diff options
| author | Kees Cook <keescook@chromium.org> | 2012-08-09 19:01:26 -0700 |
|---|---|---|
| committer | James Morris <james.l.morris@oracle.com> | 2012-08-10 19:58:07 +1000 |
| commit | 9d8dad742ad1c74d7e7210ee05d0b44961d5ea16 (patch) | |
| tree | b1e738bf17987552cdace2695d8b77328dc29bcf /Documentation | |
| parent | f4ba394c1b02e7fc2179fda8d3941a5b3b65efb6 (diff) | |
Yama: higher restrictions should block PTRACE_TRACEME
The higher ptrace restriction levels should be blocking even
PTRACE_TRACEME requests. The comments in the LSM documentation are
misleading about when the checks happen (the parent does not go through
security_ptrace_access_check() on a PTRACE_TRACEME call).
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org # 3.5.x and later
Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/security/Yama.txt | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/Documentation/security/Yama.txt b/Documentation/security/Yama.txt index e369de2d48c..dd908cf64ec 100644 --- a/Documentation/security/Yama.txt +++ b/Documentation/security/Yama.txt @@ -46,14 +46,13 @@ restrictions, it can call prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, ...) so that any otherwise allowed process (even those in external pid namespaces) may attach. -These restrictions do not change how ptrace via PTRACE_TRACEME operates. - -The sysctl settings are: +The sysctl settings (writable only with CAP_SYS_PTRACE) are: 0 - classic ptrace permissions: a process can PTRACE_ATTACH to any other process running under the same uid, as long as it is dumpable (i.e. did not transition uids, start privileged, or have called - prctl(PR_SET_DUMPABLE...) already). + prctl(PR_SET_DUMPABLE...) already). Similarly, PTRACE_TRACEME is + unchanged. 1 - restricted ptrace: a process must have a predefined relationship with the inferior it wants to call PTRACE_ATTACH on. By default, @@ -61,12 +60,13 @@ The sysctl settings are: classic criteria is also met. To change the relationship, an inferior can call prctl(PR_SET_PTRACER, debugger, ...) to declare an allowed debugger PID to call PTRACE_ATTACH on the inferior. + Using PTRACE_TRACEME is unchanged. 2 - admin-only attach: only processes with CAP_SYS_PTRACE may use ptrace - with PTRACE_ATTACH. + with PTRACE_ATTACH, or through children calling PTRACE_TRACEME. -3 - no attach: no processes may use ptrace with PTRACE_ATTACH. Once set, - this sysctl cannot be changed to a lower value. +3 - no attach: no processes may use ptrace with PTRACE_ATTACH nor via + PTRACE_TRACEME. Once set, this sysctl value cannot be changed. The original children-only logic was based on the restrictions in grsecurity. |