Merge pull request #23061 from poettering/chase-symlinks-tweaks,-new

some chase_symlinks() tweaks

src/basic/chase-symlinks.c

@@ -24,7 +24,7 @@ bool unsafe_transition(const struct stat *a, const struct stat *b) {
         return a->st_uid != b->st_uid; /* Otherwise we need to stay within the same UID */
 }
 
-static int log_unsafe_transition(int a, int b, const char *path, unsigned flags) {
+static int log_unsafe_transition(int a, int b, const char *path, ChaseSymlinksFlags flags) {
         _cleanup_free_ char *n1 = NULL, *n2 = NULL, *user_a = NULL, *user_b = NULL;
         struct stat st;
 
@@ -44,7 +44,7 @@ static int log_unsafe_transition(int a, int b, const char *path, unsigned flags)
                                  strna(n1), strna(user_a), special_glyph(SPECIAL_GLYPH_ARROW_RIGHT), strna(n2), strna(user_b), path);
 }
 
-static int log_autofs_mount_point(int fd, const char *path, unsigned flags) {
+static int log_autofs_mount_point(int fd, const char *path, ChaseSymlinksFlags flags) {
         _cleanup_free_ char *n1 = NULL;
 
         if (!FLAGS_SET(flags, CHASE_WARN))
@@ -57,7 +57,13 @@ static int log_autofs_mount_point(int fd, const char *path, unsigned flags) {
                                  strna(n1), path);
 }
 
-int chase_symlinks(const char *path, const char *original_root, unsigned flags, char **ret_path, int *ret_fd) {
+int chase_symlinks(
+                const char *path,
+                const char *original_root,
+                ChaseSymlinksFlags flags,
+                char **ret_path,
+                int *ret_fd) {
+
         _cleanup_free_ char *buffer = NULL, *done = NULL, *root = NULL;
         _cleanup_close_ int fd = -1;
         unsigned max_follow = CHASE_SYMLINKS_MAX; /* how many symlinks to follow before giving up and returning ELOOP */
@@ -78,6 +84,10 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
         if (isempty(path))
                 return -EINVAL;
 
+        /* We don't support relative paths in combination with a root directory */
+        if (FLAGS_SET(flags, CHASE_PREFIX_ROOT) && !path_is_absolute(path))
+                return -EINVAL;
+
         /* This is a lot like canonicalize_file_name(), but takes an additional "root" parameter, that allows following
          * symlinks relative to a root directory, instead of the root of the host.
          *
@@ -155,19 +165,19 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                 path_simplify(root);
 
                 if (flags & CHASE_PREFIX_ROOT) {
-                        /* We don't support relative paths in combination with a root directory */
-                        if (!path_is_absolute(path))
-                                return -EINVAL;
-
-                        path = prefix_roota(root, path);
+                        buffer = path_join(root, path);
+                        if (!buffer)
+                                return -ENOMEM;
                 }
         }
 
-        r = path_make_absolute_cwd(path, &buffer);
-        if (r < 0)
-                return r;
+        if (!buffer) {
+                r = path_make_absolute_cwd(path, &buffer);
+                if (r < 0)
+                        return r;
+        }
 
-        fd = open(root ?: "/", O_CLOEXEC|O_DIRECTORY|O_PATH);
+        fd = open(empty_to_root(root), O_CLOEXEC|O_DIRECTORY|O_PATH);
         if (fd < 0)
                 return -errno;
 
@@ -193,6 +203,8 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                 todo = buffer;
                 done = strdup("/");
         }
+        if (!done)
+                return -ENOMEM;
 
         for (;;) {
                 _cleanup_free_ char *first = NULL;
@@ -200,7 +212,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                 struct stat st;
                 const char *e;
 
-                r = path_find_first_component(&todo, true, &e);
+                r = path_find_first_component(&todo, /* accept_dot_dot= */ true, &e);
                 if (r < 0)
                         return r;
                 if (r == 0) { /* We reached the end. */
@@ -224,9 +236,9 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                         if (empty_or_root(done))
                                 continue;
 
-                        parent = dirname_malloc(done);
-                        if (!parent)
-                                return -ENOMEM;
+                        r = path_extract_directory(done, &parent);
+                        if (r < 0)
+                                return r;
 
                         /* Don't allow this to leave the root dir.  */
                         if (root &&
@@ -311,7 +323,7 @@ int chase_symlinks(const char *path, const char *original_root, unsigned flags,
                                  * directory as base. */
 
                                 safe_close(fd);
-                                fd = open(root ?: "/", O_CLOEXEC|O_DIRECTORY|O_PATH);
+                                fd = open(empty_to_root(root), O_CLOEXEC|O_DIRECTORY|O_PATH);
                                 if (fd < 0)
                                         return -errno;
 
@@ -375,7 +387,7 @@ chased_one:
                 const char *e;
 
                 /* todo may contain slashes at the beginning. */
-                r = path_find_first_component(&todo, true, &e);
+                r = path_find_first_component(&todo, /* accept_dot_dot= */ true, &e);
                 if (r < 0)
                         return r;
                 if (r == 0)
@@ -397,7 +409,7 @@ chased_one:
 int chase_symlinks_and_open(
                 const char *path,
                 const char *root,
-                unsigned chase_flags,
+                ChaseSymlinksFlags chase_flags,
                 int open_flags,
                 char **ret_path) {
 
@@ -435,7 +447,7 @@ int chase_symlinks_and_open(
 int chase_symlinks_and_opendir(
                 const char *path,
                 const char *root,
-                unsigned chase_flags,
+                ChaseSymlinksFlags chase_flags,
                 char **ret_path,
                 DIR **ret_dir) {
 
@@ -478,7 +490,7 @@ int chase_symlinks_and_opendir(
 int chase_symlinks_and_stat(
                 const char *path,
                 const char *root,
-                unsigned chase_flags,
+                ChaseSymlinksFlags chase_flags,
                 char **ret_path,
                 struct stat *ret_stat,
                 int *ret_fd) {
@@ -520,7 +532,7 @@ int chase_symlinks_and_stat(
 int chase_symlinks_and_fopen_unlocked(
                 const char *path,
                 const char *root,
-                unsigned chase_flags,
+                ChaseSymlinksFlags chase_flags,
                 const char *open_flags,
                 char **ret_path,
                 FILE **ret_file) {

src/basic/chase-symlinks.h

@@ -6,7 +6,7 @@
 
 #include "stat-util.h"
 
-enum {
+typedef enum ChaseSymlinksFlags {
         CHASE_PREFIX_ROOT = 1 << 0, /* The specified path will be prefixed by the specified root before beginning the iteration */
         CHASE_NONEXISTENT = 1 << 1, /* It's OK if the path doesn't actually exist. */
         CHASE_NO_AUTOFS   = 1 << 2, /* Return -EREMOTE if autofs mount point found */
@@ -16,17 +16,17 @@ enum {
         CHASE_NOFOLLOW    = 1 << 6, /* Do not follow the path's right-most component. With ret_fd, when the path's
                                      * right-most component refers to symlink, return O_PATH fd of the symlink. */
         CHASE_WARN        = 1 << 7, /* Emit an appropriate warning when an error is encountered */
-};
+} ChaseSymlinksFlags;
 
 bool unsafe_transition(const struct stat *a, const struct stat *b);
 
 /* How many iterations to execute before returning -ELOOP */
 #define CHASE_SYMLINKS_MAX 32
 
-int chase_symlinks(const char *path_with_prefix, const char *root, unsigned flags, char **ret_path, int *ret_fd);
+int chase_symlinks(const char *path_with_prefix, const char *root, ChaseSymlinksFlags chase_flags, char **ret_path, int *ret_fd);
 
-int chase_symlinks_and_open(const char *path, const char *root, unsigned chase_flags, int open_flags, char **ret_path);
-int chase_symlinks_and_opendir(const char *path, const char *root, unsigned chase_flags, char **ret_path, DIR **ret_dir);
-int chase_symlinks_and_stat(const char *path, const char *root, unsigned chase_flags, char **ret_path, struct stat *ret_stat, int *ret_fd);
+int chase_symlinks_and_open(const char *path, const char *root, ChaseSymlinksFlags chase_flags, int open_flags, char **ret_path);
+int chase_symlinks_and_opendir(const char *path, const char *root, ChaseSymlinksFlags chase_flags, char **ret_path, DIR **ret_dir);
+int chase_symlinks_and_stat(const char *path, const char *root, ChaseSymlinksFlags chase_flags, char **ret_path, struct stat *ret_stat, int *ret_fd);
 
-int chase_symlinks_and_fopen_unlocked(const char *path, const char *root, unsigned chase_flags, const char *open_flags, char **ret_path, FILE **ret_file);
+int chase_symlinks_and_fopen_unlocked(const char *path, const char *root, ChaseSymlinksFlags chase_flags, const char *open_flags, char **ret_path, FILE **ret_file);

src/core/main.c

@@ -2051,7 +2051,7 @@ static void log_execution_mode(bool *ret_first_boot) {
                         }
                 }
 
-                assert(uname(&uts) >= 0);
+                assert_se(uname(&uts) >= 0);
 
                 if (strverscmp_improved(uts.release, KERNEL_BASELINE_VERSION) < 0)
                         log_warning("Warning! Reported kernel version %s is older than systemd's required baseline kernel version %s. "