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120 lines
4.1 KiB
Diff
120 lines
4.1 KiB
Diff
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From 149cf87192059fab0cb49ec5c691783c3565c215 Mon Sep 17 00:00:00 2001
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From: Jeff Vander Stoep <jeffv@google.com>
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Date: Sun, 29 May 2016 14:22:32 -0700
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Subject: FROMLIST: security,perf: Allow further restriction of perf_event_open
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When kernel.perf_event_open is set to 3 (or greater), disallow all
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access to performance events by users without CAP_SYS_ADMIN.
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Add a Kconfig symbol CONFIG_SECURITY_PERF_EVENTS_RESTRICT that
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makes this value the default.
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This is based on a similar feature in grsecurity
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(CONFIG_GRKERNSEC_PERF_HARDEN). This version doesn't include making
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the variable read-only. It also allows enabling further restriction
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at run-time regardless of whether the default is changed.
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https://lkml.org/lkml/2016/1/11/587
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Conflicts:
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kernel/events/core.c
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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org>
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Bug: 29054680
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Bug: 29119870
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Change-Id: Iff5bff4fc1042e85866df9faa01bce8d04335ab8
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(cherry picked from commit f16929ac8586f37949c638c738a6f0de969ed1ea)
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---
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Documentation/sysctl/kernel.txt | 4 +++-
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include/linux/perf_event.h | 5 +++++
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kernel/events/core.c | 6 ++++++
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security/Kconfig | 9 +++++++++
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4 files changed, 23 insertions(+), 1 deletion(-)
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diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt
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index 942d769..d438fd2 100644
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--- a/Documentation/sysctl/kernel.txt
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+++ b/Documentation/sysctl/kernel.txt
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@@ -492,12 +492,14 @@ the existing panic controls already in that directory.
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perf_event_paranoid:
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Controls use of the performance events system by unprivileged
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-users (without CAP_SYS_ADMIN). The default value is 1.
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+users (without CAP_SYS_ADMIN). The default value is 3 if
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+CONFIG_SECURITY_PERF_EVENTS_RESTRICT is set, or 1 otherwise.
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-1: Allow use of (almost) all events by all users
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>=0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
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>=1: Disallow CPU event access by users without CAP_SYS_ADMIN
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>=2: Disallow kernel profiling by users without CAP_SYS_ADMIN
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+>=3: Disallow all event access by users without CAP_SYS_ADMIN
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==============================================================
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diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
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index 4410efa..86b43c1 100644
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--- a/include/linux/perf_event.h
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+++ b/include/linux/perf_event.h
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@@ -715,6 +715,11 @@ extern int perf_cpu_time_max_percent_handler(struct ctl_table *table, int write,
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loff_t *ppos);
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+static inline bool perf_paranoid_any(void)
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+{
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+ return sysctl_perf_event_paranoid > 2;
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+}
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+
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static inline bool perf_paranoid_tracepoint_raw(void)
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{
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return sysctl_perf_event_paranoid > -1;
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diff --git a/kernel/events/core.c b/kernel/events/core.c
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index 7ab36de..e8cae75 100644
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--- a/kernel/events/core.c
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+++ b/kernel/events/core.c
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@@ -166,9 +166,12 @@ static struct srcu_struct pmus_srcu;
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* 0 - disallow raw tracepoint access for unpriv
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* 1 - disallow cpu events for unpriv
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* 2 - disallow kernel profiling for unpriv
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+ * 3 - disallow all unpriv perf event use
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*/
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#ifdef CONFIG_PERF_EVENTS_USERMODE
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int sysctl_perf_event_paranoid __read_mostly = -1;
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+#elif defined CONFIG_SECURITY_PERF_EVENTS_RESTRICT
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+int sysctl_perf_event_paranoid __read_mostly = 3;
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#else
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int sysctl_perf_event_paranoid __read_mostly = 1;
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#endif
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@@ -6826,6 +6829,9 @@ SYSCALL_DEFINE5(perf_event_open,
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if (flags & ~PERF_FLAG_ALL)
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return -EINVAL;
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+ if (perf_paranoid_any() && !capable(CAP_SYS_ADMIN))
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+ return -EACCES;
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+
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err = perf_copy_attr(attr_uptr, &attr);
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if (err)
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return err;
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diff --git a/security/Kconfig b/security/Kconfig
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index 0114543..66a5f80 100644
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--- a/security/Kconfig
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+++ b/security/Kconfig
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@@ -18,6 +18,15 @@ config SECURITY_DMESG_RESTRICT
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If you are unsure how to answer this question, answer N.
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+config SECURITY_PERF_EVENTS_RESTRICT
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+ bool "Restrict unprivileged use of performance events"
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+ depends on PERF_EVENTS
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+ help
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+ If you say Y here, the kernel.perf_event_paranoid sysctl
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+ will be set to 3 by default, and no unprivileged use of the
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+ perf_event_open syscall will be permitted unless it is
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+ changed.
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+
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config SECURITY
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bool "Enable different security models"
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depends on SYSFS
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--
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cgit v1.1
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