Eric Lee / smarc-ti-linux-kernel

Download as
Browse Code ยป

Commit 992fb6e170639b0849bace8e49bf31bd37c4123c

Authored by Oleg Nesterov
Committed by Linus Torvalds
1 parent 462e471107
Exists in master and in 20 other branches dlt-processor-sdk-linux-03.00.00.04, newt-ti-linux-3.12.y, processor-sdk-linux-01.00.00, processor-sdk-linux-02.00.01, smarc-ti-linux-3.12.10, smarc-ti-linux-3.12.y, smarc-ti-linux-3.14.y, smarc-ti-linux-3.15.y, smarc-ti-lsk-linux-4.1.y, smarct3x-processor-sdk-04.01.00.06, smarct3x-processor-sdk-linux-02.00.01, smarct3x-processor-sdk-linux-03.00.00.04, smarct4x-800-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-04.01.00.06, smarct4x-processor-sdk-linux-02.00.01, smarct4x-processor-sdk-linux-03.00.00.04, ti-linux-3.12.y, ti-linux-3.14.y, ti-linux-3.15.y, ti-lsk-linux-4.1.y

ptrace: introduce PTRACE_O_EXITKILL 

Ptrace jailers want to be sure that the tracee can never escape
from the control. However if the tracer dies unexpectedly the
tracee continues to run in potentially unsafe mode.

Add the new ptrace option PTRACE_O_EXITKILL. If the tracer exits
it sends SIGKILL to every tracee which has this bit set.

Note that the new option is not equal to the last-option << 1.  Because
currently all options have an event, and the new one starts the eventless
group.  It uses the random 20 bit, so we have the room for 12 more events,
but we can also add the new eventless options below this one.

Suggested by Amnon Shiloh.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Amnon Shiloh <u3557@miso.sublimeip.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Chris Evans <scarybeasts@gmail.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 3 changed files with 9 additions and 1 deletions Side-by-side Diff

include/linux/ptrace.h
Diff comments   View file @ 992fb6e
... ... @@ -32,6 +32,8 @@
32 32 #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
33 33 #define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
34 34  
  35 +#define PT_EXITKILL (PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
  36 +
35 37 /* single stepping state bits (used on ARM and PA-RISC) */
36 38 #define PT_SINGLESTEP_BIT 31
37 39 #define PT_SINGLESTEP (1<<PT_SINGLESTEP_BIT)
include/uapi/linux/ptrace.h
Diff comments   View file @ 992fb6e
... ... @@ -73,7 +73,10 @@
73 73 #define PTRACE_O_TRACEEXIT (1 << PTRACE_EVENT_EXIT)
74 74 #define PTRACE_O_TRACESECCOMP (1 << PTRACE_EVENT_SECCOMP)
75 75  
76   -#define PTRACE_O_MASK 0x000000ff
  76 +/* eventless options */
  77 +#define PTRACE_O_EXITKILL (1 << 20)
  78 +
  79 +#define PTRACE_O_MASK (0x000000ff | PTRACE_O_EXITKILL)
77 80  
78 81 #include <asm/ptrace.h>
79 82  
... ... @@ -457,6 +457,9 @@
457 457 return;
458 458  
459 459 list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
  460 + if (unlikely(p->ptrace & PT_EXITKILL))
  461 + send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
  462 +
460 463 if (__ptrace_detach(tracer, p))
461 464 list_add(&p->ptrace_entry, &ptrace_dead);
462 465 }