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| author | Andy Lutomirski <luto@amacapital.net> | 2012-10-01 20:40:45 +0200 |
|---|---|---|
| committer | James Morris <james.l.morris@oracle.com> | 2012-10-02 13:14:29 +0200 |
| commit | 87b526d349b04c31d7b3a40b434eb3f825d22305 (patch) | |
| tree | 2aeec0465901c9623ef7f5b3eb451ea6ccce6ecc /kernel | |
| parent | Merge tag 'v3.6-rc7' into next (diff) | |
| download | linux-87b526d349b04c31d7b3a40b434eb3f825d22305.tar.xz linux-87b526d349b04c31d7b3a40b434eb3f825d22305.zip | |
seccomp: Make syscall skipping and nr changes more consistent
This fixes two issues that could cause incompatibility between
kernel versions:
- If a tracer uses SECCOMP_RET_TRACE to select a syscall number
higher than the largest known syscall, emulate the unknown
vsyscall by returning -ENOSYS. (This is unlikely to make a
noticeable difference on x86-64 due to the way the system call
entry works.)
- On x86-64 with vsyscall=emulate, skipped vsyscalls were buggy.
This updates the documentation accordingly.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Acked-by: Will Drewry <wad@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/seccomp.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index ee376beedaf9..5af44b593770 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -396,25 +396,29 @@ int __secure_computing(int this_syscall) #ifdef CONFIG_SECCOMP_FILTER case SECCOMP_MODE_FILTER: { int data; + struct pt_regs *regs = task_pt_regs(current); ret = seccomp_run_filters(this_syscall); data = ret & SECCOMP_RET_DATA; ret &= SECCOMP_RET_ACTION; switch (ret) { case SECCOMP_RET_ERRNO: /* Set the low-order 16-bits as a errno. */ - syscall_set_return_value(current, task_pt_regs(current), + syscall_set_return_value(current, regs, -data, 0); goto skip; case SECCOMP_RET_TRAP: /* Show the handler the original registers. */ - syscall_rollback(current, task_pt_regs(current)); + syscall_rollback(current, regs); /* 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)) + if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) { + syscall_set_return_value(current, regs, + -ENOSYS, 0); goto skip; + } /* Allow the BPF to provide the event message */ ptrace_event(PTRACE_EVENT_SECCOMP, data); /* @@ -425,6 +429,9 @@ int __secure_computing(int this_syscall) */ if (fatal_signal_pending(current)) break; + if (syscall_get_nr(current, regs) < 0) + goto skip; /* Explicit request to skip. */ + return 0; case SECCOMP_RET_ALLOW: return 0; |