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authorEric W. Biederman <ebiederm@xmission.com>2021-06-23 16:44:32 -0500
committerEric W. Biederman <ebiederm@xmission.com>2021-08-26 10:30:12 -0500
commit307d522f5eb86cd6ac8c905f5b0577dedac54ec5 (patch)
tree826a8de8128133767b650120882b4edea7ee728b /kernel/signal.c
parenta3616a3c02722d1edb95acc7fceade242f6553ba (diff)
signal/seccomp: Refactor seccomp signal and coredump generation
Factor out force_sig_seccomp from the seccomp signal generation and place it in kernel/signal.c. The function force_sig_seccomp takes a parameter force_coredump to indicate that the sigaction field should be reset to SIGDFL so that a coredump will be generated when the signal is delivered. force_sig_seccomp is then used to replace both seccomp_send_sigsys and seccomp_init_siginfo. force_sig_info_to_task gains an extra parameter to force using the default signal action. With this change seccomp is no longer a special case and there becomes exactly one place do_coredump is called from. Further it no longer becomes necessary for __seccomp_filter to call do_group_exit. Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/87r1gr6qc4.fsf_-_@disp2133 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c30
1 files changed, 26 insertions, 4 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index a3229add4455..fbf941b80dd4 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -54,6 +54,7 @@
#include <asm/unistd.h>
#include <asm/siginfo.h>
#include <asm/cacheflush.h>
+#include <asm/syscall.h> /* for syscall_get_* */
/*
* SLAB caches for signal bits.
@@ -1322,7 +1323,7 @@ int do_send_sig_info(int sig, struct kernel_siginfo *info, struct task_struct *p
* that is why we also clear SIGNAL_UNKILLABLE.
*/
static int
-force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
+force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t, bool sigdfl)
{
unsigned long int flags;
int ret, blocked, ignored;
@@ -1333,7 +1334,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
action = &t->sighand->action[sig-1];
ignored = action->sa.sa_handler == SIG_IGN;
blocked = sigismember(&t->blocked, sig);
- if (blocked || ignored) {
+ if (blocked || ignored || sigdfl) {
action->sa.sa_handler = SIG_DFL;
if (blocked) {
sigdelset(&t->blocked, sig);
@@ -1354,7 +1355,7 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t)
int force_sig_info(struct kernel_siginfo *info)
{
- return force_sig_info_to_task(info, current);
+ return force_sig_info_to_task(info, current, false);
}
/*
@@ -1685,7 +1686,7 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr
info.si_flags = flags;
info.si_isr = isr;
#endif
- return force_sig_info_to_task(&info, t);
+ return force_sig_info_to_task(&info, t, false);
}
int force_sig_fault(int sig, int code, void __user *addr
@@ -1793,6 +1794,27 @@ int force_sig_perf(void __user *addr, u32 type, u64 sig_data)
return force_sig_info(&info);
}
+/**
+ * force_sig_seccomp - 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.
+ */
+int force_sig_seccomp(int syscall, int reason, bool force_coredump)
+{
+ struct kernel_siginfo info;
+
+ clear_siginfo(&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);
+ info.si_syscall = syscall;
+ return force_sig_info_to_task(&info, current, force_coredump);
+}
+
/* For the crazy architectures that include trap information in
* the errno field, instead of an actual errno value.
*/

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