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Merge pull request #26883 from yuwata/rm-rf

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rm-rf: also chmod directory if cannot be opened
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2023-03-30 14:54:59 +02:00 committed by GitHub
commit e61bab2b55
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2 changed files with 193 additions and 32 deletions
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161
src/shared/rm-rf.c
View File

@ -11,6 +11,7 @@
#include "cgroup-util.h"
#include "dirent-util.h"
#include "fd-util.h"
#include "fs-util.h"
#include "log.h"
#include "macro.h"
#include "mountpoint-util.h"
@ -28,9 +29,11 @@ static bool is_physical_fs(const struct statfs *sfs) {
static int patch_dirfd_mode(
int dfd,
bool refuse_already_set,
mode_t *ret_old_mode) {
struct stat st;
int r;
assert(dfd >= 0);
assert(ret_old_mode);
@ -39,16 +42,24 @@ static int patch_dirfd_mode(
return -errno;
if (!S_ISDIR(st.st_mode))
return -ENOTDIR;
if (FLAGS_SET(st.st_mode, 0700)) /* Already set? */
return -EACCES; /* original error */
if (FLAGS_SET(st.st_mode, 0700)) { /* Already set? */
if (refuse_already_set)
return -EACCES; /* original error */
*ret_old_mode = st.st_mode;
return 0;
}
if (st.st_uid != geteuid()) /* this only works if the UID matches ours */
return -EACCES;
if (fchmod(dfd, (st.st_mode | 0700) & 07777) < 0)
return -errno;
r = fchmod_opath(dfd, (st.st_mode | 0700) & 07777);
if (r < 0)
return r;
*ret_old_mode = st.st_mode;
return 0;
return 1;
}
int unlinkat_harder(int dfd, const char *filename, int unlink_flags, RemoveFlags remove_flags) {
@ -64,18 +75,18 @@ int unlinkat_harder(int dfd, const char *filename, int unlink_flags, RemoveFlags
if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
return -errno;
r = patch_dirfd_mode(dfd, &old_mode);
r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
if (r < 0)
return r;
if (unlinkat(dfd, filename, unlink_flags) < 0) {
r = -errno;
/* Try to restore the original access mode if this didn't work */
(void) fchmod(dfd, old_mode);
(void) fchmod(dfd, old_mode & 07777);
return r;
}
if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 0)
if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
return -errno;
/* If this worked, we won't reset the old mode by default, since we'll need it for other entries too,
@ -99,22 +110,84 @@ int fstatat_harder(int dfd,
if (errno != EACCES || !FLAGS_SET(remove_flags, REMOVE_CHMOD))
return -errno;
r = patch_dirfd_mode(dfd, &old_mode);
r = patch_dirfd_mode(dfd, /* refuse_already_set = */ true, &old_mode);
if (r < 0)
return r;
if (fstatat(dfd, filename, ret, fstatat_flags) < 0) {
r = -errno;
(void) fchmod(dfd, old_mode);
(void) fchmod(dfd, old_mode & 07777);
return r;
}
if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode) < 0)
if (FLAGS_SET(remove_flags, REMOVE_CHMOD_RESTORE) && fchmod(dfd, old_mode & 07777) < 0)
return -errno;
return 0;
}
static int openat_harder(int dfd, const char *path, int open_flags, RemoveFlags remove_flags, mode_t *ret_old_mode) {
_cleanup_close_ int pfd = -EBADF, fd = -EBADF;
bool chmod_done = false;
mode_t old_mode;
int r;
assert(dfd >= 0 || dfd == AT_FDCWD);
assert(path);
/* Unlike unlink_harder() and fstatat_harder(), this chmod the specified path. */
if (FLAGS_SET(open_flags, O_PATH) ||
!FLAGS_SET(open_flags, O_DIRECTORY) ||
!FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
fd = RET_NERRNO(openat(dfd, path, open_flags));
if (fd < 0)
return fd;
if (ret_old_mode) {
struct stat st;
if (fstat(fd, &st) < 0)
return -errno;
*ret_old_mode = st.st_mode;
}
return TAKE_FD(fd);
}
pfd = RET_NERRNO(openat(dfd, path, (open_flags & (O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW)) | O_PATH));
if (pfd < 0)
return pfd;
if (FLAGS_SET(remove_flags, REMOVE_CHMOD)) {
r = patch_dirfd_mode(pfd, /* refuse_already_set = */ false, &old_mode);
if (r < 0)
return r;
chmod_done = r;
}
fd = fd_reopen(pfd, open_flags);
if (fd < 0) {
if (chmod_done)
(void) fchmod_opath(pfd, old_mode & 07777);
return fd;
}
if (ret_old_mode)
*ret_old_mode = old_mode;
return TAKE_FD(fd);
}
static int rm_rf_children_impl(
int fd,
RemoveFlags flags,
const struct stat *root_dev,
mode_t old_mode);
static int rm_rf_inner_child(
int fd,
const char *fname,
@ -169,13 +242,16 @@ static int rm_rf_inner_child(
if (!allow_recursion)
return -EISDIR;
int subdir_fd = openat(fd, fname, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
mode_t old_mode;
int subdir_fd = openat_harder(fd, fname,
O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
flags, &old_mode);
if (subdir_fd < 0)
return -errno;
return subdir_fd;
/* We pass REMOVE_PHYSICAL here, to avoid doing the fstatfs() to check the file system type
* again for each directory */
q = rm_rf_children(subdir_fd, flags | REMOVE_PHYSICAL, root_dev);
q = rm_rf_children_impl(subdir_fd, flags | REMOVE_PHYSICAL, root_dev, old_mode);
} else if (flags & REMOVE_ONLY_DIRECTORIES)
return 0;
@ -191,6 +267,7 @@ static int rm_rf_inner_child(
typedef struct TodoEntry {
DIR *dir; /* A directory that we were operating on. */
char *dirname; /* The filename of that directory itself. */
mode_t old_mode; /* The original file mode. */
} TodoEntry;
static void free_todo_entries(TodoEntry **todos) {
@ -207,6 +284,22 @@ int rm_rf_children(
RemoveFlags flags,
const struct stat *root_dev) {
struct stat st;
assert(fd >= 0);
if (fstat(fd, &st) < 0)
return -errno;
return rm_rf_children_impl(fd, flags, root_dev, st.st_mode);
}
static int rm_rf_children_impl(
int fd,
RemoveFlags flags,
const struct stat *root_dev,
mode_t old_mode) {
_cleanup_(free_todo_entries) TodoEntry *todos = NULL;
size_t n_todo = 0;
_cleanup_free_ char *dirname = NULL; /* Set when we are recursing and want to delete ourselves */
@ -223,14 +316,20 @@ int rm_rf_children(
* We need to remove the inner directory we were operating on. */
assert(dirname);
r = unlinkat_harder(dirfd(todos[n_todo-1].dir), dirname, AT_REMOVEDIR, flags);
if (r < 0 && r != -ENOENT && ret == 0)
ret = r;
if (r < 0 && r != -ENOENT) {
if (ret == 0)
ret = r;
if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE))
(void) fchmodat(dirfd(todos[n_todo-1].dir), dirname, old_mode & 07777, 0);
}
dirname = mfree(dirname);
/* And now let's back out one level up */
n_todo --;
d = TAKE_PTR(todos[n_todo].dir);
dirname = TAKE_PTR(todos[n_todo].dirname);
old_mode = todos[n_todo].old_mode;
assert(d);
fd = dirfd(d); /* Retrieve the file descriptor from the DIR object */
@ -287,17 +386,25 @@ int rm_rf_children(
if (!newdirname)
return log_oom();
int newfd = openat(fd, de->d_name,
O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
mode_t mode;
int newfd = openat_harder(fd, de->d_name,
O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME,
flags, &mode);
if (newfd >= 0) {
todos[n_todo++] = (TodoEntry) { TAKE_PTR(d), TAKE_PTR(dirname) };
todos[n_todo++] = (TodoEntry) {
.dir = TAKE_PTR(d),
.dirname = TAKE_PTR(dirname),
.old_mode = old_mode
};
fd = newfd;
dirname = TAKE_PTR(newdirname);
old_mode = mode;
goto next_fd;
} else if (errno != -ENOENT && ret == 0)
ret = -errno;
} else if (newfd != -ENOENT && ret == 0)
ret = newfd;
} else if (r < 0 && r != -ENOENT && ret == 0)
ret = r;
@ -306,14 +413,20 @@ int rm_rf_children(
if (FLAGS_SET(flags, REMOVE_SYNCFS) && syncfs(fd) < 0 && ret >= 0)
ret = -errno;
if (n_todo == 0)
if (n_todo == 0) {
if (FLAGS_SET(flags, REMOVE_CHMOD_RESTORE) &&
fchmod(fd, old_mode & 07777) < 0 && ret >= 0)
ret = -errno;
break;
}
}
return ret;
}
int rm_rf(const char *path, RemoveFlags flags) {
mode_t old_mode;
int fd, r, q = 0;
assert(path);
@ -345,10 +458,10 @@ int rm_rf(const char *path, RemoveFlags flags) {
/* Not btrfs or not a subvolume */
}
fd = open(path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME);
fd = openat_harder(AT_FDCWD, path, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|O_NOFOLLOW|O_NOATIME, flags, &old_mode);
if (fd >= 0) {
/* We have a dir */
r = rm_rf_children(fd, flags, NULL);
r = rm_rf_children_impl(fd, flags, NULL, old_mode);
if (FLAGS_SET(flags, REMOVE_ROOT))
q = RET_NERRNO(rmdir(path));

64
src/test/test-rm-rf.c
View File

@ -10,31 +10,79 @@
#include "tmpfile-util.h"
static void test_rm_rf_chmod_inner(void) {
_cleanup_free_ char *d = NULL;
const char *x, *y;
_cleanup_(rm_rf_physical_and_freep) char *d = NULL;
const char *a, *b, *x, *y;
struct stat st;
assert_se(getuid() != 0);
assert_se(mkdtemp_malloc(NULL, &d) >= 0);
assert_se(mkdtemp_malloc("/tmp/test-rm-rf.XXXXXXX", &d) >= 0);
a = strjoina(d, "/a");
b = strjoina(a, "/b");
x = strjoina(d, "/x");
y = strjoina(x, "/y");
x = strjoina(d, "/d");
assert_se(mkdir(x, 0700) >= 0);
y = strjoina(x, "/f");
assert_se(mknod(y, S_IFREG | 0600, 0) >= 0);
assert_se(chmod(y, 0400) >= 0);
assert_se(chmod(x, 0500) >= 0);
assert_se(chmod(d, 0500) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_ROOT) == -EACCES);
assert_se(rm_rf(d, REMOVE_PHYSICAL) == -EACCES);
assert_se(access(d, F_OK) >= 0);
assert_se(access(x, F_OK) >= 0);
assert_se(access(y, F_OK) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_ROOT|REMOVE_CHMOD) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_CHMOD) >= 0);
assert_se(access(d, F_OK) >= 0);
assert_se(access(x, F_OK) < 0 && errno == ENOENT);
assert_se(access(y, F_OK) < 0 && errno == ENOENT);
assert_se(mkdir(a, 0700) >= 0);
assert_se(mkdir(b, 0700) >= 0);
assert_se(mkdir(x, 0700) >= 0);
assert_se(mknod(y, S_IFREG | 0600, 0) >= 0);
assert_se(chmod(b, 0000) >= 0);
assert_se(chmod(a, 0000) >= 0);
assert_se(chmod(y, 0000) >= 0);
assert_se(chmod(x, 0000) >= 0);
assert_se(chmod(d, 0500) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_CHMOD|REMOVE_CHMOD_RESTORE|REMOVE_ONLY_DIRECTORIES) == -ENOTEMPTY);
assert_se(access(a, F_OK) < 0 && errno == ENOENT);
assert_se(access(d, F_OK) >= 0);
assert_se(stat(d, &st) >= 0 && (st.st_mode & 07777) == 0500);
assert_se(access(x, F_OK) >= 0);
assert_se(stat(x, &st) >= 0 && (st.st_mode & 07777) == 0000);
assert_se(chmod(x, 0700) >= 0);
assert_se(access(y, F_OK) >= 0);
assert_se(stat(y, &st) >= 0 && (st.st_mode & 07777) == 0000);
assert_se(chmod(y, 0000) >= 0);
assert_se(chmod(x, 0000) >= 0);
assert_se(chmod(d, 0000) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_CHMOD|REMOVE_CHMOD_RESTORE) >= 0);
assert_se(stat(d, &st) >= 0 && (st.st_mode & 07777) == 0000);
assert_se(access(d, F_OK) >= 0);
assert_se(chmod(d, 0700) >= 0);
assert_se(access(x, F_OK) < 0 && errno == ENOENT);
assert_se(mkdir(x, 0700) >= 0);
assert_se(mknod(y, S_IFREG | 0600, 0) >= 0);
assert_se(chmod(y, 0000) >= 0);
assert_se(chmod(x, 0000) >= 0);
assert_se(chmod(d, 0000) >= 0);
assert_se(rm_rf(d, REMOVE_PHYSICAL|REMOVE_CHMOD|REMOVE_ROOT) >= 0);
errno = 0;
assert_se(access(d, F_OK) < 0 && errno == ENOENT);
}