556567f40
Denys Vlasenko
2026-09-22
Subject
mount: document a possible bug in comment, no code changes.
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util-linux/mount.c+22 -5
| @@ -321,8 +321,8 @@ enum { | |
| // TODO: more "user" flag compatibility. | |
| // "user" option (from mount manpage): | |
| // Only the user that mounted a filesystem can unmount it again. | |
| - | // If any user should be able to unmount, then use users instead of user |
| - | // in the fstab line. The owner option is similar to the user option, |
| + | // If any user should be able to unmount, then use "users" instead of "user" |
| + | // in the fstab line. The "owner" option is similar to the "user" option, |
| // with the restriction that the user must be the owner of the special file. | |
| // This may be useful e.g. for /dev/fd if a login script makes | |
| // the console user owner of this device. | |
| @@ -595,7 +595,7 @@ static void append_mount_options(char **oldopts, const char *newopts) | |
| // Use the mount_options list to parse options into flags. | |
| // Also update list of unrecognized options if unrecognized != NULL | |
| - | static unsigned long parse_mount_options(char *options, char **unrecognized, uint32_t *opt) |
| + | static unsigned long parse_mount_options(char *options, char **unrecognized, uint32_t *optmask32) |
| { | |
| unsigned long flags = MS_SILENT; | |
| @@ -626,8 +626,8 @@ static unsigned long parse_mount_options(char *options, char **unrecognized, uin | |
| /* If we see "-o rw" on command line, it's the same as -w: | |
| * "do not try to fall back to RO mounts" | |
| */ | |
| - | if (fl == ~MS_RDONLY && opt) |
| - | (*opt) |= OPT_w; |
| + | if (fl == ~MS_RDONLY && optmask32) |
| + | (*optmask32) |= OPT_w; |
| goto found; | |
| } | |
| option_str += opt_len + 1; | |
| @@ -2368,6 +2368,23 @@ int mount_main(int argc UNUSED_PARAM, char **argv) | |
| cmdopt_flags = parse_mount_options(cmdopts, NULL, &option_mask32); | |
| if (nonroot && (cmdopt_flags & ~MS_SILENT)) // Non-root users cannot specify flags | |
| bb_simple_error_msg_and_die(bb_msg_you_must_be_root); | |
| + | // NB: parse_mount_options() starts with just MS_SILENT and adds bits as it sees options. |
| + | // Some options clear a flag, not set it: |
| + | // suid ~MS_NOSUID |
| + | // dev ~MS_NODEV |
| + | // exec ~MS_NOEXEC |
| + | // async ~MS_SYNCHRONOUS |
| + | // atime ~MS_NOATIME |
| + | // diratime ~MS_NODIRATIME |
| + | // norelatime ~MS_RELATIME |
| + | // nostrictatime ~MS_STRICTATIME |
| + | // nolazytime ~MS_LAZYTIME |
| + | // nomand ~MS_MANDLOCK |
| + | // rw ~MS_RDONLY |
| + | // therefore the above check does not catch them, |
| + | // they are allowed for non-root (and ignored): they essentially request a default behavior. |
| + | // Is it a bug? |
| + | // Should they be disallowed for non-root, and override fstab options for "mount -o OPTS ONE_PARAM" form for root? |
| // If we have a shared subtree flag, don't worry about fstab or mtab. | |
| if (ENABLE_FEATURE_MOUNT_FLAGS | |