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@xxxxxxxxxx>
---
fs/fuse/dir.c | 2 +-
fs/nfs/dir.c | 2 +-
fs/open.c | 6 +++---
include/linux/fs.h | 1 +
4 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 4787ae6..7c8c55b 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -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)) {
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index be46f26..4c7d8fc 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1927,7 +1927,7 @@ 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) {
diff --git a/fs/open.c b/fs/open.c
index b93eac3..d01e116 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -534,7 +534,7 @@ 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;
@@ -563,7 +563,7 @@ 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:
@@ -581,7 +581,7 @@ 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;
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 14d8597..188d3e4 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -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
--
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