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selinux: cache enforced status and treat retrieve failure as enforced mode

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This commit is contained in:
Christian Göttsche 2020-03-02 21:12:18 +01:00
parent 61f3e897f1
commit 257188f80c
3 changed files with 42 additions and 17 deletions
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45
src/basic/selinux-util.c
View file

@ -35,10 +35,11 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free);
static int mac_selinux_reload(int seqno);
static int cached_use = -1;
static int cached_enforcing = -1;
static struct selabel_handle *label_hnd = NULL;
#define log_enforcing(...) log_full(security_getenforce() == 1 ? LOG_ERR : LOG_WARNING, __VA_ARGS__)
#define log_enforcing_errno(r, ...) log_full_errno(security_getenforce() == 1 ? LOG_ERR : LOG_WARNING, r, __VA_ARGS__)
#define log_enforcing(...) log_full(mac_selinux_enforcing() ? LOG_ERR : LOG_WARNING, __VA_ARGS__)
#define log_enforcing_errno(r, ...) log_full_errno(mac_selinux_enforcing() ? LOG_ERR : LOG_WARNING, r, __VA_ARGS__)
#endif
bool mac_selinux_use(void) {
@ -52,12 +53,37 @@ bool mac_selinux_use(void) {
#endif
}
bool mac_selinux_enforcing(void) {
#if HAVE_SELINUX
if (cached_enforcing < 0) {
cached_enforcing = security_getenforce();
if (cached_enforcing == -1) {
log_error_errno(errno, "Failed to get SELinux enforced status: %m");
}
}
/* treat failure as enforced mode */
return (cached_enforcing != 0);
#else
return false;
#endif
}
void mac_selinux_retest(void) {
#if HAVE_SELINUX
cached_use = -1;
cached_enforcing = -1;
#endif
}
#if HAVE_SELINUX
static int setenforce_callback(int enforcing) {
cached_enforcing = enforcing;
return 0;
}
#endif
int mac_selinux_init(void) {
int r = 0;
@ -66,6 +92,7 @@ int mac_selinux_init(void) {
struct mallinfo before_mallinfo, after_mallinfo;
selinux_set_callback(SELINUX_CB_POLICYLOAD, (union selinux_callback) mac_selinux_reload);
selinux_set_callback(SELINUX_CB_SETENFORCE, (union selinux_callback) setenforce_callback);
if (label_hnd)
return 0;
@ -79,7 +106,7 @@ int mac_selinux_init(void) {
label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0);
if (!label_hnd) {
log_enforcing_errno(errno, "Failed to initialize SELinux context: %m");
r = security_getenforce() == 1 ? -errno : 0;
r = mac_selinux_enforcing() ? -errno : 0;
} else {
char timespan[FORMAT_TIMESPAN_MAX];
int l;
@ -195,7 +222,7 @@ int mac_selinux_fix(const char *path, LabelFixFlags flags) {
fail:
log_enforcing_errno(r, "Unable to fix SELinux security context of %s: %m", path);
if (security_getenforce() == 1)
if (mac_selinux_enforcing())
return r;
#endif
@ -213,7 +240,7 @@ int mac_selinux_apply(const char *path, const char *label) {
if (setfilecon(path, label) < 0) {
log_enforcing_errno(errno, "Failed to set SELinux security context %s on path %s: %m", label, path);
if (security_getenforce() > 0)
if (mac_selinux_enforcing())
return -errno;
}
#endif
@ -375,7 +402,7 @@ static int selinux_create_file_prepare_abspath(const char *abspath, mode_t mode)
log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", filecon, abspath);
}
if (security_getenforce() > 0)
if (mac_selinux_enforcing())
return -errno;
return 0;
@ -456,7 +483,7 @@ int mac_selinux_create_socket_prepare(const char *label) {
if (setsockcreatecon(label) < 0) {
log_enforcing_errno(errno, "Failed to set SELinux security context %s for sockets: %m", label);
if (security_getenforce() == 1)
if (mac_selinux_enforcing())
return -errno;
}
#endif
@ -530,13 +557,13 @@ int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) {
goto skipped;
log_enforcing_errno(errno, "Failed to determine SELinux security context for %s: %m", path);
if (security_getenforce() > 0)
if (mac_selinux_enforcing())
return -errno;
} else {
if (setfscreatecon_raw(fcon) < 0) {
log_enforcing_errno(errno, "Failed to set SELinux security context %s for %s: %m", fcon, path);
if (security_getenforce() > 0)
if (mac_selinux_enforcing())
return -errno;
} else
context_changed = true;

1
src/basic/selinux-util.h
View file

@ -16,6 +16,7 @@ DEFINE_TRIVIAL_CLEANUP_FUNC(char*, freecon);
#endif
bool mac_selinux_use(void);
bool mac_selinux_enforcing(void);
void mac_selinux_retest(void);
int mac_selinux_init(void);

13
src/core/selinux-access.c
View file

@ -143,16 +143,16 @@ static int access_init(sd_bus_error *error) {
return 1;
if (avc_open(NULL, 0) != 0) {
int enforce, saved_errno = errno;
int saved_errno = errno;
const bool enforce = mac_selinux_enforcing();
enforce = security_getenforce();
log_full_errno(enforce != 0 ? LOG_ERR : LOG_WARNING, saved_errno, "Failed to open the SELinux AVC: %m");
log_full_errno(enforce ? LOG_ERR : LOG_WARNING, saved_errno, "Failed to open the SELinux AVC: %m");
/* If enforcement isn't on, then let's suppress this
* error, and just don't do any AVC checks. The
* warning we printed is hence all the admin will
* see. */
if (enforce == 0)
if (!enforce)
return 0;
/* Return an access denied error, if we couldn't load
@ -185,7 +185,7 @@ int mac_selinux_generic_access_check(
_cleanup_free_ char *cl = NULL;
_cleanup_freecon_ char *fcon = NULL;
char **cmdline = NULL;
bool enforce = false; /* Will be set to the real value later if needed */
const bool enforce = mac_selinux_enforcing();
int r = 0;
assert(message);
@ -223,7 +223,6 @@ int mac_selinux_generic_access_check(
if (getfilecon_raw(path, &fcon) < 0) {
r = -errno;
enforce = security_getenforce() > 0;
log_warning_errno(r, "SELinux getfilecon_raw on '%s' failed%s (perm=%s): %m",
path,
@ -240,7 +239,6 @@ int mac_selinux_generic_access_check(
} else {
if (getcon_raw(&fcon) < 0) {
r = -errno;
enforce = security_getenforce() > 0;
log_warning_errno(r, "SELinux getcon_raw failed%s (perm=%s): %m",
enforce ? "" : ", ignoring",
@ -266,7 +264,6 @@ int mac_selinux_generic_access_check(
r = selinux_check_access(scon, fcon, tclass, permission, &audit_info);
if (r < 0) {
r = errno_or_else(EPERM);
enforce = security_getenforce() > 0;
if (enforce)
sd_bus_error_setf(error, SD_BUS_ERROR_ACCESS_DENIED, "SELinux policy denies access.");