Messages in this thread Patch in this message | | | Date | Thu, 7 Aug 2003 05:03:31 +0200 | From | Herbert Pötzl <> | Subject | Bind Mount Extensions 0.02 for 2.6.x |
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I thought, maybe this would be useful for 2.6 too, so here is a preliminary patch for 2.6.0-test2 ...
I would be happy to hear about any misbehaviour (read: difference in behaviour regarding a 'normal' read only mounted filesystem ...)
patch is for 2.6.0-test2 but should apply and work for all available 2.6.0 including -bkx ...
enjoy, Herbert
---------------
; ; Bind Mount Extensions ; ; this patch adds some functionality to the --bind ; type of vfs mounts. ; ; (C) 2003 Herbert Pötzl <herbert@13thfloor.at> ; ; Changelog: ; ; 0.01 - readonly bind mounts ; 0.02 - correct ro truncate handling ; - correct ro (f)chown, (f)chmod handling ; ; this patch is free software; you can redistribute it and/or ; modify it under the terms of the GNU General Public License ; as published by the Free Software Foundation; either version 2 ; of the License, or (at your option) any later version. ; ; this patch is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ; GNU General Public License for more details. ;
diff -NurP --minimal linux-2.6.0-test2/fs/namei.c linux-2.6.0-test2-bme0.02/fs/namei.c --- linux-2.6.0-test2/fs/namei.c 2003-07-14 05:32:42.000000000 +0200 +++ linux-2.6.0-test2-bme0.02/fs/namei.c 2003-08-07 03:39:39.000000000 +0200 @@ -207,10 +207,14 @@ { int retval; int submask; + umode_t mode = inode->i_mode; /* Ordinary permission routines do not understand MAY_APPEND. */ submask = mask & ~MAY_APPEND; + if (nd && (mask & MAY_WRITE) && MNT_IS_RDONLY(nd->mnt) && + (S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) + return -EROFS; if (inode->i_op && inode->i_op->permission) retval = inode->i_op->permission(inode, submask, nd); else @@ -1039,6 +1043,24 @@ return permission(dir,MAY_WRITE | MAY_EXEC, nd); } +static inline int mnt_may_create(struct vfsmount *mnt, struct inode *dir, struct dentry *child) { + if (child->d_inode) + return -EEXIST; + if (IS_DEADDIR(dir)) + return -ENOENT; + if (mnt->mnt_flags & MNT_RDONLY) + return -EROFS; + return 0; +} + +static inline int mnt_may_unlink(struct vfsmount *mnt, struct inode *dir, struct dentry *child) { + if (!child->d_inode) + return -ENOENT; + if (mnt->mnt_flags & MNT_RDONLY) + return -EROFS; + return 0; +} + /* * Special case: O_CREAT|O_EXCL implies O_NOFOLLOW for security * reasons. @@ -1160,7 +1182,8 @@ return -EACCES; flag &= ~O_TRUNC; - } else if (IS_RDONLY(inode) && (flag & FMODE_WRITE)) + } else if ((IS_RDONLY(inode) || MNT_IS_RDONLY(nd->mnt)) && + (flag & FMODE_WRITE)) return -EROFS; /* * An append-only file must be opened in append mode for writing. @@ -1379,23 +1402,28 @@ static struct dentry *lookup_create(struct nameidata *nd, int is_dir) { struct dentry *dentry; + int error; down(&nd->dentry->d_inode->i_sem); - dentry = ERR_PTR(-EEXIST); + error = -EEXIST; if (nd->last_type != LAST_NORM) - goto fail; + goto out; nd->flags &= ~LOOKUP_PARENT; dentry = lookup_hash(&nd->last, nd->dentry); if (IS_ERR(dentry)) + goto ret; + error = mnt_may_create(nd->mnt, nd->dentry->d_inode, dentry); + if (error) goto fail; + error = -ENOENT; if (!is_dir && nd->last.name[nd->last.len] && !dentry->d_inode) - goto enoent; + goto fail; +ret: return dentry; -enoent: - dput(dentry); - dentry = ERR_PTR(-ENOENT); fail: - return dentry; + dput(dentry); +out: + return ERR_PTR(error); } int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) @@ -1620,7 +1648,11 @@ dentry = lookup_hash(&nd.last, nd.dentry); error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { + error = mnt_may_unlink(nd.mnt, nd.dentry->d_inode, dentry); + if (error) + goto exit2; error = vfs_rmdir(nd.dentry->d_inode, dentry); + exit2: dput(dentry); } up(&nd.dentry->d_inode->i_sem); @@ -1692,6 +1724,9 @@ /* Why not before? Because we want correct error value */ if (nd.last.name[nd.last.len]) goto slashes; + error = mnt_may_unlink(nd.mnt, nd.dentry->d_inode, dentry); + if (error) + goto exit2; inode = dentry->d_inode; if (inode) atomic_inc(&inode->i_count); @@ -2056,6 +2091,9 @@ error = -EINVAL; if (old_dentry == trap) goto exit4; + error = -EROFS; + if (MNT_IS_RDONLY(newnd.mnt)) + goto exit4; new_dentry = lookup_hash(&newnd.last, new_dir); error = PTR_ERR(new_dentry); if (IS_ERR(new_dentry)) diff -NurP --minimal linux-2.6.0-test2/fs/namespace.c linux-2.6.0-test2-bme0.02/fs/namespace.c --- linux-2.6.0-test2/fs/namespace.c 2003-07-29 01:58:01.000000000 +0200 +++ linux-2.6.0-test2-bme0.02/fs/namespace.c 2003-08-07 03:45:02.000000000 +0200 @@ -225,7 +225,8 @@ seq_path(m, mnt, mnt->mnt_root, " \t\n\\"); seq_putc(m, ' '); mangle(m, mnt->mnt_sb->s_type->name); - seq_puts(m, mnt->mnt_sb->s_flags & MS_RDONLY ? " ro" : " rw"); + seq_puts(m, (MNT_IS_RDONLY(mnt) || + (mnt->mnt_sb->s_flags & MS_RDONLY)) ? " ro" : " rw"); for (fs_infop = fs_info; fs_infop->flag; fs_infop++) { if (mnt->mnt_sb->s_flags & fs_infop->flag) seq_puts(m, fs_infop->str); @@ -516,11 +517,13 @@ /* * do loopback mount. */ -static int do_loopback(struct nameidata *nd, char *old_name, int recurse) +static int do_loopback(struct nameidata *nd, char *old_name, unsigned long flags, int mnt_flags) { struct nameidata old_nd; struct vfsmount *mnt = NULL; + int recurse = flags & MS_REC; int err = mount_is_safe(nd); + if (err) return err; if (!old_name || !*old_name) @@ -547,6 +550,7 @@ spin_unlock(&vfsmount_lock); } else mntput(mnt); + mnt->mnt_flags = mnt_flags; } up_write(¤t->namespace->sem); @@ -750,6 +754,8 @@ return -EINVAL; /* Separate the per-mountpoint flags */ + if (flags & MS_RDONLY) + mnt_flags |= MNT_RDONLY; if (flags & MS_NOSUID) mnt_flags |= MNT_NOSUID; if (flags & MS_NODEV) @@ -771,7 +777,7 @@ retval = do_remount(&nd, flags & ~MS_REMOUNT, mnt_flags, data_page); else if (flags & MS_BIND) - retval = do_loopback(&nd, dev_name, flags & MS_REC); + retval = do_loopback(&nd, dev_name, flags, mnt_flags); else if (flags & MS_MOVE) retval = do_move_mount(&nd, dev_name); else diff -NurP --minimal linux-2.6.0-test2/fs/open.c linux-2.6.0-test2-bme0.02/fs/open.c --- linux-2.6.0-test2/fs/open.c 2003-07-14 05:29:30.000000000 +0200 +++ linux-2.6.0-test2-bme0.02/fs/open.c 2003-08-07 02:50:42.000000000 +0200 @@ -224,7 +224,7 @@ goto dput_and_out; error = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(nd.mnt)) goto dput_and_out; error = -EPERM; @@ -348,7 +348,7 @@ inode = nd.dentry->d_inode; error = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(nd.mnt)) goto dput_and_out; /* Don't worry, the checks are done in inode_change_ok() */ @@ -397,7 +397,7 @@ inode = nd.dentry->d_inode; error = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(nd.mnt)) goto dput_and_out; /* Don't worry, the checks are done in inode_change_ok() */ @@ -577,7 +577,7 @@ inode = dentry->d_inode; err = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(file->f_vfsmnt)) goto out_putf; err = -EPERM; if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) @@ -609,7 +609,7 @@ inode = nd.dentry->d_inode; error = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(nd.mnt)) goto dput_and_out; error = -EPERM; @@ -630,7 +630,7 @@ return error; } -static int chown_common(struct dentry * dentry, uid_t user, gid_t group) +static int chown_common(struct vfsmount *mnt, struct dentry * dentry, uid_t user, gid_t group) { struct inode * inode; int error; @@ -642,7 +642,7 @@ goto out; } error = -EROFS; - if (IS_RDONLY(inode)) + if (IS_RDONLY(inode) || MNT_IS_RDONLY(mnt)) goto out; error = -EPERM; if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) @@ -672,7 +672,7 @@ error = user_path_walk(filename, &nd); if (!error) { - error = chown_common(nd.dentry, user, group); + error = chown_common(nd.mnt, nd.dentry, user, group); path_release(&nd); } return error; @@ -685,7 +685,7 @@ error = user_path_walk_link(filename, &nd); if (!error) { - error = chown_common(nd.dentry, user, group); + error = chown_common(nd.mnt, nd.dentry, user, group); path_release(&nd); } return error; @@ -699,7 +699,7 @@ file = fget(fd); if (file) { - error = chown_common(file->f_dentry, user, group); + error = chown_common(file->f_vfsmnt, file->f_dentry, user, group); fput(file); } return error; diff -NurP --minimal linux-2.6.0-test2/include/linux/mount.h linux-2.6.0-test2-bme0.02/include/linux/mount.h --- linux-2.6.0-test2/include/linux/mount.h 2003-07-14 05:30:35.000000000 +0200 +++ linux-2.6.0-test2-bme0.02/include/linux/mount.h 2003-08-07 02:50:24.000000000 +0200 @@ -14,9 +14,10 @@ #include <linux/list.h> -#define MNT_NOSUID 1 -#define MNT_NODEV 2 -#define MNT_NOEXEC 4 +#define MNT_RDONLY 1 +#define MNT_NOSUID 2 +#define MNT_NODEV 4 +#define MNT_NOEXEC 8 struct vfsmount { @@ -33,6 +34,8 @@ struct list_head mnt_list; }; +#define MNT_IS_RDONLY(m) ((m)->mnt_flags & MNT_RDONLY) + static inline struct vfsmount *mntget(struct vfsmount *mnt) { if (mnt) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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