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SubjectRe: [WTF] ->setattr() locking changes


On Sat, 6 Apr 2002, Linus Torvalds wrote:

> I agree with you that doing the locking outside would clean some stuff up,
> since things like write already have the lock for other reasons.

OK, how about that? It builds, but it's completely untested.

diff -urN C8-pre2/Documentation/filesystems/Locking C8-pre2-current/Documentation/filesystems/Locking
--- C8-pre2/Documentation/filesystems/Locking Sat Apr 6 00:29:14 2002
+++ C8-pre2-current/Documentation/filesystems/Locking Sat Apr 6 14:02:43 2002
@@ -65,7 +65,7 @@
readlink: no no
follow_link: no no
truncate: no yes (see below)
-setattr: yes if ATTR_SIZE
+setattr: no yes
permission: yes no
getattr: (see below)
revalidate: no (see below)
diff -urN C8-pre2/Documentation/filesystems/porting C8-pre2-current/Documentation/filesystems/porting
--- C8-pre2/Documentation/filesystems/porting Tue Mar 19 16:05:44 2002
+++ C8-pre2-current/Documentation/filesystems/porting Sat Apr 6 14:04:40 2002
@@ -116,3 +116,10 @@
FS_SINGLE is gone (actually, that had happened back when ->get_sb()
went in - and hadn't been documented ;-/). Just remove it from fs_flags
(and see ->get_sb() entry for other actions).
+
+---
+[mandatory]
+
+->setattr() is called without BKL now. Caller _always_ holds ->i_sem, so
+watch for ->i_sem-grabbing code that might be used by your ->setattr().
+Callers of notify_change() need ->i_sem now.
diff -urN C8-pre2/fs/attr.c C8-pre2-current/fs/attr.c
--- C8-pre2/fs/attr.c Sat Apr 6 00:29:28 2002
+++ C8-pre2-current/fs/attr.c Sat Apr 6 13:23:18 2002
@@ -119,6 +119,7 @@
int notify_change(struct dentry * dentry, struct iattr * attr)
{
struct inode *inode = dentry->d_inode;
+ mode_t mode = inode->i_mode;
int error;
time_t now = CURRENT_TIME;
unsigned int ia_valid = attr->ia_valid;
@@ -131,8 +132,25 @@
attr->ia_atime = now;
if (!(ia_valid & ATTR_MTIME_SET))
attr->ia_mtime = now;
+ if (ia_valid & ATTR_KILL_SUID) {
+ if (mode & S_ISUID) {
+ if (!ia_valid & ATTR_MODE) {
+ ia_valid = attr->ia_valid |= ATTR_MODE;
+ attr->ia_mode = inode->i_mode;
+ }
+ attr->ia_mode &= ~S_ISUID;
+ }
+ }
+ if (ia_valid & ATTR_KILL_SGID) {
+ if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ if (!ia_valid & ATTR_MODE) {
+ ia_valid = attr->ia_valid |= ATTR_MODE;
+ attr->ia_mode = inode->i_mode;
+ }
+ attr->ia_mode &= ~S_ISGID;
+ }
+ }

- down(&inode->i_sem);
if (inode->i_op && inode->i_op->setattr)
error = inode->i_op->setattr(dentry, attr);
else {
@@ -145,7 +163,6 @@
error = inode_setattr(inode, attr);
}
}
- up(&inode->i_sem);
if (!error) {
unsigned long dn_mask = setattr_mask(ia_valid);
if (dn_mask)
diff -urN C8-pre2/fs/dquot.c C8-pre2-current/fs/dquot.c
--- C8-pre2/fs/dquot.c Sat Apr 6 00:29:28 2002
+++ C8-pre2-current/fs/dquot.c Sat Apr 6 13:26:12 2002
@@ -429,7 +429,7 @@
count = nr_free_dquots / priority;
prune_dqcache(count);
unlock_kernel();
- return kmem_cache_shrink_nr(dquot_cachep);
+ return kmem_cache_shrink(dquot_cachep);
}

/* NOTE: If you change this function please check whether dqput_blocks() works right... */
diff -urN C8-pre2/fs/fat/inode.c C8-pre2-current/fs/fat/inode.c
--- C8-pre2/fs/fat/inode.c Sat Apr 6 00:29:29 2002
+++ C8-pre2-current/fs/fat/inode.c Sat Apr 6 13:21:12 2002
@@ -1086,7 +1086,8 @@
error = 0;
goto out;
}
- if( error = inode_setattr(inode, attr) )
+ error = inode_setattr(inode, attr);
+ if (error)
goto out;

if (S_ISDIR(inode->i_mode))
diff -urN C8-pre2/fs/hpfs/namei.c C8-pre2-current/fs/hpfs/namei.c
--- C8-pre2/fs/hpfs/namei.c Tue Feb 19 22:33:03 2002
+++ C8-pre2-current/fs/hpfs/namei.c Sat Apr 6 12:20:54 2002
@@ -365,11 +365,9 @@
goto ret;
}
/*printk("HPFS: truncating file before delete.\n");*/
- down(&inode->i_sem);
newattrs.ia_size = 0;
newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
err = notify_change(dentry, &newattrs);
- up(&inode->i_sem);
put_write_access(inode);
if (err)
goto ret;
diff -urN C8-pre2/fs/jffs2/file.c C8-pre2-current/fs/jffs2/file.c
--- C8-pre2/fs/jffs2/file.c Sat Apr 6 00:29:29 2002
+++ C8-pre2-current/fs/jffs2/file.c Sat Apr 6 13:21:44 2002
@@ -43,6 +43,7 @@
#include <linux/pagemap.h>
#include <linux/crc32.h>
#include <linux/jffs2.h>
+#include <linux/smp_lock.h>
#include "nodelist.h"

extern int generic_file_open(struct inode *, struct file *) __attribute__((weak));
diff -urN C8-pre2/fs/ncpfs/inode.c C8-pre2-current/fs/ncpfs/inode.c
--- C8-pre2/fs/ncpfs/inode.c Sat Apr 6 00:29:30 2002
+++ C8-pre2-current/fs/ncpfs/inode.c Sat Apr 6 13:22:56 2002
@@ -27,6 +27,7 @@
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
+#include <linux/smp_lock.h>

#include <linux/ncp_fs.h>

diff -urN C8-pre2/fs/nfsd/vfs.c C8-pre2-current/fs/nfsd/vfs.c
--- C8-pre2/fs/nfsd/vfs.c Fri Mar 8 02:09:52 2002
+++ C8-pre2-current/fs/nfsd/vfs.c Sat Apr 6 12:39:54 2002
@@ -264,6 +264,7 @@
if (err)
goto out_nfserr;

+ size_change = 1;
err = locks_verify_truncate(inode, NULL, iap->ia_size);
if (err) {
put_write_access(inode);
@@ -279,35 +280,24 @@
}

/* Revoke setuid/setgid bit on chown/chgrp */
- if ((iap->ia_valid & ATTR_UID) && (imode & S_ISUID)
- && iap->ia_uid != inode->i_uid) {
- iap->ia_valid |= ATTR_MODE;
- iap->ia_mode = imode &= ~S_ISUID;
- }
- if ((iap->ia_valid & ATTR_GID) && (imode & S_ISGID)
- && iap->ia_gid != inode->i_gid) {
- iap->ia_valid |= ATTR_MODE;
- iap->ia_mode = imode &= ~S_ISGID;
- }
+ if ((iap->ia_valid & ATTR_UID) && iap->ia_uid != inode->i_uid)
+ iap->ia_valid |= ATTR_KILL_SUID;
+ if ((iap->ia_valid & ATTR_GID) && iap->ia_gid != inode->i_gid)
+ iap->ia_valid |= ATTR_KILL_SGID;

/* Change the attributes. */

-
iap->ia_valid |= ATTR_CTIME;

- if (iap->ia_valid & ATTR_SIZE) {
- fh_lock(fhp);
- size_change = 1;
- }
err = nfserr_notsync;
if (!check_guard || guardtime == inode->i_ctime) {
+ fh_lock(fhp);
err = notify_change(dentry, iap);
err = nfserrno(err);
- }
- if (size_change) {
fh_unlock(fhp);
- put_write_access(inode);
}
+ if (size_change)
+ put_write_access(inode);
if (!err)
if (EX_ISSYNC(fhp->fh_export))
write_inode_now(inode, 1);
@@ -725,10 +715,11 @@
/* clear setuid/setgid flag after write */
if (err >= 0 && (inode->i_mode & (S_ISUID | S_ISGID))) {
struct iattr ia;
+ ia.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID;

- ia.ia_valid = ATTR_MODE;
- ia.ia_mode = inode->i_mode & ~(S_ISUID | S_ISGID);
+ down(&inode->i_sem);
notify_change(dentry, &ia);
+ up(&inode->i_sem);
}

if (err >= 0 && stable) {
@@ -1157,7 +1148,9 @@
iap->ia_valid |= ATTR_CTIME;
iap->ia_mode = (iap->ia_mode&S_IALLUGO)
| S_IFLNK;
+ down(&dentry->d_inode->i_sem);
err = notify_change(dnew, iap);
+ up(&dentry->d_inode->i_sem);
if (!err && EX_ISSYNC(fhp->fh_export))
write_inode_now(dentry->d_inode, 1);
}
diff -urN C8-pre2/fs/open.c C8-pre2-current/fs/open.c
--- C8-pre2/fs/open.c Sat Apr 6 00:29:30 2002
+++ C8-pre2-current/fs/open.c Sat Apr 6 12:37:36 2002
@@ -73,6 +73,7 @@

int do_truncate(struct dentry *dentry, loff_t length)
{
+ int err;
struct iattr newattrs;

/* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
@@ -81,7 +82,10 @@

newattrs.ia_size = length;
newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
- return notify_change(dentry, &newattrs);
+ down(&dentry->d_inode->i_sem);
+ err = notify_change(dentry, &newattrs);
+ up(&dentry->d_inode->i_sem);
+ return err;
}

static inline long do_sys_truncate(const char * path, loff_t length)
@@ -255,7 +259,9 @@
(error = permission(inode,MAY_WRITE)) != 0)
goto dput_and_out;
}
+ down(&inode->i_sem);
error = notify_change(nd.dentry, &newattrs);
+ up(&inode->i_sem);
dput_and_out:
path_release(&nd);
out:
@@ -299,7 +305,9 @@
if ((error = permission(inode,MAY_WRITE)) != 0)
goto dput_and_out;
}
+ down(&inode->i_sem);
error = notify_change(nd.dentry, &newattrs);
+ up(&inode->i_sem);
dput_and_out:
path_release(&nd);
out:
@@ -449,11 +457,13 @@
err = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out_putf;
+ down(&inode->i_sem);
if (mode == (mode_t) -1)
mode = inode->i_mode;
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
err = notify_change(dentry, &newattrs);
+ up(&inode->i_sem);

out_putf:
fput(file);
@@ -481,11 +491,13 @@
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto dput_and_out;

+ down(&inode->i_sem);
if (mode == (mode_t) -1)
mode = inode->i_mode;
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
error = notify_change(nd.dentry, &newattrs);
+ up(&inode->i_sem);

dput_and_out:
path_release(&nd);
@@ -510,45 +522,20 @@
error = -EPERM;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
goto out;
- if (user == (uid_t) -1)
- user = inode->i_uid;
- if (group == (gid_t) -1)
- group = inode->i_gid;
- newattrs.ia_mode = inode->i_mode;
- newattrs.ia_uid = user;
- newattrs.ia_gid = group;
- newattrs.ia_valid = ATTR_UID | ATTR_GID | ATTR_CTIME;
- /*
- * If the user or group of a non-directory has been changed by a
- * non-root user, remove the setuid bit.
- * 19981026 David C Niemi <niemi@tux.org>
- *
- * Changed this to apply to all users, including root, to avoid
- * some races. This is the behavior we had in 2.0. The check for
- * non-root was definitely wrong for 2.2 anyway, as it should
- * have been using CAP_FSETID rather than fsuid -- 19990830 SD.
- */
- if ((inode->i_mode & S_ISUID) == S_ISUID &&
- !S_ISDIR(inode->i_mode))
- {
- newattrs.ia_mode &= ~S_ISUID;
- newattrs.ia_valid |= ATTR_MODE;
+ newattrs.ia_valid = ATTR_CTIME;
+ if (user != (uid_t) -1) {
+ newattrs.ia_valid = ATTR_UID;
+ newattrs.ia_uid = user;
}
- /*
- * Likewise, if the user or group of a non-directory has been changed
- * by a non-root user, remove the setgid bit UNLESS there is no group
- * execute bit (this would be a file marked for mandatory locking).
- * 19981026 David C Niemi <niemi@tux.org>
- *
- * Removed the fsuid check (see the comment above) -- 19990830 SD.
- */
- if (((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
- && !S_ISDIR(inode->i_mode))
- {
- newattrs.ia_mode &= ~S_ISGID;
- newattrs.ia_valid |= ATTR_MODE;
+ if (group != (gid_t) -1) {
+ newattrs.ia_valid = ATTR_GID;
+ newattrs.ia_gid = group;
}
+ if (!S_ISDIR(inode->i_mode))
+ newattrs.ia_valid |= ATTR_KILL_SUID|ATTR_KILL_SGID;
+ down(&inode->i_sem);
error = notify_change(dentry, &newattrs);
+ up(&inode->i_sem);
out:
return error;
}
diff -urN C8-pre2/include/linux/fs.h C8-pre2-current/include/linux/fs.h
--- C8-pre2/include/linux/fs.h Sat Apr 6 00:29:32 2002
+++ C8-pre2-current/include/linux/fs.h Sat Apr 6 12:58:55 2002
@@ -305,6 +305,8 @@
#define ATTR_MTIME_SET 256
#define ATTR_FORCE 512 /* Not a change, but a change it */
#define ATTR_ATTR_FLAG 1024
+#define ATTR_KILL_SUID 2048
+#define ATTR_KILL_SGID 4096

/*
* This is the Inode Attributes structure, used for notify_change(). It
@@ -1313,7 +1315,7 @@

extern void clear_inode(struct inode *);
extern struct inode *new_inode(struct super_block *);
-extern void remove_suid(struct inode *inode);
+extern void remove_suid(struct dentry *);
extern void insert_inode_hash(struct inode *);
extern void remove_inode_hash(struct inode *);
extern struct file * get_empty_filp(void);
diff -urN C8-pre2/mm/filemap.c C8-pre2-current/mm/filemap.c
--- C8-pre2/mm/filemap.c Sat Apr 6 00:29:32 2002
+++ C8-pre2-current/mm/filemap.c Sat Apr 6 12:53:58 2002
@@ -2503,18 +2503,19 @@
return page;
}

-inline void remove_suid(struct inode *inode)
+inline void remove_suid(struct dentry *dentry)
{
- unsigned int mode;
+ struct iattr newattrs;
+ struct inode *inode = dentry->d_inode;
+ unsigned int mode = inode->i_mode & (S_ISUID|S_ISGID|S_IXGRP);

- /* set S_IGID if S_IXGRP is set, and always set S_ISUID */
- mode = (inode->i_mode & S_IXGRP)*(S_ISGID/S_IXGRP) | S_ISUID;
+ if (!(mode & S_IXGRP))
+ mode &= S_ISUID;

/* was any of the uid bits set? */
- mode &= inode->i_mode;
if (mode && !capable(CAP_FSETID)) {
- inode->i_mode &= ~mode;
- mark_inode_dirty(inode);
+ newattrs.ia_valid = ATTR_KILL_SUID | ATTR_KILL_SGID;
+ notify_change(dentry, &newattrs);
}
}

@@ -2646,7 +2647,7 @@
if (count == 0)
goto out;

- remove_suid(inode);
+ remove_suid(file->f_dentry);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
mark_inode_dirty_sync(inode);

diff -urN C8-pre2/mm/shmem.c C8-pre2-current/mm/shmem.c
--- C8-pre2/mm/shmem.c Sat Apr 6 00:29:32 2002
+++ C8-pre2-current/mm/shmem.c Sat Apr 6 12:43:50 2002
@@ -802,7 +802,7 @@

status = 0;
if (count) {
- remove_suid(inode);
+ remove_suid(file->f_dentry);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}

-
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