bootctl,bootspec: make use of CHASE_PROHIBIT_SYMLINKS whenever we access the ESP...

Let's make use of the new flag whenever we access the ESP or XBOOTLDR.
The resources we make use of in these partitions can't possibly use
symlinks (because UEFI knows no symlink concept), and they are untrusted
territory, hence under no circumstances we should be tricked into
following symlinks that shouldn't be there in the first place.

Of course, you might argue thta ESP/XBOOTLDR are VFAT and thus don#t
know symlinks. But the thing is, they don#t have to be. Firmware can
support other file systems too, and people can use efifs to gain access
to arbitrary Linux file systems from EFI. Hence, let's better be safe
than sorry.

diff --git a/src/boot/bootctl.c b/src/boot/bootctl.c
index 79b26765373c6d5d4ef5d879d3e6feb40c6d8d72..0f142bff87ee9bda60aa0aefb39542dc7ff993de 100644 (file)
--- a/src/boot/bootctl.c
+++ b/src/boot/bootctl.c
@@ -484,7 +484,7 @@ static int enumerate_binaries(
         assert(previous);
         assert(is_first);
 
-        r = chase_symlinks_and_opendir(path, esp_path, CHASE_PREFIX_ROOT, &p, &d);
+        r = chase_symlinks_and_opendir(path, esp_path, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &p, &d);
         if (r == -ENOENT)
                 return 0;
         if (r < 0)
@@ -913,10 +913,10 @@ static int copy_one_file(const char *esp_path, const char *name, bool force) {
         if (!p)
                 return log_oom();
 
-        r = chase_symlinks(p, root, CHASE_PREFIX_ROOT, &source_path, NULL);
+        r = chase_symlinks(p, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &source_path, NULL);
         /* If we had a root directory to try, we didn't find it and we are in auto mode, retry on the host */
         if (r == -ENOENT && root && arg_install_source == ARG_INSTALL_SOURCE_AUTO)
-                r = chase_symlinks(p, NULL, CHASE_PREFIX_ROOT, &source_path, NULL);
+                r = chase_symlinks(p, NULL, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &source_path, NULL);
         if (r < 0)
                 return log_error_errno(r,
                                        "Failed to resolve path %s%s%s: %m",
@@ -928,7 +928,7 @@ static int copy_one_file(const char *esp_path, const char *name, bool force) {
         if (!q)
                 return log_oom();
 
-        r = chase_symlinks(q, esp_path, CHASE_PREFIX_ROOT | CHASE_NONEXISTENT, &dest_path, NULL);
+        r = chase_symlinks(q, esp_path, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS|CHASE_NONEXISTENT, &dest_path, NULL);
         if (r < 0)
                 return log_error_errno(r, "Failed to resolve path %s under directory %s: %m", q, esp_path);
 
@@ -945,7 +945,7 @@ static int copy_one_file(const char *esp_path, const char *name, bool force) {
                 v = strjoina("/EFI/BOOT/BOOT", e);
                 ascii_strupper(strrchr(v, '/') + 1);
 
-                r = chase_symlinks(v, esp_path, CHASE_PREFIX_ROOT | CHASE_NONEXISTENT, &default_dest_path, NULL);
+                r = chase_symlinks(v, esp_path, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS|CHASE_NONEXISTENT, &default_dest_path, NULL);
                 if (r < 0)
                         return log_error_errno(r, "Failed to resolve path %s under directory %s: %m", v, esp_path);
 
@@ -963,10 +963,10 @@ static int install_binaries(const char *esp_path, const char *arch, bool force)
         _cleanup_free_ char *path = NULL;
         int r;
 
-        r = chase_symlinks_and_opendir(BOOTLIBDIR, root, CHASE_PREFIX_ROOT, &path, &d);
+        r = chase_symlinks_and_opendir(BOOTLIBDIR, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &path, &d);
         /* If we had a root directory to try, we didn't find it and we are in auto mode, retry on the host */
         if (r == -ENOENT && root && arg_install_source == ARG_INSTALL_SOURCE_AUTO)
-                r = chase_symlinks_and_opendir(BOOTLIBDIR, NULL, CHASE_PREFIX_ROOT, &path, &d);
+                r = chase_symlinks_and_opendir(BOOTLIBDIR, NULL, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &path, &d);
         if (r < 0)
                 return log_error_errno(r, "Failed to open boot loader directory %s%s: %m", strempty(root), BOOTLIBDIR);
 
@@ -1136,7 +1136,7 @@ static int install_variables(
                 return 0;
         }
 
-        r = chase_symlinks_and_access(path, esp_path, CHASE_PREFIX_ROOT, F_OK, NULL, NULL);
+        r = chase_symlinks_and_access(path, esp_path, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, F_OK, NULL, NULL);
         if (r == -ENOENT)
                 return 0;
         if (r < 0)
@@ -1167,7 +1167,7 @@ static int remove_boot_efi(const char *esp_path) {
         _cleanup_free_ char *p = NULL;
         int r, c = 0;
 
-        r = chase_symlinks_and_opendir("/EFI/BOOT", esp_path, CHASE_PREFIX_ROOT, &p, &d);
+        r = chase_symlinks_and_opendir("/EFI/BOOT", esp_path, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &p, &d);
         if (r == -ENOENT)
                 return 0;
         if (r < 0)

diff --git a/src/shared/bootspec.c b/src/shared/bootspec.c
index c3015487c502aacdc813265366449fe1cedc32a8..0afc41d200bd03d23f5afbe10cd1cffbdefb0d0a 100644 (file)
--- a/src/shared/bootspec.c
+++ b/src/shared/bootspec.c
@@ -508,7 +508,7 @@ static int boot_loader_read_conf_path(BootConfig *config, const char *root, cons
         assert(config);
         assert(path);
 
-        r = chase_symlinks_and_fopen_unlocked(path, root, CHASE_PREFIX_ROOT, "re", &full, &f);
+        r = chase_symlinks_and_fopen_unlocked(path, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, "re", &full, &f);
         if (r == -ENOENT)
                 return 0;
         if (r < 0)
@@ -593,7 +593,7 @@ static int boot_entries_find_type1(
         assert(root);
         assert(dir);
 
-        dir_fd = chase_symlinks_and_open(dir, root, CHASE_PREFIX_ROOT, O_DIRECTORY|O_CLOEXEC, &full);
+        dir_fd = chase_symlinks_and_open(dir, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, O_DIRECTORY|O_CLOEXEC, &full);
         if (dir_fd == -ENOENT)
                 return 0;
         if (dir_fd < 0)
@@ -853,7 +853,7 @@ static int boot_entries_find_unified(
         assert(config);
         assert(dir);
 
-        r = chase_symlinks_and_opendir(dir, root, CHASE_PREFIX_ROOT, &full, &d);
+        r = chase_symlinks_and_opendir(dir, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, &full, &d);
         if (r == -ENOENT)
                 return 0;
         if (r < 0)
@@ -1260,7 +1260,7 @@ static void boot_entry_file_list(
         assert(p);
         assert(ret_status);
 
-        int status = chase_symlinks_and_access(p, root, CHASE_PREFIX_ROOT, F_OK, NULL, NULL);
+        int status = chase_symlinks_and_access(p, root, CHASE_PREFIX_ROOT|CHASE_PROHIBIT_SYMLINKS, F_OK, NULL, NULL);
 
         printf("%13s%s ", strempty(field), field ? ":" : " ");
         if (status < 0) {