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[PATCH] add a file_permission helper
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A few more callers of permission() just want to check for a different access
pattern on an already open file.  This patch adds a wrapper for permission()
that takes a file in preparation of per-mount read-only support and to clean
up the callers a little.  The helper is not intended for new code, everything
without the interface set in stone should use vfs_permission()

Signed-off-by: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Christoph Hellwig authored and Linus Torvalds committed Nov 9, 2005
1 parent e4543ed commit 8c744fb
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Showing 8 changed files with 47 additions and 21 deletions.
3 changes: 1 addition & 2 deletions drivers/block/floppy.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3776,8 +3776,7 @@ static int floppy_open(struct inode *inode, struct file *filp)
/* Allow ioctls if we have write-permissions even if read-only open.
* Needed so that programs such as fdrawcmd still can work on write
* protected disks */
if (filp->f_mode & 2
|| permission(filp->f_dentry->d_inode, 2, NULL) == 0)
if ((filp->f_mode & FMODE_WRITE) || !file_permission(filp, MAY_WRITE))
filp->private_data = (void *)8;

if (UFDCS->rawcmd == 1)
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2 changes: 1 addition & 1 deletion fs/binfmt_misc.c
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Expand Up @@ -150,7 +150,7 @@ static int load_misc_binary(struct linux_binprm *bprm, struct pt_regs *regs)

/* if the binary is not readable than enforce mm->dumpable=0
regardless of the interpreter's permissions */
if (permission(bprm->file->f_dentry->d_inode, MAY_READ, NULL))
if (file_permission(bprm->file, MAY_READ))
bprm->interp_flags |= BINPRM_FLAGS_ENFORCE_NONDUMP;

allow_write_access(bprm->file);
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2 changes: 1 addition & 1 deletion fs/exec.c
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Original file line number Diff line number Diff line change
Expand Up @@ -896,7 +896,7 @@ int flush_old_exec(struct linux_binprm * bprm)
flush_thread();

if (bprm->e_uid != current->euid || bprm->e_gid != current->egid ||
permission(bprm->file->f_dentry->d_inode,MAY_READ, NULL) ||
file_permission(bprm->file, MAY_READ) ||
(bprm->interp_flags & BINPRM_FLAGS_ENFORCE_NONDUMP)) {
suid_keys(current);
current->mm->dumpable = suid_dumpable;
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18 changes: 18 additions & 0 deletions fs/namei.c
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Expand Up @@ -271,6 +271,23 @@ int vfs_permission(struct nameidata *nd, int mask)
return permission(nd->dentry->d_inode, mask, nd);
}

/**
* file_permission - check for additional access rights to a given file
* @file: file to check access rights for
* @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
*
* Used to check for read/write/execute permissions on an already opened
* file.
*
* Note:
* Do not use this function in new code. All access checks should
* be done using vfs_permission().
*/
int file_permission(struct file *file, int mask)
{
return permission(file->f_dentry->d_inode, mask, NULL);
}

/*
* get_write_access() gets write permission for a file.
* put_write_access() releases this write permission.
Expand Down Expand Up @@ -2551,6 +2568,7 @@ EXPORT_SYMBOL(path_release);
EXPORT_SYMBOL(path_walk);
EXPORT_SYMBOL(permission);
EXPORT_SYMBOL(vfs_permission);
EXPORT_SYMBOL(file_permission);
EXPORT_SYMBOL(unlock_rename);
EXPORT_SYMBOL(vfs_create);
EXPORT_SYMBOL(vfs_follow_link);
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34 changes: 19 additions & 15 deletions fs/ncpfs/ioctl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,11 +30,13 @@
#define NCP_PACKET_SIZE_INTERNAL 65536

static int
ncp_get_fs_info(struct ncp_server* server, struct inode* inode, struct ncp_fs_info __user *arg)
ncp_get_fs_info(struct ncp_server * server, struct file *file,
struct ncp_fs_info __user *arg)
{
struct inode *inode = file->f_dentry->d_inode;
struct ncp_fs_info info;

if ((permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(file, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid)) {
return -EACCES;
}
Expand All @@ -58,11 +60,13 @@ ncp_get_fs_info(struct ncp_server* server, struct inode* inode, struct ncp_fs_in
}

static int
ncp_get_fs_info_v2(struct ncp_server* server, struct inode* inode, struct ncp_fs_info_v2 __user * arg)
ncp_get_fs_info_v2(struct ncp_server * server, struct file *file,
struct ncp_fs_info_v2 __user * arg)
{
struct inode *inode = file->f_dentry->d_inode;
struct ncp_fs_info_v2 info2;

if ((permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(file, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid)) {
return -EACCES;
}
Expand Down Expand Up @@ -190,7 +194,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
switch (cmd) {
case NCP_IOC_NCPREQUEST:

if ((permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(filp, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid)) {
return -EACCES;
}
Expand Down Expand Up @@ -245,16 +249,16 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
return ncp_conn_logged_in(inode->i_sb);

case NCP_IOC_GET_FS_INFO:
return ncp_get_fs_info(server, inode, argp);
return ncp_get_fs_info(server, filp, argp);

case NCP_IOC_GET_FS_INFO_V2:
return ncp_get_fs_info_v2(server, inode, argp);
return ncp_get_fs_info_v2(server, filp, argp);

case NCP_IOC_GETMOUNTUID2:
{
unsigned long tmp = server->m.mounted_uid;

if ( (permission(inode, MAY_READ, NULL) != 0)
if ((file_permission(filp, MAY_READ) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand All @@ -268,7 +272,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
{
struct ncp_setroot_ioctl sr;

if ( (permission(inode, MAY_READ, NULL) != 0)
if ((file_permission(filp, MAY_READ) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand Down Expand Up @@ -343,7 +347,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,

#ifdef CONFIG_NCPFS_PACKET_SIGNING
case NCP_IOC_SIGN_INIT:
if ((permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(filp, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand All @@ -366,7 +370,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
return 0;

case NCP_IOC_SIGN_WANTED:
if ( (permission(inode, MAY_READ, NULL) != 0)
if ((file_permission(filp, MAY_READ) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand All @@ -379,7 +383,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
{
int newstate;

if ( (permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(filp, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand All @@ -400,7 +404,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,

#ifdef CONFIG_NCPFS_IOCTL_LOCKING
case NCP_IOC_LOCKUNLOCK:
if ( (permission(inode, MAY_WRITE, NULL) != 0)
if ((file_permission(filp, MAY_WRITE) != 0)
&& (current->uid != server->m.mounted_uid))
{
return -EACCES;
Expand Down Expand Up @@ -605,7 +609,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
#endif /* CONFIG_NCPFS_NLS */

case NCP_IOC_SETDENTRYTTL:
if ((permission(inode, MAY_WRITE, NULL) != 0) &&
if ((file_permission(filp, MAY_WRITE) != 0) &&
(current->uid != server->m.mounted_uid))
return -EACCES;
{
Expand Down Expand Up @@ -635,7 +639,7 @@ int ncp_ioctl(struct inode *inode, struct file *filp,
so we have this out of switch */
if (cmd == NCP_IOC_GETMOUNTUID) {
__kernel_uid_t uid = 0;
if ((permission(inode, MAY_READ, NULL) != 0)
if ((file_permission(filp, MAY_READ) != 0)
&& (current->uid != server->m.mounted_uid)) {
return -EACCES;
}
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2 changes: 1 addition & 1 deletion fs/open.c
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Original file line number Diff line number Diff line change
Expand Up @@ -563,7 +563,7 @@ asmlinkage long sys_fchdir(unsigned int fd)
if (!S_ISDIR(inode->i_mode))
goto out_putf;

error = permission(inode, MAY_EXEC, NULL);
error = file_permission(file, MAY_EXEC);
if (!error)
set_fs_pwd(current->fs, mnt, dentry);
out_putf:
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2 changes: 1 addition & 1 deletion fs/udf/file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -186,7 +186,7 @@ int udf_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
{
int result = -EINVAL;

if ( permission(inode, MAY_READ, NULL) != 0 )
if ( file_permission(filp, MAY_READ) != 0 )
{
udf_debug("no permission to access inode %lu\n",
inode->i_ino);
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5 changes: 5 additions & 0 deletions include/linux/fs.h
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Expand Up @@ -889,6 +889,11 @@ extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct de
*/
extern void dentry_unhash(struct dentry *dentry);

/*
* VFS file helper functions.
*/
extern int file_permission(struct file *, int);

/*
* File types
*
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