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-rw-r--r--src/shared/acl-util.c597
1 files changed, 597 insertions, 0 deletions
diff --git a/src/shared/acl-util.c b/src/shared/acl-util.c
new file mode 100644
index 0000000..c9752ab
--- /dev/null
+++ b/src/shared/acl-util.c
@@ -0,0 +1,597 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <stdbool.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#include "acl-util.h"
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "user-util.h"
+#include "util.h"
+
+#if HAVE_ACL
+
+int acl_find_uid(acl_t acl, uid_t uid, acl_entry_t *ret_entry) {
+ acl_entry_t i;
+ int r;
+
+ assert(acl);
+ assert(uid_is_valid(uid));
+ assert(ret_entry);
+
+ for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
+
+ acl_tag_t tag;
+ uid_t *u;
+ bool b;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if (tag != ACL_USER)
+ continue;
+
+ u = acl_get_qualifier(i);
+ if (!u)
+ return -errno;
+
+ b = *u == uid;
+ acl_free(u);
+
+ if (b) {
+ *ret_entry = i;
+ return 1;
+ }
+ }
+ if (r < 0)
+ return -errno;
+
+ *ret_entry = NULL;
+ return 0;
+}
+
+int calc_acl_mask_if_needed(acl_t *acl_p) {
+ acl_entry_t i;
+ int r;
+ bool need = false;
+
+ assert(acl_p);
+
+ for (r = acl_get_entry(*acl_p, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(*acl_p, ACL_NEXT_ENTRY, &i)) {
+ acl_tag_t tag;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if (tag == ACL_MASK)
+ return 0;
+
+ if (IN_SET(tag, ACL_USER, ACL_GROUP))
+ need = true;
+ }
+ if (r < 0)
+ return -errno;
+
+ if (need && acl_calc_mask(acl_p) < 0)
+ return -errno;
+
+ return need;
+}
+
+int add_base_acls_if_needed(acl_t *acl_p, const char *path) {
+ acl_entry_t i;
+ int r;
+ bool have_user_obj = false, have_group_obj = false, have_other = false;
+ struct stat st;
+ _cleanup_(acl_freep) acl_t basic = NULL;
+
+ assert(acl_p);
+
+ for (r = acl_get_entry(*acl_p, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(*acl_p, ACL_NEXT_ENTRY, &i)) {
+ acl_tag_t tag;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if (tag == ACL_USER_OBJ)
+ have_user_obj = true;
+ else if (tag == ACL_GROUP_OBJ)
+ have_group_obj = true;
+ else if (tag == ACL_OTHER)
+ have_other = true;
+ if (have_user_obj && have_group_obj && have_other)
+ return 0;
+ }
+ if (r < 0)
+ return -errno;
+
+ r = stat(path, &st);
+ if (r < 0)
+ return -errno;
+
+ basic = acl_from_mode(st.st_mode);
+ if (!basic)
+ return -errno;
+
+ for (r = acl_get_entry(basic, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(basic, ACL_NEXT_ENTRY, &i)) {
+ acl_tag_t tag;
+ acl_entry_t dst;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if ((tag == ACL_USER_OBJ && have_user_obj) ||
+ (tag == ACL_GROUP_OBJ && have_group_obj) ||
+ (tag == ACL_OTHER && have_other))
+ continue;
+
+ r = acl_create_entry(acl_p, &dst);
+ if (r < 0)
+ return -errno;
+
+ r = acl_copy_entry(dst, i);
+ if (r < 0)
+ return -errno;
+ }
+ if (r < 0)
+ return -errno;
+ return 0;
+}
+
+int acl_search_groups(const char *path, char ***ret_groups) {
+ _cleanup_strv_free_ char **g = NULL;
+ _cleanup_(acl_freep) acl_t acl = NULL;
+ bool ret = false;
+ acl_entry_t entry;
+ int r;
+
+ assert(path);
+
+ acl = acl_get_file(path, ACL_TYPE_DEFAULT);
+ if (!acl)
+ return -errno;
+
+ r = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
+ for (;;) {
+ _cleanup_(acl_free_gid_tpp) gid_t *gid = NULL;
+ acl_tag_t tag;
+
+ if (r < 0)
+ return -errno;
+ if (r == 0)
+ break;
+
+ if (acl_get_tag_type(entry, &tag) < 0)
+ return -errno;
+
+ if (tag != ACL_GROUP)
+ goto next;
+
+ gid = acl_get_qualifier(entry);
+ if (!gid)
+ return -errno;
+
+ if (in_gid(*gid) > 0) {
+ if (!ret_groups)
+ return true;
+
+ ret = true;
+ }
+
+ if (ret_groups) {
+ char *name;
+
+ name = gid_to_name(*gid);
+ if (!name)
+ return -ENOMEM;
+
+ r = strv_consume(&g, name);
+ if (r < 0)
+ return r;
+ }
+
+ next:
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
+ }
+
+ if (ret_groups)
+ *ret_groups = TAKE_PTR(g);
+
+ return ret;
+}
+
+int parse_acl(const char *text, acl_t *acl_access, acl_t *acl_default, bool want_mask) {
+ _cleanup_free_ char **a = NULL, **d = NULL; /* strings are not freed */
+ _cleanup_strv_free_ char **split = NULL;
+ int r = -EINVAL;
+ _cleanup_(acl_freep) acl_t a_acl = NULL, d_acl = NULL;
+
+ split = strv_split(text, ",");
+ if (!split)
+ return -ENOMEM;
+
+ STRV_FOREACH(entry, split) {
+ char *p;
+
+ p = STARTSWITH_SET(*entry, "default:", "d:");
+ if (p)
+ r = strv_push(&d, p);
+ else
+ r = strv_push(&a, *entry);
+ if (r < 0)
+ return r;
+ }
+
+ if (!strv_isempty(a)) {
+ _cleanup_free_ char *join = NULL;
+
+ join = strv_join(a, ",");
+ if (!join)
+ return -ENOMEM;
+
+ a_acl = acl_from_text(join);
+ if (!a_acl)
+ return -errno;
+
+ if (want_mask) {
+ r = calc_acl_mask_if_needed(&a_acl);
+ if (r < 0)
+ return r;
+ }
+ }
+
+ if (!strv_isempty(d)) {
+ _cleanup_free_ char *join = NULL;
+
+ join = strv_join(d, ",");
+ if (!join)
+ return -ENOMEM;
+
+ d_acl = acl_from_text(join);
+ if (!d_acl)
+ return -errno;
+
+ if (want_mask) {
+ r = calc_acl_mask_if_needed(&d_acl);
+ if (r < 0)
+ return r;
+ }
+ }
+
+ *acl_access = TAKE_PTR(a_acl);
+ *acl_default = TAKE_PTR(d_acl);
+
+ return 0;
+}
+
+static int acl_entry_equal(acl_entry_t a, acl_entry_t b) {
+ acl_tag_t tag_a, tag_b;
+
+ if (acl_get_tag_type(a, &tag_a) < 0)
+ return -errno;
+
+ if (acl_get_tag_type(b, &tag_b) < 0)
+ return -errno;
+
+ if (tag_a != tag_b)
+ return false;
+
+ switch (tag_a) {
+ case ACL_USER_OBJ:
+ case ACL_GROUP_OBJ:
+ case ACL_MASK:
+ case ACL_OTHER:
+ /* can have only one of those */
+ return true;
+ case ACL_USER: {
+ _cleanup_(acl_free_uid_tpp) uid_t *uid_a = NULL, *uid_b = NULL;
+
+ uid_a = acl_get_qualifier(a);
+ if (!uid_a)
+ return -errno;
+
+ uid_b = acl_get_qualifier(b);
+ if (!uid_b)
+ return -errno;
+
+ return *uid_a == *uid_b;
+ }
+ case ACL_GROUP: {
+ _cleanup_(acl_free_gid_tpp) gid_t *gid_a = NULL, *gid_b = NULL;
+
+ gid_a = acl_get_qualifier(a);
+ if (!gid_a)
+ return -errno;
+
+ gid_b = acl_get_qualifier(b);
+ if (!gid_b)
+ return -errno;
+
+ return *gid_a == *gid_b;
+ }
+ default:
+ assert_not_reached();
+ }
+}
+
+static int find_acl_entry(acl_t acl, acl_entry_t entry, acl_entry_t *out) {
+ acl_entry_t i;
+ int r;
+
+ for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
+
+ r = acl_entry_equal(i, entry);
+ if (r < 0)
+ return r;
+ if (r > 0) {
+ *out = i;
+ return 1;
+ }
+ }
+ if (r < 0)
+ return -errno;
+ return 0;
+}
+
+int acls_for_file(const char *path, acl_type_t type, acl_t new, acl_t *acl) {
+ _cleanup_(acl_freep) acl_t old;
+ acl_entry_t i;
+ int r;
+
+ old = acl_get_file(path, type);
+ if (!old)
+ return -errno;
+
+ for (r = acl_get_entry(new, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(new, ACL_NEXT_ENTRY, &i)) {
+
+ acl_entry_t j;
+
+ r = find_acl_entry(old, i, &j);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ if (acl_create_entry(&old, &j) < 0)
+ return -errno;
+
+ if (acl_copy_entry(j, i) < 0)
+ return -errno;
+ }
+ if (r < 0)
+ return -errno;
+
+ *acl = TAKE_PTR(old);
+
+ return 0;
+}
+
+/* POSIX says that ACL_{READ,WRITE,EXECUTE} don't have to be bitmasks. But that is a natural thing to do and
+ * all extant implementations do it. Let's make sure that we fail verbosely in the (imho unlikely) scenario
+ * that we get a new implementation that does not satisfy this. */
+assert_cc(!(ACL_READ & ACL_WRITE));
+assert_cc(!(ACL_WRITE & ACL_EXECUTE));
+assert_cc(!(ACL_EXECUTE & ACL_READ));
+assert_cc((unsigned) ACL_READ == ACL_READ);
+assert_cc((unsigned) ACL_WRITE == ACL_WRITE);
+assert_cc((unsigned) ACL_EXECUTE == ACL_EXECUTE);
+
+int fd_add_uid_acl_permission(
+ int fd,
+ uid_t uid,
+ unsigned mask) {
+
+ _cleanup_(acl_freep) acl_t acl = NULL;
+ acl_permset_t permset;
+ acl_entry_t entry;
+ int r;
+
+ /* Adds an ACL entry for the specified file to allow the indicated access to the specified
+ * user. Operates purely incrementally. */
+
+ assert(fd >= 0);
+ assert(uid_is_valid(uid));
+
+ acl = acl_get_fd(fd);
+ if (!acl)
+ return -errno;
+
+ r = acl_find_uid(acl, uid, &entry);
+ if (r <= 0) {
+ if (acl_create_entry(&acl, &entry) < 0 ||
+ acl_set_tag_type(entry, ACL_USER) < 0 ||
+ acl_set_qualifier(entry, &uid) < 0)
+ return -errno;
+ }
+
+ if (acl_get_permset(entry, &permset) < 0)
+ return -errno;
+
+ if ((mask & ACL_READ) && acl_add_perm(permset, ACL_READ) < 0)
+ return -errno;
+ if ((mask & ACL_WRITE) && acl_add_perm(permset, ACL_WRITE) < 0)
+ return -errno;
+ if ((mask & ACL_EXECUTE) && acl_add_perm(permset, ACL_EXECUTE) < 0)
+ return -errno;
+
+ r = calc_acl_mask_if_needed(&acl);
+ if (r < 0)
+ return r;
+
+ if (acl_set_fd(fd, acl) < 0)
+ return -errno;
+
+ return 0;
+}
+
+int fd_acl_make_read_only(int fd) {
+ _cleanup_(acl_freep) acl_t acl = NULL;
+ bool changed = false;
+ acl_entry_t i;
+ int r;
+
+ assert(fd >= 0);
+
+ /* Safely drops all W bits from all relevant ACL entries of the file, without changing entries which
+ * are masked by the ACL mask */
+
+ acl = acl_get_fd(fd);
+ if (!acl) {
+
+ if (!ERRNO_IS_NOT_SUPPORTED(errno))
+ return -errno;
+
+ /* No ACLs? Then just update the regular mode_t */
+ return fd_acl_make_read_only_fallback(fd);
+ }
+
+ for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
+ acl_permset_t permset;
+ acl_tag_t tag;
+ int b;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ /* These three control the x bits overall (as ACL_MASK affects all remaining tags) */
+ if (!IN_SET(tag, ACL_USER_OBJ, ACL_MASK, ACL_OTHER))
+ continue;
+
+ if (acl_get_permset(i, &permset) < 0)
+ return -errno;
+
+ b = acl_get_perm(permset, ACL_WRITE);
+ if (b < 0)
+ return -errno;
+
+ if (b) {
+ if (acl_delete_perm(permset, ACL_WRITE) < 0)
+ return -errno;
+
+ changed = true;
+ }
+ }
+ if (r < 0)
+ return -errno;
+
+ if (!changed)
+ return 0;
+
+ if (acl_set_fd(fd, acl) < 0) {
+ if (!ERRNO_IS_NOT_SUPPORTED(errno))
+ return -errno;
+
+ return fd_acl_make_read_only_fallback(fd);
+ }
+
+ return 1;
+}
+
+int fd_acl_make_writable(int fd) {
+ _cleanup_(acl_freep) acl_t acl = NULL;
+ acl_entry_t i;
+ int r;
+
+ /* Safely adds the writable bit to the owner's ACL entry of this inode. (And only the owner's! – This
+ * not the obvious inverse of fd_acl_make_read_only() hence!) */
+
+ acl = acl_get_fd(fd);
+ if (!acl) {
+ if (!ERRNO_IS_NOT_SUPPORTED(errno))
+ return -errno;
+
+ /* No ACLs? Then just update the regular mode_t */
+ return fd_acl_make_writable_fallback(fd);
+ }
+
+ for (r = acl_get_entry(acl, ACL_FIRST_ENTRY, &i);
+ r > 0;
+ r = acl_get_entry(acl, ACL_NEXT_ENTRY, &i)) {
+ acl_permset_t permset;
+ acl_tag_t tag;
+ int b;
+
+ if (acl_get_tag_type(i, &tag) < 0)
+ return -errno;
+
+ if (tag != ACL_USER_OBJ)
+ continue;
+
+ if (acl_get_permset(i, &permset) < 0)
+ return -errno;
+
+ b = acl_get_perm(permset, ACL_WRITE);
+ if (b < 0)
+ return -errno;
+
+ if (b)
+ return 0; /* Already set? Then there's nothing to do. */
+
+ if (acl_add_perm(permset, ACL_WRITE) < 0)
+ return -errno;
+
+ break;
+ }
+ if (r < 0)
+ return -errno;
+
+ if (acl_set_fd(fd, acl) < 0) {
+ if (!ERRNO_IS_NOT_SUPPORTED(errno))
+ return -errno;
+
+ return fd_acl_make_writable_fallback(fd);
+ }
+
+ return 1;
+}
+#endif
+
+int fd_acl_make_read_only_fallback(int fd) {
+ struct stat st;
+
+ assert(fd >= 0);
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if ((st.st_mode & 0222) == 0)
+ return 0;
+
+ if (fchmod(fd, st.st_mode & 0555) < 0)
+ return -errno;
+
+ return 1;
+}
+
+int fd_acl_make_writable_fallback(int fd) {
+ struct stat st;
+
+ assert(fd >= 0);
+
+ if (fstat(fd, &st) < 0)
+ return -errno;
+
+ if ((st.st_mode & 0200) != 0) /* already set */
+ return 0;
+
+ if (fchmod(fd, (st.st_mode & 07777) | 0200) < 0)
+ return -errno;
+
+ return 1;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-18 19:24:44 +0000