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authorWill Drewry <wad@chromium.org>2012-04-12 17:48:02 -0400
committerJames Morris <james.l.morris@oracle.com>2012-04-13 21:13:21 -0400
commitfb0fadf9b213f55ca9368f3edafe51101d5d2deb (patch)
treee3e999f0b44a7b4a08b208ae222f509917fc675b /kernel/seccomp.c
parentbb6ea4301a1109afdacaee576fedbfcd7152fc86 (diff)
ptrace,seccomp: Add PTRACE_SECCOMP support
This change adds support for a new ptrace option, PTRACE_O_TRACESECCOMP, and a new return value for seccomp BPF programs, SECCOMP_RET_TRACE. When a tracer specifies the PTRACE_O_TRACESECCOMP ptrace option, the tracer will be notified, via PTRACE_EVENT_SECCOMP, for any syscall that results in a BPF program returning SECCOMP_RET_TRACE. The 16-bit SECCOMP_RET_DATA mask of the BPF program return value will be passed as the ptrace_message and may be retrieved using PTRACE_GETEVENTMSG. If the subordinate process is not using seccomp filter, then no system call notifications will occur even if the option is specified. If there is no tracer with PTRACE_O_TRACESECCOMP when SECCOMP_RET_TRACE is returned, the system call will not be executed and an -ENOSYS errno will be returned to userspace. This change adds a dependency on the system call slow path. Any future efforts to use the system call fast path for seccomp filter will need to address this restriction. Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> v18: - rebase - comment fatal_signal check - acked-by - drop secure_computing_int comment v17: - ... v16: - update PT_TRACE_MASK to 0xbf4 so that STOP isn't clear on SETOPTIONS call (indan@nul.nu) [note PT_TRACE_MASK disappears in linux-next] v15: - add audit support for non-zero return codes - clean up style (indan@nul.nu) v14: - rebase/nochanges v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc (Brings back a change to ptrace.c and the masks.) v12: - rebase to linux-next - use ptrace_event and update arch/Kconfig to mention slow-path dependency - drop all tracehook changes and inclusion (oleg@redhat.com) v11: - invert the logic to just make it a PTRACE_SYSCALL accelerator (indan@nul.nu) v10: - moved to PTRACE_O_SECCOMP / PT_TRACE_SECCOMP v9: - n/a v8: - guarded PTRACE_SECCOMP use with an ifdef v7: - introduced Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r--kernel/seccomp.c16
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 9c3830692a08..d9db6ec46bc9 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -24,6 +24,7 @@
24#ifdef CONFIG_SECCOMP_FILTER 24#ifdef CONFIG_SECCOMP_FILTER
25#include <asm/syscall.h> 25#include <asm/syscall.h>
26#include <linux/filter.h> 26#include <linux/filter.h>
27#include <linux/ptrace.h>
27#include <linux/security.h> 28#include <linux/security.h>
28#include <linux/slab.h> 29#include <linux/slab.h>
29#include <linux/tracehook.h> 30#include <linux/tracehook.h>
@@ -408,6 +409,21 @@ int __secure_computing(int this_syscall)
408 /* Let the filter pass back 16 bits of data. */ 409 /* Let the filter pass back 16 bits of data. */
409 seccomp_send_sigsys(this_syscall, data); 410 seccomp_send_sigsys(this_syscall, data);
410 goto skip; 411 goto skip;
412 case SECCOMP_RET_TRACE:
413 /* Skip these calls if there is no tracer. */
414 if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP))
415 goto skip;
416 /* Allow the BPF to provide the event message */
417 ptrace_event(PTRACE_EVENT_SECCOMP, data);
418 /*
419 * The delivery of a fatal signal during event
420 * notification may silently skip tracer notification.
421 * Terminating the task now avoids executing a system
422 * call that may not be intended.
423 */
424 if (fatal_signal_pending(current))
425 break;
426 return 0;
411 case SECCOMP_RET_ALLOW: 427 case SECCOMP_RET_ALLOW:
412 return 0; 428 return 0;
413 case SECCOMP_RET_KILL: 429 case SECCOMP_RET_KILL: