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

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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.
This commit is contained in:
Lennart Poettering 2022-11-11 17:36:29 +01:00 committed by Yu Watanabe
parent d43e78b643
commit b353d5eee9
2 changed files with 13 additions and 13 deletions
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18
src/boot/bootctl.c
View File

@ -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)

8
src/shared/bootspec.c
View File

@ -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) {