[PATCH 01/28] prepare for write access checks: collapse if()

Dave Hansen
2006-08-01T23:55:09Z

We're shortly going to be adding a bunch more permission
checks in these functions. That requires adding either a
bunch of new if() conditions, or some gotos. This patch
collapses existing if()s and uses gotos instead to
prepare for the upcoming changes.

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
---

lxc-dave/fs/namei.c | 93 +++++++++++++++++++++++++++-------------------------
lxc-dave/fs/open.c | 64 ++++++++++++++++++++---------------
2 files changed, 87 insertions(+), 70 deletions(-)

diff -puN fs/namei.c~B-prepwork-collapse-ifs fs/namei.c
--- lxc/fs/namei.c~B-prepwork-collapse-ifs 2006-08-01 16:35:12.000000000 -0700
+++ lxc-dave/fs/namei.c 2006-08-01 16:35:13.000000000 -0700
@@ -1924,30 +1924,32 @@ asmlinkage long sys_mkdirat(int dfd, con
{
int error = 0;
char * tmp;
+ struct dentry *dentry;
+ struct nameidata nd;

tmp = getname(pathname);
error = PTR_ERR(tmp);
- if (!IS_ERR(tmp)) {
- struct dentry *dentry;
- struct nameidata nd;
+ if (IS_ERR(tmp))
+ goto out_err;

- error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
- if (error)
- goto out;
- dentry = lookup_create(&nd, 1);
- error = PTR_ERR(dentry);
- if (!IS_ERR(dentry)) {
- if (!IS_POSIXACL(nd.dentry->d_inode))
- mode &= ~current->fs->umask;
- error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
- dput(dentry);
- }
- mutex_unlock(&nd.dentry->d_inode->i_mutex);
- path_release(&nd);
-out:
- putname(tmp);
- }
+ error = do_path_lookup(dfd, tmp, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ dentry = lookup_create(&nd, 1);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto out_unlock;

+ if (!IS_POSIXACL(nd.dentry->d_inode))
+ mode &= ~current->fs->umask;
+ error = vfs_mkdir(nd.dentry->d_inode, dentry, mode);
+ dput(dentry);
+out_unlock:
+ mutex_unlock(&nd.dentry->d_inode->i_mutex);
+ path_release(&nd);
+out:
+ putname(tmp);
+out_err:
return error;
}

@@ -2046,10 +2048,11 @@ static long do_rmdir(int dfd, const char
mutex_lock_nested(&nd.dentry->d_inode->i_mutex, I_MUTEX_PARENT);
dentry = lookup_hash(&nd);
error = PTR_ERR(dentry);
- if (!IS_ERR(dentry)) {
- error = vfs_rmdir(nd.dentry->d_inode, dentry);
- dput(dentry);
- }
+ if (IS_ERR(dentry))
+ goto exit2;
+ error = vfs_rmdir(nd.dentry->d_inode, dentry);
+ dput(dentry);
+exit2:
mutex_unlock(&nd.dentry->d_inode->i_mutex);
exit1:
path_release(&nd);
@@ -2189,30 +2192,33 @@ asmlinkage long sys_symlinkat(const char
int error = 0;
char * from;
char * to;
+ struct dentry *dentry;
+ struct nameidata nd;

from = getname(oldname);
if(IS_ERR(from))
return PTR_ERR(from);
to = getname(newname);
error = PTR_ERR(to);
- if (!IS_ERR(to)) {
- struct dentry *dentry;
- struct nameidata nd;
+ if (IS_ERR(to))
+ goto out_putname;

- error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
- if (error)
- goto out;
- dentry = lookup_create(&nd, 0);
- error = PTR_ERR(dentry);
- if (!IS_ERR(dentry)) {
- error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
- dput(dentry);
- }
- mutex_unlock(&nd.dentry->d_inode->i_mutex);
- path_release(&nd);
+ error = do_path_lookup(newdfd, to, LOOKUP_PARENT, &nd);
+ if (error)
+ goto out;
+ dentry = lookup_create(&nd, 0);
+ error = PTR_ERR(dentry);
+ if (IS_ERR(dentry))
+ goto out_unlock;
+
+ error = vfs_symlink(nd.dentry->d_inode, dentry, from, S_IALLUGO);
+ dput(dentry);
+out_unlock:
+ mutex_unlock(&nd.dentry->d_inode->i_mutex);
+ path_release(&nd);
out:
- putname(to);
- }
+ putname(to);
+out_putname:
putname(from);
return error;
}
@@ -2298,10 +2304,11 @@ asmlinkage long sys_linkat(int olddfd, c
goto out_release;
new_dentry = lookup_create(&nd, 0);
error = PTR_ERR(new_dentry);
- if (!IS_ERR(new_dentry)) {
- error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
- dput(new_dentry);
- }
+ if (IS_ERR(new_dentry))
+ goto out_unlock;
+ error = vfs_link(old_nd.dentry, nd.dentry->d_inode, new_dentry);
+ dput(new_dentry);
+out_unlock:
mutex_unlock(&nd.dentry->d_inode->i_mutex);
out_release:
path_release(&nd);
diff -puN fs/open.c~B-prepwork-collapse-ifs fs/open.c
--- lxc/fs/open.c~B-prepwork-collapse-ifs 2006-08-01 16:35:12.000000000 -0700
+++ lxc-dave/fs/open.c 2006-08-01 16:35:13.000000000 -0700
@@ -520,15 +520,21 @@ asmlinkage long sys_faccessat(int dfd, c
current->cap_effective = current->cap_permitted;

res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
- if (!res) {
- res = vfs_permission(&nd, mode);
- /* SuS v2 requires we report a read only fs too */
- if(!res && (mode & S_IWOTH) && IS_RDONLY(nd.dentry->d_inode)
- && !special_file(nd.dentry->d_inode->i_mode))
- res = -EROFS;
- path_release(&nd);
- }
+ if (res)
+ goto out;
+
+ res = vfs_permission(&nd, mode);
+ /* SuS v2 requires we report a read only fs too */
+ if(res || !(mode & S_IWOTH) ||
+ special_file(nd.dentry->d_inode->i_mode))
+ goto out_path_release;
+
+ if(IS_RDONLY(nd.dentry->d_inode))
+ res = -EROFS;

+out_path_release:
+ path_release(&nd);
+out:
current->fsuid = old_fsuid;
current->fsgid = old_fsgid;
current->cap_effective = old_cap;
@@ -736,10 +742,11 @@ asmlinkage long sys_chown(const char __u
int error;

error = user_path_walk(filename, &nd);
- if (!error) {
- error = chown_common(nd.dentry, user, group);
- path_release(&nd);
- }
+ if (error)
+ goto out;
+ error = chown_common(nd.dentry, user, group);
+ path_release(&nd);
+out:
return error;
}

@@ -755,10 +762,10 @@ asmlinkage long sys_fchownat(int dfd, co

follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
error = __user_walk_fd(dfd, filename, follow, &nd);
- if (!error) {
- error = chown_common(nd.dentry, user, group);
- path_release(&nd);
- }
+ if (error)
+ goto out;
+ error = chown_common(nd.dentry, user, group);
+ path_release(&nd);
out:
return error;
}
@@ -769,10 +776,11 @@ asmlinkage long sys_lchown(const char __
int error;

error = user_path_walk_link(filename, &nd);
- if (!error) {
- error = chown_common(nd.dentry, user, group);
- path_release(&nd);
- }
+ if (error)
+ goto out;
+ error = chown_common(nd.dentry, user, group);
+ path_release(&nd);
+out:
return error;
}

@@ -781,15 +789,17 @@ asmlinkage long sys_fchown(unsigned int
{
struct file * file;
int error = -EBADF;
+ struct dentry * dentry;

file = fget(fd);
- if (file) {
- struct dentry * dentry;
- dentry = file->f_dentry;
- audit_inode(NULL, dentry->d_inode);
- error = chown_common(dentry, user, group);
- fput(file);
- }
+ if (!file)
+ goto out;
+
+ dentry = file->f_dentry;
+ audit_inode(NULL, dentry->d_inode);
+ error = chown_common(dentry, user, group);
+ fput(file);
+out:
return error;
}

_