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| author | Will Drewry <wad@chromium.org> | 2012-04-12 16:48:02 -0500 |
|---|---|---|
| committer | James Morris <james.l.morris@oracle.com> | 2012-04-14 11:13:21 +1000 |
| commit | fb0fadf9b213f55ca9368f3edafe51101d5d2deb (patch) | |
| tree | e3e999f0b44a7b4a08b208ae222f509917fc675b /kernel | |
| parent | bb6ea4301a1109afdacaee576fedbfcd7152fc86 (diff) | |
| download | linux-fb0fadf9b213f55ca9368f3edafe51101d5d2deb.tar.bz2 | |
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')
| -rw-r--r-- | kernel/seccomp.c | 16 |
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 @@ #ifdef CONFIG_SECCOMP_FILTER #include <asm/syscall.h> #include <linux/filter.h> +#include <linux/ptrace.h> #include <linux/security.h> #include <linux/slab.h> #include <linux/tracehook.h> @@ -408,6 +409,21 @@ int __secure_computing(int this_syscall) /* Let the filter pass back 16 bits of data. */ seccomp_send_sigsys(this_syscall, data); goto skip; + case SECCOMP_RET_TRACE: + /* Skip these calls if there is no tracer. */ + if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) + goto skip; + /* Allow the BPF to provide the event message */ + ptrace_event(PTRACE_EVENT_SECCOMP, data); + /* + * The delivery of a fatal signal during event + * notification may silently skip tracer notification. + * Terminating the task now avoids executing a system + * call that may not be intended. + */ + if (fatal_signal_pending(current)) + break; + return 0; case SECCOMP_RET_ALLOW: return 0; case SECCOMP_RET_KILL: |