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This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
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It's quite possible that opcodes that have payloads attached to them,
like IORING_OP_OPENAT/OPENAT2 or IORING_OP_SOCKET, that these paylods
can change over time. For example, on the openat/openat2 side, the
struct open_how argument is extensible, and could be extended in the
future to allow further arguments to be passed in.
Allow registration of a cBPF filter to give the size of the filter as
seen by userspace. If that filter is for an opcode that takes extra
payload data, allow it if the application payload expectation is the
same size than the kernels. If that is the case, the kernel supports
filtering on the payload that the application expects. If the size
differs, the behavior depends on the IO_URING_BPF_FILTER_SZ_STRICT flag:
1) If IO_URING_BPF_FILTER_SZ_STRICT is set and the size expectation
differs, fail the attempt to load the filter.
2) If IO_URING_BPF_FILTER_SZ_STRICT isn't set, allow the filter if
the userspace pdu size is smaller than what the kernel offers.
3) Regardless if IO_URING_BPF_FILTER_SZ_STRICT, fail loading the filter
if the userspace pdu size is bigger than what the kernel supports.
An attempt to load a filter due to sizing will error with -EMSGSIZE.
For that error, the registration struct will have filter->pdu_size
populated with the pdu size that the kernel uses.
Reported-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Rather than open-code this logic in io_uring_populate_bpf_ctx() with
a switch, move it to the issue side definitions. Outside of making this
easier to extend in the future, it's also a prep patch for using the
pdu size for a given opcode filter elsewhere.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently io_uring supports restricting operations on a per-ring basis.
To use those, the ring must be setup in a disabled state by setting
IORING_SETUP_R_DISABLED. Then restrictions can be set for the ring, and
the ring can then be enabled.
This commit adds support for IORING_REGISTER_RESTRICTIONS with ring_fd
== -1, like the other "blind" register opcodes which work on the task
rather than a specific ring. This allows registration of the same kind
of restrictions as can been done on a specific ring, but with the task
itself. Once done, any ring created will inherit these restrictions.
If a restriction filter is registered with a task, then it's inherited
on fork for its children. Children may only further restrict operations,
not extend them.
Inheriting restrictions include both the classic
IORING_REGISTER_RESTRICTIONS based restrictions, as well as the BPF
filters that have been registered with the task via
IORING_REGISTER_BPF_FILTER.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In preparation for allowing inheritance of BPF filters and filter
tables, add a reference count to the filter. This allows multiple tables
to safely include the same filter.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently a few pointer dereferences need to be made to both check if
BPF filters are installed, and then also to retrieve the actual filter
for the opcode. Cache the table in ctx->bpf_filters to avoid that.
Add a bit of debug info on ring exit to show if we ever got this wrong.
Small risk of that given that the table is currently only updated in one
spot, but once task forking is enabled, that will add one more spot.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This adds custom filtering for IORING_OP_OPENAT and IORING_OP_OPENAT2,
where the open_how flags, mode, and resolve can be checked by filters.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Example population method for the BPF based opcode filtering. This
exposes the socket family, type, and protocol to a registered BPF
filter. This in turn enables the filter to make decisions based on
what was passed in to the IORING_OP_SOCKET request type.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add support for loading classic BPF programs with io_uring to provide
fine-grained filtering of SQE operations. Unlike
IORING_REGISTER_RESTRICTIONS which only allows bitmap-based allow/deny
of opcodes, BPF filters can inspect request attributes and make dynamic
decisions.
The filter is registered via IORING_REGISTER_BPF_FILTER with a struct
io_uring_bpf:
struct io_uring_bpf_filter {
__u32 opcode; /* io_uring opcode to filter */
__u32 flags;
__u32 filter_len; /* number of BPF instructions */
__u32 resv;
__u64 filter_ptr; /* pointer to BPF filter */
__u64 resv2[5];
};
enum {
IO_URING_BPF_CMD_FILTER = 1,
};
struct io_uring_bpf {
__u16 cmd_type; /* IO_URING_BPF_* values */
__u16 cmd_flags; /* none so far */
__u32 resv;
union {
struct io_uring_bpf_filter filter;
};
};
and the filters get supplied a struct io_uring_bpf_ctx:
struct io_uring_bpf_ctx {
__u64 user_data;
__u8 opcode;
__u8 sqe_flags;
__u8 pdu_size;
__u8 pad[5];
};
where it's possible to filter on opcode and sqe_flags, with pdu_size
indicating how much extra data is being passed in beyond the pad field.
This will used for specific finer grained filtering inside an opcode.
An example of that for sockets is in one of the following patches.
Anything the opcode supports can end up in this struct, populated by
the opcode itself, and hence can be filtered for.
Filters have the following semantics:
- Return 1 to allow the request
- Return 0 to deny the request with -EACCES
- Multiple filters can be stacked per opcode. All filters must
return 1 for the opcode to be allowed.
- Filters are evaluated in registration order (most recent first)
The implementation uses classic BPF (cBPF) rather than eBPF for as
that's required for containers, and since they can be used by any
user in the system.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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