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authorWill Drewry <wad@chromium.org>2012-04-12 16:48:01 -0500
committerJames Morris <james.l.morris@oracle.com>2012-04-14 11:13:21 +1000
commitbb6ea4301a1109afdacaee576fedbfcd7152fc86 (patch)
tree5412219057d8e0ec2a30d0a1ad4f6b7dd398c754 /kernel/seccomp.c
parenta0727e8ce513fe6890416da960181ceb10fbfae6 (diff)
seccomp: Add SECCOMP_RET_TRAP
Adds a new return value to seccomp filters that triggers a SIGSYS to be delivered with the new SYS_SECCOMP si_code. This allows in-process system call emulation, including just specifying an errno or cleanly dumping core, rather than just dying. Suggested-by: Markus Gutschke <markus@chromium.org> Suggested-by: Julien Tinnes <jln@chromium.org> Signed-off-by: Will Drewry <wad@chromium.org> Acked-by: Eric Paris <eparis@redhat.com> v18: - acked-by, rebase - don't mention secure_computing_int() anymore v15: - use audit_seccomp/skip - pad out error spacing; clean up switch (indan@nul.nu) v14: - n/a v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc v12: - rebase on to linux-next v11: - clarify the comment (indan@nul.nu) - s/sigtrap/sigsys v10: - use SIGSYS, syscall_get_arch, updates arch/Kconfig note suggested-by (though original suggestion had other behaviors) v9: - changes to SIGILL v8: - clean up based on changes to dependent patches v7: - introduction Signed-off-by: James Morris <james.l.morris@oracle.com>
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r--kernel/seccomp.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 5f78fb6d221..9c3830692a0 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -332,6 +332,26 @@ void put_seccomp_filter(struct task_struct *tsk)
kfree(freeme);
}
}
+
+/**
+ * seccomp_send_sigsys - signals the task to allow in-process syscall emulation
+ * @syscall: syscall number to send to userland
+ * @reason: filter-supplied reason code to send to userland (via si_errno)
+ *
+ * Forces a SIGSYS with a code of SYS_SECCOMP and related sigsys info.
+ */
+static void seccomp_send_sigsys(int syscall, int reason)
+{
+ struct siginfo info;
+ memset(&info, 0, sizeof(info));
+ info.si_signo = SIGSYS;
+ info.si_code = SYS_SECCOMP;
+ info.si_call_addr = (void __user *)KSTK_EIP(current);
+ info.si_errno = reason;
+ info.si_arch = syscall_get_arch(current, task_pt_regs(current));
+ info.si_syscall = syscall;
+ force_sig_info(SIGSYS, &info, current);
+}
#endif /* CONFIG_SECCOMP_FILTER */
/*
@@ -382,6 +402,12 @@ int __secure_computing(int this_syscall)
syscall_set_return_value(current, task_pt_regs(current),
-data, 0);
goto skip;
+ case SECCOMP_RET_TRAP:
+ /* Show the handler the original registers. */
+ syscall_rollback(current, task_pt_regs(current));
+ /* Let the filter pass back 16 bits of data. */
+ seccomp_send_sigsys(this_syscall, data);
+ goto skip;
case SECCOMP_RET_ALLOW:
return 0;
case SECCOMP_RET_KILL: