Add a paragraph explaining what sort of capabilities a process would need to read procfs data for some other process. Also mention that reading data for its own process doesn't require any extra permissions. Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> --- Documentation/filesystems/proc.rst | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 09f0aed5a08b..0e7825bb1e3a 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -128,6 +128,16 @@ process running on the system, which is named after the process ID (PID). The link 'self' points to the process reading the file system. Each process subdirectory has the entries listed in Table 1-1. +A process can read its own information from /proc/PID/* with no extra +permissions. When reading /proc/PID/* information for other processes, reading +process is required to have either CAP_SYS_PTRACE capability with +PTRACE_MODE_READ access permissions, or, alternatively, CAP_PERFMON +capability. This applies to all read-only information like `maps`, `environ`, +`pagemap`, etc. The only exception is `mem` file due to its read-write nature, +which requires CAP_SYS_PTRACE capabilities with more elevated +PTRACE_MODE_ATTACH permissions; CAP_PERFMON capability does not grant access +to /proc/PID/mem for other processes. + Note that an open file descriptor to /proc/<pid> or to any of its contained files or subdirectories does not prevent <pid> being reused for some other process in the event that <pid> exits. Operations on -- 2.43.5
