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samples/seccomp: Adjust sample to also provide kill option

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As a quick way to test SECCOMP_RET_KILL, have a negative errno mean to
kill the process.

While we're in here, also swap the arch and syscall arguments so they're
ordered more like how seccomp filters order them.

Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Kees Cook 2022-02-07 20:53:34 -08:00
parent 495ac3069a
commit eed09ad261
1 changed files with 7 additions and 2 deletions
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9
samples/seccomp/dropper.c
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@ -25,7 +25,7 @@
#include <sys/prctl.h>
#include <unistd.h>
static int install_filter(int nr, int arch, int error)
static int install_filter(int arch, int nr, int error)
{
struct sock_filter filter[] = {
BPF_STMT(BPF_LD+BPF_W+BPF_ABS,
@ -42,6 +42,10 @@ static int install_filter(int nr, int arch, int error)
.len = (unsigned short)(sizeof(filter)/sizeof(filter[0])),
.filter = filter,
};
if (error == -1) {
struct sock_filter kill = BPF_STMT(BPF_RET+BPF_K, SECCOMP_RET_KILL);
filter[4] = kill;
}
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
perror("prctl(NO_NEW_PRIVS)");
return 1;
@ -57,9 +61,10 @@ int main(int argc, char **argv)
{
if (argc < 5) {
fprintf(stderr, "Usage:\n"
"dropper <syscall_nr> <arch> <errno> <prog> [<args>]\n"
"dropper <arch> <syscall_nr> <errno> <prog> [<args>]\n"
"Hint: AUDIT_ARCH_I386: 0x%X\n"
" AUDIT_ARCH_X86_64: 0x%X\n"
" errno == -1 means SECCOMP_RET_KILL\n"
"\n", AUDIT_ARCH_I386, AUDIT_ARCH_X86_64);
return 1;
}