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12b5b138d1
Extend the coredump socket to allow the coredump server to tell the
kernel how to process individual coredumps.
When the crashing task connects to the coredump socket the kernel will
send a struct coredump_req to the coredump server. The kernel will set
the size member of struct coredump_req allowing the coredump server how
much data can be read.
The coredump server uses MSG_PEEK to peek the size of struct
coredump_req. If the kernel uses a newer struct coredump_req the
coredump server just reads the size it knows and discard any remaining
bytes in the buffer. If the kernel uses an older struct coredump_req
the coredump server just reads the size the kernel knows.
The returned struct coredump_req will inform the coredump server what
features the kernel supports. The coredump_req->mask member is set to
the currently know features.
The coredump server may only use features whose bits were raised by the
kernel in coredump_req->mask.
In response to a coredump_req from the kernel the coredump server sends
a struct coredump_ack to the kernel. The kernel informs the coredump
server what version of struct coredump_ack it supports by setting struct
coredump_req->size_ack to the size it knows about. The coredump server
may only send as many bytes as coredump_req->size_ack indicates (a
smaller size is fine of course). The coredump server must set
coredump_ack->size accordingly.
The coredump server sets the features it wants to use in struct
coredump_ack->mask. Only bits returned in struct coredump_req->mask may
be used.
In case an invalid struct coredump_ack is sent to the kernel a non-zero
u32 integer is sent indicating the reason for the failure. If it was
successful a zero u32 integer is sent.
In the initial version the following features are supported in
coredump_{req,ack}->mask:
* COREDUMP_KERNEL
The kernel will write the coredump data to the socket.
* COREDUMP_USERSPACE
The kernel will not write coredump data but will indicate to the
parent that a coredump has been generated. This is used when userspace
generates its own coredumps.
* COREDUMP_REJECT
The kernel will skip generating a coredump for this task.
* COREDUMP_WAIT
The kernel will prevent the task from exiting until the coredump
server has shutdown the socket connection.
The flexible coredump socket can be enabled by using the "@@" prefix
instead of the single "@" prefix for the regular coredump socket:
@@/run/systemd/coredump.socket
will enable flexible coredump handling. Current kernels already enforce
that "@" must be followed by "/" and will reject anything else. So
extending this is backward and forward compatible.
Link: https://lore.kernel.org/20250603-work-coredump-socket-protocol-v2-1-05a5f0c18ecc@kernel.org
Acked-by: Lennart Poettering <lennart@poettering.net>
Reviewed-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
105 lines
3.3 KiB
C
105 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_COREDUMP_H
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#define _UAPI_LINUX_COREDUMP_H
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#include <linux/types.h>
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/**
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* coredump_{req,ack} flags
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* @COREDUMP_KERNEL: kernel writes coredump
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* @COREDUMP_USERSPACE: userspace writes coredump
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* @COREDUMP_REJECT: don't generate coredump
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* @COREDUMP_WAIT: wait for coredump server
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*/
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enum {
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COREDUMP_KERNEL = (1ULL << 0),
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COREDUMP_USERSPACE = (1ULL << 1),
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COREDUMP_REJECT = (1ULL << 2),
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COREDUMP_WAIT = (1ULL << 3),
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};
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/**
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* struct coredump_req - message kernel sends to userspace
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* @size: size of struct coredump_req
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* @size_ack: known size of struct coredump_ack on this kernel
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* @mask: supported features
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*
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* When a coredump happens the kernel will connect to the coredump
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* socket and send a coredump request to the coredump server. The @size
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* member is set to the size of struct coredump_req and provides a hint
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* to userspace how much data can be read. Userspace may use MSG_PEEK to
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* peek the size of struct coredump_req and then choose to consume it in
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* one go. Userspace may also simply read a COREDUMP_ACK_SIZE_VER0
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* request. If the size the kernel sends is larger userspace simply
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* discards any remaining data.
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*
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* The coredump_req->mask member is set to the currently know features.
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* Userspace may only set coredump_ack->mask to the bits raised by the
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* kernel in coredump_req->mask.
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*
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* The coredump_req->size_ack member is set by the kernel to the size of
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* struct coredump_ack the kernel knows. Userspace may only send up to
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* coredump_req->size_ack bytes to the kernel and must set
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* coredump_ack->size accordingly.
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*/
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struct coredump_req {
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__u32 size;
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__u32 size_ack;
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__u64 mask;
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};
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enum {
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COREDUMP_REQ_SIZE_VER0 = 16U, /* size of first published struct */
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};
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/**
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* struct coredump_ack - message userspace sends to kernel
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* @size: size of the struct
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* @spare: unused
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* @mask: features kernel is supposed to use
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*
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* The @size member must be set to the size of struct coredump_ack. It
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* may never exceed what the kernel returned in coredump_req->size_ack
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* but it may of course be smaller (>= COREDUMP_ACK_SIZE_VER0 and <=
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* coredump_req->size_ack).
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*
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* The @mask member must be set to the features the coredump server
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* wants the kernel to use. Only bits the kernel returned in
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* coredump_req->mask may be set.
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*/
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struct coredump_ack {
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__u32 size;
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__u32 spare;
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__u64 mask;
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};
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enum {
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COREDUMP_ACK_SIZE_VER0 = 16U, /* size of first published struct */
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};
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/**
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* enum coredump_mark - Markers for the coredump socket
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*
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* The kernel will place a single byte on the coredump socket. The
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* markers notify userspace whether the coredump ack succeeded or
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* failed.
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*
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* @COREDUMP_MARK_MINSIZE: the provided coredump_ack size was too small
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* @COREDUMP_MARK_MAXSIZE: the provided coredump_ack size was too big
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* @COREDUMP_MARK_UNSUPPORTED: the provided coredump_ack mask was invalid
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* @COREDUMP_MARK_CONFLICTING: the provided coredump_ack mask has conflicting options
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* @COREDUMP_MARK_REQACK: the coredump request and ack was successful
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* @__COREDUMP_MARK_MAX: the maximum coredump mark value
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*/
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enum coredump_mark {
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COREDUMP_MARK_REQACK = 0U,
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COREDUMP_MARK_MINSIZE = 1U,
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COREDUMP_MARK_MAXSIZE = 2U,
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COREDUMP_MARK_UNSUPPORTED = 3U,
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COREDUMP_MARK_CONFLICTING = 4U,
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__COREDUMP_MARK_MAX = (1U << 31),
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};
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#endif /* _UAPI_LINUX_COREDUMP_H */
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