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There are several scenarios that have come up where having a user_event persist even if the process that registered it exits. The main one is having a daemon create events on bootup that shouldn't get deleted if the daemon has to exit or reload. Another is within OpenTelemetry exporters, they wish to potentially check if a user_event exists on the system to determine if exporting the data out should occur. The user_event in this case must exist even in the absence of the owning process running (such as the above daemon case). Expose the previously internal flag USER_EVENT_REG_PERSIST to user processes. Upon register or delete of events with this flag, ensure the user is perfmon_capable to prevent random user processes with access to tracefs from creating events that persist after exit. Link: https://lkml.kernel.org/r/20230912180704.1284-2-beaub@linux.microsoft.com Signed-off-by: Beau Belgrave <beaub@linux.microsoft.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
91 lines
2.3 KiB
C
91 lines
2.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* Copyright (c) 2021-2022, Microsoft Corporation.
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*
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* Authors:
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* Beau Belgrave <beaub@linux.microsoft.com>
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*/
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#ifndef _UAPI_LINUX_USER_EVENTS_H
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#define _UAPI_LINUX_USER_EVENTS_H
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#include <linux/types.h>
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#include <linux/ioctl.h>
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#define USER_EVENTS_SYSTEM "user_events"
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#define USER_EVENTS_PREFIX "u:"
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/* Create dynamic location entry within a 32-bit value */
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#define DYN_LOC(offset, size) ((size) << 16 | (offset))
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/* List of supported registration flags */
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enum user_reg_flag {
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/* Event will not delete upon last reference closing */
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USER_EVENT_REG_PERSIST = 1U << 0,
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/* This value or above is currently non-ABI */
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USER_EVENT_REG_MAX = 1U << 1,
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};
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/*
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* Describes an event registration and stores the results of the registration.
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* This structure is passed to the DIAG_IOCSREG ioctl, callers at a minimum
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* must set the size and name_args before invocation.
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*/
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struct user_reg {
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/* Input: Size of the user_reg structure being used */
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__u32 size;
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/* Input: Bit in enable address to use */
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__u8 enable_bit;
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/* Input: Enable size in bytes at address */
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__u8 enable_size;
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/* Input: Flags to use, if any */
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__u16 flags;
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/* Input: Address to update when enabled */
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__u64 enable_addr;
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/* Input: Pointer to string with event name, description and flags */
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__u64 name_args;
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/* Output: Index of the event to use when writing data */
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__u32 write_index;
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} __attribute__((__packed__));
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/*
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* Describes an event unregister, callers must set the size, address and bit.
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* This structure is passed to the DIAG_IOCSUNREG ioctl to disable bit updates.
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*/
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struct user_unreg {
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/* Input: Size of the user_unreg structure being used */
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__u32 size;
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/* Input: Bit to unregister */
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__u8 disable_bit;
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/* Input: Reserved, set to 0 */
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__u8 __reserved;
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/* Input: Reserved, set to 0 */
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__u16 __reserved2;
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/* Input: Address to unregister */
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__u64 disable_addr;
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} __attribute__((__packed__));
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#define DIAG_IOC_MAGIC '*'
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/* Request to register a user_event */
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#define DIAG_IOCSREG _IOWR(DIAG_IOC_MAGIC, 0, struct user_reg *)
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/* Request to delete a user_event */
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#define DIAG_IOCSDEL _IOW(DIAG_IOC_MAGIC, 1, char *)
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/* Requests to unregister a user_event */
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#define DIAG_IOCSUNREG _IOW(DIAG_IOC_MAGIC, 2, struct user_unreg*)
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#endif /* _UAPI_LINUX_USER_EVENTS_H */
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