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    Subject[PATCH v7 02/12] perf/core: open access to the core for CAP_PERFMON privileged process
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    Open access to monitoring of kernel code, cpus, tracepoints and
    namespaces data for a CAP_PERFMON privileged process. Providing the
    access under CAP_PERFMON capability singly, without the rest of
    CAP_SYS_ADMIN credentials, excludes chances to misuse the credentials
    and makes operation more secure.

    CAP_PERFMON implements the principal of least privilege for performance
    monitoring and observability operations (POSIX IEEE 1003.1e 2.2.2.39
    principle of least privilege: A security design principle that states
    that a process or program be granted only those privileges (e.g.,
    capabilities) necessary to accomplish its legitimate function, and only
    for the time that such privileges are actually required)

    For backward compatibility reasons access to perf_events subsystem
    remains open for CAP_SYS_ADMIN privileged processes but CAP_SYS_ADMIN
    usage for secure perf_events monitoring is discouraged with respect to
    CAP_PERFMON capability.

    Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
    ---
    include/linux/perf_event.h | 6 +++---
    kernel/events/core.c | 2 +-
    2 files changed, 4 insertions(+), 4 deletions(-)

    diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
    index 68e21e828893..5cbfc06c56b3 100644
    --- a/include/linux/perf_event.h
    +++ b/include/linux/perf_event.h
    @@ -1297,7 +1297,7 @@ static inline int perf_is_paranoid(void)

    static inline int perf_allow_kernel(struct perf_event_attr *attr)
    {
    - if (sysctl_perf_event_paranoid > 1 && !capable(CAP_SYS_ADMIN))
    + if (sysctl_perf_event_paranoid > 1 && !perfmon_capable())
    return -EACCES;

    return security_perf_event_open(attr, PERF_SECURITY_KERNEL);
    @@ -1305,7 +1305,7 @@ static inline int perf_allow_kernel(struct perf_event_attr *attr)

    static inline int perf_allow_cpu(struct perf_event_attr *attr)
    {
    - if (sysctl_perf_event_paranoid > 0 && !capable(CAP_SYS_ADMIN))
    + if (sysctl_perf_event_paranoid > 0 && !perfmon_capable())
    return -EACCES;

    return security_perf_event_open(attr, PERF_SECURITY_CPU);
    @@ -1313,7 +1313,7 @@ static inline int perf_allow_cpu(struct perf_event_attr *attr)

    static inline int perf_allow_tracepoint(struct perf_event_attr *attr)
    {
    - if (sysctl_perf_event_paranoid > -1 && !capable(CAP_SYS_ADMIN))
    + if (sysctl_perf_event_paranoid > -1 && !perfmon_capable())
    return -EPERM;

    return security_perf_event_open(attr, PERF_SECURITY_TRACEPOINT);
    diff --git a/kernel/events/core.c b/kernel/events/core.c
    index 3f1f77de7247..46464367c47a 100644
    --- a/kernel/events/core.c
    +++ b/kernel/events/core.c
    @@ -11205,7 +11205,7 @@ SYSCALL_DEFINE5(perf_event_open,
    }

    if (attr.namespaces) {
    - if (!capable(CAP_SYS_ADMIN))
    + if (!perfmon_capable())
    return -EACCES;
    }

    --
    2.20.1
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