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vfs: re-introduce MAY_CHDIR 

Currently MAY_ACCESS means that filesystems must check the permissions
right then and not rely on cached results or the results of future
operations on the object.  This can be because of a call to sys_access() or
because of a call to chdir() which needs to check search without relying on
any future operations inside that dir.  I plan to use MAY_ACCESS for other
purposes in the security system, so I split the MAY_ACCESS and the
MAY_CHDIR cases.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by:  Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Eric Paris 2010-07-23 11:43:51 -04:00 committed by James Morris
parent 692a8a231b
commit 9cfcac810e
4 changed files with 6 additions and 5 deletions
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2
fs/fuse/dir.c
View File

@ -1016,7 +1016,7 @@ static int fuse_permission(struct inode *inode, int mask)
exist. So if permissions are revoked this won't be
noticed immediately, only after the attribute
timeout has expired */
} else if (mask & MAY_ACCESS) {
} else if (mask & (MAY_ACCESS | MAY_CHDIR)) {
err = fuse_access(inode, mask);
} else if ((mask & MAY_EXEC) && S_ISREG(inode->i_mode)) {
if (!(inode->i_mode & S_IXUGO)) {

2
fs/nfs/dir.c
View File

@ -1953,7 +1953,7 @@ int nfs_permission(struct inode *inode, int mask)
if ((mask & (MAY_READ | MAY_WRITE | MAY_EXEC)) == 0)
goto out;
/* Is this sys_access() ? */
if (mask & MAY_ACCESS)
if (mask & (MAY_ACCESS | MAY_CHDIR))
goto force_lookup;
switch (inode->i_mode & S_IFMT) {

6
fs/open.c
View File

@ -366,7 +366,7 @@ SYSCALL_DEFINE1(chdir, const char __user *, filename)
if (error)
goto out;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;
@ -395,7 +395,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
if (!S_ISDIR(inode->i_mode))
goto out_putf;
error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
if (!error)
set_fs_pwd(current->fs, &file->f_path);
out_putf:
@ -413,7 +413,7 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
if (error)
goto out;
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
if (error)
goto dput_and_out;

1
include/linux/fs.h
View File

@ -53,6 +53,7 @@ struct inodes_stat_t {
#define MAY_APPEND 8
#define MAY_ACCESS 16
#define MAY_OPEN 32
#define MAY_CHDIR 64
/*
* flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond