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Emanuele Rocca
701f7f4fba
The struct pidfd_info currently exposes in a field called coredump_signal the
signal number (si_signo) that triggered the dump (for example, 11 for SIGSEGV).
However, it is also valuable to understand the reason why that signal was sent.
This additional context is provided by the signal code (si_code), such as 2 for
SEGV_ACCERR.
Add a new field to struct pidfd_info called coredump_code with the value of
si_code for the benefit of sysadmins who pipe core dumps to user-space programs
for later analysis. The following snippet illustrates a simplified C program
that consumes coredump_signal and coredump_code, and then logs core dump
signals and codes to a file:
int pidfd = (int)atoi(argv[1]);
struct pidfd_info info = {
.mask = PIDFD_INFO_EXIT | PIDFD_INFO_COREDUMP,
};
if (ioctl(pidfd, PIDFD_GET_INFO, &info) == 0)
if (info.mask & PIDFD_INFO_COREDUMP)
fprintf(f, "PID=%d, si_signo: %d si_code: %d\n",
info.pid, info.coredump_signal, info.coredump_code);
Assuming the program is installed under /usr/local/bin/core-logger, core dump
processing can be enabled by setting /proc/sys/kernel/core_pattern to
'|/usr/local/bin/dumpstuff %F'.
systemd-coredump(8) already uses pidfds to process core dumps, and it could be
extended to include the values of coredump_code too.
Signed-off-by: Emanuele Rocca <emanuele.rocca@arm.com>
Link: https://patch.msgid.link/acE52HIFivNZN3nE@NH27D9T0LF
Acked-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
125 lines
4.9 KiB
C
125 lines
4.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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#ifndef _UAPI_LINUX_PIDFD_H
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#define _UAPI_LINUX_PIDFD_H
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#include <linux/types.h>
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#include <linux/fcntl.h>
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#include <linux/ioctl.h>
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/* Flags for pidfd_open(). */
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#define PIDFD_NONBLOCK O_NONBLOCK
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#define PIDFD_THREAD O_EXCL
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#ifdef __KERNEL__
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#include <linux/sched.h>
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#define PIDFD_STALE CLONE_PIDFD
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#define PIDFD_AUTOKILL O_TRUNC
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#endif
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/* Flags for pidfd_send_signal(). */
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#define PIDFD_SIGNAL_THREAD (1UL << 0)
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#define PIDFD_SIGNAL_THREAD_GROUP (1UL << 1)
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#define PIDFD_SIGNAL_PROCESS_GROUP (1UL << 2)
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/* Flags for pidfd_info. */
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#define PIDFD_INFO_PID (1UL << 0) /* Always returned, even if not requested */
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#define PIDFD_INFO_CREDS (1UL << 1) /* Always returned, even if not requested */
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#define PIDFD_INFO_CGROUPID (1UL << 2) /* Always returned if available, even if not requested */
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#define PIDFD_INFO_EXIT (1UL << 3) /* Only returned if requested. */
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#define PIDFD_INFO_COREDUMP (1UL << 4) /* Only returned if requested. */
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#define PIDFD_INFO_SUPPORTED_MASK (1UL << 5) /* Want/got supported mask flags */
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#define PIDFD_INFO_COREDUMP_SIGNAL (1UL << 6) /* Always returned if PIDFD_INFO_COREDUMP is requested. */
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#define PIDFD_INFO_COREDUMP_CODE (1UL << 7) /* Always returned if PIDFD_INFO_COREDUMP is requested. */
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#define PIDFD_INFO_SIZE_VER0 64 /* sizeof first published struct */
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#define PIDFD_INFO_SIZE_VER1 72 /* sizeof second published struct */
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#define PIDFD_INFO_SIZE_VER2 80 /* sizeof third published struct */
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#define PIDFD_INFO_SIZE_VER3 88 /* sizeof fourth published struct */
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/*
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* Values for @coredump_mask in pidfd_info.
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* Only valid if PIDFD_INFO_COREDUMP is set in @mask.
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*
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* Note, the @PIDFD_COREDUMP_ROOT flag indicates that the generated
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* coredump should be treated as sensitive and access should only be
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* granted to privileged users.
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*/
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#define PIDFD_COREDUMPED (1U << 0) /* Did crash and... */
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#define PIDFD_COREDUMP_SKIP (1U << 1) /* coredumping generation was skipped. */
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#define PIDFD_COREDUMP_USER (1U << 2) /* coredump was done as the user. */
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#define PIDFD_COREDUMP_ROOT (1U << 3) /* coredump was done as root. */
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/*
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* ...and for userland we make life simpler - PIDFD_SELF refers to the current
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* thread, PIDFD_SELF_PROCESS refers to the process thread group leader.
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*
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* For nearly all practical uses, a user will want to use PIDFD_SELF.
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*/
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#define PIDFD_SELF PIDFD_SELF_THREAD
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#define PIDFD_SELF_PROCESS PIDFD_SELF_THREAD_GROUP
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struct pidfd_info {
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/*
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* This mask is similar to the request_mask in statx(2).
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*
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* Userspace indicates what extensions or expensive-to-calculate fields
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* they want by setting the corresponding bits in mask. The kernel
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* will ignore bits that it does not know about.
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*
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* When filling the structure, the kernel will only set bits
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* corresponding to the fields that were actually filled by the kernel.
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* This also includes any future extensions that might be automatically
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* filled. If the structure size is too small to contain a field
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* (requested or not), to avoid confusion the mask will not
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* contain a bit for that field.
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*
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* As such, userspace MUST verify that mask contains the
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* corresponding flags after the ioctl(2) returns to ensure that it is
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* using valid data.
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*/
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__u64 mask;
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/*
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* The information contained in the following fields might be stale at the
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* time it is received, as the target process might have exited as soon as
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* the IOCTL was processed, and there is no way to avoid that. However, it
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* is guaranteed that if the call was successful, then the information was
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* correct and referred to the intended process at the time the work was
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* performed. */
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__u64 cgroupid;
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__u32 pid;
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__u32 tgid;
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__u32 ppid;
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__u32 ruid;
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__u32 rgid;
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__u32 euid;
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__u32 egid;
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__u32 suid;
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__u32 sgid;
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__u32 fsuid;
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__u32 fsgid;
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__s32 exit_code;
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struct /* coredump info */ {
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__u32 coredump_mask;
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__u32 coredump_signal;
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__u32 coredump_code;
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__u32 coredump_pad; /* align supported_mask to 8 bytes */
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};
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__u64 supported_mask; /* Mask flags that this kernel supports */
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};
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#define PIDFS_IOCTL_MAGIC 0xFF
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#define PIDFD_GET_CGROUP_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 1)
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#define PIDFD_GET_IPC_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 2)
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#define PIDFD_GET_MNT_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 3)
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#define PIDFD_GET_NET_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 4)
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#define PIDFD_GET_PID_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 5)
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#define PIDFD_GET_PID_FOR_CHILDREN_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 6)
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#define PIDFD_GET_TIME_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 7)
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#define PIDFD_GET_TIME_FOR_CHILDREN_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 8)
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#define PIDFD_GET_USER_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 9)
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#define PIDFD_GET_UTS_NAMESPACE _IO(PIDFS_IOCTL_MAGIC, 10)
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#define PIDFD_GET_INFO _IOWR(PIDFS_IOCTL_MAGIC, 11, struct pidfd_info)
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#endif /* _UAPI_LINUX_PIDFD_H */
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