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Message-ID: <20190906231053.1276792-4-ast@kernel.org>
Date: Fri, 6 Sep 2019 16:10:52 -0700
From: Alexei Starovoitov <ast@...nel.org>
To: <davem@...emloft.net>
CC: <daniel@...earbox.net>, <peterz@...radead.org>,
<luto@...capital.net>, <netdev@...r.kernel.org>,
<bpf@...r.kernel.org>, <kernel-team@...com>,
<linux-api@...r.kernel.org>
Subject: [PATCH v4 bpf-next 3/4] perf: implement CAP_TRACING
Implement permissions as stated in uapi/linux/capability.h
and update Documentation.
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
---
Documentation/admin-guide/perf-security.rst | 4 ++--
Documentation/admin-guide/sysctl/kernel.rst | 10 ++++------
arch/powerpc/perf/core-book3s.c | 4 ++--
arch/x86/events/intel/bts.c | 2 +-
arch/x86/events/intel/core.c | 2 +-
arch/x86/events/intel/p4.c | 2 +-
kernel/events/core.c | 14 +++++++-------
kernel/events/hw_breakpoint.c | 2 +-
kernel/trace/trace_event_perf.c | 4 ++--
9 files changed, 21 insertions(+), 23 deletions(-)
diff --git a/Documentation/admin-guide/perf-security.rst b/Documentation/admin-guide/perf-security.rst
index 72effa7c23b9..c84152d1dfd4 100644
--- a/Documentation/admin-guide/perf-security.rst
+++ b/Documentation/admin-guide/perf-security.rst
@@ -66,8 +66,8 @@ into distinct units, known as capabilities [6]_ , which can be
independently enabled and disabled on per-thread basis for processes and
files of unprivileged users.
-Unprivileged processes with enabled CAP_SYS_ADMIN capability are treated
-as privileged processes with respect to perf_events performance
+Unprivileged processes with enabled CAP_SYS_ADMIN or CAP_TRACING capability
+are treated as privileged processes with respect to perf_events performance
monitoring and bypass *scope* permissions checks in the kernel.
Unprivileged processes using perf_events system call API is also subject
diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index 032c7cd3cede..595bf2b1363f 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -720,20 +720,18 @@ allowed to execute.
====================
Controls use of the performance events system by unprivileged
-users (without CAP_SYS_ADMIN). The default value is 2.
+users (without CAP_SYS_ADMIN and without CAP_TRACING). 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
->=0 Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
+>=0 Disallow ftrace function tracepoint and raw tracepoint
- Disallow raw tracepoint access by users without CAP_SYS_ADMIN
+>=1 Disallow CPU event access
->=1 Disallow CPU event access by users without CAP_SYS_ADMIN
-
->=2 Disallow kernel profiling by users without CAP_SYS_ADMIN
+>=2 Disallow kernel profiling
=== ==================================================================
diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c
index ca92e01d0bd1..a204a3c6c68b 100644
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -204,7 +204,7 @@ static inline void perf_get_data_addr(struct pt_regs *regs, u64 *addrp)
if (!(mmcra & MMCRA_SAMPLE_ENABLE) || sdar_valid)
*addrp = mfspr(SPRN_SDAR);
- if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
+ if (perf_paranoid_kernel() && !capable_tracing() &&
is_kernel_addr(mfspr(SPRN_SDAR)))
*addrp = 0;
}
@@ -472,7 +472,7 @@ static void power_pmu_bhrb_read(struct cpu_hw_events *cpuhw)
* exporting it to userspace (avoid exposure of regions
* where we could have speculative execution)
*/
- if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN) &&
+ if (perf_paranoid_kernel() && !capable_tracing() &&
is_kernel_addr(addr))
continue;
diff --git a/arch/x86/events/intel/bts.c b/arch/x86/events/intel/bts.c
index 5ee3fed881d3..bd713b2dd7c2 100644
--- a/arch/x86/events/intel/bts.c
+++ b/arch/x86/events/intel/bts.c
@@ -550,7 +550,7 @@ static int bts_event_init(struct perf_event *event)
* users to profile the kernel.
*/
if (event->attr.exclude_kernel && perf_paranoid_kernel() &&
- !capable(CAP_SYS_ADMIN))
+ !capable_tracing())
return -EACCES;
if (x86_add_exclusive(x86_lbr_exclusive_bts))
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index e4c2cb65ea50..a7f8c18bd82b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -3307,7 +3307,7 @@ static int intel_pmu_hw_config(struct perf_event *event)
if (x86_pmu.version < 3)
return -EINVAL;
- if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_cpu() && !capable_tracing())
return -EACCES;
event->hw.config |= ARCH_PERFMON_EVENTSEL_ANY;
diff --git a/arch/x86/events/intel/p4.c b/arch/x86/events/intel/p4.c
index dee579efb2b2..f379a358c9cb 100644
--- a/arch/x86/events/intel/p4.c
+++ b/arch/x86/events/intel/p4.c
@@ -776,7 +776,7 @@ static int p4_validate_raw_event(struct perf_event *event)
* the user needs special permissions to be able to use it
*/
if (p4_ht_active() && p4_event_bind_map[v].shared) {
- if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_cpu() && !capable_tracing())
return -EACCES;
}
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 0463c1151bae..eaba102e5d91 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -4134,7 +4134,7 @@ find_get_context(struct pmu *pmu, struct task_struct *task,
if (!task) {
/* Must be root to operate on a CPU event: */
- if (perf_paranoid_cpu() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_cpu() && !capable_tracing())
return ERR_PTR(-EACCES);
cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
@@ -8741,7 +8741,7 @@ static int perf_kprobe_event_init(struct perf_event *event)
if (event->attr.type != perf_kprobe.type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable_tracing())
return -EACCES;
/*
@@ -8801,7 +8801,7 @@ static int perf_uprobe_event_init(struct perf_event *event)
if (event->attr.type != perf_uprobe.type)
return -ENOENT;
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable_tracing())
return -EACCES;
/*
@@ -10588,7 +10588,7 @@ static int perf_copy_attr(struct perf_event_attr __user *uattr,
}
/* privileged levels capture (kernel, hv): check permissions */
if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM)
- && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+ && perf_paranoid_kernel() && !capable_tracing())
return -EACCES;
}
@@ -10807,12 +10807,12 @@ SYSCALL_DEFINE5(perf_event_open,
return err;
if (!attr.exclude_kernel) {
- if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_kernel() && !capable_tracing())
return -EACCES;
}
if (attr.namespaces) {
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable_tracing())
return -EACCES;
}
@@ -10826,7 +10826,7 @@ SYSCALL_DEFINE5(perf_event_open,
/* Only privileged users can get physical addresses */
if ((attr.sample_type & PERF_SAMPLE_PHYS_ADDR) &&
- perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN))
+ perf_paranoid_kernel() && !capable_tracing())
return -EACCES;
/*
diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
index c5cd852fe86b..8bc4d7d8c913 100644
--- a/kernel/events/hw_breakpoint.c
+++ b/kernel/events/hw_breakpoint.c
@@ -404,7 +404,7 @@ static int hw_breakpoint_parse(struct perf_event *bp,
* Don't let unprivileged users set a breakpoint in the trap
* path to avoid trap recursion attacks.
*/
- if (!capable(CAP_SYS_ADMIN))
+ if (!capable_tracing())
return -EPERM;
}
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 0892e38ed6fb..6861307f14d6 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -46,7 +46,7 @@ static int perf_trace_event_perm(struct trace_event_call *tp_event,
/* The ftrace function trace is allowed only for root. */
if (ftrace_event_is_function(tp_event)) {
- if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_tracepoint_raw() && !capable_tracing())
return -EPERM;
if (!is_sampling_event(p_event))
@@ -82,7 +82,7 @@ static int perf_trace_event_perm(struct trace_event_call *tp_event,
* ...otherwise raw tracepoint data can be a severe data leak,
* only allow root to have these.
*/
- if (perf_paranoid_tracepoint_raw() && !capable(CAP_SYS_ADMIN))
+ if (perf_paranoid_tracepoint_raw() && !capable_tracing())
return -EPERM;
return 0;
--
2.20.0
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