145 lines
5.2 KiB
Diff
145 lines
5.2 KiB
Diff
From 6cb356ca9fe063846cfb883ef484f7e7e411096c Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Tue, 3 Mar 2020 11:51:50 +0100
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Subject: [PATCH 2/3] basic/fs-util: add a version of chmod_and_chown that
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doesn not use /proc
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---
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src/basic/fs-util.c | 46 +++++++++++++++++++++++++++++++++++++++++
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src/basic/fs-util.h | 1 +
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src/test/test-fs-util.c | 45 ++++++++++++++++++++++++++++++++++++++++
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3 files changed, 92 insertions(+)
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diff --git a/src/basic/fs-util.c b/src/basic/fs-util.c
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index f8095e85d8..558cafbcaf 100644
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--- a/src/basic/fs-util.c
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+++ b/src/basic/fs-util.c
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@@ -272,6 +272,52 @@ int fchmod_and_chown(int fd, mode_t mode, uid_t uid, gid_t gid) {
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return do_chown || do_chmod;
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}
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+int chmod_and_chown_unsafe(const char *path, mode_t mode, uid_t uid, gid_t gid) {
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+ bool do_chown, do_chmod;
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+ struct stat st;
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+
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+ assert(path);
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+
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+ /* Change ownership and access mode of the specified path, see description of fchmod_and_chown().
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+ * Should only be used on trusted paths. */
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+
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+ if (lstat(path, &st) < 0)
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+ return -errno;
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+
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+ do_chown =
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+ (uid != UID_INVALID && st.st_uid != uid) ||
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+ (gid != GID_INVALID && st.st_gid != gid);
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+
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+ do_chmod =
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+ !S_ISLNK(st.st_mode) && /* chmod is not defined on symlinks */
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+ ((mode != MODE_INVALID && ((st.st_mode ^ mode) & 07777) != 0) ||
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+ do_chown); /* If we change ownership, make sure we reset the mode afterwards, since chown()
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+ * modifies the access mode too */
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+
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+ if (mode == MODE_INVALID)
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+ mode = st.st_mode; /* If we only shall do a chown(), save original mode, since chown() might break it. */
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+ else if ((mode & S_IFMT) != 0 && ((mode ^ st.st_mode) & S_IFMT) != 0)
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+ return -EINVAL; /* insist on the right file type if it was specified */
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+
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+ if (do_chown && do_chmod) {
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+ mode_t minimal = st.st_mode & mode; /* the subset of the old and the new mask */
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+
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+ if (((minimal ^ st.st_mode) & 07777) != 0)
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+ if (chmod(path, minimal & 07777) < 0)
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+ return -errno;
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+ }
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+
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+ if (do_chown)
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+ if (lchown(path, uid, gid) < 0)
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+ return -errno;
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+
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+ if (do_chmod)
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+ if (chmod(path, mode & 07777) < 0)
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+ return -errno;
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+
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+ return do_chown || do_chmod;
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+}
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+
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int fchmod_umask(int fd, mode_t m) {
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mode_t u;
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int r;
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diff --git a/src/basic/fs-util.h b/src/basic/fs-util.h
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index 78d68be9fd..6b9ade2ec1 100644
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--- a/src/basic/fs-util.h
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+++ b/src/basic/fs-util.h
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@@ -34,6 +34,7 @@ int readlink_and_make_absolute(const char *p, char **r);
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int chmod_and_chown(const char *path, mode_t mode, uid_t uid, gid_t gid);
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int fchmod_and_chown(int fd, mode_t mode, uid_t uid, gid_t gid);
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+int chmod_and_chown_unsafe(const char *path, mode_t mode, uid_t uid, gid_t gid);
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int fchmod_umask(int fd, mode_t mode);
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int fchmod_opath(int fd, mode_t m);
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diff --git a/src/test/test-fs-util.c b/src/test/test-fs-util.c
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index d0c6fb82bf..d97ccfda3b 100644
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--- a/src/test/test-fs-util.c
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+++ b/src/test/test-fs-util.c
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@@ -802,6 +802,50 @@ static void test_chmod_and_chown(void) {
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assert_se(S_ISLNK(st.st_mode));
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}
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+static void test_chmod_and_chown_unsafe(void) {
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+ _cleanup_(rm_rf_physical_and_freep) char *d = NULL;
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+ _unused_ _cleanup_umask_ mode_t u = umask(0000);
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+ struct stat st;
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+ const char *p;
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+
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+ if (geteuid() != 0)
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+ return;
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+
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+ log_info("/* %s */", __func__);
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+
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+ assert_se(mkdtemp_malloc(NULL, &d) >= 0);
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+
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+ p = strjoina(d, "/reg");
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+ assert_se(mknod(p, S_IFREG | 0123, 0) >= 0);
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+
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+ assert_se(chmod_and_chown_unsafe(p, S_IFREG | 0321, 1, 2) >= 0);
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+ assert_se(chmod_and_chown_unsafe(p, S_IFDIR | 0555, 3, 4) == -EINVAL);
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+
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+ assert_se(lstat(p, &st) >= 0);
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+ assert_se(S_ISREG(st.st_mode));
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+ assert_se((st.st_mode & 07777) == 0321);
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+
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+ p = strjoina(d, "/dir");
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+ assert_se(mkdir(p, 0123) >= 0);
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+
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+ assert_se(chmod_and_chown_unsafe(p, S_IFDIR | 0321, 1, 2) >= 0);
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+ assert_se(chmod_and_chown_unsafe(p, S_IFREG | 0555, 3, 4) == -EINVAL);
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+
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+ assert_se(lstat(p, &st) >= 0);
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+ assert_se(S_ISDIR(st.st_mode));
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+ assert_se((st.st_mode & 07777) == 0321);
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+
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+ p = strjoina(d, "/lnk");
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+ assert_se(symlink("idontexist", p) >= 0);
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+
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+ assert_se(chmod_and_chown_unsafe(p, S_IFLNK | 0321, 1, 2) >= 0);
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+ assert_se(chmod_and_chown_unsafe(p, S_IFREG | 0555, 3, 4) == -EINVAL);
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+ assert_se(chmod_and_chown_unsafe(p, S_IFDIR | 0555, 3, 4) == -EINVAL);
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+
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+ assert_se(lstat(p, &st) >= 0);
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+ assert_se(S_ISLNK(st.st_mode));
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+}
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+
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int main(int argc, char *argv[]) {
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test_setup_logging(LOG_INFO);
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@@ -819,6 +863,7 @@ int main(int argc, char *argv[]) {
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test_fsync_directory_of_file();
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test_rename_noreplace();
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test_chmod_and_chown();
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+ test_chmod_and_chown_unsafe();
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return 0;
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}
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