81 lines
2.7 KiB
Diff
81 lines
2.7 KiB
Diff
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From: Ben Hutchings <ben@decadent.org.uk>
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Date: Mon, 11 Jan 2016 15:23:55 +0000
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Subject: security,perf: Allow further restriction of perf_event_open
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Forwarded: https://lore.kernel.org/all/20160111152355.GS28542@decadent.org.uk/
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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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Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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---
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include/linux/perf_event.h | 5 +++++
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kernel/events/core.c | 8 ++++++++
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security/Kconfig | 9 +++++++++
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3 files changed, 22 insertions(+)
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--- a/include/linux/perf_event.h
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+++ b/include/linux/perf_event.h
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@@ -1589,6 +1589,11 @@ int perf_cpu_time_max_percent_handler(co
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int perf_event_max_stack_handler(const struct ctl_table *table, int write,
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void *buffer, size_t *lenp, 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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/* Access to perf_event_open(2) syscall. */
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#define PERF_SECURITY_OPEN 0
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--- a/kernel/events/core.c
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+++ b/kernel/events/core.c
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@@ -419,8 +419,13 @@ static struct kmem_cache *perf_event_cac
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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_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 = 2;
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+#endif
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/* Minimum for 512 kiB + 1 user control page */
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int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
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@@ -12506,6 +12511,9 @@ SYSCALL_DEFINE5(perf_event_open,
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if (err)
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return err;
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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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/* Do we allow access to perf_event_open(2) ? */
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err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
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if (err)
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--- a/security/Kconfig
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+++ b/security/Kconfig
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@@ -51,6 +51,15 @@ config PROC_MEM_NO_FORCE
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endchoice
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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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