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When a coherent mapping is created in dma_direct_alloc_pages(), it needs
to be decrypted if the device requires unencrypted DMA before returning.
Fixes: 3acac065508f ("dma-mapping: merge the generic remapping helpers into dma-direct")
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Set map_btf_name and map_btf_id for all map types so that map fields can
be accessed by bpf programs.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/a825f808f22af52b018dbe82f1c7d29dab5fc978.1592600985.git.rdna@fb.com
There are multiple use-cases when it's convenient to have access to bpf
map fields, both `struct bpf_map` and map type specific struct-s such as
`struct bpf_array`, `struct bpf_htab`, etc.
For example while working with sock arrays it can be necessary to
calculate the key based on map->max_entries (some_hash % max_entries).
Currently this is solved by communicating max_entries via "out-of-band"
channel, e.g. via additional map with known key to get info about target
map. That works, but is not very convenient and error-prone while
working with many maps.
In other cases necessary data is dynamic (i.e. unknown at loading time)
and it's impossible to get it at all. For example while working with a
hash table it can be convenient to know how much capacity is already
used (bpf_htab.count.counter for BPF_F_NO_PREALLOC case).
At the same time kernel knows this info and can provide it to bpf
program.
Fill this gap by adding support to access bpf map fields from bpf
program for both `struct bpf_map` and map type specific fields.
Support is implemented via btf_struct_access() so that a user can define
their own `struct bpf_map` or map type specific struct in their program
with only necessary fields and preserve_access_index attribute, cast a
map to this struct and use a field.
For example:
struct bpf_map {
__u32 max_entries;
} __attribute__((preserve_access_index));
struct bpf_array {
struct bpf_map map;
__u32 elem_size;
} __attribute__((preserve_access_index));
struct {
__uint(type, BPF_MAP_TYPE_ARRAY);
__uint(max_entries, 4);
__type(key, __u32);
__type(value, __u32);
} m_array SEC(".maps");
SEC("cgroup_skb/egress")
int cg_skb(void *ctx)
{
struct bpf_array *array = (struct bpf_array *)&m_array;
struct bpf_map *map = (struct bpf_map *)&m_array;
/* .. use map->max_entries or array->map.max_entries .. */
}
Similarly to other btf_struct_access() use-cases (e.g. struct tcp_sock
in net/ipv4/bpf_tcp_ca.c) the patch allows access to any fields of
corresponding struct. Only reading from map fields is supported.
For btf_struct_access() to work there should be a way to know btf id of
a struct that corresponds to a map type. To get btf id there should be a
way to get a stringified name of map-specific struct, such as
"bpf_array", "bpf_htab", etc for a map type. Two new fields are added to
`struct bpf_map_ops` to handle it:
* .map_btf_name keeps a btf name of a struct returned by map_alloc();
* .map_btf_id is used to cache btf id of that struct.
To make btf ids calculation cheaper they're calculated once while
preparing btf_vmlinux and cached same way as it's done for btf_id field
of `struct bpf_func_proto`
While calculating btf ids, struct names are NOT checked for collision.
Collisions will be checked as a part of the work to prepare btf ids used
in verifier in compile time that should land soon. The only known
collision for `struct bpf_htab` (kernel/bpf/hashtab.c vs
net/core/sock_map.c) was fixed earlier.
Both new fields .map_btf_name and .map_btf_id must be set for a map type
for the feature to work. If neither is set for a map type, verifier will
return ENOTSUPP on a try to access map_ptr of corresponding type. If
just one of them set, it's verifier misconfiguration.
Only `struct bpf_array` for BPF_MAP_TYPE_ARRAY and `struct bpf_htab` for
BPF_MAP_TYPE_HASH are supported by this patch. Other map types will be
supported separately.
The feature is available only for CONFIG_DEBUG_INFO_BTF=y and gated by
perfmon_capable() so that unpriv programs won't have access to bpf map
fields.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/6479686a0cd1e9067993df57b4c3eef0e276fec9.1592600985.git.rdna@fb.com
btf_parse_vmlinux() implements manual search for struct bpf_ctx_convert
since at the time of implementing btf_find_by_name_kind() was not
available.
Later btf_find_by_name_kind() was introduced in 27ae7997a661 ("bpf:
Introduce BPF_PROG_TYPE_STRUCT_OPS"). It provides similar search
functionality and can be leveraged in btf_parse_vmlinux(). Do it.
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/6e12d5c3e8a3d552925913ef73a695dd1bb27800.1592600985.git.rdna@fb.com
This reverts commit 8ece3b3eb576a78d2e67ad4c3a80a39fa6708809.
This commit broke userspace. Bash uses ESPIPE to determine whether or
not the file should be read using "unbuffered I/O", which means reading
1 byte at a time instead of 128 bytes at a time. I used to use bash to
read through kmsg in a really quite nasty way:
while read -t 0.1 -r line 2>/dev/null || [[ $? -ne 142 ]]; do
echo "SARU $line"
done < /dev/kmsg
This will show all lines that can fit into the 128 byte buffer, and skip
lines that don't. That's pretty awful, but at least it worked.
With this change, bash now tries to do 1-byte reads, which means it
skips all the lines, which is worse than before.
Now, I don't really care very much about this, and I'm already look for
a workaround. But I did just spend an hour trying to figure out why my
scripts were broken. Either way, it makes no difference to me personally
whether this is reverted, but it might be something to consider. If you
declare that "trying to read /dev/kmsg with bash is terminally stupid
anyway," I might be inclined to agree with you. But do note that bash
uses lseek(fd, 0, SEEK_CUR)==>ESPIPE to determine whether or not it's
reading from a pipe.
Cc: Bruno Meneguele <bmeneg@redhat.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Have recordmcount work with > 64K sections (to support LTO)
- kprobe RCU fixes
- Correct a kprobe critical section with missing mutex
- Remove redundant arch_disarm_kprobe() call
- Fix lockup when kretprobe triggers within kprobe_flush_task()
- Fix memory leak in fetch_op_data operations
- Fix sleep in atomic in ftrace trace array sample code
- Free up memory on failure in sample trace array code
- Fix incorrect reporting of function_graph fields in format file
- Fix quote within quote parsing in bootconfig
- Fix return value of bootconfig tool
- Add testcases for bootconfig tool
- Fix maybe uninitialized warning in ftrace pid file code
- Remove unused variable in tracing_iter_reset()
- Fix some typos
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Merge tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Have recordmcount work with > 64K sections (to support LTO)
- kprobe RCU fixes
- Correct a kprobe critical section with missing mutex
- Remove redundant arch_disarm_kprobe() call
- Fix lockup when kretprobe triggers within kprobe_flush_task()
- Fix memory leak in fetch_op_data operations
- Fix sleep in atomic in ftrace trace array sample code
- Free up memory on failure in sample trace array code
- Fix incorrect reporting of function_graph fields in format file
- Fix quote within quote parsing in bootconfig
- Fix return value of bootconfig tool
- Add testcases for bootconfig tool
- Fix maybe uninitialized warning in ftrace pid file code
- Remove unused variable in tracing_iter_reset()
- Fix some typos
* tag 'trace-v5.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace: Fix maybe-uninitialized compiler warning
tools/bootconfig: Add testcase for show-command and quotes test
tools/bootconfig: Fix to return 0 if succeeded to show the bootconfig
tools/bootconfig: Fix to use correct quotes for value
proc/bootconfig: Fix to use correct quotes for value
tracing: Remove unused event variable in tracing_iter_reset
tracing/probe: Fix memleak in fetch_op_data operations
trace: Fix typo in allocate_ftrace_ops()'s comment
tracing: Make ftrace packed events have align of 1
sample-trace-array: Remove trace_array 'sample-instance'
sample-trace-array: Fix sleeping function called from invalid context
kretprobe: Prevent triggering kretprobe from within kprobe_flush_task
kprobes: Remove redundant arch_disarm_kprobe() call
kprobes: Fix to protect kick_kprobe_optimizer() by kprobe_mutex
kprobes: Use non RCU traversal APIs on kprobe_tables if possible
kprobes: Suppress the suspicious RCU warning on kprobes
recordmcount: support >64k sections
When do experiments with llvm (disabling instcombine and
simplifyCFG), I hit the following error with test_seg6_loop.o.
; R1=pkt(id=0,off=0,r=48,imm=0), R7=pkt(id=0,off=40,r=48,imm=0)
w2 = w7
; R2_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff))
w2 -= w1
R2 32-bit pointer arithmetic prohibited
The corresponding source code is:
uint32_t srh_off
// srh and skb->data are all packet pointers
srh_off = (char *)srh - (char *)(long)skb->data;
The verifier does not support 32-bit pointer/scalar arithmetic.
Without my llvm change, the code looks like
; R3=pkt(id=0,off=40,r=48,imm=0), R8=pkt(id=0,off=0,r=48,imm=0)
w3 -= w8
; R3_w=inv(id=0)
This is explicitly allowed in verifier if both registers are
pointers and the opcode is BPF_SUB.
To fix this problem, I changed the verifier to allow
32-bit pointer/scaler BPF_SUB operations.
At the source level, the issue could be workarounded with
inline asm or changing "uint32_t srh_off" to "uint64_t srh_off".
But I feel that verifier change might be the right thing to do.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200618234631.3321118-1-yhs@fb.com
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Merge tag 'block-5.8-2020-06-19' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
- Use import_uuid() where appropriate (Andy)
- bcache fixes (Coly, Mauricio, Zhiqiang)
- blktrace sparse warnings fix (Jan)
- blktrace concurrent setup fix (Luis)
- blkdev_get use-after-free fix (Jason)
- Ensure all blk-mq maps are updated (Weiping)
- Loop invalidate bdev fix (Zheng)
* tag 'block-5.8-2020-06-19' of git://git.kernel.dk/linux-block:
block: make function 'kill_bdev' static
loop: replace kill_bdev with invalidate_bdev
partitions/ldm: Replace uuid_copy() with import_uuid() where it makes sense
block: update hctx map when use multiple maps
blktrace: Avoid sparse warnings when assigning q->blk_trace
blktrace: break out of blktrace setup on concurrent calls
block: Fix use-after-free in blkdev_get()
trace/events/block.h: drop kernel-doc for dropped function parameter
blk-mq: Remove redundant 'return' statement
bcache: pr_info() format clean up in bcache_device_init()
bcache: use delayed kworker fo asynchronous devices registration
bcache: check and adjust logical block size for backing devices
bcache: fix potential deadlock problem in btree_gc_coalesce
Merge non-faulting memory access cleanups from Christoph Hellwig:
"Andrew and I decided to drop the patches implementing your suggested
rename of the probe_kernel_* and probe_user_* helpers from -mm as
there were way to many conflicts.
After -rc1 might be a good time for this as all the conflicts are
resolved now"
This also adds a type safety checking patch on top of the renaming
series to make the subtle behavioral difference between 'get_user()' and
'get_kernel_nofault()' less potentially dangerous and surprising.
* emailed patches from Christoph Hellwig <hch@lst.de>:
maccess: make get_kernel_nofault() check for minimal type compatibility
maccess: rename probe_kernel_address to get_kernel_nofault
maccess: rename probe_user_{read,write} to copy_{from,to}_user_nofault
maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault
A 5.7 kernel hangs during a tcrypt test of padata that waits for an AEAD
request to finish. This is only seen on large machines running many
concurrent requests.
The issue is that padata never serializes the request. The removal of
the reorder_objects atomic missed that the memory barrier in
padata_do_serial() depends on it.
Upgrade the barrier from smp_mb__after_atomic to smp_mb to get correct
ordering again.
Fixes: 3facced7aeed1 ("padata: remove reorder_objects")
Signed-off-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Cc: linux-kernel@vger.kernel.org
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
During build compiler reports some 'false positive' warnings about
variables {'seq_ops', 'filtered_pids', 'other_pids'} may be used
uninitialized. This patch silences these warnings.
Also delete some useless spaces
Link: https://lkml.kernel.org/r/20200529141214.37648-1-pilgrimtao@gmail.com
Signed-off-by: Kaitao Cheng <pilgrimtao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Alexei Starovoitov says:
====================
pull-request: bpf 2020-06-17
The following pull-request contains BPF updates for your *net* tree.
We've added 10 non-merge commits during the last 2 day(s) which contain
a total of 14 files changed, 158 insertions(+), 59 deletions(-).
The main changes are:
1) Important fix for bpf_probe_read_kernel_str() return value, from Andrii.
2) [gs]etsockopt fix for large optlen, from Stanislav.
3) devmap allocation fix, from Toke.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
- fixes for the SEV atomic pool (Geert Uytterhoeven and David Rientjes)
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Merge tag 'dma-mapping-5.8-3' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping fixes from Christoph Hellwig:
"Fixes for the SEV atomic pool (Geert Uytterhoeven and David Rientjes)"
* tag 'dma-mapping-5.8-3' of git://git.infradead.org/users/hch/dma-mapping:
dma-pool: decouple DMA_REMAP from DMA_COHERENT_POOL
dma-pool: fix too large DMA pools on medium memory size systems
Attaching to these hooks can break iptables because its optval is
usually quite big, or at least bigger than the current PAGE_SIZE limit.
David also mentioned some SCTP options can be big (around 256k).
For such optvals we expose only the first PAGE_SIZE bytes to
the BPF program. BPF program has two options:
1. Set ctx->optlen to 0 to indicate that the BPF's optval
should be ignored and the kernel should use original userspace
value.
2. Set ctx->optlen to something that's smaller than the PAGE_SIZE.
v5:
* use ctx->optlen == 0 with trimmed buffer (Alexei Starovoitov)
* update the docs accordingly
v4:
* use temporary buffer to avoid optval == optval_end == NULL;
this removes the corner case in the verifier that might assume
non-zero PTR_TO_PACKET/PTR_TO_PACKET_END.
v3:
* don't increase the limit, bypass the argument
v2:
* proper comments formatting (Jakub Kicinski)
Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Link: https://lore.kernel.org/bpf/20200617010416.93086-1-sdf@google.com
Syzkaller discovered that creating a hash of type devmap_hash with a large
number of entries can hit the memory allocator limit for allocating
contiguous memory regions. There's really no reason to use kmalloc_array()
directly in the devmap code, so just switch it to the existing
bpf_map_area_alloc() function that is used elsewhere.
Fixes: 6f9d451ab1a3 ("xdp: Add devmap_hash map type for looking up devices by hashed index")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616142829.114173-1-toke@redhat.com
During recent refactorings, bpf_probe_read_kernel_str() started returning 0 on
success, instead of amount of data successfully read. This majorly breaks
applications relying on bpf_probe_read_kernel_str() and bpf_probe_read_str()
and their results. Fix this by returning actual number of bytes read.
Fixes: 8d92db5c04d1 ("bpf: rework the compat kernel probe handling")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20200616050432.1902042-1-andriin@fb.com
Mostly for historical reasons, q->blk_trace is assigned through xchg()
and cmpxchg() atomic operations. Although this is correct, sparse
complains about this because it violates rcu annotations since commit
c780e86dd48e ("blktrace: Protect q->blk_trace with RCU") which started
to use rcu for accessing q->blk_trace. Furthermore there's no real need
for atomic operations anymore since all changes to q->blk_trace happen
under q->blk_trace_mutex and since it also makes more sense to check if
q->blk_trace is set with the mutex held earlier.
So let's just replace xchg() with rcu_replace_pointer() and cmpxchg()
with explicit check and rcu_assign_pointer(). This makes the code more
efficient and sparse happy.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
We use one blktrace per request_queue, that means one per the entire
disk. So we cannot run one blktrace on say /dev/vda and then /dev/vda1,
or just two calls on /dev/vda.
We check for concurrent setup only at the very end of the blktrace setup though.
If we try to run two concurrent blktraces on the same block device the
second one will fail, and the first one seems to go on. However when
one tries to kill the first one one will see things like this:
The kernel will show these:
```
debugfs: File 'dropped' in directory 'nvme1n1' already present!
debugfs: File 'msg' in directory 'nvme1n1' already present!
debugfs: File 'trace0' in directory 'nvme1n1' already present!
``
And userspace just sees this error message for the second call:
```
blktrace /dev/nvme1n1
BLKTRACESETUP(2) /dev/nvme1n1 failed: 5/Input/output error
```
The first userspace process #1 will also claim that the files
were taken underneath their nose as well. The files are taken
away form the first process given that when the second blktrace
fails, it will follow up with a BLKTRACESTOP and BLKTRACETEARDOWN.
This means that even if go-happy process #1 is waiting for blktrace
data, we *have* been asked to take teardown the blktrace.
This can easily be reproduced with break-blktrace [0] run_0005.sh test.
Just break out early if we know we're already going to fail, this will
prevent trying to create the files all over again, which we know still
exist.
[0] https://github.com/mcgrof/break-blktrace
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
__change_page_attr() can fail which will cause set_memory_encrypted() and
set_memory_decrypted() to return non-zero.
If the device requires unencrypted DMA memory and decryption fails, simply
free the memory and fail.
If attempting to re-encrypt in the failure path and that encryption fails,
there is no alternative other than to leak the memory.
Fixes: c10f07aa27da ("dma/direct: Handle force decryption for DMA coherent buffers in common code")
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
If arch_dma_set_uncached() fails after memory has been decrypted, it needs
to be re-encrypted before freeing.
Fixes: fa7e2247c572 ("dma-direct: make uncached_kernel_address more general")
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
dma_alloc_contiguous() does size >> PAGE_SHIFT and set_memory_decrypted()
works at page granularity. It's necessary to page align the allocation
size in dma_direct_alloc_pages() for consistent behavior.
This also fixes an issue when arch_dma_prep_coherent() is called on an
unaligned allocation size for dma_alloc_need_uncached() when
CONFIG_DMA_DIRECT_REMAP is disabled but CONFIG_ARCH_HAS_DMA_SET_UNCACHED
is enabled.
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
nommu configfs can trivially map the coherent allocations to user space,
as no actual page table setup is required and the kernel and the user
space programs share the same address space.
Fixes: 62fcee9a3bd7 ("dma-mapping: remove CONFIG_ARCH_NO_COHERENT_DMA_MMAP")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reported-by: dillon min <dillon.minfei@gmail.com>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>
Tested-by: dillon min <dillon.minfei@gmail.com>
We do not use the event variable, just remove it.
Signed-off-by: YangHui <yanghui.def@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
kmemleak report:
[<57dcc2ca>] __kmalloc_track_caller+0x139/0x2b0
[<f1c45d0f>] kstrndup+0x37/0x80
[<f9761eb0>] parse_probe_arg.isra.7+0x3cc/0x630
[<055bf2ba>] traceprobe_parse_probe_arg+0x2f5/0x810
[<655a7766>] trace_kprobe_create+0x2ca/0x950
[<4fc6a02a>] create_or_delete_trace_kprobe+0xf/0x30
[<6d1c8a52>] trace_run_command+0x67/0x80
[<be812cc0>] trace_parse_run_command+0xa7/0x140
[<aecfe401>] probes_write+0x10/0x20
[<2027641c>] __vfs_write+0x30/0x1e0
[<6a4aeee1>] vfs_write+0x96/0x1b0
[<3517fb7d>] ksys_write+0x53/0xc0
[<dad91db7>] __ia32_sys_write+0x15/0x20
[<da347f64>] do_syscall_32_irqs_on+0x3d/0x260
[<fd0b7e7d>] do_fast_syscall_32+0x39/0xb0
[<ea5ae810>] entry_SYSENTER_32+0xaf/0x102
Post parse_probe_arg(), the FETCH_OP_DATA operation type is overwritten
to FETCH_OP_ST_STRING, as a result memory is never freed since
traceprobe_free_probe_arg() iterates only over SYMBOL and DATA op types
Setup fetch string operation correctly after fetch_op_data operation.
Link: https://lkml.kernel.org/r/20200615143034.GA1734@cosmos
Cc: stable@vger.kernel.org
Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support")
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
When using trace-cmd on 5.6-rt for the function graph tracer, the output was
corrupted. It gave output like this:
funcgraph_entry: func=0xffffffff depth=38982
funcgraph_entry: func=0x1ffffffff depth=16044
funcgraph_exit: func=0xffffffff overrun=0x92539aaf00000000 calltime=0x92539c9900000072 rettime=0x100000072 depth=11084
funcgraph_exit: func=0xffffffff overrun=0x9253946e00000000 calltime=0x92539e2100000072 rettime=0x72 depth=26033702
funcgraph_entry: func=0xffffffff depth=85798
funcgraph_entry: func=0x1ffffffff depth=12044
The reason was because the tracefs/events/ftrace/funcgraph_entry/exit format
file was incorrect. The -rt kernel adds more common fields to the trace
events. Namely, common_migrate_disable and common_preempt_lazy_count. Each
is one byte in size. This changes the alignment of the normal payload. Most
events are aligned normally, but the function and function graph events are
defined with a "PACKED" macro, that packs their payload. As the offsets
displayed in the format files are now calculated by an aligned field, the
aligned field for function and function graph events should be 1, not their
normal alignment.
With aligning of the funcgraph_entry event, the format file has:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:unsigned char common_migrate_disable; offset:8; size:1; signed:0;
field:unsigned char common_preempt_lazy_count; offset:9; size:1; signed:0;
field:unsigned long func; offset:16; size:8; signed:0;
field:int depth; offset:24; size:4; signed:1;
But the actual alignment is:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:unsigned char common_migrate_disable; offset:8; size:1; signed:0;
field:unsigned char common_preempt_lazy_count; offset:9; size:1; signed:0;
field:unsigned long func; offset:12; size:8; signed:0;
field:int depth; offset:20; size:4; signed:1;
Link: https://lkml.kernel.org/r/20200609220041.2a3b527f@oasis.local.home
Cc: stable@vger.kernel.org
Fixes: 04ae87a52074e ("ftrace: Rework event_create_dir()")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Ziqian reported lockup when adding retprobe on _raw_spin_lock_irqsave.
My test was also able to trigger lockdep output:
============================================
WARNING: possible recursive locking detected
5.6.0-rc6+ #6 Not tainted
--------------------------------------------
sched-messaging/2767 is trying to acquire lock:
ffffffff9a492798 (&(kretprobe_table_locks[i].lock)){-.-.}, at: kretprobe_hash_lock+0x52/0xa0
but task is already holding lock:
ffffffff9a491a18 (&(kretprobe_table_locks[i].lock)){-.-.}, at: kretprobe_trampoline+0x0/0x50
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(kretprobe_table_locks[i].lock));
lock(&(kretprobe_table_locks[i].lock));
*** DEADLOCK ***
May be due to missing lock nesting notation
1 lock held by sched-messaging/2767:
#0: ffffffff9a491a18 (&(kretprobe_table_locks[i].lock)){-.-.}, at: kretprobe_trampoline+0x0/0x50
stack backtrace:
CPU: 3 PID: 2767 Comm: sched-messaging Not tainted 5.6.0-rc6+ #6
Call Trace:
dump_stack+0x96/0xe0
__lock_acquire.cold.57+0x173/0x2b7
? native_queued_spin_lock_slowpath+0x42b/0x9e0
? lockdep_hardirqs_on+0x590/0x590
? __lock_acquire+0xf63/0x4030
lock_acquire+0x15a/0x3d0
? kretprobe_hash_lock+0x52/0xa0
_raw_spin_lock_irqsave+0x36/0x70
? kretprobe_hash_lock+0x52/0xa0
kretprobe_hash_lock+0x52/0xa0
trampoline_handler+0xf8/0x940
? kprobe_fault_handler+0x380/0x380
? find_held_lock+0x3a/0x1c0
kretprobe_trampoline+0x25/0x50
? lock_acquired+0x392/0xbc0
? _raw_spin_lock_irqsave+0x50/0x70
? __get_valid_kprobe+0x1f0/0x1f0
? _raw_spin_unlock_irqrestore+0x3b/0x40
? finish_task_switch+0x4b9/0x6d0
? __switch_to_asm+0x34/0x70
? __switch_to_asm+0x40/0x70
The code within the kretprobe handler checks for probe reentrancy,
so we won't trigger any _raw_spin_lock_irqsave probe in there.
The problem is in outside kprobe_flush_task, where we call:
kprobe_flush_task
kretprobe_table_lock
raw_spin_lock_irqsave
_raw_spin_lock_irqsave
where _raw_spin_lock_irqsave triggers the kretprobe and installs
kretprobe_trampoline handler on _raw_spin_lock_irqsave return.
The kretprobe_trampoline handler is then executed with already
locked kretprobe_table_locks, and first thing it does is to
lock kretprobe_table_locks ;-) the whole lockup path like:
kprobe_flush_task
kretprobe_table_lock
raw_spin_lock_irqsave
_raw_spin_lock_irqsave ---> probe triggered, kretprobe_trampoline installed
---> kretprobe_table_locks locked
kretprobe_trampoline
trampoline_handler
kretprobe_hash_lock(current, &head, &flags); <--- deadlock
Adding kprobe_busy_begin/end helpers that mark code with fake
probe installed to prevent triggering of another kprobe within
this code.
Using these helpers in kprobe_flush_task, so the probe recursion
protection check is hit and the probe is never set to prevent
above lockup.
Link: http://lkml.kernel.org/r/158927059835.27680.7011202830041561604.stgit@devnote2
Fixes: ef53d9c5e4da ("kprobes: improve kretprobe scalability with hashed locking")
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Gustavo A . R . Silva" <gustavoars@kernel.org>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Reported-by: "Ziqian SUN (Zamir)" <zsun@redhat.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Fix to remove redundant arch_disarm_kprobe() call in
force_unoptimize_kprobe(). This arch_disarm_kprobe()
will be invoked if the kprobe is optimized but disabled,
but that means the kprobe (optprobe) is unused (and
unoptimized) state.
In that case, unoptimize_kprobe() puts it in freeing_list
and kprobe_optimizer (do_unoptimize_kprobes()) automatically
disarm it. Thus this arch_disarm_kprobe() is redundant.
Link: http://lkml.kernel.org/r/158927058719.27680.17183632908465341189.stgit@devnote2
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
In kprobe_optimizer() kick_kprobe_optimizer() is called
without kprobe_mutex, but this can race with other caller
which is protected by kprobe_mutex.
To fix that, expand kprobe_mutex protected area to protect
kick_kprobe_optimizer() call.
Link: http://lkml.kernel.org/r/158927057586.27680.5036330063955940456.stgit@devnote2
Fixes: cd7ebe2298ff ("kprobes: Use text_poke_smp_batch for optimizing")
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Gustavo A . R . Silva" <gustavoars@kernel.org>
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ziqian SUN <zsun@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Current kprobes uses RCU traversal APIs on kprobe_tables
even if it is safe because kprobe_mutex is locked.
Make those traversals to non-RCU APIs where the kprobe_mutex
is locked.
Link: http://lkml.kernel.org/r/158927056452.27680.9710575332163005121.stgit@devnote2
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Anders reported that the lockdep warns that suspicious
RCU list usage in register_kprobe() (detected by
CONFIG_PROVE_RCU_LIST.) This is because get_kprobe()
access kprobe_table[] by hlist_for_each_entry_rcu()
without rcu_read_lock.
If we call get_kprobe() from the breakpoint handler context,
it is run with preempt disabled, so this is not a problem.
But in other cases, instead of rcu_read_lock(), we locks
kprobe_mutex so that the kprobe_table[] is not updated.
So, current code is safe, but still not good from the view
point of RCU.
Joel suggested that we can silent that warning by passing
lockdep_is_held() to the last argument of
hlist_for_each_entry_rcu().
Add lockdep_is_held(&kprobe_mutex) at the end of the
hlist_for_each_entry_rcu() to suppress the warning.
Link: http://lkml.kernel.org/r/158927055350.27680.10261450713467997503.stgit@devnote2
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Suggested-by: Joel Fernandes <joel@joelfernandes.org>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
The LTP testsuite reported a regression where users would now see EBADF
returned instead of EINVAL when an fd was passed that referred to an open
file but the file was not a nsfd. Fix this by continuing to report EINVAL.
Reported-by: kernel test robot <rong.a.chen@intel.com>
Cc: Jan Stancek <jstancek@redhat.com>
Cc: Cyril Hrubis <chrubis@suse.cz>
Link: https://lore.kernel.org/lkml/20200615085836.GR12456@shao2-debian
Fixes: 303cc571d107 ("nsproxy: attach to namespaces via pidfds")
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
There is a regular need in the kernel to provide a way to declare having a
dynamically sized set of trailing elements in a structure. Kernel code should
always use “flexible array members”[1] for these cases. The older style of
one-element or zero-length arrays should no longer be used[2].
[1] https://en.wikipedia.org/wiki/Flexible_array_member
[2] https://github.com/KSPP/linux/issues/21
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
DMA_REMAP is an unnecessary requirement for AMD SEV, which requires
DMA_COHERENT_POOL, so avoid selecting it when it is otherwise unnecessary.
The only other requirement for DMA coherent pools is DMA_DIRECT_REMAP, so
ensure that properly selects the config option when needed.
Fixes: 82fef0ad811f ("x86/mm: unencrypted non-blocking DMA allocations use coherent pools")
Reported-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: David Rientjes <rientjes@google.com>
Tested-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: Christoph Hellwig <hch@lst.de>
SafeSetID is capable of making allow/deny decisions for set*uid calls
on a system, and we want to add similar functionality for set*gid
calls. The work to do that is not yet complete, so probably won't make
it in for v5.8, but we are looking to get this simple patch in for
v5.8 since we have it ready. We are planning on the rest of the work
for extending the SafeSetID LSM being merged during the v5.9 merge
window.
This patch was sent to the security mailing list and there were no objections.
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Merge tag 'LSM-add-setgid-hook-5.8-author-fix' of git://github.com/micah-morton/linux
Pull SafeSetID update from Micah Morton:
"Add additional LSM hooks for SafeSetID
SafeSetID is capable of making allow/deny decisions for set*uid calls
on a system, and we want to add similar functionality for set*gid
calls.
The work to do that is not yet complete, so probably won't make it in
for v5.8, but we are looking to get this simple patch in for v5.8
since we have it ready.
We are planning on the rest of the work for extending the SafeSetID
LSM being merged during the v5.9 merge window"
* tag 'LSM-add-setgid-hook-5.8-author-fix' of git://github.com/micah-morton/linux:
security: Add LSM hooks to set*gid syscalls
The SafeSetID LSM uses the security_task_fix_setuid hook to filter
set*uid() syscalls according to its configured security policy. In
preparation for adding analagous support in the LSM for set*gid()
syscalls, we add the requisite hook here. Tested by putting print
statements in the security_task_fix_setgid hook and seeing them get hit
during kernel boot.
Signed-off-by: Thomas Cedeno <thomascedeno@google.com>
Signed-off-by: Micah Morton <mortonm@chromium.org>
Pull networking fixes from David Miller:
1) Fix cfg80211 deadlock, from Johannes Berg.
2) RXRPC fails to send norigications, from David Howells.
3) MPTCP RM_ADDR parsing has an off by one pointer error, fix from
Geliang Tang.
4) Fix crash when using MSG_PEEK with sockmap, from Anny Hu.
5) The ucc_geth driver needs __netdev_watchdog_up exported, from
Valentin Longchamp.
6) Fix hashtable memory leak in dccp, from Wang Hai.
7) Fix how nexthops are marked as FDB nexthops, from David Ahern.
8) Fix mptcp races between shutdown and recvmsg, from Paolo Abeni.
9) Fix crashes in tipc_disc_rcv(), from Tuong Lien.
10) Fix link speed reporting in iavf driver, from Brett Creeley.
11) When a channel is used for XSK and then reused again later for XSK,
we forget to clear out the relevant data structures in mlx5 which
causes all kinds of problems. Fix from Maxim Mikityanskiy.
12) Fix memory leak in genetlink, from Cong Wang.
13) Disallow sockmap attachments to UDP sockets, it simply won't work.
From Lorenz Bauer.
* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (83 commits)
net: ethernet: ti: ale: fix allmulti for nu type ale
net: ethernet: ti: am65-cpsw-nuss: fix ale parameters init
net: atm: Remove the error message according to the atomic context
bpf: Undo internal BPF_PROBE_MEM in BPF insns dump
libbpf: Support pre-initializing .bss global variables
tools/bpftool: Fix skeleton codegen
bpf: Fix memlock accounting for sock_hash
bpf: sockmap: Don't attach programs to UDP sockets
bpf: tcp: Recv() should return 0 when the peer socket is closed
ibmvnic: Flush existing work items before device removal
genetlink: clean up family attributes allocations
net: ipa: header pad field only valid for AP->modem endpoint
net: ipa: program upper nibbles of sequencer type
net: ipa: fix modem LAN RX endpoint id
net: ipa: program metadata mask differently
ionic: add pcie_print_link_status
rxrpc: Fix race between incoming ACK parser and retransmitter
net/mlx5: E-Switch, Fix some error pointer dereferences
net/mlx5: Don't fail driver on failure to create debugfs
net/mlx5e: CT: Fix ipv6 nat header rewrite actions
...
Alexei Starovoitov says:
====================
pull-request: bpf 2020-06-12
The following pull-request contains BPF updates for your *net* tree.
We've added 26 non-merge commits during the last 10 day(s) which contain
a total of 27 files changed, 348 insertions(+), 93 deletions(-).
The main changes are:
1) sock_hash accounting fix, from Andrey.
2) libbpf fix and probe_mem sanitizing, from Andrii.
3) sock_hash fixes, from Jakub.
4) devmap_val fix, from Jesper.
5) load_bytes_relative fix, from YiFei.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
- fix build rules in binderfs sample
- fix build errors when Kbuild recurses to the top Makefile
- covert '---help---' in Kconfig to 'help'
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Merge tag 'kbuild-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull more Kbuild updates from Masahiro Yamada:
- fix build rules in binderfs sample
- fix build errors when Kbuild recurses to the top Makefile
- covert '---help---' in Kconfig to 'help'
* tag 'kbuild-v5.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
treewide: replace '---help---' in Kconfig files with 'help'
kbuild: fix broken builds because of GZIP,BZIP2,LZOP variables
samples: binderfs: really compile this sample and fix build issues
This all started about 6 month ago with the attempt to move the Posix CPU
timer heavy lifting out of the timer interrupt code and just have lockless
quick checks in that code path. Trivial 5 patches.
This unearthed an inconsistency in the KVM handling of task work and the
review requested to move all of this into generic code so other
architectures can share.
Valid request and solved with another 25 patches but those unearthed
inconsistencies vs. RCU and instrumentation.
Digging into this made it obvious that there are quite some inconsistencies
vs. instrumentation in general. The int3 text poke handling in particular
was completely unprotected and with the batched update of trace events even
more likely to expose to endless int3 recursion.
In parallel the RCU implications of instrumenting fragile entry code came
up in several discussions.
The conclusion of the X86 maintainer team was to go all the way and make
the protection against any form of instrumentation of fragile and dangerous
code pathes enforcable and verifiable by tooling.
A first batch of preparatory work hit mainline with commit d5f744f9a2ac.
The (almost) full solution introduced a new code section '.noinstr.text'
into which all code which needs to be protected from instrumentation of all
sorts goes into. Any call into instrumentable code out of this section has
to be annotated. objtool has support to validate this. Kprobes now excludes
this section fully which also prevents BPF from fiddling with it and all
'noinstr' annotated functions also keep ftrace off. The section, kprobes
and objtool changes are already merged.
The major changes coming with this are:
- Preparatory cleanups
- Annotating of relevant functions to move them into the noinstr.text
section or enforcing inlining by marking them __always_inline so the
compiler cannot misplace or instrument them.
- Splitting and simplifying the idtentry macro maze so that it is now
clearly separated into simple exception entries and the more
interesting ones which use interrupt stacks and have the paranoid
handling vs. CR3 and GS.
- Move quite some of the low level ASM functionality into C code:
- enter_from and exit to user space handling. The ASM code now calls
into C after doing the really necessary ASM handling and the return
path goes back out without bells and whistels in ASM.
- exception entry/exit got the equivivalent treatment
- move all IRQ tracepoints from ASM to C so they can be placed as
appropriate which is especially important for the int3 recursion
issue.
- Consolidate the declaration and definition of entry points between 32
and 64 bit. They share a common header and macros now.
- Remove the extra device interrupt entry maze and just use the regular
exception entry code.
- All ASM entry points except NMI are now generated from the shared header
file and the corresponding macros in the 32 and 64 bit entry ASM.
- The C code entry points are consolidated as well with the help of
DEFINE_IDTENTRY*() macros. This allows to ensure at one central point
that all corresponding entry points share the same semantics. The
actual function body for most entry points is in an instrumentable
and sane state.
There are special macros for the more sensitive entry points,
e.g. INT3 and of course the nasty paranoid #NMI, #MCE, #DB and #DF.
They allow to put the whole entry instrumentation and RCU handling
into safe places instead of the previous pray that it is correct
approach.
- The INT3 text poke handling is now completely isolated and the
recursion issue banned. Aside of the entry rework this required other
isolation work, e.g. the ability to force inline bsearch.
- Prevent #DB on fragile entry code, entry relevant memory and disable
it on NMI, #MC entry, which allowed to get rid of the nested #DB IST
stack shifting hackery.
- A few other cleanups and enhancements which have been made possible
through this and already merged changes, e.g. consolidating and
further restricting the IDT code so the IDT table becomes RO after
init which removes yet another popular attack vector
- About 680 lines of ASM maze are gone.
There are a few open issues:
- An escape out of the noinstr section in the MCE handler which needs
some more thought but under the aspect that MCE is a complete
trainwreck by design and the propability to survive it is low, this was
not high on the priority list.
- Paravirtualization
When PV is enabled then objtool complains about a bunch of indirect
calls out of the noinstr section. There are a few straight forward
ways to fix this, but the other issues vs. general correctness were
more pressing than parawitz.
- KVM
KVM is inconsistent as well. Patches have been posted, but they have
not yet been commented on or picked up by the KVM folks.
- IDLE
Pretty much the same problems can be found in the low level idle code
especially the parts where RCU stopped watching. This was beyond the
scope of the more obvious and exposable problems and is on the todo
list.
The lesson learned from this brain melting exercise to morph the evolved
code base into something which can be validated and understood is that once
again the violation of the most important engineering principle
"correctness first" has caused quite a few people to spend valuable time on
problems which could have been avoided in the first place. The "features
first" tinkering mindset really has to stop.
With that I want to say thanks to everyone involved in contributing to this
effort. Special thanks go to the following people (alphabetical order):
Alexandre Chartre
Andy Lutomirski
Borislav Petkov
Brian Gerst
Frederic Weisbecker
Josh Poimboeuf
Juergen Gross
Lai Jiangshan
Macro Elver
Paolo Bonzini
Paul McKenney
Peter Zijlstra
Vitaly Kuznetsov
Will Deacon
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Merge tag 'x86-entry-2020-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 entry updates from Thomas Gleixner:
"The x86 entry, exception and interrupt code rework
This all started about 6 month ago with the attempt to move the Posix
CPU timer heavy lifting out of the timer interrupt code and just have
lockless quick checks in that code path. Trivial 5 patches.
This unearthed an inconsistency in the KVM handling of task work and
the review requested to move all of this into generic code so other
architectures can share.
Valid request and solved with another 25 patches but those unearthed
inconsistencies vs. RCU and instrumentation.
Digging into this made it obvious that there are quite some
inconsistencies vs. instrumentation in general. The int3 text poke
handling in particular was completely unprotected and with the batched
update of trace events even more likely to expose to endless int3
recursion.
In parallel the RCU implications of instrumenting fragile entry code
came up in several discussions.
The conclusion of the x86 maintainer team was to go all the way and
make the protection against any form of instrumentation of fragile and
dangerous code pathes enforcable and verifiable by tooling.
A first batch of preparatory work hit mainline with commit
d5f744f9a2ac ("Pull x86 entry code updates from Thomas Gleixner")
That (almost) full solution introduced a new code section
'.noinstr.text' into which all code which needs to be protected from
instrumentation of all sorts goes into. Any call into instrumentable
code out of this section has to be annotated. objtool has support to
validate this.
Kprobes now excludes this section fully which also prevents BPF from
fiddling with it and all 'noinstr' annotated functions also keep
ftrace off. The section, kprobes and objtool changes are already
merged.
The major changes coming with this are:
- Preparatory cleanups
- Annotating of relevant functions to move them into the
noinstr.text section or enforcing inlining by marking them
__always_inline so the compiler cannot misplace or instrument
them.
- Splitting and simplifying the idtentry macro maze so that it is
now clearly separated into simple exception entries and the more
interesting ones which use interrupt stacks and have the paranoid
handling vs. CR3 and GS.
- Move quite some of the low level ASM functionality into C code:
- enter_from and exit to user space handling. The ASM code now
calls into C after doing the really necessary ASM handling and
the return path goes back out without bells and whistels in
ASM.
- exception entry/exit got the equivivalent treatment
- move all IRQ tracepoints from ASM to C so they can be placed as
appropriate which is especially important for the int3
recursion issue.
- Consolidate the declaration and definition of entry points between
32 and 64 bit. They share a common header and macros now.
- Remove the extra device interrupt entry maze and just use the
regular exception entry code.
- All ASM entry points except NMI are now generated from the shared
header file and the corresponding macros in the 32 and 64 bit
entry ASM.
- The C code entry points are consolidated as well with the help of
DEFINE_IDTENTRY*() macros. This allows to ensure at one central
point that all corresponding entry points share the same
semantics. The actual function body for most entry points is in an
instrumentable and sane state.
There are special macros for the more sensitive entry points, e.g.
INT3 and of course the nasty paranoid #NMI, #MCE, #DB and #DF.
They allow to put the whole entry instrumentation and RCU handling
into safe places instead of the previous pray that it is correct
approach.
- The INT3 text poke handling is now completely isolated and the
recursion issue banned. Aside of the entry rework this required
other isolation work, e.g. the ability to force inline bsearch.
- Prevent #DB on fragile entry code, entry relevant memory and
disable it on NMI, #MC entry, which allowed to get rid of the
nested #DB IST stack shifting hackery.
- A few other cleanups and enhancements which have been made
possible through this and already merged changes, e.g.
consolidating and further restricting the IDT code so the IDT
table becomes RO after init which removes yet another popular
attack vector
- About 680 lines of ASM maze are gone.
There are a few open issues:
- An escape out of the noinstr section in the MCE handler which needs
some more thought but under the aspect that MCE is a complete
trainwreck by design and the propability to survive it is low, this
was not high on the priority list.
- Paravirtualization
When PV is enabled then objtool complains about a bunch of indirect
calls out of the noinstr section. There are a few straight forward
ways to fix this, but the other issues vs. general correctness were
more pressing than parawitz.
- KVM
KVM is inconsistent as well. Patches have been posted, but they
have not yet been commented on or picked up by the KVM folks.
- IDLE
Pretty much the same problems can be found in the low level idle
code especially the parts where RCU stopped watching. This was
beyond the scope of the more obvious and exposable problems and is
on the todo list.
The lesson learned from this brain melting exercise to morph the
evolved code base into something which can be validated and understood
is that once again the violation of the most important engineering
principle "correctness first" has caused quite a few people to spend
valuable time on problems which could have been avoided in the first
place. The "features first" tinkering mindset really has to stop.
With that I want to say thanks to everyone involved in contributing to
this effort. Special thanks go to the following people (alphabetical
order): Alexandre Chartre, Andy Lutomirski, Borislav Petkov, Brian
Gerst, Frederic Weisbecker, Josh Poimboeuf, Juergen Gross, Lai
Jiangshan, Macro Elver, Paolo Bonzin,i Paul McKenney, Peter Zijlstra,
Vitaly Kuznetsov, and Will Deacon"
* tag 'x86-entry-2020-06-12' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (142 commits)
x86/entry: Force rcu_irq_enter() when in idle task
x86/entry: Make NMI use IDTENTRY_RAW
x86/entry: Treat BUG/WARN as NMI-like entries
x86/entry: Unbreak __irqentry_text_start/end magic
x86/entry: __always_inline CR2 for noinstr
lockdep: __always_inline more for noinstr
x86/entry: Re-order #DB handler to avoid *SAN instrumentation
x86/entry: __always_inline arch_atomic_* for noinstr
x86/entry: __always_inline irqflags for noinstr
x86/entry: __always_inline debugreg for noinstr
x86/idt: Consolidate idt functionality
x86/idt: Cleanup trap_init()
x86/idt: Use proper constants for table size
x86/idt: Add comments about early #PF handling
x86/idt: Mark init only functions __init
x86/entry: Rename trace_hardirqs_off_prepare()
x86/entry: Clarify irq_{enter,exit}_rcu()
x86/entry: Remove DBn stacks
x86/entry: Remove debug IDT frobbing
x86/entry: Optimize local_db_save() for virt
...
Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.
This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.
There are a variety of indentation styles found.
a) 4 spaces + '---help---'
b) 7 spaces + '---help---'
c) 8 spaces + '---help---'
d) 1 space + 1 tab + '---help---'
e) 1 tab + '---help---' (correct indentation)
f) 1 tab + 1 space + '---help---'
g) 1 tab + 2 spaces + '---help---'
In order to convert all of them to 1 tab + 'help', I ran the
following commend:
$ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
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Merge tag 'notifications-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull notification queue from David Howells:
"This adds a general notification queue concept and adds an event
source for keys/keyrings, such as linking and unlinking keys and
changing their attributes.
Thanks to Debarshi Ray, we do have a pull request to use this to fix a
problem with gnome-online-accounts - as mentioned last time:
https://gitlab.gnome.org/GNOME/gnome-online-accounts/merge_requests/47
Without this, g-o-a has to constantly poll a keyring-based kerberos
cache to find out if kinit has changed anything.
[ There are other notification pending: mount/sb fsinfo notifications
for libmount that Karel Zak and Ian Kent have been working on, and
Christian Brauner would like to use them in lxc, but let's see how
this one works first ]
LSM hooks are included:
- A set of hooks are provided that allow an LSM to rule on whether or
not a watch may be set. Each of these hooks takes a different
"watched object" parameter, so they're not really shareable. The
LSM should use current's credentials. [Wanted by SELinux & Smack]
- A hook is provided to allow an LSM to rule on whether or not a
particular message may be posted to a particular queue. This is
given the credentials from the event generator (which may be the
system) and the watch setter. [Wanted by Smack]
I've provided SELinux and Smack with implementations of some of these
hooks.
WHY
===
Key/keyring notifications are desirable because if you have your
kerberos tickets in a file/directory, your Gnome desktop will monitor
that using something like fanotify and tell you if your credentials
cache changes.
However, we also have the ability to cache your kerberos tickets in
the session, user or persistent keyring so that it isn't left around
on disk across a reboot or logout. Keyrings, however, cannot currently
be monitored asynchronously, so the desktop has to poll for it - not
so good on a laptop. This facility will allow the desktop to avoid the
need to poll.
DESIGN DECISIONS
================
- The notification queue is built on top of a standard pipe. Messages
are effectively spliced in. The pipe is opened with a special flag:
pipe2(fds, O_NOTIFICATION_PIPE);
The special flag has the same value as O_EXCL (which doesn't seem
like it will ever be applicable in this context)[?]. It is given up
front to make it a lot easier to prohibit splice&co from accessing
the pipe.
[?] Should this be done some other way? I'd rather not use up a new
O_* flag if I can avoid it - should I add a pipe3() system call
instead?
The pipe is then configured::
ioctl(fds[1], IOC_WATCH_QUEUE_SET_SIZE, queue_depth);
ioctl(fds[1], IOC_WATCH_QUEUE_SET_FILTER, &filter);
Messages are then read out of the pipe using read().
- It should be possible to allow write() to insert data into the
notification pipes too, but this is currently disabled as the
kernel has to be able to insert messages into the pipe *without*
holding pipe->mutex and the code to make this work needs careful
auditing.
- sendfile(), splice() and vmsplice() are disabled on notification
pipes because of the pipe->mutex issue and also because they
sometimes want to revert what they just did - but one or more
notification messages might've been interleaved in the ring.
- The kernel inserts messages with the wait queue spinlock held. This
means that pipe_read() and pipe_write() have to take the spinlock
to update the queue pointers.
- Records in the buffer are binary, typed and have a length so that
they can be of varying size.
This allows multiple heterogeneous sources to share a common
buffer; there are 16 million types available, of which I've used
just a few, so there is scope for others to be used. Tags may be
specified when a watchpoint is created to help distinguish the
sources.
- Records are filterable as types have up to 256 subtypes that can be
individually filtered. Other filtration is also available.
- Notification pipes don't interfere with each other; each may be
bound to a different set of watches. Any particular notification
will be copied to all the queues that are currently watching for it
- and only those that are watching for it.
- When recording a notification, the kernel will not sleep, but will
rather mark a queue as having lost a message if there's
insufficient space. read() will fabricate a loss notification
message at an appropriate point later.
- The notification pipe is created and then watchpoints are attached
to it, using one of:
keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fds[1], 0x01);
watch_mount(AT_FDCWD, "/", 0, fd, 0x02);
watch_sb(AT_FDCWD, "/mnt", 0, fd, 0x03);
where in both cases, fd indicates the queue and the number after is
a tag between 0 and 255.
- Watches are removed if either the notification pipe is destroyed or
the watched object is destroyed. In the latter case, a message will
be generated indicating the enforced watch removal.
Things I want to avoid:
- Introducing features that make the core VFS dependent on the
network stack or networking namespaces (ie. usage of netlink).
- Dumping all this stuff into dmesg and having a daemon that sits
there parsing the output and distributing it as this then puts the
responsibility for security into userspace and makes handling
namespaces tricky. Further, dmesg might not exist or might be
inaccessible inside a container.
- Letting users see events they shouldn't be able to see.
TESTING AND MANPAGES
====================
- The keyutils tree has a pipe-watch branch that has keyctl commands
for making use of notifications. Proposed manual pages can also be
found on this branch, though a couple of them really need to go to
the main manpages repository instead.
If the kernel supports the watching of keys, then running "make
test" on that branch will cause the testing infrastructure to spawn
a monitoring process on the side that monitors a notifications pipe
for all the key/keyring changes induced by the tests and they'll
all be checked off to make sure they happened.
https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/keyutils.git/log/?h=pipe-watch
- A test program is provided (samples/watch_queue/watch_test) that
can be used to monitor for keyrings, mount and superblock events.
Information on the notifications is simply logged to stdout"
* tag 'notifications-20200601' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
smack: Implement the watch_key and post_notification hooks
selinux: Implement the watch_key security hook
keys: Make the KEY_NEED_* perms an enum rather than a mask
pipe: Add notification lossage handling
pipe: Allow buffers to be marked read-whole-or-error for notifications
Add sample notification program
watch_queue: Add a key/keyring notification facility
security: Add hooks to rule on setting a watch
pipe: Add general notification queue support
pipe: Add O_NOTIFICATION_PIPE
security: Add a hook for the point of notification insertion
uapi: General notification queue definitions
BPF_PROBE_MEM is kernel-internal implmementation details. When dumping BPF
instructions to user-space, it needs to be replaced back with BPF_MEM mode.
Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200613002115.1632142-1-andriin@fb.com
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Merge tag 'printk-for-5.8-kdb-nmi' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux
Pull printk fix from Petr Mladek:
"One more printk change for 5.8: make sure that messages printed from
KDB context are redirected to KDB console handlers. It did not work
when KDB interrupted NMI or printk_safe contexts.
Arm people started hitting this problem more often recently. I forgot
to add the fix into the previous pull request by mistake"
* tag 'printk-for-5.8-kdb-nmi' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
printk/kdb: Redirect printk messages into kdb in any context
KCSAN is a dynamic race detector, which relies on compile-time
instrumentation, and uses a watchpoint-based sampling approach to detect
races.
The feature was under development for quite some time and has already found
legitimate bugs.
Unfortunately it comes with a limitation, which was only understood late in
the development cycle:
It requires an up to date CLANG-11 compiler
CLANG-11 is not yet released (scheduled for June), but it's the only
compiler today which handles the kernel requirements and especially the
annotations of functions to exclude them from KCSAN instrumentation
correctly.
These annotations really need to work so that low level entry code and
especially int3 text poke handling can be completely isolated.
A detailed discussion of the requirements and compiler issues can be found
here:
https://lore.kernel.org/lkml/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com/
We came to the conclusion that trying to work around compiler limitations
and bugs again would end up in a major trainwreck, so requiring a working
compiler seemed to be the best choice.
For Continous Integration purposes the compiler restriction is manageable
and that's where most xxSAN reports come from.
For a change this limitation might make GCC people actually look at their
bugs. Some issues with CSAN in GCC are 7 years old and one has been 'fixed'
3 years ago with a half baken solution which 'solved' the reported issue
but not the underlying problem.
The KCSAN developers also ponder to use a GCC plugin to become independent,
but that's not something which will show up in a few days.
Blocking KCSAN until wide spread compiler support is available is not a
really good alternative because the continuous growth of lockless
optimizations in the kernel demands proper tooling support.
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Merge tag 'locking-kcsan-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull the Kernel Concurrency Sanitizer from Thomas Gleixner:
"The Kernel Concurrency Sanitizer (KCSAN) is a dynamic race detector,
which relies on compile-time instrumentation, and uses a
watchpoint-based sampling approach to detect races.
The feature was under development for quite some time and has already
found legitimate bugs.
Unfortunately it comes with a limitation, which was only understood
late in the development cycle:
It requires an up to date CLANG-11 compiler
CLANG-11 is not yet released (scheduled for June), but it's the only
compiler today which handles the kernel requirements and especially
the annotations of functions to exclude them from KCSAN
instrumentation correctly.
These annotations really need to work so that low level entry code and
especially int3 text poke handling can be completely isolated.
A detailed discussion of the requirements and compiler issues can be
found here:
https://lore.kernel.org/lkml/CANpmjNMTsY_8241bS7=XAfqvZHFLrVEkv_uM4aDUWE_kh3Rvbw@mail.gmail.com/
We came to the conclusion that trying to work around compiler
limitations and bugs again would end up in a major trainwreck, so
requiring a working compiler seemed to be the best choice.
For Continous Integration purposes the compiler restriction is
manageable and that's where most xxSAN reports come from.
For a change this limitation might make GCC people actually look at
their bugs. Some issues with CSAN in GCC are 7 years old and one has
been 'fixed' 3 years ago with a half baken solution which 'solved' the
reported issue but not the underlying problem.
The KCSAN developers also ponder to use a GCC plugin to become
independent, but that's not something which will show up in a few
days.
Blocking KCSAN until wide spread compiler support is available is not
a really good alternative because the continuous growth of lockless
optimizations in the kernel demands proper tooling support"
* tag 'locking-kcsan-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (76 commits)
compiler_types.h, kasan: Use __SANITIZE_ADDRESS__ instead of CONFIG_KASAN to decide inlining
compiler.h: Move function attributes to compiler_types.h
compiler.h: Avoid nested statement expression in data_race()
compiler.h: Remove data_race() and unnecessary checks from {READ,WRITE}_ONCE()
kcsan: Update Documentation to change supported compilers
kcsan: Remove 'noinline' from __no_kcsan_or_inline
kcsan: Pass option tsan-instrument-read-before-write to Clang
kcsan: Support distinguishing volatile accesses
kcsan: Restrict supported compilers
kcsan: Avoid inserting __tsan_func_entry/exit if possible
ubsan, kcsan: Don't combine sanitizer with kcov on clang
objtool, kcsan: Add kcsan_disable_current() and kcsan_enable_current_nowarn()
kcsan: Add __kcsan_{enable,disable}_current() variants
checkpatch: Warn about data_race() without comment
kcsan: Use GFP_ATOMIC under spin lock
Improve KCSAN documentation a bit
kcsan: Make reporting aware of KCSAN tests
kcsan: Fix function matching in report
kcsan: Change data_race() to no longer require marking racing accesses
kcsan: Move kcsan_{disable,enable}_current() to kcsan-checks.h
...
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Merge tag 'block-5.8-2020-06-11' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe:
"Some followup fixes for this merge window. In particular:
- Seqcount write missing preemption disable for stats (Ahmed)
- blktrace fixes (Chaitanya)
- Redundant initializations (Colin)
- Various small NVMe fixes (Chaitanya, Christoph, Daniel, Max,
Niklas, Rikard)
- loop flag bug regression fix (Martijn)
- blk-mq tagging fixes (Christoph, Ming)"
* tag 'block-5.8-2020-06-11' of git://git.kernel.dk/linux-block:
umem: remove redundant initialization of variable ret
pktcdvd: remove redundant initialization of variable ret
nvmet: fail outstanding host posted AEN req
nvme-pci: use simple suspend when a HMB is enabled
nvme-fc: don't call nvme_cleanup_cmd() for AENs
nvmet-tcp: constify nvmet_tcp_ops
nvme-tcp: constify nvme_tcp_mq_ops and nvme_tcp_admin_mq_ops
nvme: do not call del_gendisk() on a disk that was never added
blk-mq: fix blk_mq_all_tag_iter
blk-mq: split out a __blk_mq_get_driver_tag helper
blktrace: fix endianness for blk_log_remap()
blktrace: fix endianness in get_pdu_int()
blktrace: use errno instead of bi_status
block: nr_sects_write(): Disable preemption on seqcount write
block: remove the error argument to the block_bio_complete tracepoint
loop: Fix wrong masking of status flags
block/bio-integrity: don't free 'buf' if bio_integrity_add_page() failed
- Unbreak paravirt VDSO clocks. While the VDSO code was moved into lib
for sharing a subtle check for the validity of paravirt clocks got
replaced. While the replacement works perfectly fine for bare metal as
the update of the VDSO clock mode is synchronous, it fails for paravirt
clocks because the hypervisor can invalidate them asynchronous. Bring
it back as an optional function so it does not inflict this on
architectures which are free of PV damage.
- Fix the jiffies to jiffies64 mapping on 64bit so it does not trigger
an ODR violation on newer compilers
- Three fixes for the SSBD and *IB* speculation mitigation maze to ensure
consistency, not disabling of some *IB* variants wrongly and to prevent
a rogue cross process shutdown of SSBD. All marked for stable.
- Add yet more CPU models to the splitlock detection capable list !@#%$!
- Bring the pr_info() back which tells that TSC deadline timer is enabled.
- Reboot quirk for MacBook6,1
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Merge tag 'x86-urgent-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull more x86 updates from Thomas Gleixner:
"A set of fixes and updates for x86:
- Unbreak paravirt VDSO clocks.
While the VDSO code was moved into lib for sharing a subtle check
for the validity of paravirt clocks got replaced. While the
replacement works perfectly fine for bare metal as the update of
the VDSO clock mode is synchronous, it fails for paravirt clocks
because the hypervisor can invalidate them asynchronously.
Bring it back as an optional function so it does not inflict this
on architectures which are free of PV damage.
- Fix the jiffies to jiffies64 mapping on 64bit so it does not
trigger an ODR violation on newer compilers
- Three fixes for the SSBD and *IB* speculation mitigation maze to
ensure consistency, not disabling of some *IB* variants wrongly and
to prevent a rogue cross process shutdown of SSBD. All marked for
stable.
- Add yet more CPU models to the splitlock detection capable list
!@#%$!
- Bring the pr_info() back which tells that TSC deadline timer is
enabled.
- Reboot quirk for MacBook6,1"
* tag 'x86-urgent-2020-06-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/vdso: Unbreak paravirt VDSO clocks
lib/vdso: Provide sanity check for cycles (again)
clocksource: Remove obsolete ifdef
x86_64: Fix jiffies ODR violation
x86/speculation: PR_SPEC_FORCE_DISABLE enforcement for indirect branches.
x86/speculation: Prevent rogue cross-process SSBD shutdown
x86/speculation: Avoid force-disabling IBPB based on STIBP and enhanced IBRS.
x86/cpu: Add Sapphire Rapids CPU model number
x86/split_lock: Add Icelake microserver and Tigerlake CPU models
x86/apic: Make TSC deadline timer detection message visible
x86/reboot/quirks: Add MacBook6,1 reboot quirk
David Rientjes
Andrey Ignatov
Jason A. Donenfeld
Linus Torvalds
Yonghong Song
Daniel Jordan
Kaitao Cheng
David S. Miller
Christoph Hellwig
Stanislav Fomichev
Toke Høiland-Jørgensen
Andrii Nakryiko
Jan Kara
Luis Chamberlain
YangHui
Vamshi K Sthambamkadi
Wei Yang
Steven Rostedt (VMware)
Jiri Olsa
Masami Hiramatsu
Christian Brauner
Gustavo A. R. Silva
Thomas Cedeno
Masahiro Yamada