Extend perf_event_open 2 man page with the information about CAP_PERFMON capability designed to secure performance monitoring and observability operation in a system according to the principle of least privilege [1] (POSIX IEEE 1003.1e, 2.2.2.39). [1] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> --- man2/perf_event_open.2 | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index 4827a359d..9810bc554 100644 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2 @@ -97,6 +97,8 @@ when running on the specified CPU. .BR "pid == \-1" " and " "cpu >= 0" This measures all processes/threads on the specified CPU. This requires +.B CAP_PERFMON +(since Linux 5.8) or .B CAP_SYS_ADMIN capability or a .I /proc/sys/kernel/perf_event_paranoid @@ -108,9 +110,11 @@ This setting is invalid and will return an error. When .I pid is greater than zero, permission to perform this system call -is governed by a ptrace access mode +is governed by +.B CAP_PERFMON +(since Linux 5.9) and a ptrace access mode .B PTRACE_MODE_READ_REALCREDS -check; see +check on older Linux versions; see .BR ptrace (2). .PP The @@ -2925,6 +2929,8 @@ to hold the result. This allows attaching a Berkeley Packet Filter (BPF) program to an existing kprobe tracepoint event. You need +.B CAP_PERFMON +(since Linux 5.8) or .B CAP_SYS_ADMIN privileges to use this ioctl. .IP @@ -2967,6 +2973,8 @@ have multiple events attached to a tracepoint. Querying this value on one tracepoint event returns the id of all BPF programs in all events attached to the tracepoint. You need +.B CAP_PERFMON +(since Linux 5.8) or .B CAP_SYS_ADMIN privileges to use this ioctl. .IP @@ -3175,6 +3183,8 @@ it was expecting. .TP .B EACCES Returned when the requested event requires +.B CAP_PERFMON +(since Linux 5.8) or .B CAP_SYS_ADMIN permissions (or a more permissive perf_event paranoid setting). Some common cases where an unprivileged process @@ -3296,6 +3306,8 @@ setting is specified. It can also happen, as with .BR EACCES , when the requested event requires +.B CAP_PERFMON +(since Linux 5.8) or .B CAP_SYS_ADMIN permissions (or a more permissive perf_event paranoid setting). This includes setting a breakpoint on a kernel address, @@ -3326,6 +3338,22 @@ The official way of knowing if support is enabled is checking for the existence of the file .IR /proc/sys/kernel/perf_event_paranoid . +.PP +.B CAP_PERFMON +capability (since Linux 5.8) provides secure approach to +performance monitoring and observability operations in a system +according to the principal of least privilege (POSIX IEEE 1003.1e). +Accessing system performance monitoring and observability operations +using +.B CAP_PERFMON +rather than the much more powerful +.B CAP_SYS_ADMIN +excludes chances to misuse credentials and makes operations more secure. +.B CAP_SYS_ADMIN +usage for secure system performance monitoring and observability +is discouraged with respect to +.B CAP_PERFMON +capability. .SH BUGS The .B F_SETOWN_EX -- 2.24.1
