Introduce ERRNO_IS_FS_WRITE_REFUSED(), and use it in binfmt_mounted() (#38117)

- This introduces ERRNO_IS_FS_WRITE_REFUSED(), and apply it where
usable.
- This makes unexpected errors in access_fd() called by binfmt_mounted()
propagated to the caller.
- Renames binfmt_mounted() to binfmt_mounted_and_writable(), as it also
checks the fs is writable.
- Voidifies one disable_binfmt() call in shutdown.c.

src/basic/errno-util.h

@@ -188,6 +188,12 @@ static inline bool ERRNO_IS_NEG_PRIVILEGE(intmax_t r) {
 }
 _DEFINE_ABS_WRAPPER(PRIVILEGE);
 
+/* Three different errors for writing on a filesystem */
+static inline bool ERRNO_IS_NEG_FS_WRITE_REFUSED(intmax_t r) {
+        return r == -EROFS || ERRNO_IS_NEG_PRIVILEGE(r);
+}
+_DEFINE_ABS_WRAPPER(FS_WRITE_REFUSED);
+
 /* Three different errors for "not enough disk space" */
 static inline bool ERRNO_IS_NEG_DISK_SPACE(intmax_t r) {
         return IN_SET(r,

src/binfmt/binfmt.c

@@ -193,10 +193,10 @@ static int parse_argv(int argc, char *argv[]) {
         return 1;
 }
 
-static int binfmt_mounted_warn(void) {
+static int binfmt_mounted_and_writable_warn(void) {
         int r;
 
-        r = binfmt_mounted();
+        r = binfmt_mounted_and_writable();
         if (r < 0)
                 return log_error_errno(r, "Failed to check if /proc/sys/fs/binfmt_misc is mounted: %m");
         if (r == 0)
@@ -222,7 +222,7 @@ static int run(int argc, char *argv[]) {
                 return disable_binfmt();
 
         if (argc > optind) {
-                r = binfmt_mounted_warn();
+                r = binfmt_mounted_and_writable_warn();
                 if (r <= 0)
                         return r;
 
@@ -239,7 +239,7 @@ static int run(int argc, char *argv[]) {
                 if (arg_cat_flags != CAT_CONFIG_OFF)
                         return cat_config(files);
 
-                r = binfmt_mounted_warn();
+                r = binfmt_mounted_and_writable_warn();
                 if (r <= 0)
                         return r;
 

src/core/cgroup.c

@@ -62,7 +62,7 @@
 /* Returns the log level to use when cgroup attribute writes fail. When an attribute is missing or we have access
  * problems we downgrade to LOG_DEBUG. This is supposed to be nice to container managers and kernels which want to mask
  * out specific attributes from us. */
-#define LOG_LEVEL_CGROUP_WRITE(r) (IN_SET(ABS(r), ENOENT, EROFS, EACCES, EPERM) ? LOG_DEBUG : LOG_WARNING)
+#define LOG_LEVEL_CGROUP_WRITE(r) ((ABS(r) == ENOENT || ERRNO_IS_FS_WRITE_REFUSED(r)) ? LOG_DEBUG : LOG_WARNING)
 
 static void unit_remove_from_cgroup_empty_queue(Unit *u);
 

src/core/main.c

@@ -1271,8 +1271,8 @@ static void bump_file_max_and_nr_open(void) {
          * different, but the operation would fail silently.) */
         r = sysctl_write("fs/file-max", LONG_MAX_STR);
         if (r < 0)
-                log_full_errno(IN_SET(r, -EROFS, -EPERM, -EACCES) ? LOG_DEBUG : LOG_WARNING,
-                               r, "Failed to bump fs.file-max, ignoring: %m");
+                log_full_errno(ERRNO_IS_NEG_FS_WRITE_REFUSED(r) ? LOG_DEBUG : LOG_WARNING, r,
+                               "Failed to bump fs.file-max, ignoring: %m");
 #endif
 
 #if BUMP_PROC_SYS_FS_NR_OPEN
@@ -1293,7 +1293,8 @@ static void bump_file_max_and_nr_open(void) {
                         continue;
                 }
                 if (r < 0) {
-                        log_full_errno(IN_SET(r, -EROFS, -EPERM, -EACCES) ? LOG_DEBUG : LOG_WARNING, r, "Failed to bump fs.nr_open, ignoring: %m");
+                        log_full_errno(ERRNO_IS_NEG_FS_WRITE_REFUSED(r) ? LOG_DEBUG : LOG_WARNING, r,
+                                       "Failed to bump fs.nr_open, ignoring: %m");
                         break;
                 }
 
@@ -1534,7 +1535,7 @@ static int bump_unix_max_dgram_qlen(void) {
 
         r = sysctl_write("net/unix/max_dgram_qlen", STRINGIFY(DEFAULT_UNIX_MAX_DGRAM_QLEN));
         if (r < 0)
-                return log_full_errno(IN_SET(r, -EROFS, -EPERM, -EACCES) ? LOG_DEBUG : LOG_WARNING, r,
+                return log_full_errno(ERRNO_IS_NEG_FS_WRITE_REFUSED(r) ? LOG_DEBUG : LOG_WARNING, r,
                                       "Failed to bump AF_UNIX datagram queue length, ignoring: %m");
 
         return 1;

src/core/mount.c

@@ -1269,7 +1269,7 @@ static void mount_enter_mounting(Mount *m) {
                  * when the path is on NFS. See issue #24120. All such errors will be logged in the debug level. */
                 if (r < 0 && r != -EEXIST)
                         log_unit_full_errno(UNIT(m),
-                                            (r == -EROFS || ERRNO_IS_PRIVILEGE(r)) ? LOG_DEBUG : LOG_WARNING,
+                                            ERRNO_IS_NEG_FS_WRITE_REFUSED(r) ? LOG_DEBUG : LOG_WARNING,
                                             r, "Failed to make bind mount source '%s', ignoring: %m", p->what);
         }
 

src/nspawn/nspawn.c

@@ -1907,14 +1907,14 @@ static int setup_timezone(const char *dest) {
                         log_debug_errno(r, "Timezone %s does not exist (or is not accessible) in container, not creating symlink: %m", z);
                 else {
                         if (unlink(where) < 0 && errno != ENOENT) {
-                                log_full_errno(IN_SET(errno, EROFS, EACCES, EPERM) ? LOG_DEBUG : LOG_WARNING, /* Don't complain on read-only images */
+                                log_full_errno(ERRNO_IS_FS_WRITE_REFUSED(errno) ? LOG_DEBUG : LOG_WARNING, /* Don't complain on read-only images */
                                                errno, "Failed to remove existing timezone info %s in container, ignoring: %m", where);
                                 return 0;
                         }
 
                         what = strjoina("../usr/share/zoneinfo/", z);
                         if (symlink(what, where) < 0) {
-                                log_full_errno(IN_SET(errno, EROFS, EACCES, EPERM) ? LOG_DEBUG : LOG_WARNING,
+                                log_full_errno(ERRNO_IS_FS_WRITE_REFUSED(errno) ? LOG_DEBUG : LOG_WARNING,
                                                errno, "Failed to correct timezone of container, ignoring: %m");
                                 return 0;
                         }
@@ -1949,7 +1949,7 @@ static int setup_timezone(const char *dest) {
                 /* If mounting failed, try to copy */
                 r = copy_file_atomic("/etc/localtime", where, 0644, COPY_REFLINK|COPY_REPLACE);
                 if (r < 0) {
-                        log_full_errno(IN_SET(r, -EROFS, -EACCES, -EPERM) ? LOG_DEBUG : LOG_WARNING, r,
+                        log_full_errno(ERRNO_IS_NEG_FS_WRITE_REFUSED(r) ? LOG_DEBUG : LOG_WARNING, r,
                                        "Failed to copy /etc/localtime to %s, ignoring: %m", where);
                         return 0;
                 }
@@ -2085,7 +2085,7 @@ static int setup_resolv_conf(const char *dest) {
                  * If the disk image is read-only, there's also no point in complaining.
                  */
                 log_full_errno(!IN_SET(RESOLV_CONF_COPY_HOST, RESOLV_CONF_COPY_STATIC, RESOLV_CONF_COPY_UPLINK, RESOLV_CONF_COPY_STUB) &&
-                               IN_SET(r, -ELOOP, -EROFS, -EACCES, -EPERM) ? LOG_DEBUG : LOG_WARNING, r,
+                               (r == -ELOOP || ERRNO_IS_NEG_FS_WRITE_REFUSED(r)) ? LOG_DEBUG : LOG_WARNING, r,
                                "Failed to copy /etc/resolv.conf to %s, ignoring: %m", where);
                 return 0;
         }

src/shared/binfmt-util.c

@@ -11,7 +11,7 @@
 #include "missing_magic.h"
 #include "stat-util.h"
 
-int binfmt_mounted(void) {
+int binfmt_mounted_and_writable(void) {
         _cleanup_close_ int fd = -EBADF;
         int r;
 
@@ -25,7 +25,13 @@ int binfmt_mounted(void) {
         if (r <= 0)
                 return r;
 
-        return access_fd(fd, W_OK) >= 0;
+        r = access_fd(fd, W_OK);
+        if (ERRNO_IS_NEG_FS_WRITE_REFUSED(r))
+                return false;
+        if (r < 0)
+                return r;
+
+        return true;
 }
 
 int disable_binfmt(void) {
@@ -37,7 +43,7 @@ int disable_binfmt(void) {
          * We are a bit careful here, since binfmt_misc might still be an autofs which we don't want to
          * trigger. */
 
-        r = binfmt_mounted();
+        r = binfmt_mounted_and_writable();
         if (r < 0)
                 return log_warning_errno(r, "Failed to determine whether binfmt_misc is mounted: %m");
         if (r == 0) {

src/shared/binfmt-util.h

@@ -1,5 +1,5 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #pragma once
 
-int binfmt_mounted(void);
+int binfmt_mounted_and_writable(void);
 int disable_binfmt(void);

src/shared/loop-util.c

@@ -660,7 +660,7 @@ int loop_device_make_by_path_at(
                 r = fd;
 
                 /* Retry read-only? */
-                if (open_flags >= 0 || !(ERRNO_IS_PRIVILEGE(r) || r == -EROFS))
+                if (open_flags >= 0 || !ERRNO_IS_NEG_FS_WRITE_REFUSED(r))
                         return r;
 
                 fd = xopenat(dir_fd, path, basic_flags|direct_flags|O_RDONLY);

src/shutdown/shutdown.c

@@ -447,7 +447,7 @@ int main(int argc, char *argv[]) {
                 (void) sync_with_progress(-EBADF);
 
         disable_coredumps();
-        disable_binfmt();
+        (void) disable_binfmt();
 
         log_info("Sending SIGTERM to remaining processes...");
         broadcast_signal(SIGTERM, true, true, arg_timeout);

src/ssh-generator/ssh-generator.c

@@ -321,7 +321,7 @@ static int add_export_unix_socket(
                         log_debug("Container manager does not provide /run/host/unix-export/ mount, not binding AF_UNIX socket there.");
                         return 0;
                 }
-                if (errno == EROFS || ERRNO_IS_PRIVILEGE(errno)) {
+                if (ERRNO_IS_FS_WRITE_REFUSED(errno)) {
                         log_debug("Container manager does not provide write access to /run/host/unix-export/, not binding AF_UNIX socket there.");
                         return 0;
                 }

src/sysctl/sysctl.c

@@ -95,7 +95,7 @@ static int sysctl_write_or_warn(const char *key, const char *value, bool ignore_
                  * permission problem here, since that's how container managers usually protected their
                  * sysctls.)
                  * In all other cases log an error and make the tool fail. */
-                if (ignore_failure || (!arg_strict && (r == -EROFS || ERRNO_IS_PRIVILEGE(r))))
+                if (ignore_failure || (!arg_strict && ERRNO_IS_NEG_FS_WRITE_REFUSED(r)))
                         log_debug_errno(r, "Couldn't write '%s' to '%s', ignoring: %m", value, key);
                 else if (ignore_enoent && r == -ENOENT)
                         log_warning_errno(r, "Couldn't write '%s' to '%s', ignoring: %m", value, key);

src/test/test-binfmt-util.c

@@ -3,8 +3,8 @@
 #include "binfmt-util.h"
 #include "tests.h"
 
-TEST(binfmt_mounted) {
-        ASSERT_OK(binfmt_mounted());
+TEST(binfmt_mounted_and_writable) {
+        ASSERT_OK(binfmt_mounted_and_writable());
 }
 
 DEFINE_TEST_MAIN(LOG_DEBUG);

src/test/test-cgroup.c

@@ -64,10 +64,8 @@ TEST(cg_create) {
         (void) cg_trim(test_b, /* delete_root= */ true);
 
         r = cg_create(test_a);
-        if (IN_SET(r, -EPERM, -EACCES, -EROFS)) {
-                log_info_errno(r, "Skipping %s: %m", __func__);
-                return;
-        }
+        if (ERRNO_IS_NEG_FS_WRITE_REFUSED(r))
+                return (void) log_tests_skipped_errno(r, "%s: Failed to create cgroup %s", __func__, test_a);
 
         ASSERT_OK_EQ(r, 1);
         ASSERT_OK_ZERO(cg_create(test_a));

src/test/test-procfs-util.c

@@ -51,7 +51,7 @@ int main(int argc, char *argv[]) {
                 log_info("Reducing limit by one to %"PRIu64"…", limit-1);
 
                 r = procfs_tasks_set_limit(limit-1);
-                if (IN_SET(r, -ENOENT, -EROFS) || ERRNO_IS_PRIVILEGE(r))
+                if (r == -ENOENT || ERRNO_IS_NEG_FS_WRITE_REFUSED(r))
                         return log_tests_skipped_errno(r, "can't set tasks limit");
                 assert_se(r >= 0);
 

src/test/test-sysctl-util.c

@@ -54,14 +54,14 @@ TEST(sysctl_read) {
         assert_se(STR_IN_SET(s, "0", "1"));
 
         r = sysctl_write_ip_property(AF_INET, "lo", "forwarding", s, NULL);
-        assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r) || r == -EROFS);
+        assert_se(r >= 0 || ERRNO_IS_NEG_FS_WRITE_REFUSED(r));
         s = mfree(s);
 
         assert_se(sysctl_read_ip_property(AF_INET, NULL, "ip_forward", &s));
         assert_se(STR_IN_SET(s, "0", "1"));
 
         r = sysctl_write_ip_property(AF_INET, NULL, "ip_forward", s, NULL);
-        assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r) || r == -EROFS);
+        assert_se(r >= 0 || ERRNO_IS_NEG_FS_WRITE_REFUSED(r));
         s = mfree(s);
 
         assert_se(sysctl_read("kernel/hostname", &s) >= 0);
@@ -69,7 +69,7 @@ TEST(sysctl_read) {
         ASSERT_STREQ(s, u.nodename);
 
         r = sysctl_write("kernel/hostname", s);
-        assert_se(r >= 0 || ERRNO_IS_PRIVILEGE(r) || r == -EROFS);
+        assert_se(r >= 0 || ERRNO_IS_NEG_FS_WRITE_REFUSED(r));
 }
 
 DEFINE_TEST_MAIN(LOG_INFO);