17c/0x1e0
[ 104.990467] memcpy+0x39/0x60
[ 104.990670] __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990982] ? __wake_up_common+0x4d/0x230
[ 104.991256] ? htab_of_map_free+0x130/0x130
[ 104.991541] bpf_map_do_batch+0x1fb/0x220
[...]
In hashtable, if the elements' keys have the same jhash() value, the
elements will be put into the same bucket. By putting a lot of elements
into a single bucket, the value of bucket_size can be increased to
trigger the integer overflow.
Triggering the overflow is possible for both callers with CAP_SYS_ADMIN
and callers without CAP_SYS_ADMIN.
It will be trivial for a caller with CAP_SYS_ADMIN to intentionally
reach this overflow by enabling BPF_F_ZERO_SEED. As this flag will set
the random seed passed to jhash() to 0, it will be easy for the caller
to prepare keys which will be hashed into the same value, and thus put
all the elements into the same bucket.
If the caller does not have CAP_SYS_ADMIN, BPF_F_ZERO_SEED cannot be
used. However, it will be still technically possible to trigger the
overflow, by guessing the random seed value passed to jhash() (32bit)
and repeating the attempt to trigger the overflow. In this case,
the probability to trigger the overflow will be low and will take
a very long time.
Fix the integer overflow by calling kvmalloc_array() instead of
kvmalloc() to allocate memory.
Fixes: 057996380a42 ("bpf: Add batch ops to all htab bpf map")
Change-Id: I47ff340e7702ebeaddd657153f2686b946ec15aa
Signed-off-by: Tatsuhiko Yasumatsu <th.yasumatsu@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210806150419.109658-1-th.yasumatsu@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
