Refactor x86 JITing of LDX, STX, CALL instructions into separate helper
functions. No functional changes in LDX and STX helpers. There is a minor
change in CALL helper. It will populate target address correctly on the first
pass of JIT instead of second pass. That won't reduce total number of JIT
passes though.
Change-Id: Ia0fe3e1714a7134c769438bacb308107970b3d58
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191114185720.1641606-3-ast@kernel.org
Replace 'cmp reg, 0' with 'test reg, reg' for comparisons against
zero. Saves 1 byte of instruction encoding per occurrence. The flag
results of test 'reg, reg' are identical to 'cmp reg, 0' in all
cases except for AF which we don't use/care about. In terms of
macro-fusibility in combination with a subsequent conditional jump
instruction, both have the same properties for the jumps used in
the JIT translation. For example, same JITed Cilium program can
shrink a bit from e.g. 12,455 to 12,317 bytes as tests with 0 are
used quite frequently.
Change-Id: Idb3a3e3eb63f9530ca23c93aba3ef19b50b4d64e
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Add bpf_arch_text_poke() helper that is used by BPF trampoline logic to patch
nops/calls in kernel text into calls into BPF trampoline and to patch
calls/nops inside BPF programs too.
Change-Id: I1956e58f0b2bb39786d9660bb931e785437aa350
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191114185720.1641606-4-ast@kernel.org
Currently passing alignment greater than 4 to bpf_jit_binary_alloc does
not work: in such cases it silently aligns only to 4 bytes.
On s390, in order to load a constant from memory in a large (>512k) BPF
program, one must use lgrl instruction, whose memory operand must be
aligned on an 8-byte boundary.
This patch makes it possible to request 8-byte alignment from
bpf_jit_binary_alloc, and also makes it issue a warning when an
unsupported alignment is requested.
Change-Id: Iee3d04012d22d54adb739c627fc7b9c31262dbc7
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191115123722.58462-1-iii@linux.ibm.com
kernfs_node->id is currently a union kernfs_node_id which represents
either a 32bit (ino, gen) pair or u64 value. I can't see much value
in the usage of the union - all that's needed is a 64bit ID which the
current code is already limited to. Using a union makes the code
unnecessarily complicated and prevents using 64bit ino without adding
practical benefits.
This patch drops union kernfs_node_id and makes kernfs_node->id a u64.
ino is stored in the lower 32bits and gen upper. Accessors -
kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the
ino and gen. This simplifies ID handling less cumbersome and will
allow using 64bit inos on supported archs.
This patch doesn't make any functional changes.
Change-Id: I4b33899e4953febd5553772c7969fc4cb2ca750a
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexei Starovoitov <ast@kernel.org>
We need to convert flags to atomic_t in order to later fix an ordering
issue on atomic_cmpxchg() failure. This will allow us to use atomic_fetch_or().
Also clarify the nature of those flags.
[ mingo: Converted two more usage site the original patch missed. ]
Change-Id: Iffe159596630a7996d1570dee5bc3cf73ddff1de
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191108160858.31665-2-frederic@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This patch adds array support to btf_struct_access().
It supports array of int, array of struct and multidimensional
array.
It also allows using u8[] as a scratch space. For example,
it allows access the "char cb[48]" with size larger than
the array's element "char". Another potential use case is
"u64 icsk_ca_priv[]" in the tcp congestion control.
btf_resolve_size() is added to resolve the size of any type.
It will follow the modifier if there is any. Please
see the function comment for details.
This patch also adds the "off < moff" check at the beginning
of the for loop. It is to reject cases when "off" is pointing
to a "hole" in a struct.
Change-Id: Ief5c702c75157f42de78c943fd198dd38eb87646
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191107180903.4097702-1-kafai@fb.com
In the bpf interpreter mode, bpf_probe_read_kernel is used to read
from PTR_TO_BTF_ID's kernel object. It currently missed considering
the insn->off. This patch fixes it.
Fixes: 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
Change-Id: I79cd212d8b34f5e366e82f2b9b5d696b797e4fa8
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191107014640.384083-1-kafai@fb.com
Commit 2a02759ef5f8 ("bpf: Add support for BTF pointers to interpreter")
explicitly states that the pointer to BTF object is a pointer to a kernel
object or NULL. Therefore we should also switch to using the strict kernel
probe helper which is restricted to kernel addresses only when architectures
have non-overlapping address spaces.
Change-Id: I75c8c80b0d7cc2281b3fd2235d5553721cbb0382
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/d2b90827837685424a4b8008dfe0460558abfada.1572649915.git.daniel@iogearbox.net
The current bpf_probe_read() and bpf_probe_read_str() helpers are broken
in that they assume they can be used for probing memory access for kernel
space addresses /as well as/ user space addresses.
However, plain use of probe_kernel_read() for both cases will attempt to
always access kernel space address space given access is performed under
KERNEL_DS and some archs in-fact have overlapping address spaces where a
kernel pointer and user pointer would have the /same/ address value and
therefore accessing application memory via bpf_probe_read{,_str}() would
read garbage values.
Lets fix BPF side by making use of recently added 3d7081822f ("uaccess:
Add non-pagefault user-space read functions"). Unfortunately, the only way
to fix this status quo is to add dedicated bpf_probe_read_{user,kernel}()
and bpf_probe_read_{user,kernel}_str() helpers. The bpf_probe_read{,_str}()
helpers are kept as-is to retain their current behavior.
The two *_user() variants attempt the access always under USER_DS set, the
two *_kernel() variants will -EFAULT when accessing user memory if the
underlying architecture has non-overlapping address ranges, also avoiding
throwing the kernel warning via 00c42373d3 ("x86-64: add warning for
non-canonical user access address dereferences").
Fixes: a5e8c07059 ("bpf: add bpf_probe_read_str helper")
Fixes: 2541517c32 ("tracing, perf: Implement BPF programs attached to kprobes")
Change-Id: Iab261cc1a414c6f6a0c7ec39fda9a5d666f76b8a
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/796ee46e948bc808d54891a1108435f8652c6ca4.1572649915.git.daniel@iogearbox.net
Add two new probe_kernel_read_strict() and strncpy_from_unsafe_strict()
helpers which by default alias to the __probe_kernel_read() and the
__strncpy_from_unsafe(), respectively, but can be overridden by archs
which have non-overlapping address ranges for kernel space and user
space in order to bail out with -EFAULT when attempting to probe user
memory including non-canonical user access addresses [0]:
4-level page tables:
user-space mem: 0x0000000000000000 - 0x00007fffffffffff
non-canonical: 0x0000800000000000 - 0xffff7fffffffffff
5-level page tables:
user-space mem: 0x0000000000000000 - 0x00ffffffffffffff
non-canonical: 0x0100000000000000 - 0xfeffffffffffffff
The idea is that these helpers are complementary to the probe_user_read()
and strncpy_from_unsafe_user() which probe user-only memory. Both added
helpers here do the same, but for kernel-only addresses.
Both set of helpers are going to be used for BPF tracing. They also
explicitly avoid throwing the splat for non-canonical user addresses from
00c42373d3 ("x86-64: add warning for non-canonical user access address
dereferences").
For compat, the current probe_kernel_read() and strncpy_from_unsafe() are
left as-is.
[0] Documentation/x86/x86_64/mm.txt
Change-Id: I82fb94bc1f76ff318c4c7d71746f583bd711b830
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: x86@kernel.org
Link: https://lore.kernel.org/bpf/eefeefd769aa5a013531f491a71f0936779e916b.1572649915.git.daniel@iogearbox.net
x86 has an nmi_uaccess_okay(), but other architectures do not.
Arch-independent code might need to know whether access to user
addresses is ok in an NMI context or in other code whose execution
context is unknown. Specifically, this function is needed for
bpf_probe_write_user().
Add a default implementation of nmi_uaccess_okay() for architectures
that do not have such a function.
Change-Id: Ie710d06700a2c5b392bff0dbc82798f9c0d985cc
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-23-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In this commit the XSKMAP entry lookup function used by the XDP
redirect code is moved from the xskmap.c file to the xdp_sock.h
header, so the lookup can be inlined from, e.g., the
bpf_xdp_redirect_map() function.
Further the __xsk_map_redirect() and __xsk_map_flush() is moved to the
xsk.c, which lets the compiler inline the xsk_rcv() and xsk_flush()
functions.
Finally, all the XDP socket functions were moved from linux/bpf.h to
net/xdp_sock.h, where most of the XDP sockets functions are anyway.
This yields a ~2% performance boost for the xdpsock "rx_drop"
scenario.
Change-Id: I045aa7c44454340e6af3cd93c45f62323f4c7406
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191101110346.15004-4-bjorn.topel@gmail.com
Inline the xsk_map_lookup_elem() via implementing the map_gen_lookup()
callback. This results in emitting the bpf instructions in place of
bpf_map_lookup_elem() helper call and better performance of bpf
programs.
Change-Id: Ica4d9a58854a3ac2b9da819e84eccabef7d8adeb
Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/bpf/20191101110346.15004-3-bjorn.topel@gmail.com
Prior this commit, the array storing XDP socket instances were stored
in a separate allocated array of the XSKMAP. Now, we store the sockets
as a flexible array member in a similar fashion as the arraymap. Doing
so, we do less pointer chasing in the lookup.
Change-Id: Iae24fe35cf8f2dce2ec41ad58968a26645fbed9e
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Link: https://lore.kernel.org/bpf/20191101110346.15004-2-bjorn.topel@gmail.com
The bpf program type raw_tp together with 'expected_attach_type'
was the most appropriate api to indicate BTF-enabled raw_tp programs.
But during development it became apparent that 'expected_attach_type'
cannot be used and new 'attach_btf_id' field had to be introduced.
Which means that the information is duplicated in two fields where
one of them is ignored.
Clean it up by introducing new program type where both
'expected_attach_type' and 'attach_btf_id' fields have
specific meaning.
In the future 'expected_attach_type' will be extended
with other attach points that have similar semantics to raw_tp.
This patch is replacing BTF-enabled BPF_PROG_TYPE_RAW_TRACEPOINT with
prog_type = BPF_RPOG_TYPE_TRACING
expected_attach_type = BPF_TRACE_RAW_TP
attach_btf_id = btf_id of raw tracepoint inside the kernel
Future patches will add
expected_attach_type = BPF_TRACE_FENTRY or BPF_TRACE_FEXIT
where programs have the same input context and the same helpers,
but different attach points.
Change-Id: If19aaa2fc33fc4923931e4fb589e9b066d9d5695
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191030223212.953010-2-ast@kernel.org
Jiri reported crash when JIT is on, but net.core.bpf_jit_kallsyms is off.
bpf_prog_kallsyms_find() was skipping addr->bpf_prog resolution
logic in oops and stack traces. That's incorrect.
It should only skip addr->name resolution for 'cat /proc/kallsyms'.
That's what bpf_jit_kallsyms and bpf_jit_harden protect.
Fixes: 3dec541b2e63 ("bpf: Add support for BTF pointers to x86 JIT")
Reported-by: Jiri Olsa <jolsa@redhat.com>
Change-Id: I97955f0f9aa51745493f2399c3154f8a2ade6f56
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191030233019.1187404-1-ast@kernel.org
This commit replaces the use of rcu_swap_protected() with the more
intuitively appealing rcu_replace_pointer() as a step towards removing
rcu_swap_protected().
Link: https://lore.kernel.org/lkml/CAHk-=wiAsJLw1egFEE=Z7-GGtM6wcvtyytXZA1+BHqta4gg6Hw@mail.gmail.com/
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
[ paulmck: From rcu_replace() to rcu_replace_pointer() per Ingo Molnar. ]
Change-Id: I49e16f57052bd11695036615d36bcd5ec6f20266
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: <netdev@vger.kernel.org>
Cc: <bpf@vger.kernel.org>
The return value of raw_tp programs is ignored by __bpf_trace_run()
that calls them. The verifier also allows any value to be returned.
For BTF-enabled raw_tp lets enforce 'return 0', so that return value
can be used for something in the future.
Change-Id: I11bae02f217565a577dccbaf5a7c5b105be83cd9
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20191029032426.1206762-1-ast@kernel.org
This patch makes a few changes to btf_ctx_access() to prepare
it for non raw_tp use case where the attach_btf_id is not
necessary a BTF_KIND_TYPEDEF.
It moves the "btf_trace_" prefix check and typedef-follow logic to a new
function "check_attach_btf_id()" which is called only once during
bpf_check(). btf_ctx_access() only operates on a BTF_KIND_FUNC_PROTO
type now. That should also be more efficient since it is done only
one instead of every-time check_ctx_access() is called.
"check_attach_btf_id()" needs to find the func_proto type from
the attach_btf_id. It needs to store the result into the
newly added prog->aux->attach_func_proto. func_proto
btf type has no name, so a proper name should be stored into
"attach_func_name" also.
v2:
- Move the "btf_trace_" check to an earlier verifier phase (Alexei)
Change-Id: I2716756b4f85b1e068b8f8f2245e992d7b97cc6b
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20191025001811.1718491-1-kafai@fb.com
Only raw_tracepoint program type can have bpf_attr.attach_btf_id >= 0.
Make sure to reject other program types that accidentally set it to non-zero.
Fixes: ccfe29eb29c2 ("bpf: Add attach_btf_id attribute to program load")
Reported-by: Andrii Nakryiko <andriin@fb.com>
Change-Id: If05e54cff182417e681379c8c6adb0b85cd8d984
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20191018060933.2950231-1-ast@kernel.org
Introduce new helper that reuses existing skb perf_event output
implementation, but can be called from raw_tracepoint programs
that receive 'struct sk_buff *' as tracepoint argument or
can walk other kernel data structures to skb pointer.
In order to do that teach verifier to resolve true C types
of bpf helpers into in-kernel BTF ids.
The type of kernel pointer passed by raw tracepoint into bpf
program will be tracked by the verifier all the way until
it's passed into helper function.
For example:
kfree_skb() kernel function calls trace_kfree_skb(skb, loc);
bpf programs receives that skb pointer and may eventually
pass it into bpf_skb_output() bpf helper which in-kernel is
implemented via bpf_skb_event_output() kernel function.
Its first argument in the kernel is 'struct sk_buff *'.
The verifier makes sure that types match all the way.
Change-Id: I2782993220c91f02cd53321bac032c8049c80273
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-11-ast@kernel.org
Pointer to BTF object is a pointer to kernel object or NULL.
Such pointers can only be used by BPF_LDX instructions.
The verifier changed their opcode from LDX|MEM|size
to LDX|PROBE_MEM|size to make JITing easier.
The number of entries in extable is the number of BPF_LDX insns
that access kernel memory via "pointer to BTF type".
Only these load instructions can fault.
Since x86 extable is relative it has to be allocated in the same
memory region as JITed code.
Allocate it prior to last pass of JITing and let the last pass populate it.
Pointer to extable in bpf_prog_aux is necessary to make page fault
handling fast.
Page fault handling is done in two steps:
1. bpf_prog_kallsyms_find() finds BPF program that page faulted.
It's done by walking rb tree.
2. then extable for given bpf program is binary searched.
This process is similar to how page faulting is done for kernel modules.
The exception handler skips over faulting x86 instruction and
initializes destination register with zero. This mimics exact
behavior of bpf_probe_read (when probe_kernel_read faults dest is zeroed).
JITs for other architectures can add support in similar way.
Until then they will reject unknown opcode and fallback to interpreter.
Since extable should be aligned and placed near JITed code
make bpf_jit_binary_alloc() return 4 byte aligned image offset,
so that extable aligning formula in bpf_int_jit_compile() doesn't need
to rely on internal implementation of bpf_jit_binary_alloc().
On x86 gcc defaults to 16-byte alignment for regular kernel functions
due to better performance. JITed code may be aligned to 16 in the future,
but it will use 4 in the meantime.
Change-Id: Ic2a23af52b7b88482f524c9b98a62c14ea2a52c1
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-10-ast@kernel.org
Pointer to BTF object is a pointer to kernel object or NULL.
The memory access in the interpreter has to be done via probe_kernel_read
to avoid page faults.
Change-Id: Ief5b8d67dbcc988362dfb302b486e99ca6eec7b6
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-9-ast@kernel.org
BTF type id specified at program load time has all
necessary information to attach that program to raw tracepoint.
Use kernel type name to find raw tracepoint.
Add missing CHECK_ATTR() condition.
Change-Id: I545792a45a62a9d2086e474a6857340215842407
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-8-ast@kernel.org
libbpf analyzes bpf C program, searches in-kernel BTF for given type name
and stores it into expected_attach_type.
The kernel verifier expects this btf_id to point to something like:
typedef void (*btf_trace_kfree_skb)(void *, struct sk_buff *skb, void *loc);
which represents signature of raw_tracepoint "kfree_skb".
Then btf_ctx_access() matches ctx+0 access in bpf program with 'skb'
and 'ctx+8' access with 'loc' arguments of "kfree_skb" tracepoint.
In first case it passes btf_id of 'struct sk_buff *' back to the verifier core
and 'void *' in second case.
Then the verifier tracks PTR_TO_BTF_ID as any other pointer type.
Like PTR_TO_SOCKET points to 'struct bpf_sock',
PTR_TO_TCP_SOCK points to 'struct bpf_tcp_sock', and so on.
PTR_TO_BTF_ID points to in-kernel structs.
If 1234 is btf_id of 'struct sk_buff' in vmlinux's BTF
then PTR_TO_BTF_ID#1234 points to one of in kernel skbs.
When PTR_TO_BTF_ID#1234 is dereferenced (like r2 = *(u64 *)r1 + 32)
the btf_struct_access() checks which field of 'struct sk_buff' is
at offset 32. Checks that size of access matches type definition
of the field and continues to track the dereferenced type.
If that field was a pointer to 'struct net_device' the r2's type
will be PTR_TO_BTF_ID#456. Where 456 is btf_id of 'struct net_device'
in vmlinux's BTF.
Such verifier analysis prevents "cheating" in BPF C program.
The program cannot cast arbitrary pointer to 'struct sk_buff *'
and access it. C compiler would allow type cast, of course,
but the verifier will notice type mismatch based on BPF assembly
and in-kernel BTF.
Change-Id: Icd510a80078dca9aceb6ee7e7db93644e08ea773
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-7-ast@kernel.org
Add attach_btf_id attribute to prog_load command.
It's similar to existing expected_attach_type attribute which is
used in several cgroup based program types.
Unfortunately expected_attach_type is ignored for
tracing programs and cannot be reused for new purpose.
Hence introduce attach_btf_id to verify bpf programs against
given in-kernel BTF type id at load time.
It is strictly checked to be valid for raw_tp programs only.
In a later patches it will become:
btf_id == 0 semantics of existing raw_tp progs.
btd_id > 0 raw_tp with BTF and additional type safety.
Change-Id: I16a13a9f199ba3923608b610a61b58a26d757034
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-5-ast@kernel.org
If in-kernel BTF exists parse it and prepare 'struct btf *btf_vmlinux'
for further use by the verifier.
In-kernel BTF is trusted just like kallsyms and other build artifacts
embedded into vmlinux.
Yet run this BTF image through BTF verifier to make sure
that it is valid and it wasn't mangled during the build.
If in-kernel BTF is incorrect it means either gcc or pahole or kernel
are buggy. In such case disallow loading BPF programs.
Change-Id: I80a64018a8ce4390c8c3d4284c4cc1fdcd0fd81f
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-4-ast@kernel.org
It's useful for implementing EDT related tests (set tstamp, run the
test, see how the tstamp is changed or observe some other parameter).
Note that bpf_ktime_get_ns() helper is using monotonic clock, so for
the BPF programs that compare tstamp against it, tstamp should be
derived from clock_gettime(CLOCK_MONOTONIC, ...).
Change-Id: I6fdeccb4baac4c4ead931dc2d3c0730163d1c470
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191015183125.124413-1-sdf@google.com
Do not risk spanning these small structures on two cache lines.
Change-Id: Ie13182cdff956b270296b5999b78c41d77133e23
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20191011181140.2898-1-edumazet@google.com
Don't use bool array in struct sk_msg_sg, save 12 bytes.
Change-Id: I50359c5cd6101a1c4f2c78f7d83877fbbaa16063
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Dirk van der Merwe <dirk.vandermerwe@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Various small fixes to BPF helper documentation comments, enabling
automatic header generation with a list of BPF helpers.
Change-Id: If4c1db80f20522013d5823e1c5928e4f4b8193b9
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Commit b0a0c2615f6f ("epoll: wire up syscall epoll_pwait2") wired up
the 64 bit syscall instead of the compat variant in a couple of places.
Fixes: b0a0c2615f6f ("epoll: wire up syscall epoll_pwait2")
Change-Id: Ida2267e953240c036d64bc61177ee72bb20f35a3
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Split off from prev patch in the series that implements the syscall.
Link: https://lkml.kernel.org/r/20201121144401.3727659-4-willemdebruijn.kernel@gmail.com
Change-Id: I48dfae6f721b24ebc53de603e393289954a95908
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add syscall epoll_pwait2, an epoll_wait variant with nsec resolution that
replaces int timeout with struct timespec. It is equivalent otherwise.
int epoll_pwait2(int fd, struct epoll_event *events,
int maxevents,
const struct timespec *timeout,
const sigset_t *sigset);
The underlying hrtimer is already programmed with nsec resolution.
pselect and ppoll also set nsec resolution timeout with timespec.
The sigset_t in epoll_pwait has a compat variant. epoll_pwait2 needs
the same.
For timespec, only support this new interface on 2038 aware platforms
that define __kernel_timespec_t. So no CONFIG_COMPAT_32BIT_TIME.
Link: https://lkml.kernel.org/r/20201121144401.3727659-3-willemdebruijn.kernel@gmail.com
Change-Id: I8cb4e756aacb4bee7cbe1c2cb5320a59e07626f8
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "add epoll_pwait2 syscall", v4.
Enable nanosecond timeouts for epoll.
Analogous to pselect and ppoll, introduce an epoll_wait syscall
variant that takes a struct timespec instead of int timeout.
This patch (of 4):
Make epoll more consistent with select/poll: pass along the timeout as
timespec64 pointer.
In anticipation of additional changes affecting all three polling
mechanisms:
- add epoll_pwait2 syscall with timespec semantics,
and share poll_select_set_timeout implementation.
- compute slack before conversion to absolute time,
to save one ktime_get_ts64 call.
Link: https://lkml.kernel.org/r/20201121144401.3727659-1-willemdebruijn.kernel@gmail.com
Link: https://lkml.kernel.org/r/20201121144401.3727659-2-willemdebruijn.kernel@gmail.com
Change-Id: Id5851ad620849d202d18a99351a98b8bc3b6820a
Signed-off-by: Willem de Bruijn <willemb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
commit 678379e1d4f7443b170939525d3312cfc37bf86b upstream.
Cloning a descriptor table picks the size that would cover all currently
opened files. That's fine for clone() and unshare(), but for close_range()
there's an additional twist - we clone before we close, and it would be
a shame to have
close_range(3, ~0U, CLOSE_RANGE_UNSHARE)
leave us with a huge descriptor table when we are not going to keep
anything past stderr, just because some large file descriptor used to
be open before our call has taken it out.
Unfortunately, it had been dealt with in an inherently racy way -
sane_fdtable_size() gets a "don't copy anything past that" argument
(passed via unshare_fd() and dup_fd()), close_range() decides how much
should be trimmed and passes that to unshare_fd().
The problem is, a range that used to extend to the end of descriptor
table back when close_range() had looked at it might very well have stuff
grown after it by the time dup_fd() has allocated a new files_struct
and started to figure out the capacity of fdtable to be attached to that.
That leads to interesting pathological cases; at the very least it's a
QoI issue, since unshare(CLONE_FILES) is atomic in a sense that it takes
a snapshot of descriptor table one might have observed at some point.
Since CLOSE_RANGE_UNSHARE close_range() is supposed to be a combination
of unshare(CLONE_FILES) with plain close_range(), ending up with a
weird state that would never occur with unshare(2) is confusing, to put
it mildly.
It's not hard to get rid of - all it takes is passing both ends of the
range down to sane_fdtable_size(). There we are under ->files_lock,
so the race is trivially avoided.
So we do the following:
* switch close_files() from calling unshare_fd() to calling
dup_fd().
* undo the calling convention change done to unshare_fd() in
60997c3d45d9 "close_range: add CLOSE_RANGE_UNSHARE"
* introduce struct fd_range, pass a pointer to that to dup_fd()
and sane_fdtable_size() instead of "trim everything past that point"
they are currently getting. NULL means "we are not going to be punching
any holes"; NR_OPEN_MAX is gone.
* make sane_fdtable_size() use find_last_bit() instead of
open-coding it; it's easier to follow that way.
* while we are at it, have dup_fd() report errors by returning
ERR_PTR(), no need to use a separate int *errorp argument.
Fixes: 60997c3d45d9 "close_range: add CLOSE_RANGE_UNSHARE"
Cc: stable@vger.kernel.org
Change-Id: I6782a2edf98970b6c2d662048061e28f7e57b9c9
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit d888c83fcec75194a8a48ccd283953bdba7b2550 ]
Jason Donenfeld reports that my commit 1c24a186398f ("fs: fd tables have
to be multiples of BITS_PER_LONG") doesn't work, and the reason is an
embarrassing brown-paper-bag bug.
Yes, we want to align the number of fds to BITS_PER_LONG, and yes, the
reason they might not be aligned is because the incoming 'max_fd'
argument might not be aligned.
But aligining the argument - while simple - will cause a "infinitely
big" maxfd (eg NR_OPEN_MAX) to just overflow to zero. Which most
definitely isn't what we want either.
The obvious fix was always just to do the alignment last, but I had
moved it earlier just to make the patch smaller and the code look
simpler. Duh. It certainly made _me_ look simple.
Fixes: 1c24a186398f ("fs: fd tables have to be multiples of BITS_PER_LONG")
Reported-and-tested-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Fedor Pchelkin <aissur0002@gmail.com>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Christian Brauner <brauner@kernel.org>
Change-Id: I6d3a0c28896e8cf8cab30f60679aab785aeee193
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 1c24a186398f59c80adb9a967486b65c1423a59d ]
This has always been the rule: fdtables have several bitmaps in them,
and as a result they have to be sized properly for bitmaps. We walk
those bitmaps in chunks of 'unsigned long' in serveral cases, but even
when we don't, we use the regular kernel bitops that are defined to work
on arrays of 'unsigned long', not on some byte array.
Now, the distinction between arrays of bytes and 'unsigned long'
normally only really ends up being noticeable on big-endian systems, but
Fedor Pchelkin and Alexey Khoroshilov reported that copy_fd_bitmaps()
could be called with an argument that wasn't even a multiple of
BITS_PER_BYTE. And then it fails to do the proper copy even on
little-endian machines.
The bug wasn't in copy_fd_bitmap(), but in sane_fdtable_size(), which
didn't actually sanitize the fdtable size sufficiently, and never made
sure it had the proper BITS_PER_LONG alignment.
That's partly because the alignment historically came not from having to
explicitly align things, but simply from previous fdtable sizes, and
from count_open_files(), which counts the file descriptors by walking
them one 'unsigned long' word at a time and thus naturally ends up doing
sizing in the proper 'chunks of unsigned long'.
But with the introduction of close_range(), we now have an external
source of "this is how many files we want to have", and so
sane_fdtable_size() needs to do a better job.
This also adds that explicit alignment to alloc_fdtable(), although
there it is mainly just for documentation at a source code level. The
arithmetic we do there to pick a reasonable fdtable size already aligns
the result sufficiently.
In fact,clang notices that the added ALIGN() in that function doesn't
actually do anything, and does not generate any extra code for it.
It turns out that gcc ends up confusing itself by combining a previous
constant-sized shift operation with the variable-sized shift operations
in roundup_pow_of_two(). And probably due to that doesn't notice that
the ALIGN() is a no-op. But that's a (tiny) gcc misfeature that doesn't
matter. Having the explicit alignment makes sense, and would actually
matter on a 128-bit architecture if we ever go there.
This also adds big comments above both functions about how fdtable sizes
have to have that BITS_PER_LONG alignment.
Fixes: 60997c3d45d9 ("close_range: add CLOSE_RANGE_UNSHARE")
Reported-by: Fedor Pchelkin <aissur0002@gmail.com>
Reported-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Link: https://lore.kernel.org/all/20220326114009.1690-1-aissur0002@gmail.com/
Tested-and-acked-by: Christian Brauner <brauner@kernel.org>
Change-Id: Ib64319f20fecec1c367bf0167e1b14b47751537a
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
It never looked too pleasant and it doesn't really buy us anything
anymore now that CLOSE_RANGE_CLOEXEC exists and we need to retake the
current maximum under the lock for it anyway. This also makes the logic
easier to follow.
Cc: Christoph Hellwig <hch@lst.de>
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Change-Id: I72be5b078d7edc061318b0eda36a351e1dc01e56
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
syzbot reported a bug when putting the last reference to a tasks file
descriptor table. Debugging this showed we didn't recalculate the
current maximum fd number for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC
after we unshared the file descriptors table. So max_fd could exceed the
current fdtable maximum causing us to set excessive bits. As a concrete
example, let's say the user requested everything from fd 4 to ~0UL to be
closed and their current fdtable size is 256 with their highest open fd
being 4. With CLOSE_RANGE_UNSHARE the caller will end up with a new
fdtable which has room for 64 file descriptors since that is the lowest
fdtable size we accept. But now max_fd will still point to 255 and needs
to be adjusted. Fix this by retrieving the correct maximum fd value in
__range_cloexec().
Reported-by: syzbot+283ce5a46486d6acdbaf@syzkaller.appspotmail.com
Fixes: 582f1fb6b721 ("fs, close_range: add flag CLOSE_RANGE_CLOEXEC")
Fixes: fec8a6a69103 ("close_range: unshare all fds for CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC")
Cc: Christoph Hellwig <hch@lst.de>
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
(cherry picked from commit 9b5b872215fe6d1ca6a1ef411f130bd58e269012)
Bug: 216276716
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Id04f75bfeb49dcff0457136f74b47a2d05bd9d51
After introducing CLOSE_RANGE_CLOEXEC syzbot reported a crash when
CLOSE_RANGE_CLOEXEC is specified in conjunction with CLOSE_RANGE_UNSHARE.
When CLOSE_RANGE_UNSHARE is specified the caller will receive a private
file descriptor table in case their file descriptor table is currently
shared.
For the case where the caller has requested all file descriptors to be
actually closed via e.g. close_range(3, ~0U, 0) the kernel knows that
the caller does not need any of the file descriptors anymore and will
optimize the close operation by only copying all files in the range from
0 to 3 and no others.
However, if the caller requested CLOSE_RANGE_CLOEXEC together with
CLOSE_RANGE_UNSHARE the caller wants to still make use of the file
descriptors so the kernel needs to copy all of them and can't optimize.
The original patch didn't account for this and thus could cause oopses
as evidenced by the syzbot report because it assumed that all fds had
been copied. Fix this by handling the CLOSE_RANGE_CLOEXEC case.
syzbot reported
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: null-ptr-deref in atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
BUG: KASAN: null-ptr-deref in atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
BUG: KASAN: null-ptr-deref in filp_close+0x22/0x170 fs/open.c:1274
Read of size 8 at addr 0000000000000077 by task syz-executor511/8522
CPU: 1 PID: 8522 Comm: syz-executor511 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
__kasan_report mm/kasan/report.c:549 [inline]
kasan_report.cold+0x5/0x37 mm/kasan/report.c:562
check_memory_region_inline mm/kasan/generic.c:186 [inline]
check_memory_region+0x13d/0x180 mm/kasan/generic.c:192
instrument_atomic_read include/linux/instrumented.h:71 [inline]
atomic64_read include/asm-generic/atomic-instrumented.h:837 [inline]
atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
filp_close+0x22/0x170 fs/open.c:1274
close_files fs/file.c:402 [inline]
put_files_struct fs/file.c:417 [inline]
put_files_struct+0x1cc/0x350 fs/file.c:414
exit_files+0x12a/0x170 fs/file.c:435
do_exit+0xb4f/0x2a00 kernel/exit.c:818
do_group_exit+0x125/0x310 kernel/exit.c:920
get_signal+0x428/0x2100 kernel/signal.c:2792
arch_do_signal_or_restart+0x2a8/0x1eb0 arch/x86/kernel/signal.c:811
handle_signal_work kernel/entry/common.c:147 [inline]
exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
exit_to_user_mode_prepare+0x124/0x200 kernel/entry/common.c:201
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x19/0x50 kernel/entry/common.c:302
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x447039
Code: Unable to access opcode bytes at RIP 0x44700f.
RSP: 002b:00007f1b1225cdb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00000000006dbc28 RCX: 0000000000447039
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00000000006dbc2c
RBP: 00000000006dbc20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006dbc2c
R13: 00007fff223b6bef R14: 00007f1b1225d9c0 R15: 00000000006dbc2c
==================================================================
syzbot has tested the proposed patch and the reproducer did not trigger any issue:
Reported-and-tested-by: syzbot+96cfd2b22b3213646a93@syzkaller.appspotmail.com
Tested on:
commit: 10f7cddd selftests/core: add regression test for CLOSE_RAN..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git vfs
kernel config: https://syzkaller.appspot.com/x/.config?x=5d42216b510180e3
dashboard link: https://syzkaller.appspot.com/bug?extid=96cfd2b22b3213646a93
compiler: gcc (GCC) 10.1.0-syz 20200507
Reported-by: syzbot+96cfd2b22b3213646a93@syzkaller.appspotmail.com
Fixes: 582f1fb6b721 ("fs, close_range: add flag CLOSE_RANGE_CLOEXEC")
Cc: Giuseppe Scrivano <gscrivan@redhat.com>
Cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20201217213303.722643-1-christian.brauner@ubuntu.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
(cherry picked from commit fec8a6a691033f2538cd46848f17f337f0739923)
Bug: 216276716
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I0c6bbd8a46b93293c212fff08728514915d5c690
When the flag CLOSE_RANGE_CLOEXEC is set, close_range doesn't
immediately close the files but it sets the close-on-exec bit.
It is useful for e.g. container runtimes that usually install a
seccomp profile "as late as possible" before execv'ing the container
process itself. The container runtime could either do:
1 2
- install_seccomp_profile(); - close_range(MIN_FD, MAX_INT, 0);
- close_range(MIN_FD, MAX_INT, 0); - install_seccomp_profile();
- execve(...); - execve(...);
Both alternative have some disadvantages.
In the first variant the seccomp_profile cannot block the close_range
syscall, as well as opendir/read/close/... for the fallback on older
kernels.
In the second variant, close_range() can be used only on the fds
that are not going to be needed by the runtime anymore, and it must be
potentially called multiple times to account for the different ranges
that must be closed.
Using close_range(..., ..., CLOSE_RANGE_CLOEXEC) solves these issues.
The runtime is able to use the existing open fds, the seccomp profile
can block close_range() and the syscalls used for its fallback.
Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
Link: https://lore.kernel.org/r/20201118104746.873084-2-gscrivan@redhat.com
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
(cherry picked from commit 582f1fb6b721facf04848d2ca57f34468da1813e)
Bug: 216276716
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ib2d44f9760a80e3febdb25925d17ce5ffd14910e
One of the use-cases of close_range() is to drop file descriptors just before
execve(). This would usually be expressed in the sequence:
unshare(CLONE_FILES);
close_range(3, ~0U);
as pointed out by Linus it might be desirable to have this be a part of
close_range() itself under a new flag CLOSE_RANGE_UNSHARE.
This expands {dup,unshare)_fd() to take a max_fds argument that indicates the
maximum number of file descriptors to copy from the old struct files. When the
user requests that all file descriptors are supposed to be closed via
close_range(min, max) then we can cap via unshare_fd(min) and hence don't need
to do any of the heavy fput() work for everything above min.
The patch makes it so that if CLOSE_RANGE_UNSHARE is requested and we do in
fact currently share our file descriptor table we create a new private copy.
We then close all fds in the requested range and finally after we're done we
install the new fd table.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Change-Id: I0813045886501e40a45693ee1edad50bdf2b66e5
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
This adds the close_range() syscall. It allows to efficiently close a range
of file descriptors up to all file descriptors of a calling task.
I was contacted by FreeBSD as they wanted to have the same close_range()
syscall as we proposed here. We've coordinated this and in the meantime, Kyle
was fast enough to merge close_range() into FreeBSD already in April:
https://reviews.freebsd.org/D21627https://svnweb.freebsd.org/base?view=revision&revision=359836
and the current plan is to backport close_range() to FreeBSD 12.2 (cf. [2])
once its merged in Linux too. Python is in the process of switching to
close_range() on FreeBSD and they are waiting on us to merge this to switch on
Linux as well: https://bugs.python.org/issue38061
The syscall came up in a recent discussion around the new mount API and
making new file descriptor types cloexec by default. During this
discussion, Al suggested the close_range() syscall (cf. [1]). Note, a
syscall in this manner has been requested by various people over time.
First, it helps to close all file descriptors of an exec()ing task. This
can be done safely via (quoting Al's example from [1] verbatim):
/* that exec is sensitive */
unshare(CLONE_FILES);
/* we don't want anything past stderr here */
close_range(3, ~0U);
execve(....);
The code snippet above is one way of working around the problem that file
descriptors are not cloexec by default. This is aggravated by the fact that
we can't just switch them over without massively regressing userspace. For
a whole class of programs having an in-kernel method of closing all file
descriptors is very helpful (e.g. demons, service managers, programming
language standard libraries, container managers etc.).
(Please note, unshare(CLONE_FILES) should only be needed if the calling
task is multi-threaded and shares the file descriptor table with another
thread in which case two threads could race with one thread allocating file
descriptors and the other one closing them via close_range(). For the
general case close_range() before the execve() is sufficient.)
Second, it allows userspace to avoid implementing closing all file
descriptors by parsing through /proc/<pid>/fd/* and calling close() on each
file descriptor. From looking at various large(ish) userspace code bases
this or similar patterns are very common in:
- service managers (cf. [4])
- libcs (cf. [6])
- container runtimes (cf. [5])
- programming language runtimes/standard libraries
- Python (cf. [2])
- Rust (cf. [7], [8])
As Dmitry pointed out there's even a long-standing glibc bug about missing
kernel support for this task (cf. [3]).
In addition, the syscall will also work for tasks that do not have procfs
mounted and on kernels that do not have procfs support compiled in. In such
situations the only way to make sure that all file descriptors are closed
is to call close() on each file descriptor up to UINT_MAX or RLIMIT_NOFILE,
OPEN_MAX trickery (cf. comment [8] on Rust).
The performance is striking. For good measure, comparing the following
simple close_all_fds() userspace implementation that is essentially just
glibc's version in [6]:
static int close_all_fds(void)
{
int dir_fd;
DIR *dir;
struct dirent *direntp;
dir = opendir("/proc/self/fd");
if (!dir)
return -1;
dir_fd = dirfd(dir);
while ((direntp = readdir(dir))) {
int fd;
if (strcmp(direntp->d_name, ".") == 0)
continue;
if (strcmp(direntp->d_name, "..") == 0)
continue;
fd = atoi(direntp->d_name);
if (fd == dir_fd || fd == 0 || fd == 1 || fd == 2)
continue;
close(fd);
}
closedir(dir);
return 0;
}
to close_range() yields:
1. closing 4 open files:
- close_all_fds(): ~280 us
- close_range(): ~24 us
2. closing 1000 open files:
- close_all_fds(): ~5000 us
- close_range(): ~800 us
close_range() is designed to allow for some flexibility. Specifically, it
does not simply always close all open file descriptors of a task. Instead,
callers can specify an upper bound.
This is e.g. useful for scenarios where specific file descriptors are
created with well-known numbers that are supposed to be excluded from
getting closed.
For extra paranoia close_range() comes with a flags argument. This can e.g.
be used to implement extension. Once can imagine userspace wanting to stop
at the first error instead of ignoring errors under certain circumstances.
There might be other valid ideas in the future. In any case, a flag
argument doesn't hurt and keeps us on the safe side.
From an implementation side this is kept rather dumb. It saw some input
from David and Jann but all nonsense is obviously my own!
- Errors to close file descriptors are currently ignored. (Could be changed
by setting a flag in the future if needed.)
- __close_range() is a rather simplistic wrapper around __close_fd().
My reasoning behind this is based on the nature of how __close_fd() needs
to release an fd. But maybe I misunderstood specifics:
We take the files_lock and rcu-dereference the fdtable of the calling
task, we find the entry in the fdtable, get the file and need to release
files_lock before calling filp_close().
In the meantime the fdtable might have been altered so we can't just
retake the spinlock and keep the old rcu-reference of the fdtable
around. Instead we need to grab a fresh reference to the fdtable.
If my reasoning is correct then there's really no point in fancyfying
__close_range(): We just need to rcu-dereference the fdtable of the
calling task once to cap the max_fd value correctly and then go on
calling __close_fd() in a loop.
/* References */
[1]: https://lore.kernel.org/lkml/20190516165021.GD17978@ZenIV.linux.org.uk/
[2]: 9e4f2f3a6b/Modules/_posixsubprocess.c (L220)
[3]: https://sourceware.org/bugzilla/show_bug.cgi?id=10353#c7
[4]: 5238e95759/src/basic/fd-util.c (L217)
[5]: ddf4b77e11/src/lxc/start.c (L236)
[6]: https://sourceware.org/git/?p=glibc.git;a=blob;f=sysdeps/unix/sysv/linux/grantpt.c;h=2030e07fa6e652aac32c775b8c6e005844c3c4eb;hb=HEAD#l17
Note that this is an internal implementation that is not exported.
Currently, libc seems to not provide an exported version of this
because of missing kernel support to do this.
Note, in a recent patch series Florian made grantpt() a nop thereby
removing the code referenced here.
[7]: https://github.com/rust-lang/rust/issues/12148
[8]: 5f47c0613e/src/libstd/sys/unix/process2.rs (L303-L308)
Rust's solution is slightly different but is equally unperformant.
Rust calls getdtablesize() which is a glibc library function that
simply returns the current RLIMIT_NOFILE or OPEN_MAX values. Rust then
goes on to call close() on each fd. That's obviously overkill for most
tasks. Rarely, tasks - especially non-demons - hit RLIMIT_NOFILE or
OPEN_MAX.
Let's be nice and assume an unprivileged user with RLIMIT_NOFILE set
to 1024. Even in this case, there's a very high chance that in the
common case Rust is calling the close() syscall 1021 times pointlessly
if the task just has 0, 1, and 2 open.
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Change-Id: I2f7abcf9210a1e79855837d1b7c580cc7f7a38e2
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kyle Evans <self@kyle-evans.net>
Cc: Jann Horn <jannh@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Dmitry V. Levin <ldv@altlinux.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: linux-api@vger.kernel.org
tcp_tso_should_defer() used the min() macro on incompatible types (u64 vs long)
error: comparison of distinct pointer types
('typeof (srtt_in_ns >> 1) *' (aka 'unsigned long long *')
and 'typeof (1000000L) *' (aka 'long *'))
Fix this up by using min_t to ensure the comparison is performed as
unsigned 64-bit integers
Fixes: 8b7ac7af3a
Change-Id: Iccd7ae5bdcc3fd77fea126389761cc30c5558315
* 'android11-5.4-lts' of https://android.googlesource.com/kernel/common:
Linux 5.4.302
Input: pegasus-notetaker - fix potential out-of-bounds access
Input: remove third argument of usb_maxpacket()
usb: deprecate the third argument of usb_maxpacket()
ata: libata-scsi: Fix system suspend for a security locked drive
fs/proc: fix uaf in proc_readdir_de()
pmdomain: imx: Fix reference count leak in imx_gpc_remove
pmdomain: arm: scmi: Fix genpd leak on provider registration failure
net: netpoll: fix incorrect refcount handling causing incorrect cleanup
net: qede: Initialize qede_ll_ops with designated initializer
uio_hv_generic: Set event for all channels on the device
net: ethernet: ti: netcp: Standardize knav_dma_open_channel to return NULL on error
ALSA: usb-audio: fix uac2 clock source at terminal parser
mm/page_alloc: fix hash table order logging in alloc_large_system_hash()
kconfig/nconf: Initialize the default locale at startup
kconfig/mconf: Initialize the default locale at startup
vsock: Ignore signal/timeout on connect() if already established
s390/ctcm: Fix double-kfree
net: openvswitch: remove never-working support for setting nsh fields
mlxsw: spectrum: Fix memory leak in mlxsw_sp_flower_stats()
MIPS: Malta: Fix !EVA SOC-it PCI MMIO
scsi: target: tcm_loop: Fix segfault in tcm_loop_tpg_address_show()
scsi: sg: Do not sleep in atomic context
Input: cros_ec_keyb - fix an invalid memory access
be2net: pass wrb_params in case of OS2BMC
HID: quirks: work around VID/PID conflict for 0x4c4a/0x4155
isdn: mISDN: hfcsusb: fix memory leak in hfcsusb_probe()
EDAC/altera: Use INTTEST register for Ethernet and USB SBE injection
EDAC/altera: Handle OCRAM ECC enable after warm reset
spi: Try to get ACPI GPIO IRQ earlier
ipv4: route: Prevent rt_bind_exception() from rebinding stale fnhe
strparser: Fix signed/unsigned mismatch bug
gcov: add support for GCC 15
mm/ksm: fix flag-dropping behavior in ksm_madvise
ALSA: usb-audio: Fix NULL pointer dereference in snd_usb_mixer_controls_badd
drm/vmwgfx: Validate command header size against SVGA_CMD_MAX_DATASIZE
ASoC: cs4271: Fix regulator leak on probe failure
regulator: fixed: fix GPIO descriptor leak on register failure
regulator: fixed: use dev_err_probe for register
Bluetooth: L2CAP: export l2cap_chan_hold for modules
net_sched: limit try_bulk_dequeue_skb() batches
net_sched: remove need_resched() from qdisc_run()
net/mlx5e: Fix wraparound in rate limiting for values above 255 Gbps
net/mlx5e: Fix maxrate wraparound in threshold between units
net: sched: act_ife: initialize struct tc_ife to fix KMSAN kernel-infoleak
wifi: mac80211: skip rate verification for not captured PSDUs
net: mdio: fix resource leak in mdiobus_register_device()
tipc: Fix use-after-free in tipc_mon_reinit_self().
tipc: simplify the finalize work queue
sctp: prevent possible shift-out-of-bounds in sctp_transport_update_rto
sctp: get netns from asoc and ep base
Bluetooth: 6lowpan: Don't hold spin lock over sleeping functions
Bluetooth: 6lowpan: fix BDADDR_LE vs ADDR_LE_DEV address type confusion
Bluetooth: 6lowpan: reset link-local header on ipv6 recv path
Bluetooth: btusb: reorder cleanup in btusb_disconnect to avoid UAF
net: fec: correct rx_bytes statistic for the case SHIFT16 is set
ASoC: max98090/91: fixed max98091 ALSA widget powering up/down
HID: quirks: avoid Cooler Master MM712 dongle wakeup bug
NFS4: Fix state renewals missing after boot
compiler_types: Move unused static inline functions warning to W=2
extcon: adc-jack: Cleanup wakeup source only if it was enabled
tracing: Fix memory leaks in create_field_var()
net: usb: qmi_wwan: initialize MAC header offset in qmimux_rx_fixup
sctp: Prevent TOCTOU out-of-bounds write
sctp: Hold RCU read lock while iterating over address list
net: dsa: b53: stop reading ARL entries if search is done
net: dsa: b53: fix enabling ip multicast
net: dsa: b53: fix resetting speed and pause on forced link
net: dsa: b53: prevent GMII_PORT_OVERRIDE_CTRL access on BCM5325
net: dsa/b53: change b53_force_port_config() pause argument
net: vlan: sync VLAN features with lower device
ceph: add checking of wait_for_completion_killable() return value
fbdev: Add bounds checking in bit_putcs to fix vmalloc-out-of-bounds
ACPI: property: Return present device nodes only on fwnode interface
9p: sysfs_init: don't hardcode error to ENOMEM
9p: fix /sys/fs/9p/caches overwriting itself
fs/hpfs: Fix error code for new_inode() failure in mkdir/create/mknod/symlink
ACPICA: Update dsmethod.c to get rid of unused variable warning
orangefs: fix xattr related buffer overflow...
page_pool: Clamp pool size to max 16K pages
Bluetooth: bcsp: receive data only if registered
Bluetooth: SCO: Fix UAF on sco_conn_free
net: macb: avoid dealing with endianness in macb_set_hwaddr()
nfs4_setup_readdir(): insufficient locking for ->d_parent->d_inode dereferencing
NFSv4.1: fix mount hang after CREATE_SESSION failure
NFSv4: handle ERR_GRACE on delegation recalls
remoteproc: qcom: q6v5: Avoid handling handover twice
sparc/module: Add R_SPARC_UA64 relocation handling
net: intel: fm10k: Fix parameter idx set but not used
jfs: fix uninitialized waitqueue in transaction manager
jfs: Verify inode mode when loading from disk
ipv6: np->rxpmtu race annotation
usb: xhci: plat: Facilitate using autosuspend for xhci plat devices
usb: mon: Increase BUFF_MAX to 64 MiB to support multi-MB URBs
allow finish_no_open(file, ERR_PTR(-E...))
scsi: lpfc: Define size of debugfs entry for xri rebalancing
scsi: lpfc: Check return status of lpfc_reset_flush_io_context during TGT_RESET
selftests/Makefile: include $(INSTALL_DEP_TARGETS) in clean target to clean net/lib dependency
net/cls_cgroup: Fix task_get_classid() during qdisc run
selftests: Replace sleep with slowwait
selftests: Disable dad for ipv6 in fcnal-test.sh
media: redrat3: use int type to store negative error codes
net: sh_eth: Disable WoL if system can not suspend
phy: cadence: cdns-dphy: Enable lower resolutions in dphy
usb: gadget: f_hid: Fix zero length packet transfer
net: call cond_resched() less often in __release_sock()
ALSA: usb-audio: apply quirk for MOONDROP Quark2
net: nfc: nci: Increase NCI_DATA_TIMEOUT to 3000 ms
dmaengine: dw-edma: Set status for callback_result
dmaengine: mv_xor: match alloc_wc and free_wc
dmaengine: sh: setup_xref error handling
scsi: pm8001: Use int instead of u32 to store error codes
mips: lantiq: xway: sysctrl: rename stp clock
mips: lantiq: danube: add missing device_type in pci node
mips: lantiq: danube: add missing properties to cpu node
media: fix uninitialized symbol warnings
drm/amdkfd: Tie UNMAP_LATENCY to queue_preemption
extcon: adc-jack: Fix wakeup source leaks on device unbind
rds: Fix endianness annotation for RDS_MPATH_HASH
PCI/P2PDMA: Fix incorrect pointer usage in devm_kfree() call
net: Call trace_sock_exceed_buf_limit() for memcg failure with SK_MEM_RECV.
net: When removing nexthops, don't call synchronize_net if it is not necessary
char: misc: Does not request module for miscdevice with dynamic minor
usb: gadget: f_ncm: Fix MAC assignment NCM ethernet
iio: adc: spear_adc: mask SPEAR_ADC_STATUS channel and avg sample before setting register
media: imon: make send_packet() more robust
net: ipv6: fix field-spanning memcpy warning in AH output
bridge: Redirect to backup port when port is administratively down
powerpc/eeh: Use result of error_detected() in uevent
x86/vsyscall: Do not require X86_PF_INSTR to emulate vsyscall
media: pci: ivtv: Don't create fake v4l2_fh
drm/amdkfd: return -ENOTTY for unsupported IOCTLs
selftests/net: Ensure assert() triggers in psock_tpacket.c
selftests/net: Replace non-standard __WORDSIZE with sizeof(long) * 8
PCI: Disable MSI on RDC PCI to PCIe bridges
drm/nouveau: replace snprintf() with scnprintf() in nvkm_snprintbf()
mfd: madera: Work around false-positive -Wininitialized warning
mfd: stmpe-i2c: Add missing MODULE_LICENSE
mfd: stmpe: Remove IRQ domain upon removal
tools/power x86_energy_perf_policy: Prefer driver HWP limits
tools/power x86_energy_perf_policy: Enhance HWP enable
tools/cpupower: Fix incorrect size in cpuidle_state_disable()
hwmon: (dell-smm) Add support for Dell OptiPlex 7040
uprobe: Do not emulate/sstep original instruction when ip is changed
clocksource/drivers/vf-pit: Replace raw_readl/writel to readl/writel
video: backlight: lp855x_bl: Set correct EPROM start for LP8556
tee: allow a driver to allocate a tee_device without a pool
ACPICA: dispatcher: Use acpi_ds_clear_operands() in acpi_ds_call_control_method()
mmc: sdhci-msm: Enable tuning for SDR50 mode for SD card
irqchip/gic-v2m: Handle Multiple MSI base IRQ Alignment
arc: Fix __fls() const-foldability via __builtin_clzl()
cpufreq/longhaul: handle NULL policy in longhaul_exit
selftests/bpf: Fix bpf_prog_detach2 usage in test_lirc_mode2
ACPI: video: force native for Lenovo 82K8
memstick: Add timeout to prevent indefinite waiting
mmc: host: renesas_sdhi: Fix the actual clock
bpf: Don't use %pK through printk
spi: loopback-test: Don't use %pK through printk
soc: qcom: smem: Fix endian-unaware access of num_entries
usb: gadget: f_fs: Fix epfile null pointer access after ep enable.
serial: 8250_dw: handle reset control deassert error
serial: 8250_dw: Use devm_add_action_or_reset()
serial: 8250_dw: Use devm_clk_get_optional() to get the input clock
can: gs_usb: increase max interface to U8_MAX
devcoredump: Fix circular locking dependency with devcd->mutex.
net: ravb: Enforce descriptor type ordering
x86/resctrl: Fix miscount of bandwidth event when reactivating previously unavailable RMID
wifi: brcmfmac: fix crash while sending Action Frames in standalone AP Mode
net: phy: dp83867: Disable EEE support as not implemented
regmap: slimbus: fix bus_context pointer in regmap init calls
drm/etnaviv: fix flush sequence logic
usbnet: Prevents free active kevent
wifi: ath10k: Fix memory leak on unsupported WMI command
ASoC: qdsp6: q6asm: do not sleep while atomic
fbdev: valkyriefb: Fix reference count leak in valkyriefb_init
fbdev: pvr2fb: Fix leftover reference to ONCHIP_NR_DMA_CHANNELS
fbdev: bitblit: bound-check glyph index in bit_putcs*
ACPI: video: Fix use-after-free in acpi_video_switch_brightness()
fbdev: atyfb: Check if pll_ops->init_pll failed
net: usb: asix_devices: Check return value of usbnet_get_endpoints
btrfs: use smp_mb__after_atomic() when forcing COW in create_pending_snapshot()
x86/bugs: Fix reporting of LFENCE retpoline
net/sched: sch_qfq: Fix null-deref in agg_dequeue
Conflicts:
drivers/mmc/host/sdhci-msm.c
drivers/usb/host/xhci-plat.c
Change-Id: I30739fea8840ace3825ea8955598d9efa687bb27
