diff options
Diffstat (limited to 'src/libbasic/selinux-util.c')
| -rw-r--r-- | src/libbasic/selinux-util.c | 493 |
1 files changed, 493 insertions, 0 deletions
diff --git a/src/libbasic/selinux-util.c b/src/libbasic/selinux-util.c new file mode 100644 index 0000000000..6c63b9d652 --- /dev/null +++ b/src/libbasic/selinux-util.c @@ -0,0 +1,493 @@ +/*** + This file is part of systemd. + + Copyright 2010 Lennart Poettering + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see <http://www.gnu.org/licenses/>. +***/ + +#include <errno.h> +#include <malloc.h> +#include <stddef.h> +#include <string.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/un.h> +#include <syslog.h> + +#ifdef HAVE_SELINUX +#include <selinux/context.h> +#include <selinux/label.h> +#include <selinux/selinux.h> +#endif + +#include "alloc-util.h" +#include "log.h" +#include "macro.h" +#include "path-util.h" +#include "selinux-util.h" +#include "time-util.h" +#include "util.h" + +#ifdef HAVE_SELINUX +DEFINE_TRIVIAL_CLEANUP_FUNC(security_context_t, freecon); +DEFINE_TRIVIAL_CLEANUP_FUNC(context_t, context_free); + +#define _cleanup_security_context_free_ _cleanup_(freeconp) +#define _cleanup_context_free_ _cleanup_(context_freep) + +static int cached_use = -1; +static struct selabel_handle *label_hnd = NULL; + +#define log_enforcing(...) log_full(security_getenforce() == 1 ? LOG_ERR : LOG_DEBUG, __VA_ARGS__) +#endif + +bool mac_selinux_have(void) { +#ifdef HAVE_SELINUX + if (cached_use < 0) + cached_use = is_selinux_enabled() > 0; + + return cached_use; +#else + return false; +#endif +} + +bool mac_selinux_use(void) { + if (!mac_selinux_have()) + return false; + + /* Never try to configure SELinux features if we aren't + * root */ + + return getuid() == 0; +} + +void mac_selinux_retest(void) { +#ifdef HAVE_SELINUX + cached_use = -1; +#endif +} + +int mac_selinux_init(const char *prefix) { + int r = 0; + +#ifdef HAVE_SELINUX + usec_t before_timestamp, after_timestamp; + struct mallinfo before_mallinfo, after_mallinfo; + + if (!mac_selinux_use()) + return 0; + + if (label_hnd) + return 0; + + before_mallinfo = mallinfo(); + before_timestamp = now(CLOCK_MONOTONIC); + + if (prefix) { + struct selinux_opt options[] = { + { .type = SELABEL_OPT_SUBSET, .value = prefix }, + }; + + label_hnd = selabel_open(SELABEL_CTX_FILE, options, ELEMENTSOF(options)); + } else + label_hnd = selabel_open(SELABEL_CTX_FILE, NULL, 0); + + if (!label_hnd) { + log_enforcing("Failed to initialize SELinux context: %m"); + r = security_getenforce() == 1 ? -errno : 0; + } else { + char timespan[FORMAT_TIMESPAN_MAX]; + int l; + + after_timestamp = now(CLOCK_MONOTONIC); + after_mallinfo = mallinfo(); + + l = after_mallinfo.uordblks > before_mallinfo.uordblks ? after_mallinfo.uordblks - before_mallinfo.uordblks : 0; + + log_debug("Successfully loaded SELinux database in %s, size on heap is %iK.", + format_timespan(timespan, sizeof(timespan), after_timestamp - before_timestamp, 0), + (l+1023)/1024); + } +#endif + + return r; +} + +void mac_selinux_finish(void) { + +#ifdef HAVE_SELINUX + if (!label_hnd) + return; + + selabel_close(label_hnd); + label_hnd = NULL; +#endif +} + +int mac_selinux_fix(const char *path, bool ignore_enoent, bool ignore_erofs) { + +#ifdef HAVE_SELINUX + struct stat st; + int r; + + assert(path); + + /* if mac_selinux_init() wasn't called before we are a NOOP */ + if (!label_hnd) + return 0; + + r = lstat(path, &st); + if (r >= 0) { + _cleanup_security_context_free_ security_context_t fcon = NULL; + + r = selabel_lookup_raw(label_hnd, &fcon, path, st.st_mode); + + /* If there's no label to set, then exit without warning */ + if (r < 0 && errno == ENOENT) + return 0; + + if (r >= 0) { + r = lsetfilecon(path, fcon); + + /* If the FS doesn't support labels, then exit without warning */ + if (r < 0 && errno == EOPNOTSUPP) + return 0; + } + } + + if (r < 0) { + /* Ignore ENOENT in some cases */ + if (ignore_enoent && errno == ENOENT) + return 0; + + if (ignore_erofs && errno == EROFS) + return 0; + + log_enforcing("Unable to fix SELinux security context of %s: %m", path); + if (security_getenforce() == 1) + return -errno; + } +#endif + + return 0; +} + +int mac_selinux_apply(const char *path, const char *label) { + +#ifdef HAVE_SELINUX + if (!mac_selinux_use()) + return 0; + + assert(path); + assert(label); + + if (setfilecon(path, (security_context_t) label) < 0) { + log_enforcing("Failed to set SELinux security context %s on path %s: %m", label, path); + if (security_getenforce() > 0) + return -errno; + } +#endif + return 0; +} + +int mac_selinux_get_create_label_from_exe(const char *exe, char **label) { + int r = -EOPNOTSUPP; + +#ifdef HAVE_SELINUX + _cleanup_security_context_free_ security_context_t mycon = NULL, fcon = NULL; + security_class_t sclass; + + assert(exe); + assert(label); + + if (!mac_selinux_have()) + return -EOPNOTSUPP; + + r = getcon_raw(&mycon); + if (r < 0) + return -errno; + + r = getfilecon_raw(exe, &fcon); + if (r < 0) + return -errno; + + sclass = string_to_security_class("process"); + r = security_compute_create(mycon, fcon, sclass, (security_context_t *) label); + if (r < 0) + return -errno; +#endif + + return r; +} + +int mac_selinux_get_our_label(char **label) { + int r = -EOPNOTSUPP; + + assert(label); + +#ifdef HAVE_SELINUX + if (!mac_selinux_have()) + return -EOPNOTSUPP; + + r = getcon_raw(label); + if (r < 0) + return -errno; +#endif + + return r; +} + +int mac_selinux_get_child_mls_label(int socket_fd, const char *exe, const char *exec_label, char **label) { + int r = -EOPNOTSUPP; + +#ifdef HAVE_SELINUX + _cleanup_security_context_free_ security_context_t mycon = NULL, peercon = NULL, fcon = NULL; + _cleanup_context_free_ context_t pcon = NULL, bcon = NULL; + security_class_t sclass; + const char *range = NULL; + + assert(socket_fd >= 0); + assert(exe); + assert(label); + + if (!mac_selinux_have()) + return -EOPNOTSUPP; + + r = getcon_raw(&mycon); + if (r < 0) + return -errno; + + r = getpeercon(socket_fd, &peercon); + if (r < 0) + return -errno; + + if (!exec_label) { + /* If there is no context set for next exec let's use context + of target executable */ + r = getfilecon_raw(exe, &fcon); + if (r < 0) + return -errno; + } + + bcon = context_new(mycon); + if (!bcon) + return -ENOMEM; + + pcon = context_new(peercon); + if (!pcon) + return -ENOMEM; + + range = context_range_get(pcon); + if (!range) + return -errno; + + r = context_range_set(bcon, range); + if (r) + return -errno; + + freecon(mycon); + mycon = strdup(context_str(bcon)); + if (!mycon) + return -ENOMEM; + + sclass = string_to_security_class("process"); + r = security_compute_create(mycon, fcon, sclass, (security_context_t *) label); + if (r < 0) + return -errno; +#endif + + return r; +} + +char* mac_selinux_free(char *label) { + +#ifdef HAVE_SELINUX + if (!label) + return NULL; + + if (!mac_selinux_have()) + return NULL; + + + freecon((security_context_t) label); +#endif + + return NULL; +} + +int mac_selinux_create_file_prepare(const char *path, mode_t mode) { + +#ifdef HAVE_SELINUX + _cleanup_security_context_free_ security_context_t filecon = NULL; + int r; + + assert(path); + + if (!label_hnd) + return 0; + + if (path_is_absolute(path)) + r = selabel_lookup_raw(label_hnd, &filecon, path, mode); + else { + _cleanup_free_ char *newpath = NULL; + + r = path_make_absolute_cwd(path, &newpath); + if (r < 0) + return r; + + r = selabel_lookup_raw(label_hnd, &filecon, newpath, mode); + } + + if (r < 0) { + /* No context specified by the policy? Proceed without setting it. */ + if (errno == ENOENT) + return 0; + + log_enforcing("Failed to determine SELinux security context for %s: %m", path); + } else { + if (setfscreatecon(filecon) >= 0) + return 0; /* Success! */ + + log_enforcing("Failed to set SELinux security context %s for %s: %m", filecon, path); + } + + if (security_getenforce() > 0) + return -errno; + +#endif + return 0; +} + +void mac_selinux_create_file_clear(void) { + +#ifdef HAVE_SELINUX + PROTECT_ERRNO; + + if (!mac_selinux_use()) + return; + + setfscreatecon(NULL); +#endif +} + +int mac_selinux_create_socket_prepare(const char *label) { + +#ifdef HAVE_SELINUX + if (!mac_selinux_use()) + return 0; + + assert(label); + + if (setsockcreatecon((security_context_t) label) < 0) { + log_enforcing("Failed to set SELinux security context %s for sockets: %m", label); + + if (security_getenforce() == 1) + return -errno; + } +#endif + + return 0; +} + +void mac_selinux_create_socket_clear(void) { + +#ifdef HAVE_SELINUX + PROTECT_ERRNO; + + if (!mac_selinux_use()) + return; + + setsockcreatecon(NULL); +#endif +} + +int mac_selinux_bind(int fd, const struct sockaddr *addr, socklen_t addrlen) { + + /* Binds a socket and label its file system object according to the SELinux policy */ + +#ifdef HAVE_SELINUX + _cleanup_security_context_free_ security_context_t fcon = NULL; + const struct sockaddr_un *un; + bool context_changed = false; + char *path; + int r; + + assert(fd >= 0); + assert(addr); + assert(addrlen >= sizeof(sa_family_t)); + + if (!label_hnd) + goto skipped; + + /* Filter out non-local sockets */ + if (addr->sa_family != AF_UNIX) + goto skipped; + + /* Filter out anonymous sockets */ + if (addrlen < offsetof(struct sockaddr_un, sun_path) + 1) + goto skipped; + + /* Filter out abstract namespace sockets */ + un = (const struct sockaddr_un*) addr; + if (un->sun_path[0] == 0) + goto skipped; + + path = strndupa(un->sun_path, addrlen - offsetof(struct sockaddr_un, sun_path)); + + if (path_is_absolute(path)) + r = selabel_lookup_raw(label_hnd, &fcon, path, S_IFSOCK); + else { + _cleanup_free_ char *newpath = NULL; + + r = path_make_absolute_cwd(path, &newpath); + if (r < 0) + return r; + + r = selabel_lookup_raw(label_hnd, &fcon, newpath, S_IFSOCK); + } + + if (r < 0) { + /* No context specified by the policy? Proceed without setting it */ + if (errno == ENOENT) + goto skipped; + + log_enforcing("Failed to determine SELinux security context for %s: %m", path); + if (security_getenforce() > 0) + return -errno; + + } else { + if (setfscreatecon(fcon) < 0) { + log_enforcing("Failed to set SELinux security context %s for %s: %m", fcon, path); + if (security_getenforce() > 0) + return -errno; + } else + context_changed = true; + } + + r = bind(fd, addr, addrlen) < 0 ? -errno : 0; + + if (context_changed) + setfscreatecon(NULL); + + return r; + +skipped: +#endif + if (bind(fd, addr, addrlen) < 0) + return -errno; + + return 0; +} |