Make sure that file context (all parts) and ownership of
files/directories in policy store does not change no matter which user
and under which context executes policy rebuild.
Fixes:
# semodule -B
# ls -lZ /etc/selinux/targeted/contexts/files
-rw-r--r--. 1 root root unconfined_u:object_r:file_context_t:s0 421397 Jul 11 09:57 file_contexts
-rw-r--r--. 1 root root unconfined_u:object_r:file_context_t:s0 593470 Jul 11 09:57 file_contexts.bin
-rw-r--r--. 1 root root unconfined_u:object_r:file_context_t:s0 14704 Jul 11 09:57 file_contexts.homedirs
-rw-r--r--. 1 root root unconfined_u:object_r:file_context_t:s0 20289 Jul 11 09:57 file_contexts.homedirs.bin
SELinux user changed from system_u to the user used to execute semodule
# capsh --user=testuser --caps="cap_dac_override,cap_chown+eip" --addamb=cap_dac_override,cap_chown -- -c "semodule -B"
# ls -lZ /etc/selinux/targeted/contexts/files
-rw-r--r--. 1 testuser testuser unconfined_u:object_r:file_context_t:s0 421397 Jul 19 09:10 file_contexts
-rw-r--r--. 1 testuser testuser unconfined_u:object_r:file_context_t:s0 593470 Jul 19 09:10 file_contexts.bin
-rw-r--r--. 1 testuser testuser unconfined_u:object_r:file_context_t:s0 14704 Jul 19 09:10 file_contexts.homedirs
-rw-r--r--. 1 testuser testuser unconfined_u:object_r:file_context_t:s0 20289 Jul 19 09:10 file_contexts.homedirs.bin
Both file context and ownership changed -- causes remote login
failures and other issues in some scenarios.
Signed-off-by: Vit Mojzis <vmojzis@xxxxxxxxxx>
---
Changes in V5:
- Check return value of fchown and warn user if it fails
Should I start creating github pull requests for each patch to catch this
type of issue in the future (so that I don't waste your time)?
libsemanage/src/semanage_store.c | 32 ++++++++++++++++++++++++++++++++
libsemanage/src/semanage_store.h | 1 +
2 files changed, 33 insertions(+)
diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c
index 27c5d349..0ac2e5b2 100644
--- a/libsemanage/src/semanage_store.c
+++ b/libsemanage/src/semanage_store.c
@@ -36,6 +36,7 @@ typedef struct dbase_policydb dbase_t;
#include "database_policydb.h"
#include "handle.h"
+#include <selinux/restorecon.h>
#include <selinux/selinux.h>
#include <sepol/policydb.h>
#include <sepol/module.h>
@@ -767,6 +768,7 @@ int semanage_copy_file(const char *src, const char *dst, mode_t mode,
if (!retval && rename(tmp, dst) == -1)
return -1;
+ semanage_setfiles(dst);
out:
errno = errsv;
return retval;
@@ -819,6 +821,8 @@ static int semanage_copy_dir_flags(const char *src, const char *dst, int flag)
goto cleanup;
}
umask(mask);
+
+ semanage_setfiles(dst);
}
for (i = 0; i < len; i++) {
@@ -837,6 +841,7 @@ static int semanage_copy_dir_flags(const char *src, const char *dst, int flag)
goto cleanup;
}
umask(mask);
+ semanage_setfiles(path2);
} else if (S_ISREG(sb.st_mode) && flag == 1) {
mask = umask(0077);
if (semanage_copy_file(path, path2, sb.st_mode,
@@ -938,6 +943,7 @@ int semanage_mkdir(semanage_handle_t *sh, const char *path)
}
umask(mask);
+ semanage_setfiles(path);
}
else {
/* check that it really is a directory */
@@ -1614,16 +1620,19 @@ static int semanage_validate_and_compile_fcontexts(semanage_handle_t * sh)
semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC)) != 0) {
goto cleanup;
}
+ semanage_setfiles(semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_BIN));
if (sefcontext_compile(sh,
semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL)) != 0) {
goto cleanup;
}
+ semanage_setfiles(semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_LOCAL_BIN));
if (sefcontext_compile(sh,
semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_HOMEDIRS)) != 0) {
goto cleanup;
}
+ semanage_setfiles(semanage_final_path(SEMANAGE_FINAL_TMP, SEMANAGE_FC_HOMEDIRS_BIN));
status = 0;
cleanup:
@@ -3018,3 +3027,26 @@ int semanage_nc_sort(semanage_handle_t * sh, const char *buf, size_t buf_len,
return 0;
}
+
+/* Make sure the file context and ownership of files in the policy
+ * store does not change */
+void semanage_setfiles(const char *path){
+ struct stat sb;
+ int fd;
+ /* Fix the user and role portions of the context, ignore errors
+ * since this is not a critical operation */
+ selinux_restorecon(path, SELINUX_RESTORECON_SET_SPECFILE_CTX | SELINUX_RESTORECON_IGNORE_NOENTRY);
+
+ /* Make sure "path" is owned by root */
+ if ((geteuid() != 0 || getegid() != 0) &&
+ ((fd = open(path, O_RDONLY)) != -1)){
+ /* Skip files with the SUID or SGID bit set -- abuse protection */
+ if ((fstat(fd, &sb) != -1) &&
+ !(S_ISREG(sb.st_mode) &&
+ (sb.st_mode & (S_ISUID | S_ISGID))) &&
+ (fchown(fd, 0, 0) == -1))
+ fprintf(stderr, "Warning! Could not set ownership of %s to root\n", path);
+
+ close(fd);
+ }
+}
diff --git a/libsemanage/src/semanage_store.h b/libsemanage/src/semanage_store.h
index 1fc77da8..e21dadeb 100644
--- a/libsemanage/src/semanage_store.h
+++ b/libsemanage/src/semanage_store.h
@@ -124,6 +124,7 @@ int semanage_get_cil_paths(semanage_handle_t * sh, semanage_module_info_t *modin
int semanage_get_active_modules(semanage_handle_t *sh,
semanage_module_info_t **modinfo, int *num_modules);
+void semanage_setfiles(const char *path);
/* lock file routines */
int semanage_get_trans_lock(semanage_handle_t * sh);
--
2.43.0
