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authorDave Hansen <haveblue@us.ibm.com>2008-02-15 14:37:38 -0800
committerAl Viro <viro@zeniv.linux.org.uk>2008-04-19 00:29:15 -0400
commit18f335aff86913de3c76f88d32c8135c1da62ce6 (patch)
treebf541547b9774137a161d200bace04ad152e80e3 /fs/xattr.c
parent9079b1eb1753f217c3de9f1b7dd7fd549cc3f0cf (diff)
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[PATCH] r/o bind mounts: elevate write count for xattr_permission() callers
This basically audits the callers of xattr_permission(), which calls permission() and can perform writes to the filesystem. [AV: add missing parts - removexattr() and nfsd posix acls, plug for a leak spotted by Miklos] Acked-by: Al Viro <viro@ZenIV.linux.org.uk> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/xattr.c')
-rw-r--r--fs/xattr.c40
1 files changed, 32 insertions, 8 deletions
diff --git a/fs/xattr.c b/fs/xattr.c
index 3acab1615460..f7062da505d4 100644
--- a/fs/xattr.c
+++ b/fs/xattr.c
@@ -11,6 +11,7 @@
#include <linux/slab.h>
#include <linux/file.h>
#include <linux/xattr.h>
+#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>
@@ -32,8 +33,6 @@ xattr_permission(struct inode *inode, const char *name, int mask)
* filesystem or on an immutable / append-only inode.
*/
if (mask & MAY_WRITE) {
- if (IS_RDONLY(inode))
- return -EROFS;
if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
return -EPERM;
}
@@ -262,7 +261,11 @@ sys_setxattr(char __user *path, char __user *name, void __user *value,
error = user_path_walk(path, &nd);
if (error)
return error;
- error = setxattr(nd.path.dentry, name, value, size, flags);
+ error = mnt_want_write(nd.path.mnt);
+ if (!error) {
+ error = setxattr(nd.path.dentry, name, value, size, flags);
+ mnt_drop_write(nd.path.mnt);
+ }
path_put(&nd.path);
return error;
}
@@ -277,7 +280,11 @@ sys_lsetxattr(char __user *path, char __user *name, void __user *value,
error = user_path_walk_link(path, &nd);
if (error)
return error;
- error = setxattr(nd.path.dentry, name, value, size, flags);
+ error = mnt_want_write(nd.path.mnt);
+ if (!error) {
+ error = setxattr(nd.path.dentry, name, value, size, flags);
+ mnt_drop_write(nd.path.mnt);
+ }
path_put(&nd.path);
return error;
}
@@ -295,7 +302,12 @@ sys_fsetxattr(int fd, char __user *name, void __user *value,
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
- error = setxattr(dentry, name, value, size, flags);
+ error = mnt_want_write(f->f_path.mnt);
+ if (!error) {
+ error = setxattr(dentry, name, value, size, flags);
+ mnt_drop_write(f->f_path.mnt);
+ }
+out_fput:
fput(f);
return error;
}
@@ -482,7 +494,11 @@ sys_removexattr(char __user *path, char __user *name)
error = user_path_walk(path, &nd);
if (error)
return error;
- error = removexattr(nd.path.dentry, name);
+ error = mnt_want_write(nd.path.mnt);
+ if (!error) {
+ error = removexattr(nd.path.dentry, name);
+ mnt_drop_write(nd.path.mnt);
+ }
path_put(&nd.path);
return error;
}
@@ -496,7 +512,11 @@ sys_lremovexattr(char __user *path, char __user *name)
error = user_path_walk_link(path, &nd);
if (error)
return error;
- error = removexattr(nd.path.dentry, name);
+ error = mnt_want_write(nd.path.mnt);
+ if (!error) {
+ error = removexattr(nd.path.dentry, name);
+ mnt_drop_write(nd.path.mnt);
+ }
path_put(&nd.path);
return error;
}
@@ -513,7 +533,11 @@ sys_fremovexattr(int fd, char __user *name)
return error;
dentry = f->f_path.dentry;
audit_inode(NULL, dentry);
- error = removexattr(dentry, name);
+ error = mnt_want_write(f->f_path.mnt);
+ if (!error) {
+ error = removexattr(dentry, name);
+ mnt_drop_write(f->f_path.mnt);
+ }
fput(f);
return error;
}