#define _GNU_SOURCE
#include <errno.h>
+#include <fcntl.h> /* AT_FOO constants */
#include <ftw.h> /* nftw() et al. */
#include <getopt.h>
-#include <libgen.h> /* dirname() */
-#include <limits.h> /* PATH_MAX */
+#include <libgen.h> /* basename(), dirname() */
+#include <limits.h> /* PATH_MAX */
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#define ACL_FAILURE 0
#define ACL_SUCCESS 1
+/* Even though most other library functions reliably return -1 for
+ * error, it feels a little wrong to re-use the ACL_ERROR constant.
+ */
+#define CLOSE_ERROR -1
+#define NFTW_ERROR -1
+#define OPEN_ERROR -1
+#define SNPRINTF_ERROR -1
+#define STAT_ERROR -1
+
+int safe_open_ex(int at_fd, char* pathname, int flags) {
+ if (pathname != NULL && strlen(pathname) == 0) {
+ /* Oops, went one level to deep with nothing to do. */
+ return at_fd;
+ }
-/* Command-line options */
-static bool no_exec_mask = false;
+ char* firstslash = strchr(pathname, '/');
+ if (firstslash == NULL) {
+ /* No more slashes, this is the base case. */
+ int r = openat(at_fd, pathname, flags);
+ return r;
+ }
+ /* Temporarily disable the slash, so that the subsequent call to
+ openat() opens only the next directory (and doesn't recurse). */
+ *firstslash = '\0';
+ int fd = safe_open_ex(at_fd, pathname, flags);
+ if (fd == OPEN_ERROR) {
+ if (errno != ELOOP) {
+ /* Don't output anything if we ignore a symlink */
+ perror("safe_open_ex (safe_open_ex)");
+ }
+ return OPEN_ERROR;
+ }
+
+ /* The ++ is safe because there needs to be at least a null byte
+ after the first slash, even if it's the last real character in
+ the string. */
+ int result = safe_open_ex(fd, firstslash+1, flags);
+ if (close(fd) == CLOSE_ERROR) {
+ perror("safe_open_ex (close)");
+ return OPEN_ERROR;
+ }
+ return result;
+}
-/**
- * @brief Get the mode bits from the given path.
- *
- * @param path
- * The path (file or directory) whose mode we want.
- *
- * @return A mode_t (st_mode) structure containing the mode bits.
- * See sys/stat.h for details.
- */
-mode_t get_mode(const char* path) {
- if (path == NULL) {
- errno = ENOENT;
- return -1;
+int safe_open(const char* pathname, int flags) {
+ if (pathname == NULL || strlen(pathname) == 0 || pathname[0] == '\0') {
+ /* error? */
+ return OPEN_ERROR;
}
- struct stat s;
- int result = stat(path, &s);
-
- if (result == 0) {
- return s.st_mode;
+ char abspath[PATH_MAX];
+ int snprintf_result = 0;
+ if (strchr(pathname, '/') == pathname) {
+ /* pathname is already absolute; just copy it. */
+ snprintf_result = snprintf(abspath, PATH_MAX, "%s", pathname);
}
else {
- /* errno will be set already by stat() */
- return result;
- }
-}
-
-
+ /* Concatenate the current working directory and pathname into an
+ * absolute path. We use realpath() ONLY on the cwd part, and not
+ * on the pathname part, because realpath() resolves symlinks. And
+ * the whole point of all this crap is to avoid following symlinks
+ * in the pathname.
+ *
+ * Using realpath() on the cwd lets us operate on relative paths
+ * while we're sitting in a directory that happens to have a
+ * symlink in it; for example: cd /var/run && apply-default-acl foo.
+ */
+ char* cwd = get_current_dir_name();
+ if (cwd == NULL) {
+ perror("safe_open (get_current_dir_name)");
+ return OPEN_ERROR;
+ }
-/**
- * @brief Determine whether or not the given path is a regular file.
- *
- * @param path
- * The path to test.
- *
- * @return true if @c path is a regular file, false otherwise.
- */
-bool is_regular_file(const char* path) {
- if (path == NULL) {
- return false;
+ char abs_cwd[PATH_MAX];
+ if (realpath(cwd, abs_cwd) == NULL) {
+ perror("safe_open (realpath)");
+ free(cwd);
+ return OPEN_ERROR;
+ }
+ snprintf_result = snprintf(abspath, PATH_MAX, "%s/%s", abs_cwd, pathname);
+ free(cwd);
+ }
+ if (snprintf_result == SNPRINTF_ERROR || snprintf_result > PATH_MAX) {
+ perror("safe_open (snprintf)");
+ return OPEN_ERROR;
}
- struct stat s;
- int result = stat(path, &s);
- if (result == 0) {
- return S_ISREG(s.st_mode);
+ int fd = open("/", flags);
+ if (strcmp(abspath, "/") == 0) {
+ return fd;
}
- else {
- return false;
+
+ int result = safe_open_ex(fd, abspath+1, flags);
+ if (close(fd) == CLOSE_ERROR) {
+ perror("safe_open (close)");
+ return OPEN_ERROR;
}
+ return result;
}
/**
- * @brief Determine whether or not the given path is a directory.
+ * @brief Determine whether or not the given path is accessible.
*
* @param path
* The path to test.
*
- * @return true if @c path is a directory, false otherwise.
+ * @return true if @c path is accessible to the current effective
+ * user/group, false otherwise.
*/
-bool is_directory(const char* path) {
+bool path_accessible(const char* path) {
if (path == NULL) {
return false;
}
- struct stat s;
- int result = stat(path, &s);
- if (result == 0) {
- return S_ISDIR(s.st_mode);
+ /* Test for access using the effective user and group rather than
+ the real one. */
+ int flags = AT_EACCESS;
+
+ /* Don't follow symlinks when checking for a path's existence,
+ since we won't follow them to set its ACLs either. */
+ flags |= AT_SYMLINK_NOFOLLOW;
+
+ /* If the path is relative, interpret it relative to the current
+ working directory (just like the access() system call). */
+ if (faccessat(AT_FDCWD, path, F_OK, flags) == 0) {
+ return true;
}
else {
return false;
* returned. Otherwise, @c ACL_SUCCESS.
*
*/
-int acl_set_entry(acl_t* aclp,
- acl_entry_t entry) {
+int acl_set_entry(acl_t* aclp, acl_entry_t entry) {
acl_tag_t entry_tag;
- int gt_result = acl_get_tag_type(entry, &entry_tag);
- if (gt_result == ACL_ERROR) {
+ if (acl_get_tag_type(entry, &entry_tag) == ACL_ERROR) {
perror("acl_set_entry (acl_get_tag_type)");
return ACL_ERROR;
}
acl_permset_t entry_permset;
- int ps_result = acl_get_permset(entry, &entry_permset);
- if (ps_result == ACL_ERROR) {
+ if (acl_get_permset(entry, &entry_permset) == ACL_ERROR) {
perror("acl_set_entry (acl_get_permset)");
return ACL_ERROR;
}
while (result == ACL_SUCCESS) {
acl_tag_t existing_tag = ACL_UNDEFINED_TAG;
- int tag_result = acl_get_tag_type(existing_entry, &existing_tag);
- if (tag_result == ACL_ERROR) {
+ if (acl_get_tag_type(existing_entry, &existing_tag) == ACL_ERROR) {
perror("set_acl_tag_permset (acl_get_tag_type)");
return ACL_ERROR;
}
match one of them, we're allowed to return ACL_SUCCESS
below and bypass the rest of the function. */
acl_permset_t existing_permset;
- int gep_result = acl_get_permset(existing_entry, &existing_permset);
- if (gep_result == ACL_ERROR) {
+ if (acl_get_permset(existing_entry, &existing_permset) == ACL_ERROR) {
perror("acl_set_entry (acl_get_permset)");
return ACL_ERROR;
}
- int s_result = acl_set_permset(existing_entry, entry_permset);
- if (s_result == ACL_ERROR) {
+ if (acl_set_permset(existing_entry, entry_permset) == ACL_ERROR) {
perror("acl_set_entry (acl_set_permset)");
return ACL_ERROR;
}
ACL. */
acl_entry_t new_entry;
- /* We allocate memory here that we should release! */
- int c_result = acl_create_entry(aclp, &new_entry);
- if (c_result == ACL_ERROR) {
+ /* 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;
}
- int st_result = acl_set_tag_type(new_entry, entry_tag);
- if (st_result == ACL_ERROR) {
+ if (acl_set_tag_type(new_entry, entry_tag) == ACL_ERROR) {
perror("acl_set_entry (acl_set_tag_type)");
return ACL_ERROR;
}
- int s_result = acl_set_permset(new_entry, entry_permset);
- if (s_result == ACL_ERROR) {
+ if (acl_set_permset(new_entry, entry_permset) == ACL_ERROR) {
perror("acl_set_entry (acl_set_permset)");
return ACL_ERROR;
}
return ACL_ERROR;
}
- int sq_result = acl_set_qualifier(new_entry, entry_qual);
- if (sq_result == ACL_ERROR) {
+ if (acl_set_qualifier(new_entry, entry_qual) == ACL_ERROR) {
perror("acl_set_entry (acl_set_qualifier)");
return ACL_ERROR;
}
* @brief Determine the number of entries in the given ACL.
*
* @param acl
- * A pointer to an @c acl_t structure.
+ * The ACL to inspect.
*
* @return Either the non-negative number of entries in @c acl, or
* @c ACL_ERROR on error.
*/
-int acl_entry_count(acl_t* acl) {
+int acl_entry_count(acl_t acl) {
acl_entry_t entry;
int entry_count = 0;
- int result = acl_get_entry(*acl, ACL_FIRST_ENTRY, &entry);
+ int result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
while (result == ACL_SUCCESS) {
entry_count++;
- result = acl_get_entry(*acl, ACL_NEXT_ENTRY, &entry);
+ result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
}
if (result == ACL_ERROR) {
* An ACL is minimal if it has fewer than four entries.
*
* @param acl
- * A pointer to an acl_t structure.
+ * The ACL whose minimality is in question.
*
* @return
* - @c ACL_SUCCESS - @c acl is minimal
* - @c ACL_FAILURE - @c acl is not minimal
* - @c ACL_ERROR - Unexpected library error
*/
-int acl_is_minimal(acl_t* acl) {
+int acl_is_minimal(acl_t acl) {
int ec = acl_entry_count(acl);
/**
- * @brief Determine whether the given path has an ACL whose mask
- * denies execute.
+ * @brief Determine whether the given ACL's mask denies execute.
*
- * @param path
- * The path to check.
+ * @param acl
+ * The ACL whose mask we want to check.
*
* @return
- * - @c ACL_SUCCESS - @c path has a mask which denies execute.
- * - @c ACL_FAILURE - The ACL for @c path does not deny execute,
- * or @c path has no extended ACL at all.
+ * - @c ACL_SUCCESS - The @c acl has a mask which denies execute.
+ * - @c ACL_FAILURE - The @c acl has a mask which does not deny execute.
* - @c ACL_ERROR - Unexpected library error.
*/
-int acl_execute_masked(const char* path) {
-
- acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
-
- if (acl == (acl_t)NULL) {
- perror("acl_execute_masked (acl_get_file)");
- return ACL_ERROR;
- }
-
- /* Our return value. */
- int result = ACL_FAILURE;
+int acl_execute_masked(acl_t acl) {
acl_entry_t entry;
int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
while (ge_result == ACL_SUCCESS) {
acl_tag_t tag = ACL_UNDEFINED_TAG;
- int tag_result = acl_get_tag_type(entry, &tag);
- if (tag_result == ACL_ERROR) {
+ if (acl_get_tag_type(entry, &tag) == ACL_ERROR) {
perror("acl_execute_masked (acl_get_tag_type)");
- result = ACL_ERROR;
- goto cleanup;
+ return ACL_ERROR;
}
if (tag == ACL_MASK) {
execute is specified. */
acl_permset_t permset;
- int ps_result = acl_get_permset(entry, &permset);
- if (ps_result == ACL_ERROR) {
+ if (acl_get_permset(entry, &permset) == ACL_ERROR) {
perror("acl_execute_masked (acl_get_permset)");
- result = ACL_ERROR;
- goto cleanup;
+ return ACL_ERROR;
}
int gp_result = acl_get_perm(permset, ACL_EXECUTE);
if (gp_result == ACL_ERROR) {
perror("acl_execute_masked (acl_get_perm)");
- result = ACL_ERROR;
- goto cleanup;
+ return ACL_ERROR;
}
if (gp_result == ACL_FAILURE) {
ge_result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
}
- cleanup:
- acl_free(acl);
- return result;
+ return ACL_FAILURE;
}
+
/**
- * @brief Determine whether @c path is executable (by anyone) or a
- * directory.
+ * @brief Determine whether @c fd is executable by anyone.
+ *
*
* This is used as part of the heuristic to determine whether or not
- * we should mask the execute bit when inheriting an ACL. If @c path
- * is a directory, the answer is a clear-cut yes. This behavior is
- * modeled after the capital 'X' perms of setfacl.
+ * we should mask the execute bit when inheriting an ACL. If @c fd
+ * describes a file, we check the @a effective permissions, contrary
+ * to what setfacl does.
*
- * If @c path is a file, we check the @a effective permissions,
- * contrary to what setfacl does.
+ * @param fd
+ * The file descriptor to check.
*
- * @param path
- * The path to check.
+ * @param sp
+ * A pointer to a stat structure for @c fd.
*
* @return
- * - @c ACL_SUCCESS - @c path is a directory, or someone has effective
- execute permissions.
- * - @c ACL_FAILURE - @c path is a regular file and nobody can execute
- it.
+ * - @c ACL_SUCCESS - Someone has effective execute permissions on @c fd.
+ * - @c ACL_FAILURE - Nobody can execute @c fd.
* - @c ACL_ERROR - Unexpected library error.
*/
-int any_can_execute_or_dir(const char* path) {
-
- if (is_directory(path)) {
- /* That was easy... */
- return ACL_SUCCESS;
- }
-
- acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
+int any_can_execute(int fd, const struct stat* sp) {
+ acl_t acl = acl_get_fd(fd);
if (acl == (acl_t)NULL) {
- perror("any_can_execute_or_dir (acl_get_file)");
+ perror("any_can_execute (acl_get_file)");
return ACL_ERROR;
}
/* Our return value. */
int result = ACL_FAILURE;
- if (acl_is_minimal(&acl)) {
- mode_t mode = get_mode(path);
- if (mode & (S_IXUSR | S_IXOTH | S_IXGRP)) {
+ if (acl_is_minimal(acl)) {
+ if (sp->st_mode & (S_IXUSR | S_IXOTH | S_IXGRP)) {
result = ACL_SUCCESS;
goto cleanup;
}
int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
while (ge_result == ACL_SUCCESS) {
+ /* The first thing we do is check to see if this is a mask
+ entry. If it is, we skip it entirely. */
+ acl_tag_t tag = ACL_UNDEFINED_TAG;
+
+ if (acl_get_tag_type(entry, &tag) == ACL_ERROR) {
+ perror("any_can_execute_or (acl_get_tag_type)");
+ result = ACL_ERROR;
+ goto cleanup;
+ }
+
+ if (tag == ACL_MASK) {
+ ge_result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
+ continue;
+ }
+
+ /* Ok, so it's not a mask entry. Check the execute perms. */
acl_permset_t permset;
- int ps_result = acl_get_permset(entry, &permset);
- if (ps_result == ACL_ERROR) {
- perror("any_can_execute_or_dir (acl_get_permset)");
+ if (acl_get_permset(entry, &permset) == ACL_ERROR) {
+ perror("any_can_execute_or (acl_get_permset)");
result = ACL_ERROR;
goto cleanup;
}
int gp_result = acl_get_perm(permset, ACL_EXECUTE);
if (gp_result == ACL_ERROR) {
- perror("any_can_execute_or_dir (acl_get_perm)");
+ perror("any_can_execute (acl_get_perm)");
result = ACL_ERROR;
goto cleanup;
}
if (gp_result == ACL_SUCCESS) {
- /* Only return one if this execute bit is not masked. */
- if (acl_execute_masked(path) != ACL_SUCCESS) {
+ /* Only return ACL_SUCCESS if this execute bit is not masked. */
+ if (acl_execute_masked(acl) != ACL_SUCCESS) {
result = ACL_SUCCESS;
goto cleanup;
}
}
if (ge_result == ACL_ERROR) {
- perror("any_can_execute_or_dir (acl_get_entry)");
+ perror("any_can_execute (acl_get_entry)");
result = ACL_ERROR;
goto cleanup;
}
/**
- * @brief Inherit the default ACL from @c parent to @c path.
+ * @brief Set @c acl as the default ACL on @c path.
*
- * The @c parent parameter does not necessarily need to be the parent
- * of @c path, although that will usually be the case. This overwrites
- * any existing default ACL on @c path.
- *
- * @param parent
- * The parent directory whose ACL we want to inherit.
+ * This overwrites any existing default ACL on @c path. If @c path is
+ * not a directory, we return ACL_ERROR and @c errno is set.
*
* @param path
- * The target directory whose ACL we wish to overwrite (or create).
+ * The target directory whose ACL we wish to replace or create.
+ *
+ * @param acl
+ * The ACL to set as default on @c path.
*
* @return
- * - @c ACL_SUCCESS - The default ACL was inherited successfully.
- * - @c ACL_FAILURE - Either @c parent or @c path is not a directory.
+ * - @c ACL_SUCCESS - The default ACL was assigned successfully.
* - @c ACL_ERROR - Unexpected library error.
*/
-int inherit_default_acl(const char* path, const char* parent) {
-
- /* Our return value. */
- int result = ACL_SUCCESS;
+int assign_default_acl(const char* path, acl_t acl) {
if (path == NULL) {
- errno = ENOENT;
- return ACL_ERROR;
- }
-
- if (!is_directory(path) || !is_directory(parent)) {
- return ACL_FAILURE;
- }
-
- acl_t parent_acl = acl_get_file(parent, ACL_TYPE_DEFAULT);
- if (parent_acl == (acl_t)NULL) {
- perror("inherit_default_acl (acl_get_file)");
+ errno = EINVAL;
+ perror("assign_default_acl (args)");
return ACL_ERROR;
}
- acl_t path_acl = acl_dup(parent_acl);
+ /* Our return value; success unless something bad happens. */
+ int result = ACL_SUCCESS;
+ acl_t path_acl = acl_dup(acl);
if (path_acl == (acl_t)NULL) {
- perror("inherit_default_acl (acl_dup)");
- acl_free(parent_acl);
- return ACL_ERROR;
+ perror("assign_default_acl (acl_dup)");
+ return ACL_ERROR; /* Nothing to clean up in this case. */
}
- int sf_result = acl_set_file(path, ACL_TYPE_DEFAULT, path_acl);
- if (sf_result == -1) {
- perror("inherit_default_acl (acl_set_file)");
+ if (acl_set_file(path, ACL_TYPE_DEFAULT, path_acl) == ACL_ERROR) {
+ perror("assign_default_acl (acl_set_file)");
result = ACL_ERROR;
- goto cleanup;
}
- cleanup:
acl_free(path_acl);
return result;
}
/**
- * @brief Remove @c ACL_USER, @c ACL_GROUP, and @c ACL_MASK entries
- * from the given path.
+ * @brief Remove all @c ACL_TYPE_ACCESS entries from the given file
+ * descriptor, leaving the UNIX permission bits.
*
- * @param path
- * The path whose ACLs we want to wipe.
+ * @param fd
+ * The file descriptor whose ACLs we want to wipe.
*
* @return
* - @c ACL_SUCCESS - The ACLs were wiped successfully, or none
* existed in the first place.
* - @c ACL_ERROR - Unexpected library error.
*/
-int wipe_acls(const char* path) {
+int wipe_acls(int fd) {
+ /* Initialize an empty ACL, and then overwrite the one on "fd" with it. */
+ acl_t empty_acl = acl_init(0);
- if (path == NULL) {
- errno = ENOENT;
+ if (empty_acl == (acl_t)NULL) {
+ perror("wipe_acls (acl_init)");
return ACL_ERROR;
}
- acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
- if (acl == (acl_t)NULL) {
- perror("wipe_acls (acl_get_file)");
+ if (acl_set_fd(fd, empty_acl) == ACL_ERROR) {
+ perror("wipe_acls (acl_set_fd)");
+ acl_free(empty_acl);
return ACL_ERROR;
}
- /* Our return value. */
- int result = ACL_SUCCESS;
-
- acl_entry_t entry;
- int ge_result = acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
-
- while (ge_result == ACL_SUCCESS) {
- int d_result = acl_delete_entry(acl, entry);
- if (d_result == ACL_ERROR) {
- perror("wipe_acls (acl_delete_entry)");
- result = ACL_ERROR;
- goto cleanup;
- }
-
- ge_result = acl_get_entry(acl, ACL_NEXT_ENTRY, &entry);
- }
-
- /* Catches the first acl_get_entry as well as the ones at the end of
- the loop. */
- if (ge_result == ACL_ERROR) {
- perror("wipe_acls (acl_get_entry)");
- result = ACL_ERROR;
- goto cleanup;
- }
-
- int sf_result = acl_set_file(path, ACL_TYPE_ACCESS, acl);
- if (sf_result == ACL_ERROR) {
- perror("wipe_acls (acl_set_file)");
- result = ACL_ERROR;
- goto cleanup;
- }
-
- cleanup:
- acl_free(acl);
- return result;
+ acl_free(empty_acl);
+ return ACL_SUCCESS;
}
* @param path
* The path whose ACL we would like to reset to its default.
*
+ * @param sp
+ * A pointer to a stat structure for @c path, or @c NULL if you don't
+ * have one handy.
+ *
+ * @param no_exec_mask
+ * The value (either true or false) of the --no-exec-mask flag.
+ *
* @return
* - @c ACL_SUCCESS - The parent default ACL was inherited successfully.
* - @c ACL_FAILURE - The target path is not a regular file/directory,
* or the parent of @c path is not a directory.
* - @c ACL_ERROR - Unexpected library error.
*/
-int apply_default_acl(const char* path) {
+int apply_default_acl(const char* path,
+ const struct stat* sp,
+ bool no_exec_mask) {
if (path == NULL) {
- errno = ENOENT;
+ errno = EINVAL;
+ perror("apply_default_acl (args)");
return ACL_ERROR;
}
- if (!is_regular_file(path) && !is_directory(path)) {
- return ACL_FAILURE;
- }
+ /* Define these next three variables here because we may have to
+ * jump to the cleanup routine which expects them to exist.
+ */
+
+ /* Our return value. */
+ int result = ACL_SUCCESS;
+
+ /* The default ACL on path's parent directory */
+ acl_t defacl = (acl_t)NULL;
- /* dirname mangles its argument */
- char path_copy[PATH_MAX];
- strncpy(path_copy, path, PATH_MAX-1);
- path_copy[PATH_MAX-1] = 0;
+ /* The file descriptor corresponding to "path" */
+ int fd = 0;
+ /* Get the parent directory of "path" with dirname(), which happens
+ * to murder its argument and necessitates a path_copy.
+ */
+ char* path_copy = strdup(path);
+ if (path_copy == NULL) {
+ perror("apply_default_acl (strdup)");
+ return ACL_ERROR;
+ }
char* parent = dirname(path_copy);
- if (!is_directory(parent)) {
- /* Make sure dirname() did what we think it did. */
- return ACL_FAILURE;
+
+ fd = safe_open(path, O_NOFOLLOW);
+ if (fd == OPEN_ERROR) {
+ if (errno == ELOOP) {
+ result = ACL_FAILURE; /* hit a symlink */
+ goto cleanup;
+ }
+ else {
+ perror("apply_default_acl (open fd)");
+ result = ACL_ERROR;
+ goto cleanup;
+ }
+ }
+
+
+ /* Refuse to operate on hard links, which can be abused by an
+ * attacker to trick us into changing the ACL on a file we didn't
+ * intend to; namely the "target" of the hard link. There is TOCTOU
+ * race condition here, but the window is as small as possible
+ * between when we open the file descriptor (look above) and when we
+ * fstat it.
+ *
+ * Note: we only need to call fstat ourselves if we weren't passed a
+ * valid pointer to a stat structure (nftw does that).
+ */
+ if (sp == NULL) {
+ struct stat s;
+ if (fstat(fd, &s) == STAT_ERROR) {
+ perror("apply_default_acl (fstat)");
+ goto cleanup;
+ }
+
+ sp = &s;
}
+ if (!S_ISDIR(sp->st_mode)) {
+ /* If it's not a directory, make sure it's a regular,
+ non-hard-linked file. */
+ if (!S_ISREG(sp->st_mode) || sp->st_nlink != 1) {
+ result = ACL_FAILURE;
+ goto cleanup;
+ }
+ }
+
+
/* Default to not masking the exec bit; i.e. applying the default
ACL literally. If --no-exec-mask was not specified, then we try
- to "guess" whether or not to mask the exec bit. */
+ to "guess" whether or not to mask the exec bit. This behavior
+ is modeled after the capital 'X' perms of setfacl. */
bool allow_exec = true;
if (!no_exec_mask) {
- int ace_result = any_can_execute_or_dir(path);
+ /* Never mask the execute bit on directories. */
+ int ace_result = any_can_execute(fd,sp) || S_ISDIR(sp->st_mode);
if (ace_result == ACL_ERROR) {
- perror("apply_default_acl (any_can_execute_or_dir)");
- return ACL_ERROR;
+ perror("apply_default_acl (any_can_execute)");
+ result = ACL_ERROR;
+ goto cleanup;
}
allow_exec = (bool)ace_result;
}
- acl_t defacl = acl_get_file(parent, ACL_TYPE_DEFAULT);
+ defacl = acl_get_file(parent, ACL_TYPE_DEFAULT);
if (defacl == (acl_t)NULL) {
perror("apply_default_acl (acl_get_file)");
- return ACL_ERROR;
+ result = ACL_ERROR;
+ goto cleanup;
}
- /* Our return value. */
- int result = ACL_SUCCESS;
-
- int wipe_result = wipe_acls(path);
- if (wipe_result == ACL_ERROR) {
+ if (wipe_acls(fd) == ACL_ERROR) {
perror("apply_default_acl (wipe_acls)");
result = ACL_ERROR;
goto cleanup;
/* Do this after wipe_acls(), otherwise we'll overwrite the wiped
ACL with this one. */
- acl_t acl = acl_get_file(path, ACL_TYPE_ACCESS);
+ acl_t acl = acl_get_fd(fd);
if (acl == (acl_t)NULL) {
- perror("apply_default_acl (acl_get_file)");
- return ACL_ERROR;
+ perror("apply_default_acl (acl_get_fd)");
+ result = ACL_ERROR;
+ goto cleanup;
}
- /* If it's a directory, inherit the parent's default. */
- int inherit_result = inherit_default_acl(path, parent);
- if (inherit_result == ACL_ERROR) {
- perror("apply_default_acl (inherit_acls)");
+ /* If it's a directory, inherit the parent's default. We sure hope
+ * that "path" still points to the same thing that "fd" and this
+ * "sp" describe. If not, we may wind up trying to set a default ACL
+ * on a file, and this will throw an error. I guess that's what we
+ * want to do?
+ */
+ if (S_ISDIR(sp->st_mode) && assign_default_acl(path, defacl) == ACL_ERROR) {
+ perror("apply_default_acl (assign_default_acl)");
result = ACL_ERROR;
goto cleanup;
}
while (ge_result == ACL_SUCCESS) {
acl_tag_t tag = ACL_UNDEFINED_TAG;
- int tag_result = acl_get_tag_type(entry, &tag);
- if (tag_result == ACL_ERROR) {
+ if (acl_get_tag_type(entry, &tag) == ACL_ERROR) {
perror("apply_default_acl (acl_get_tag_type)");
result = ACL_ERROR;
goto cleanup;
/* We've got an entry/tag from the default ACL. Get its permset. */
acl_permset_t permset;
- int ps_result = acl_get_permset(entry, &permset);
- if (ps_result == ACL_ERROR) {
+ if (acl_get_permset(entry, &permset) == ACL_ERROR) {
perror("apply_default_acl (acl_get_permset)");
result = ACL_ERROR;
goto cleanup;
/* The mask doesn't affect acl_user_obj, acl_group_obj (in
minimal ACLs) or acl_other entries, so if execute should be
masked, we have to do it manually. */
- int d_result = acl_delete_perm(permset, ACL_EXECUTE);
- if (d_result == ACL_ERROR) {
+ if (acl_delete_perm(permset, ACL_EXECUTE) == ACL_ERROR) {
perror("apply_default_acl (acl_delete_perm)");
result = ACL_ERROR;
goto cleanup;
}
- int sp_result = acl_set_permset(entry, permset);
- if (sp_result == ACL_ERROR) {
+ if (acl_set_permset(entry, permset) == ACL_ERROR) {
perror("apply_default_acl (acl_set_permset)");
result = ACL_ERROR;
goto cleanup;
}
}
- /* Finally, add the permset to the access ACL. */
- int set_result = acl_set_entry(&acl, entry);
- if (set_result == ACL_ERROR) {
+ /* Finally, add the permset to the access ACL. It's actually
+ * important that we pass in the address of "acl" here, and not
+ * "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 "acl". To do that, it needs the address of "acl".
+ */
+ if (acl_set_entry(&acl, entry) == ACL_ERROR) {
perror("apply_default_acl (acl_set_entry)");
result = ACL_ERROR;
goto cleanup;
goto cleanup;
}
- int sf_result = acl_set_file(path, ACL_TYPE_ACCESS, acl);
- if (sf_result == ACL_ERROR) {
- perror("apply_default_acl (acl_set_file)");
+ if (acl_set_fd(fd, acl) == ACL_ERROR) {
+ perror("apply_default_acl (acl_set_fd)");
result = ACL_ERROR;
goto cleanup;
}
cleanup:
- acl_free(defacl);
+ free(path_copy);
+ if (defacl != (acl_t)NULL) {
+ acl_free(defacl);
+ }
+ if (fd >= 0 && close(fd) == CLOSE_ERROR) {
+ perror("apply_default_acl (close)");
+ result = ACL_ERROR;
+ }
return result;
}
* The program name to use in the output.
*
*/
-void usage(char* program_name) {
+void usage(const char* program_name) {
printf("Apply any applicable default ACLs to the given files or "
"directories.\n\n");
printf("Usage: %s [flags] <target1> [<target2> [ <target3>...]]\n\n",
*
*/
int apply_default_acl_nftw(const char *target,
- const struct stat *s,
+ const struct stat *sp,
int info,
struct FTW *ftw) {
- bool app_result = apply_default_acl(target);
- if (app_result) {
+ if (apply_default_acl(target, sp, false)) {
+ return FTW_CONTINUE;
+ }
+ else {
+ return FTW_STOP;
+ }
+}
+
+
+
+/**
+ * @brief Wrapper around @c apply_default_acl() for use with @c nftw().
+ *
+ * This is identical to @c apply_default_acl_nftw(), except it passes
+ * @c true to @c apply_default_acl() as its no_exec_mask argument.
+ *
+ */
+int apply_default_acl_nftw_x(const char *target,
+ const struct stat *sp,
+ int info,
+ struct FTW *ftw) {
+
+ if (apply_default_acl(target, sp, true)) {
return FTW_CONTINUE;
}
else {
*
* We ignore symlinks for consistency with chmod -r.
*
+ * @param target
+ * The root (path) of the recursive application.
+ *
+ * @param no_exec_mask
+ * The value (either true or false) of the --no-exec-mask flag.
+ *
* @return
* If @c target is not a directory, we return the result of
* calling @c apply_default_acl() on @c target. Otherwise, we convert
* If there is an error, it will be reported via @c perror, but
* we still return @c false.
*/
-bool apply_default_acl_recursive(const char *target) {
-
- if (!is_directory(target)) {
- return apply_default_acl(target);
- }
-
+bool apply_default_acl_recursive(const char *target, bool no_exec_mask) {
int max_levels = 256;
int flags = FTW_PHYS; /* Don't follow links. */
- int nftw_result = nftw(target,
- apply_default_acl_nftw,
- max_levels,
- flags);
+ /* There are two separate functions that could be passed to
+ nftw(). One passes no_exec_mask = true to apply_default_acl(),
+ and the other passes no_exec_mask = false. Since the function we
+ pass to nftw() cannot have parameters, we have to create separate
+ options and make the decision here. */
+ int (*fn)(const char *, const struct stat *, int, struct FTW *) = NULL;
+ fn = no_exec_mask ? apply_default_acl_nftw_x : apply_default_acl_nftw;
+
+ int nftw_result = nftw(target, fn, max_levels, flags);
if (nftw_result == 0) {
/* Success */
return true;
}
- /* nftw will return -1 on error, or if the supplied function
+ /* nftw will return NFTW_ERROR on error, or if the supplied function
* (apply_default_acl_nftw) returns a non-zero result, nftw will
* return that.
*/
- if (nftw_result == -1) {
+ if (nftw_result == NFTW_ERROR) {
perror("apply_default_acl_recursive (nftw)");
}
}
bool recursive = false;
- /* bool no_exec_mask is declared static/global */
+ bool no_exec_mask = false;
struct option long_options[] = {
/* These options set a flag. */
const char* target = argv[arg_index];
bool reapp_result = false;
+ /* Make sure we can access the given path before we go out of our
+ * way to please it. Doing this check outside of
+ * apply_default_acl() lets us spit out a better error message for
+ * typos, too.
+ */
+ if (!path_accessible(target)) {
+ fprintf(stderr, "%s: %s: No such file or directory\n", argv[0], target);
+ result = EXIT_FAILURE;
+ continue;
+ }
+
if (recursive) {
- reapp_result = apply_default_acl_recursive(target);
+ reapp_result = apply_default_acl_recursive(target, no_exec_mask);
}
else {
- /* It's either normal file, or we're not operating recursively. */
- reapp_result = apply_default_acl(target);
+ /* It's either a normal file, or we're not operating recursively. */
+ reapp_result = apply_default_acl(target, NULL, no_exec_mask);
}
if (!reapp_result) {
projects / apply-default-acl.git / blobdiff