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(RHEL-5991) Do not assign badness to filtered-out syscalls #399

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Jan 22, 2024
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(RHEL-5991) Do not assign badness to filtered-out syscalls #399

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785a8e9
analyze security: fix recursive call of syscall_names_in_filter()
yuwata Feb 1, 2019
af05507
analyze-security: do not assign badness to filtered-out syscalls
keszybz Aug 1, 2020
ec483af
analyze-security: include an actual syscall name in the message
keszybz Aug 1, 2020
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51 changes: 28 additions & 23 deletions src/analyze/analyze-security.c
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Original file line number Diff line number Diff line change
Expand Up @@ -476,35 +476,36 @@ static int assess_system_call_architectures(
return 0;
}

static bool syscall_names_in_filter(Set *s, bool whitelist, const SyscallFilterSet *f) {
static bool syscall_names_in_filter(Set *s, bool whitelist, const SyscallFilterSet *f, const char **ret_offending_syscall) {
const char *syscall;

NULSTR_FOREACH(syscall, f->value) {
bool b;
int id;

if (syscall[0] == '@') {
const SyscallFilterSet *g;
assert_se(g = syscall_filter_set_find(syscall));
b = syscall_names_in_filter(s, whitelist, g);
} else {
#if HAVE_SECCOMP
int id;

/* Let's see if the system call actually exists on this platform, before complaining */
id = seccomp_syscall_resolve_name(syscall);
if (id < 0)
continue;
#endif
assert_se(g = syscall_filter_set_find(syscall));
if (syscall_names_in_filter(s, whitelist, g, ret_offending_syscall))
return true; /* bad! */

b = set_contains(s, syscall);
continue;
}

if (whitelist == b) {
/* Let's see if the system call actually exists on this platform, before complaining */
id = seccomp_syscall_resolve_name(syscall);
if (id < 0)
continue;

if (set_contains(s, syscall) == whitelist) {
log_debug("Offending syscall filter item: %s", syscall);
if (ret_offending_syscall)
*ret_offending_syscall = syscall;
return true; /* bad! */
}
}

*ret_offending_syscall = NULL;
return false;
}

Expand All @@ -515,43 +516,47 @@ static int assess_system_call_filter(
uint64_t *ret_badness,
char **ret_description) {

const SyscallFilterSet *f;
char *d = NULL;
uint64_t b;

assert(a);
assert(info);
assert(ret_badness);
assert(ret_description);

assert(a->parameter < _SYSCALL_FILTER_SET_MAX);
f = syscall_filter_sets + a->parameter;
const SyscallFilterSet *f = syscall_filter_sets + a->parameter;

char *d = NULL;
uint64_t b;

if (!info->system_call_filter_whitelist && set_isempty(info->system_call_filter)) {
d = strdup("Service does not filter system calls");
b = 10;
} else {
bool bad;
const char *offender = NULL;

log_debug("Analyzing system call filter, checking against: %s", f->name);
bad = syscall_names_in_filter(info->system_call_filter, info->system_call_filter_whitelist, f);
bad = syscall_names_in_filter(info->system_call_filter, info->system_call_filter_whitelist, f, &offender);
log_debug("Result: %s", bad ? "bad" : "good");

if (info->system_call_filter_whitelist) {
if (bad) {
(void) asprintf(&d, "System call whitelist defined for service, and %s is included", f->name);
(void) asprintf(&d, "System call whitelist defined for service, and %s is included "
"(e.g. %s is allowed)",
f->name, offender);
b = 9;
} else {
(void) asprintf(&d, "System call whitelist defined for service, and %s is not included", f->name);
b = 0;
}
} else {
if (bad) {
(void) asprintf(&d, "System call blacklist defined for service, and %s is not included", f->name);
(void) asprintf(&d, "System call blacklist defined for service, and %s is not included "
"(e.g. %s is allowed)",
f->name, offender);
b = 10;
} else {
(void) asprintf(&d, "System call blacklist defined for service, and %s is included", f->name);
b = 5;
b = 0;
}
}
}
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