From 71fb4fc909bc519d02ac790432d5740012424db7 Mon Sep 17 00:00:00 2001 From: Tao Huang Date: Tue, 18 Feb 2020 14:57:22 +0800 Subject: [PATCH] Revert "Revert "ANDROID: security,perf: Allow further restriction of perf_event_open"" This reverts commit 025a1ee618e74624c96d457a0cbc2377aa07bcf0. Android 10 CTS PerfEventParanoidTest check /proc/sys/kernel/perf_event_paranoid=3. Change-Id: I705a5040ab1cdd2302a22c11c31487942b69905c Signed-off-by: Tao Huang --- Documentation/sysctl/kernel.txt | 4 +++- arch/arm64/configs/gki_defconfig | 1 + arch/x86/configs/gki_defconfig | 1 + include/linux/perf_event.h | 5 +++++ kernel/events/core.c | 8 ++++++++ security/Kconfig | 9 +++++++++ 6 files changed, 27 insertions(+), 1 deletion(-) diff --git a/Documentation/sysctl/kernel.txt b/Documentation/sysctl/kernel.txt index 37a679501ddc..0e4a8129e86f 100644 --- a/Documentation/sysctl/kernel.txt +++ b/Documentation/sysctl/kernel.txt @@ -693,7 +693,8 @@ allowed to execute. perf_event_paranoid: Controls use of the performance events system by unprivileged -users (without CAP_SYS_ADMIN). The default value is 2. +users (without CAP_SYS_ADMIN). The default value is 3 if +CONFIG_SECURITY_PERF_EVENTS_RESTRICT is set, or 2 otherwise. -1: Allow use of (almost) all events by all users Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK @@ -701,6 +702,7 @@ users (without CAP_SYS_ADMIN). The default value is 2. 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 ============================================================== diff --git a/arch/arm64/configs/gki_defconfig b/arch/arm64/configs/gki_defconfig index 8c84ae41b0ac..9a97983e0eae 100644 --- a/arch/arm64/configs/gki_defconfig +++ b/arch/arm64/configs/gki_defconfig @@ -444,6 +444,7 @@ CONFIG_NLS_MAC_INUIT=y CONFIG_NLS_MAC_ROMANIAN=y CONFIG_NLS_MAC_TURKISH=y CONFIG_NLS_UTF8=y +CONFIG_SECURITY_PERF_EVENTS_RESTRICT=y CONFIG_SECURITY=y CONFIG_SECURITY_NETWORK=y CONFIG_HARDENED_USERCOPY=y diff --git a/arch/x86/configs/gki_defconfig b/arch/x86/configs/gki_defconfig index 9b63f6c54c15..4863d6187fd0 100644 --- a/arch/x86/configs/gki_defconfig +++ b/arch/x86/configs/gki_defconfig @@ -381,6 +381,7 @@ CONFIG_NLS_MAC_INUIT=y CONFIG_NLS_MAC_ROMANIAN=y CONFIG_NLS_MAC_TURKISH=y CONFIG_NLS_UTF8=y +CONFIG_SECURITY_PERF_EVENTS_RESTRICT=y CONFIG_SECURITY=y CONFIG_SECURITY_NETWORK=y CONFIG_HARDENED_USERCOPY=y diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index e07446c5546a..f40925aaf35e 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1206,6 +1206,11 @@ 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; diff --git a/kernel/events/core.c b/kernel/events/core.c index acd706c4364f..cbeab381fd8c 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -397,8 +397,13 @@ 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 */ @@ -10548,6 +10553,9 @@ 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) diff --git a/security/Kconfig b/security/Kconfig index e8d73784ea14..2b3a3ecebed8 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -18,6 +18,15 @@ 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