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Don't leak mount flags into kernel

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When calling mount(), care must be taken to avoid passing in flags
that are used only by the user space utilities.  Otherwise we may
stomp on flags that are reserved for other purposes in the kernel.

In particular, openSUSE 12.3 kernels have added a new MS_RICHACL
super-block flag whose value conflicts with our MS_COMMENT flag. This
causes incorrect behavior such as the umask being ignored.  The
MS_COMMENT flag essentially serves as a placeholder in the option_map
data structure of zfs_mount.c, but its value is never used. Therefore
we can avoid the conflict by defining it to 0.

The MS_USERS, MS_OWNER, and MS_GROUP flags also conflict with reserved
flags in the kernel. While this is not known to have caused any
problems, it is nevertheless incorrect.  For the purposes of the
mount.zfs helper, the "users", "owner", and "group" options just serve
as hints to set additional implied options.  Therefore we now define
their associated mount flags in terms of the options that they imply
rather than giving them unique values.

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1457
This commit is contained in:
Ned Bass 2013-05-13 19:48:24 -07:00 committed by Brian Behlendorf
parent fb82700616
commit da29fe63f0
2 changed files with 4 additions and 13 deletions
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9
cmd/mount_zfs/mount_zfs.c
View File

@ -131,15 +131,6 @@ parse_option(char *mntopt, unsigned long *mntflags,
if (strncmp(name, opt->name, strlen(name)) == 0) {
*mntflags |= opt->mntmask;
*zfsflags |= opt->zfsmask;
/* MS_USERS implies default user options */
if (opt->mntmask & (MS_USERS))
*mntflags |= (MS_NOEXEC|MS_NOSUID|MS_NODEV);
/* MS_OWNER|MS_GROUP imply default owner options */
if (opt->mntmask & (MS_OWNER | MS_GROUP))
*mntflags |= (MS_NOSUID|MS_NODEV);
error = 0;
goto out;
}

8
lib/libspl/include/sys/mount.h
View File

@ -51,10 +51,10 @@
#define MS_DIRSYNC S_WRITE
#endif
#define MS_USERS 0x40000000
#define MS_OWNER 0x10000000
#define MS_GROUP 0x08000000
#define MS_COMMENT 0x02000000
#define MS_USERS (MS_NOEXEC|MS_NOSUID|MS_NODEV)
#define MS_OWNER (MS_NOSUID|MS_NODEV)
#define MS_GROUP (MS_NOSUID|MS_NODEV)
#define MS_COMMENT 0
/*
* Older glibc <sys/mount.h> headers did not define all the available