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Subject[PATCH] nosuid/noexec/nodev handling
	nosuid, noexec and nodev are made vfsmount flags (instead of
superblock ones). Places that used to check them switched to checking
vfsmount->mnt_flags. get_filesystem_info() updated, ditto for
do_add_mount() and do_remount().

As the result, these flags are per-mountpoint now. E.g. we can
turn them on and off for arbitrary subtree:
mount --bind /home/luser /home/luser
mount -o remount,noexec /home/luser
will turn noexec on for subtree at /hom/luser without affecting the rest
of /home. Other obvious applications is mounting a filesystem nosuid for
chroot jail and normally outside of it, yodda, yodda.

Patch is completely straightforward. Works here and it had been in
-ac for a month (i.e. since 2.4.8-ac2). Please, apply.


diff -urN S10-pre8/arch/sparc64/solaris/fs.c S10-pre8-nosuid/arch/sparc64/solaris/fs.c
--- S10-pre8/arch/sparc64/solaris/fs.c Thu Feb 22 06:47:53 2001
+++ S10-pre8-nosuid/arch/sparc64/solaris/fs.c Wed Sep 12 12:45:59 2001
@@ -406,21 +406,21 @@
u32 f_filler[16];
};

-static int report_statvfs(struct inode *inode, u32 buf)
+static int report_statvfs(struct vfsmount *mnt, struct inode *inode, u32 buf)
{
struct statfs s;
int error;
struct sol_statvfs *ss = (struct sol_statvfs *)A(buf);

- error = vfs_statfs(inode->i_sb, &s);
+ error = vfs_statfs(mnt->mnt_sb, &s);
if (!error) {
- const char *p = inode->i_sb->s_type->name;
+ const char *p = mnt->mnt_sb->s_type->name;
int i = 0;
int j = strlen (p);

if (j > 15) j = 15;
if (IS_RDONLY(inode)) i = 1;
- if (IS_NOSUID(inode)) i |= 2;
+ if (mnt->mnt_flags & MNT_NOSUID) i |= 2;
if (put_user (s.f_bsize, &ss->f_bsize) ||
__put_user (0, &ss->f_frsize) ||
__put_user (s.f_blocks, &ss->f_blocks) ||
@@ -440,21 +440,21 @@
return error;
}

-static int report_statvfs64(struct inode *inode, u32 buf)
+static int report_statvfs64(struct vfsmount *mnt, struct inode *inode, u32 buf)
{
struct statfs s;
int error;
struct sol_statvfs64 *ss = (struct sol_statvfs64 *)A(buf);

- error = vfs_statfs(inode->i_sb, &s);
+ error = vfs_statfs(mnt->mnt_sb, &s);
if (!error) {
- const char *p = inode->i_sb->s_type->name;
+ const char *p = mnt->mnt_sb->s_type->name;
int i = 0;
int j = strlen (p);

if (j > 15) j = 15;
if (IS_RDONLY(inode)) i = 1;
- if (IS_NOSUID(inode)) i |= 2;
+ if (mnt->mnt_flags & MNT_NOSUID) i |= 2;
if (put_user (s.f_bsize, &ss->f_bsize) ||
__put_user (0, &ss->f_frsize) ||
__put_user (s.f_blocks, &ss->f_blocks) ||
@@ -482,7 +482,7 @@
error = user_path_walk((const char *)A(path),&nd);
if (!error) {
struct inode * inode = nd.dentry->d_inode;
- error = report_statvfs(inode, buf);
+ error = report_statvfs(nd.mnt, inode, buf);
path_release(&nd);
}
return error;
@@ -496,7 +496,7 @@
error = -EBADF;
file = fget(fd);
if (file) {
- error = report_statvfs(file->f_dentry->d_inode, buf);
+ error = report_statvfs(file->f_vfsmnt, file->f_dentry->d_inode, buf);
fput(file);
}

@@ -512,7 +512,7 @@
error = user_path_walk((const char *)A(path), &nd);
if (!error) {
struct inode * inode = nd.dentry->d_inode;
- error = report_statvfs64(inode, buf);
+ error = report_statvfs64(nd.mnt, inode, buf);
path_release(&nd);
}
unlock_kernel();
@@ -528,7 +528,7 @@
file = fget(fd);
if (file) {
lock_kernel();
- error = report_statvfs64(file->f_dentry->d_inode, buf);
+ error = report_statvfs64(file->f_vfsmnt, file->f_dentry->d_inode, buf);
unlock_kernel();
fput(file);
}
diff -urN S10-pre8/fs/exec.c S10-pre8-nosuid/fs/exec.c
--- S10-pre8/fs/exec.c Tue Sep 11 09:28:12 2001
+++ S10-pre8-nosuid/fs/exec.c Wed Sep 12 12:45:59 2001
@@ -347,7 +347,8 @@
if (!err) {
inode = nd.dentry->d_inode;
file = ERR_PTR(-EACCES);
- if (!IS_NOEXEC(inode) && S_ISREG(inode->i_mode)) {
+ if (!(nd.mnt->mnt_flags & MNT_NOEXEC) &&
+ S_ISREG(inode->i_mode)) {
int err = permission(inode, MAY_EXEC);
file = ERR_PTR(err);
if (!err) {
@@ -616,7 +617,7 @@
bprm->e_uid = current->euid;
bprm->e_gid = current->egid;

- if(!IS_NOSUID(inode)) {
+ if(!(bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)) {
/* Set-uid? */
if (mode & S_ISUID)
bprm->e_uid = inode->i_uid;
diff -urN S10-pre8/fs/fat/inode.c S10-pre8-nosuid/fs/fat/inode.c
--- S10-pre8/fs/fat/inode.c Thu Aug 16 20:05:50 2001
+++ S10-pre8-nosuid/fs/fat/inode.c Wed Sep 12 12:45:59 2001
@@ -919,9 +919,8 @@
} else { /* not a directory */
inode->i_generation |= 1;
inode->i_mode = MSDOS_MKMODE(de->attr,
- ((IS_NOEXEC(inode) ||
- (sbi->options.showexec &&
- !is_exec(de->ext)))
+ ((sbi->options.showexec &&
+ !is_exec(de->ext))
? S_IRUGO|S_IWUGO : S_IRWXUGO)
& ~sbi->options.fs_umask) | S_IFREG;
MSDOS_I(inode)->i_start = CF_LE_W(de->start);
@@ -1039,9 +1038,7 @@

inode_setattr(inode, attr);

- if (IS_NOEXEC(inode) && !S_ISDIR(inode->i_mode))
- inode->i_mode &= S_IFMT | S_IRUGO | S_IWUGO;
- else
+ if (S_ISDIR(inode->i_mode))
inode->i_mode |= S_IXUGO;

inode->i_mode = ((inode->i_mode & S_IFMT) | ((((inode->i_mode & S_IRWXU
diff -urN S10-pre8/fs/hfs/inode.c S10-pre8-nosuid/fs/hfs/inode.c
--- S10-pre8/fs/hfs/inode.c Tue Sep 11 09:28:12 2001
+++ S10-pre8-nosuid/fs/hfs/inode.c Wed Sep 12 12:45:59 2001
@@ -38,7 +38,7 @@
struct hfs_fork *fk;
struct hfs_cat_entry *entry = HFS_I(inode)->entry;

- if (!IS_NOEXEC(inode) && (fork == HFS_FK_DATA)) {
+ if (fork == HFS_FK_DATA) {
inode->i_mode = S_IRWXUGO | S_IFREG;
} else {
inode->i_mode = S_IRUGO | S_IWUGO | S_IFREG;
diff -urN S10-pre8/fs/namei.c S10-pre8-nosuid/fs/namei.c
--- S10-pre8/fs/namei.c Tue Sep 11 09:28:12 2001
+++ S10-pre8-nosuid/fs/namei.c Wed Sep 12 12:45:59 2001
@@ -1062,7 +1062,7 @@
flag &= ~O_TRUNC;
} else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
error = -EACCES;
- if (IS_NODEV(inode))
+ if (nd->mnt->mnt_flags & MNT_NODEV)
goto exit;

flag &= ~O_TRUNC;
diff -urN S10-pre8/fs/super.c S10-pre8-nosuid/fs/super.c
--- S10-pre8/fs/super.c Tue Sep 11 09:28:12 2001
+++ S10-pre8-nosuid/fs/super.c Wed Sep 12 12:45:59 2001
@@ -410,6 +410,7 @@
mnt->mnt_root = dget(root);
mnt->mnt_mountpoint = mnt->mnt_root;
mnt->mnt_parent = mnt;
+ mnt->mnt_flags = old->mnt_flags;

atomic_inc(&sb->s_active);
out:
@@ -520,16 +521,17 @@
int flag;
char *str;
} fs_info[] = {
- { MS_NOEXEC, ",noexec" },
- { MS_NOSUID, ",nosuid" },
- { MS_NODEV, ",nodev" },
{ MS_SYNCHRONOUS, ",sync" },
{ MS_MANDLOCK, ",mand" },
{ MS_NOATIME, ",noatime" },
{ MS_NODIRATIME, ",nodiratime" },
-#ifdef MS_NOSUB /* Can't find this except in mount.c */
- { MS_NOSUB, ",nosub" },
-#endif
+ { 0, NULL }
+};
+
+static struct proc_fs_info mnt_info[] = {
+ { MNT_NOSUID, ",nosuid" },
+ { MNT_NODEV, ",nodev" },
+ { MNT_NOEXEC, ",noexec" },
{ 0, NULL }
};

@@ -580,6 +582,10 @@
if (tmp->mnt_sb->s_flags & fs_infop->flag)
MANGLE(fs_infop->str);
}
+ for (fs_infop = mnt_info; fs_infop->flag; fs_infop++) {
+ if (tmp->mnt_flags & fs_infop->flag)
+ MANGLE(fs_infop->str);
+ }
if (!strcmp("nfs", tmp->mnt_sb->s_type->name)) {
nfss = &tmp->mnt_sb->u.nfs_sb.s_server;
len += sprintf(buf+len, ",v%d", nfss->rpc_ops->version);
@@ -917,7 +923,7 @@
if (!S_ISBLK(inode->i_mode))
goto out;
error = -EACCES;
- if (IS_NODEV(inode))
+ if (nd.mnt->mnt_flags & MNT_NODEV)
goto out;
bdev = inode->i_bdev;
bdops = devfs_get_ops ( devfs_get_handle_from_inode (inode) );
@@ -1382,7 +1388,7 @@
* on it - tough luck.
*/

-static int do_remount(struct nameidata *nd, int flags, char *data)
+static int do_remount(struct nameidata *nd,int flags,int mnt_flags,char *data)
{
int err;
struct super_block * sb = nd->mnt->mnt_sb;
@@ -1395,6 +1401,8 @@

down_write(&sb->s_umount);
err = do_remount_sb(sb, flags, data);
+ if (!err)
+ nd->mnt->mnt_flags=mnt_flags;
up_write(&sb->s_umount);
return err;
}
@@ -1463,7 +1471,7 @@
}

static int do_add_mount(struct nameidata *nd, char *type, int flags,
- char *name, void *data)
+ int mnt_flags, char *name, void *data)
{
struct vfsmount *mnt = do_kern_mount(type, flags, name, data);
int retval = PTR_ERR(mnt);
@@ -1471,6 +1479,8 @@
if (IS_ERR(mnt))
goto out;

+ mnt->mnt_flags = mnt_flags;
+
down(&mount_sem);
/* Something was mounted here while we slept */
while(d_mountpoint(nd->dentry) && follow_down(&nd->mnt, &nd->dentry))
@@ -1539,6 +1549,7 @@
{
struct nameidata nd;
int retval = 0;
+ int mnt_flags = 0;

/* Discard magic */
if ((flags & MS_MGC_MSK) == MS_MGC_VAL)
@@ -1551,6 +1562,15 @@
if (dev_name && !memchr(dev_name, 0, PAGE_SIZE))
return -EINVAL;

+ /* Separate the per-mountpoint flags */
+ if (flags & MS_NOSUID)
+ mnt_flags |= MNT_NOSUID;
+ if (flags & MS_NODEV)
+ mnt_flags |= MNT_NODEV;
+ if (flags & MS_NOEXEC)
+ mnt_flags |= MNT_NOEXEC;
+ flags &= ~(MS_NOSUID|MS_NOEXEC|MS_NODEV);
+
/* ... and get the mountpoint */
if (path_init(dir_name, LOOKUP_FOLLOW|LOOKUP_POSITIVE, &nd))
retval = path_walk(dir_name, &nd);
@@ -1558,12 +1578,12 @@
return retval;

if (flags & MS_REMOUNT)
- retval = do_remount(&nd, flags&~MS_REMOUNT,
+ retval = do_remount(&nd, flags&~MS_REMOUNT, mnt_flags,
(char *)data_page);
else if (flags & MS_BIND)
retval = do_loopback(&nd, dev_name);
else
- retval = do_add_mount(&nd, type_page, flags,
+ retval = do_add_mount(&nd, type_page, flags, mnt_flags,
dev_name, data_page);
path_release(&nd);
return retval;
diff -urN S10-pre8/include/linux/fs.h S10-pre8-nosuid/include/linux/fs.h
--- S10-pre8/include/linux/fs.h Tue Sep 11 09:28:13 2001
+++ S10-pre8-nosuid/include/linux/fs.h Wed Sep 12 12:45:59 2001
@@ -111,10 +111,10 @@
#define MS_NOUSER (1<<31)

/*
- * Flags that can be altered by MS_REMOUNT
+ * Superblock flags that can be altered by MS_REMOUNT
*/
-#define MS_RMT_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|\
- MS_SYNCHRONOUS|MS_MANDLOCK|MS_NOATIME|MS_NODIRATIME)
+#define MS_RMT_MASK (MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_NOATIME|\
+ MS_NODIRATIME)

/*
* Old magic mount flag and mask
@@ -147,9 +147,6 @@
#define __IS_FLG(inode,flg) ((inode)->i_sb->s_flags & (flg))

#define IS_RDONLY(inode) ((inode)->i_sb->s_flags & MS_RDONLY)
-#define IS_NOSUID(inode) __IS_FLG(inode, MS_NOSUID)
-#define IS_NODEV(inode) __IS_FLG(inode, MS_NODEV)
-#define IS_NOEXEC(inode) __IS_FLG(inode, MS_NOEXEC)
#define IS_SYNC(inode) (__IS_FLG(inode, MS_SYNCHRONOUS) || ((inode)->i_flags & S_SYNC))
#define IS_MANDLOCK(inode) __IS_FLG(inode, MS_MANDLOCK)

diff -urN S10-pre8/include/linux/mount.h S10-pre8-nosuid/include/linux/mount.h
--- S10-pre8/include/linux/mount.h Sat Aug 11 14:59:25 2001
+++ S10-pre8-nosuid/include/linux/mount.h Wed Sep 12 12:45:59 2001
@@ -12,6 +12,10 @@
#define _LINUX_MOUNT_H
#ifdef __KERNEL__

+#define MNT_NOSUID 1
+#define MNT_NODEV 2
+#define MNT_NOEXEC 4
+
struct vfsmount
{
struct list_head mnt_hash;
-
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