diff options
| author | Kees Cook <keescook@chromium.org> | 2012-02-14 16:48:09 -0800 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2012-02-16 10:25:18 +1100 |
| commit | bf06189e4d14641c0148bea16e9dd24943862215 (patch) | |
| tree | 5c62eb24339041baf65b8e42daac42c7a01efc0e | |
| parent | 3ab1aff89477dafb1aaeafe8c8669114a02b7226 (diff) | |
Yama: add PR_SET_PTRACER_ANY
For a process to entirely disable Yama ptrace restrictions, it can use
the special PR_SET_PTRACER_ANY pid to indicate that any otherwise allowed
process may ptrace it. This is stronger than calling PR_SET_PTRACER with
pid "1" because it includes processes in external pid namespaces. This is
currently needed by the Chrome renderer, since its crash handler (Breakpad)
runs external to the renderer's pid namespace.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <jmorris@namei.org>
| -rw-r--r-- | Documentation/security/Yama.txt | 7 | ||||
| -rw-r--r-- | include/linux/prctl.h | 1 | ||||
| -rw-r--r-- | security/yama/yama_lsm.c | 8 |
3 files changed, 13 insertions, 3 deletions
diff --git a/Documentation/security/Yama.txt b/Documentation/security/Yama.txt index 4f0b7896a21..a9511f17906 100644 --- a/Documentation/security/Yama.txt +++ b/Documentation/security/Yama.txt @@ -41,7 +41,12 @@ other process (and its descendents) are allowed to call PTRACE_ATTACH against it. Only one such declared debugging process can exists for each inferior at a time. For example, this is used by KDE, Chromium, and Firefox's crash handlers, and by Wine for allowing only Wine processes -to ptrace each other. +to ptrace each other. If a process wishes to entirely disable these ptrace +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. + +The sysctl settings 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. diff --git a/include/linux/prctl.h b/include/linux/prctl.h index 4d0e5bc5458..a0413ac3abe 100644 --- a/include/linux/prctl.h +++ b/include/linux/prctl.h @@ -119,5 +119,6 @@ * A value of 0 mean "no process". */ #define PR_SET_PTRACER 0x59616d61 +# define PR_SET_PTRACER_ANY ((unsigned long)-1) #endif /* _LINUX_PRCTL_H */ diff --git a/security/yama/yama_lsm.c b/security/yama/yama_lsm.c index dd4d36067c5..573723843a0 100644 --- a/security/yama/yama_lsm.c +++ b/security/yama/yama_lsm.c @@ -84,7 +84,7 @@ static void yama_ptracer_del(struct task_struct *tracer, spin_lock_bh(&ptracer_relations_lock); list_for_each_entry_safe(relation, safe, &ptracer_relations, node) if (relation->tracee == tracee || - relation->tracer == tracer) { + (tracer && relation->tracer == tracer)) { list_del(&relation->node); kfree(relation); } @@ -138,6 +138,8 @@ static int yama_task_prctl(int option, unsigned long arg2, unsigned long arg3, if (arg2 == 0) { yama_ptracer_del(NULL, myself); rc = 0; + } else if (arg2 == PR_SET_PTRACER_ANY) { + rc = yama_ptracer_add(NULL, myself); } else { struct task_struct *tracer; @@ -208,6 +210,7 @@ static int ptracer_exception_found(struct task_struct *tracer, int rc = 0; struct ptrace_relation *relation; struct task_struct *parent = NULL; + bool found = false; spin_lock_bh(&ptracer_relations_lock); rcu_read_lock(); @@ -216,10 +219,11 @@ static int ptracer_exception_found(struct task_struct *tracer, list_for_each_entry(relation, &ptracer_relations, node) if (relation->tracee == tracee) { parent = relation->tracer; + found = true; break; } - if (task_is_descendant(parent, tracer)) + if (found && (parent == NULL || task_is_descendant(parent, tracer))) rc = 1; rcu_read_unlock(); spin_unlock_bh(&ptracer_relations_lock); |