diff options
author | Will Drewry <wad@chromium.org> | 2012-02-09 12:08:39 -0600 |
---|---|---|
committer | John Rigby <john.rigby@linaro.org> | 2012-06-25 15:04:04 -0600 |
commit | f30e6e5a95389f12f3abcf5080dfe6c571804330 (patch) | |
tree | 67200f85ffe85df9d21bc2099bfb718e7d2f8992 | |
parent | db658622c6963776f1262224fb9c711db5fcc45b (diff) |
UBUNTU: SAUCE: SECCOMP: 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.
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: Will Drewry <wad@chromium.org>
Signed-off-by: Kees Cook <kees@ubuntu.com>
-rw-r--r-- | arch/Kconfig | 11 | ||||
-rw-r--r-- | include/linux/ptrace.h | 8 | ||||
-rw-r--r-- | include/linux/seccomp.h | 1 | ||||
-rw-r--r-- | kernel/ptrace.c | 3 | ||||
-rw-r--r-- | kernel/seccomp.c | 13 |
5 files changed, 28 insertions, 8 deletions
diff --git a/arch/Kconfig b/arch/Kconfig index d5f3869c475..ed5702dabbd 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -219,15 +219,16 @@ config ARCH_WANT_OLD_COMPAT_IPC config HAVE_ARCH_SECCOMP_FILTER bool help - This symbol should be selected by an architecure if it provides: - asm/syscall.h: + An arch should select this symbol if it provides all of these things: - syscall_get_arch() - syscall_get_arguments() - syscall_rollback() - syscall_set_return_value() - SIGSYS siginfo_t support must be implemented. - __secure_computing_int()/secure_computing()'s return value must be - checked, with -1 resulting in the syscall being skipped. + - SIGSYS siginfo_t support + - uses __secure_computing_int() or secure_computing() + - secure_computing is called from a ptrace_event()-safe context + - secure_computing return value is checked and a return value of -1 + results in the system call being skipped immediately. config SECCOMP_FILTER def_bool y diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h index 5c719627c2a..451c22f0e8d 100644 --- a/include/linux/ptrace.h +++ b/include/linux/ptrace.h @@ -58,6 +58,8 @@ #define PTRACE_EVENT_EXEC 4 #define PTRACE_EVENT_VFORK_DONE 5 #define PTRACE_EVENT_EXIT 6 +#define PTRACE_EVENT_SECCOMP 8 + /* Extended result codes which enabled by means other than options. */ #define PTRACE_EVENT_STOP 128 @@ -69,8 +71,9 @@ #define PTRACE_O_TRACEEXEC (1 << PTRACE_EVENT_EXEC) #define PTRACE_O_TRACEVFORKDONE (1 << PTRACE_EVENT_VFORK_DONE) #define PTRACE_O_TRACEEXIT (1 << PTRACE_EVENT_EXIT) +#define PTRACE_O_TRACESECCOMP 0x00000080 -#define PTRACE_O_MASK 0x0000007f +#define PTRACE_O_MASK 0x000000ff #include <asm/ptrace.h> @@ -98,6 +101,9 @@ #define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC) #define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE) #define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT) +#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP) + +#define PT_TRACE_MASK 0x00000bf4 /* single stepping state bits (used on ARM and PA-RISC) */ #define PT_SINGLESTEP_BIT 31 diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h index a5078fb30a8..306733ea821 100644 --- a/include/linux/seccomp.h +++ b/include/linux/seccomp.h @@ -21,6 +21,7 @@ #define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */ #define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */ #define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */ +#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */ #define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */ /* Masks for the return value sections. */ diff --git a/kernel/ptrace.c b/kernel/ptrace.c index ee8d49b9c30..a51f76bdcd1 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -535,6 +535,9 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data) flags |= (data << PT_OPT_FLAG_SHIFT); child->ptrace = flags; + if (data & PTRACE_O_TRACESECCOMP) + child->ptrace |= PT_TRACE_SECCOMP; + return 0; } diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 1a6146d9f75..e2b2cd8c75c 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -17,13 +17,13 @@ #include <linux/audit.h> #include <linux/compat.h> #include <linux/filter.h> +#include <linux/ptrace.h> #include <linux/sched.h> #include <linux/seccomp.h> #include <linux/security.h> #include <linux/slab.h> #include <linux/uaccess.h> -#include <linux/tracehook.h> #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER #include <asm/syscall.h> #endif @@ -400,7 +400,7 @@ int __secure_computing_int(int this_syscall) case SECCOMP_MODE_FILTER: ret = seccomp_run_filters(this_syscall); data = ret & SECCOMP_RET_DATA; - switch (code & SECCOMP_RET_ACTION) { + switch (ret & SECCOMP_RET_ACTION) { case SECCOMP_RET_ERRNO: /* Set the low-order 16-bits as a errno. */ syscall_set_return_value(current, task_pt_regs(current), @@ -412,6 +412,15 @@ int __secure_computing_int(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); + if (fatal_signal_pending(current)) + break; + return 0; case SECCOMP_RET_ALLOW: return 0; case SECCOMP_RET_KILL: |