From 2968629aa21aa275e09e19128bf2e36fe82096ad Mon Sep 17 00:00:00 2001 From: Michael Orlitzky Date: Thu, 1 Mar 2018 18:51:58 -0500 Subject: [PATCH] src/libadacl.c: rewrite acl_set_entry() as acl_update_entry(). It turns out we only need to update existing entries in our ACLs, to mask the execute permissions. Since we never need to create new entries, the name "acl_set_entry" was not quite right. The new-entry-creation code has been removed from the bottom half of the function, and it has been renamed to "acl_update_entry". --- src/libadacl.c | 103 +++++++++---------------------------------------- 1 file changed, 18 insertions(+), 85 deletions(-) diff --git a/src/libadacl.c b/src/libadacl.c index d99cb8f..22f5d7b 100644 --- a/src/libadacl.c +++ b/src/libadacl.c @@ -199,51 +199,41 @@ int safe_open(const char* pathname, int flags) { /** - * @brief Update (or create) an entry in an @b minimal ACL. - * - * This function will not work if @c aclp contains extended - * entries. This is fine for our purposes, since we call @c wipe_acls - * on each path before applying the default to it. - * - * The assumption that there are no extended entries makes things much - * simpler. For example, we only have to update the @c ACL_USER_OBJ, - * @c ACL_GROUP_OBJ, and @c ACL_OTHER entries -- all others can simply - * be created anew. This means we don't have to fool around comparing - * named-user/group entries. + * @brief Update an entry in an @b minimal ACL. * * @param aclp - * A pointer to the acl_t structure whose entry we want to modify. + * A pointer to the acl_t structure whose entry we want to update. * * @param entry - * The new entry. If @c entry contains a user/group/other entry, we - * update the existing one. Otherwise we create a new entry. - * - * @return If there is an unexpected library error, @c ACL_ERROR is - * returned. Otherwise, @c ACL_SUCCESS. + * The new entry. * + * @return + * - @c ACL_SUCCESS - If we update an existing entry. + * - @c ACL_FAILURE - If we don't find an entry to update. + * - @c ACL_ERROR - Unexpected library error. */ -int acl_set_entry(acl_t* aclp, acl_entry_t entry) { +int acl_update_entry(acl_t aclp, acl_entry_t entry) { if (aclp == NULL || entry == NULL) { errno = EINVAL; - perror("acl_set_entry (args)"); + perror("acl_update_entry (args)"); return ACL_ERROR; } acl_tag_t entry_tag; if (acl_get_tag_type(entry, &entry_tag) == ACL_ERROR) { - perror("acl_set_entry (acl_get_tag_type)"); + perror("acl_update_entry (acl_get_tag_type)"); return ACL_ERROR; } acl_permset_t entry_permset; if (acl_get_permset(entry, &entry_permset) == ACL_ERROR) { - perror("acl_set_entry (acl_get_permset)"); + perror("acl_update_entry (acl_get_permset)"); return ACL_ERROR; } acl_entry_t existing_entry; /* Loop through the given ACL looking for matching entries. */ - int result = acl_get_entry(*aclp, ACL_FIRST_ENTRY, &existing_entry); + int result = acl_get_entry(aclp, ACL_FIRST_ENTRY, &existing_entry); while (result == ACL_SUCCESS) { acl_tag_t existing_tag = ACL_UNDEFINED_TAG; @@ -256,64 +246,24 @@ int acl_set_entry(acl_t* aclp, acl_entry_t entry) { if (existing_tag == entry_tag) { /* If we update something, we're done and return ACL_SUCCESS */ if (acl_set_permset(existing_entry, entry_permset) == ACL_ERROR) { - perror("acl_set_entry (acl_set_permset)"); + perror("acl_update_entry (acl_set_permset)"); return ACL_ERROR; } return ACL_SUCCESS; } - result = acl_get_entry(*aclp, ACL_NEXT_ENTRY, &existing_entry); + result = acl_get_entry(aclp, ACL_NEXT_ENTRY, &existing_entry); } /* This catches both the initial acl_get_entry and the ones at the end of the loop. */ if (result == ACL_ERROR) { - perror("acl_set_entry (acl_get_entry)"); - return ACL_ERROR; - } - - /* If we've made it this far, we need to add a new entry to the - ACL. */ - acl_entry_t new_entry; - - /* The acl_create_entry() function can allocate new memory and/or - * change the location of the ACL structure entirely. When that - * happens, the value pointed to by aclp is updated, which means - * that a new acl_t gets "passed out" to our caller, eventually to - * be fed to acl_free(). In other words, we should still be freeing - * the right thing, even if the value pointed to by aclp changes. - */ - if (acl_create_entry(aclp, &new_entry) == ACL_ERROR) { - perror("acl_set_entry (acl_create_entry)"); - return ACL_ERROR; - } - - if (acl_set_tag_type(new_entry, entry_tag) == ACL_ERROR) { - perror("acl_set_entry (acl_set_tag_type)"); + perror("acl_update_entry (acl_get_entry)"); return ACL_ERROR; } - if (acl_set_permset(new_entry, entry_permset) == ACL_ERROR) { - perror("acl_set_entry (acl_set_permset)"); - return ACL_ERROR; - } - - if (entry_tag == ACL_USER || entry_tag == ACL_GROUP) { - /* We need to set the qualifier too. */ - void* entry_qual = acl_get_qualifier(entry); - if (entry_qual == (void*)NULL) { - perror("acl_set_entry (acl_get_qualifier)"); - return ACL_ERROR; - } - - if (acl_set_qualifier(new_entry, entry_qual) == ACL_ERROR) { - perror("acl_set_entry (acl_set_qualifier)"); - return ACL_ERROR; - } - } - - return ACL_SUCCESS; + return ACL_FAILURE; } @@ -917,25 +867,8 @@ int apply_default_acl_ex(const char* path, } } - /* Finally, add the permset to the access ACL. It's actually - * important that we pass in the address of "new_acl" here, and not - * "new_acl" itself. Why? The call to acl_create_entry() within - * acl_set_entry() can allocate new memory for the entry. - * Sometimes that can be done in-place, in which case everything - * is cool and the new memory gets released when we call - * acl_free(acl). - * - * But occasionally, the whole ACL structure will have to be moved - * in order to allocate the extra space. When that happens, - * acl_create_entry() modifies the pointer it was passed (in this - * case, &acl) to point to the new location. We want to call - * acl_free() on the new location, and since acl_free() gets - * called right here, we need acl_create_entry() to update the - * value of "new_acl". To do that, it needs the address of "new_acl". - */ - - if (acl_set_entry(&new_acl, entry) == ACL_ERROR) { - perror("apply_default_acl_ex (acl_set_entry)"); + if (acl_update_entry(new_acl, entry) == ACL_ERROR) { + perror("apply_default_acl_ex (acl_update_entry)"); result = ACL_ERROR; goto cleanup; } -- 2.43.2