Revert "ANDROID: security,perf: Allow further restriction of perf_event_open"

Unfork Android.

This reverts commit 8e5e42d5ae20f0324170d01ccf374a1571e82d9b.

Perf_event_paranoid=3 is no longer needed on Android. Access control
of perf events is now done by selinux. See:
https://patchwork.kernel.org/patch/11185793/.

Bug: 120445712
Bug: 137092007
Signed-off-by: Jeff Vander Stoep <jeffv@google.com>
Change-Id: Iba493424174b30baff460caaa25a54a472c87bd4
Git-commit: 44a6aea9c2
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>

Documentation/sysctl/kernel.txt

@@ -678,8 +678,7 @@ allowed to execute.
 perf_event_paranoid:
 
 Controls use of the performance events system by unprivileged
-users (without CAP_SYS_ADMIN).  The default value is 3 if
-CONFIG_SECURITY_PERF_EVENTS_RESTRICT is set, or 2 otherwise.
+users (without CAP_SYS_ADMIN).  The default value is 2.
 
  -1: Allow use of (almost) all events by all users
      Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
@@ -687,7 +686,6 @@ CONFIG_SECURITY_PERF_EVENTS_RESTRICT is set, or 2 otherwise.
      Disallow raw tracepoint access by users without CAP_SYS_ADMIN
 >=1: Disallow CPU event access by users without CAP_SYS_ADMIN
 >=2: Disallow kernel profiling by users without CAP_SYS_ADMIN
->=3: Disallow all event access by users without CAP_SYS_ADMIN
 
 ==============================================================
 

arch/arm64/configs/cuttlefish_defconfig

@@ -470,7 +470,6 @@ CONFIG_SCHEDSTATS=y
 CONFIG_DEBUG_LIST=y
 CONFIG_RCU_CPU_STALL_TIMEOUT=60
 CONFIG_ENABLE_DEFAULT_TRACERS=y
-CONFIG_SECURITY_PERF_EVENTS_RESTRICT=y
 CONFIG_TEST_MEMINIT=y
 CONFIG_TEST_STACKINIT=y
 CONFIG_SECURITY=y

arch/x86/configs/x86_64_cuttlefish_defconfig

@@ -504,7 +504,6 @@ CONFIG_TEST_STACKINIT=y
 CONFIG_IO_DELAY_NONE=y
 CONFIG_OPTIMIZE_INLINING=y
 CONFIG_UNWINDER_FRAME_POINTER=y
-CONFIG_SECURITY_PERF_EVENTS_RESTRICT=y
 CONFIG_SECURITY=y
 CONFIG_SECURITY_NETWORK=y
 CONFIG_SECURITY_PATH=y

include/linux/perf_event.h

@@ -1207,11 +1207,6 @@ int perf_event_max_stack_handler(struct ctl_table *table, int write,
 #define PERF_SECURITY_KERNEL		2
 #define PERF_SECURITY_TRACEPOINT	3
 
-static inline bool perf_paranoid_any(void)
-{
-	return sysctl_perf_event_paranoid > 2;
-}
-
 static inline int perf_is_paranoid(void)
 {
 	return sysctl_perf_event_paranoid > -1;

kernel/events/core.c

@@ -430,13 +430,8 @@ static cpumask_var_t perf_online_mask;
  *   0 - disallow raw tracepoint access for unpriv
  *   1 - disallow cpu events for unpriv
  *   2 - disallow kernel profiling for unpriv
- *   3 - disallow all unpriv perf event use
  */
-#ifdef CONFIG_SECURITY_PERF_EVENTS_RESTRICT
-int sysctl_perf_event_paranoid __read_mostly = 3;
-#else
 int sysctl_perf_event_paranoid __read_mostly = 2;
-#endif
 
 /* Minimum for 512 kiB + 1 user control page */
 int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */
@@ -10421,9 +10416,6 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (flags & ~PERF_FLAG_ALL)
 		return -EINVAL;
 
-	if (perf_paranoid_any() && !capable(CAP_SYS_ADMIN))
-		return -EACCES;
-
 	/* Do we allow access to perf_event_open(2) ? */
 	err = security_perf_event_open(&attr, PERF_SECURITY_OPEN);
 	if (err)

security/Kconfig

@@ -18,15 +18,6 @@ config SECURITY_DMESG_RESTRICT
 
 	  If you are unsure how to answer this question, answer N.
 
-config SECURITY_PERF_EVENTS_RESTRICT
-	bool "Restrict unprivileged use of performance events"
-	depends on PERF_EVENTS
-	help
-	  If you say Y here, the kernel.perf_event_paranoid sysctl
-	  will be set to 3 by default, and no unprivileged use of the
-	  perf_event_open syscall will be permitted unless it is
-	  changed.
-
 config SECURITY
 	bool "Enable different security models"
 	depends on SYSFS