FROMLIST: security,perf: Allow further restriction of perf_event_open
When kernel.perf_event_open is set to 3 (or greater), disallow all access to performance events by users without CAP_SYS_ADMIN. Add a Kconfig symbol CONFIG_SECURITY_PERF_EVENTS_RESTRICT that makes this value the default. This is based on a similar feature in grsecurity (CONFIG_GRKERNSEC_PERF_HARDEN). This version doesn't include making the variable read-only. It also allows enabling further restriction at run-time regardless of whether the default is changed. https://lkml.org/lkml/2016/1/11/587 Conflicts: kernel/events/core.c Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Dennis Cagle <d-cagle@codeaurora.org> Bug: 29054680 Bug: 29119870 Change-Id: Iff5bff4fc1042e85866df9faa01bce8d04335ab8 (cherry picked from commit f16929ac8586f37949c638c738a6f0de969ed1ea)
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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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@ -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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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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@ -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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err = perf_copy_attr(attr_uptr, &attr);
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if (err)
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return err;
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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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config SECURITY
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bool "Enable different security models"
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depends on SYSFS
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