Messages in this thread Patch in this message |  | | Date | Thu, 05 Sep 2002 18:32:20 -0700 | From | Inguva <> | Subject | [PATCH]:2.4.19: do_revalidate in chown |
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Greetings, Requesting for comments on the below findings and the patch.
sys_stat() does a do_revalidate() after user_path_walk() but sys_chown() does not. This causes sys_chown() to use incorrect attribute information on distributed file systems. The sys_stat does do_revalidate() to revalidate the inodes for proper NFS attibute caching. But when sys_chown calls chown_common after the user_path_walk, no checks are being done regarding the dentry values, which contain cached inode values. On Distributed File system environments there may be a likelyhood that these values may not be current and there is a likelihood of stale values being read. Hence doing a do_revalidate before the chown calls will help address this issue. Below is a patch which does that.
Regards, Inguva
diff -urN ./fs/open.c ./fs-fixed/open.c --- ./fs/open.c Thu Sep 5 02:34:38 2002 +++ ./fs-fixed/open.c Thu Sep 5 14:44:24 2002 @@ -20,6 +20,8 @@
#define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
+extern int do_revalidate(struct dentry *); + int vfs_statfs(struct super_block *sb, struct statfs *buf) { int retval = -ENODEV; @@ -608,7 +610,9 @@
error = user_path_walk(filename, &nd); if (!error) { - error = chown_common(nd.dentry, user, group); + error = do_revalidate(nd.dentry); + if (!error) + error = chown_common(nd.dentry, user, group); path_release(&nd); } return error; @@ -621,7 +625,9 @@
error = user_path_walk_link(filename, &nd); if (!error) { - error = chown_common(nd.dentry, user, group); + error = do_revalidate(nd.dentry); + if (!error) + error = chown_common(nd.dentry, user, group); path_release(&nd); } return error; @@ -632,12 +638,15 @@ { struct file * file; int error = -EBADF; - - file = fget(fd); - if (file) { - error = chown_common(file->f_dentry, user, group); - fput(file); - } + + if(!do_revalidate(file->f_dentry)) + { + file = fget(fd); + if (file) { + error = chown_common(file->f_dentry, user, group); + fput(file); + } + } return error; }
diff -urN ./fs/stat.c ./fs-fixed/stat.c --- ./fs/stat.c Thu Sep 5 09:59:52 2002 +++ ./fs-fixed/stat.c Thu Sep 5 14:44:24 2002 @@ -13,11 +13,12 @@
#include <asm/uaccess.h>
+extern int do_revalidate(struct dentry *); + /* * Revalidate the inode. This is required for proper NFS attribute caching. */ -static __inline__ int -do_revalidate(struct dentry *dentry) +int do_revalidate(struct dentry *dentry) { struct inode * inode = dentry->d_inode; if (inode->i_op && inode->i_op->revalidate)
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