Export some AFS-specific information through xattrs with an "afs." prefix.
This allows some pioctls to be emulated in userspace.
This can be tested directly using the getfattr program:
[root@andromeda ~]# getfattr -d -m - /afs
getfattr: Removing leading '/' from absolute path names
# file: afs
security.selinux="system_u:object_r:nfs_t:s0\000"
system.afs.cell="procyon.org.uk"
system.afs.fid="20000000:00000001:00000001"
A tentative wrapper for partially implementing pioctl in userspace could look
like (this implementation is designed for LD_PRELOAD overloading of syscall()
for simplicity, but should be linked in properly):
/* Userspace version of pioctl
*
* Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define syscall _X_syscall
#include <unistd.h>
#undef syscall
#include <syscall.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sys/xattr.h>
#include <errno.h>
#include <dlfcn.h>
#define RTLD_NEXT ((void *) -1l)
#define O_NOACCESS 00000003
#define O_NOFOLLOW 00400000 /* don't follow links */
#define O_NODE 04000000 /* open filesystem node, not device */
struct ViceIoctl {
caddr_t in;
caddr_t out;
short in_size;
short out_size;
};
#define _VICEIOCTL(nr) _IOW('V', nr, struct ViceIoctl)
#define _CVICEIOCTL(nr) _IOW('C', nr, struct ViceIoctl)
#define _OVICEIOCTL(nr) _IOW('O', nr, struct ViceIoctl)
#define AFS_PIOCTL 0x14
#define VIOCGETFID _VICEIOCTL(22) /* get file ID */
#define AFS_XATTR_PREFIX "system.afs."
struct afs_fid {
unsigned vid; /* volume ID */
unsigned vnode; /* file index within volume */
unsigned unique; /* unique ID number (file index version) */
};
static long (*libc_syscall)(int number, long a, long b, long c, long d, long e, long f);
/*
* VIOCGETFID
*/
static int afs_viocgetfid(int fd, int cmd, struct ViceIoctl *args)
{
struct afs_fid *fid = (void *) args->out;
char buf[8*3];
int ret;
if (args->out_size < sizeof(struct afs_fid) || !args->out) {
errno = EINVAL;
return -1;
}
ret = fgetxattr(fd, AFS_XATTR_PREFIX "fid", buf, sizeof(buf) - 1);
if (ret == -1)
return ret;
buf[23] = 0;
if (sscanf(buf, "%x:%x:%x", &fid->vid, &fid->vnode, &fid->unique) != 3) {
errno = EIO;
return -1;
}
args->out_size = sizeof(struct afs_fid);
return 0;
}
/*
* the main pioctl switch
*/
static long pioctl(const char *path, int cmd, struct ViceIoctl *args,
int follow)
{
long ret;
int fd, ret2;
printf("pioctl(%s,%x,%p,%d)\n", path, _IOC_NR(cmd), args, follow);
if (args->in_size < 0 || args->out_size < 0)
goto invalid_arg;
/* handle pathless pioctls */
switch (cmd) {
default:
if (!path) {
errno = EINVAL;
return -1;
}
break;
}
fd = open(path, O_NODE | O_NOACCESS | (follow ? 0 : O_NOFOLLOW), 0);
if (fd == -1)
return -1;
switch (cmd) {
case VIOCGETFID:
ret = afs_viocgetfid(fd, cmd, args);
break;
default:
errno = EOPNOTSUPP;
ret = -1;
break;
}
ret2 = close(fd);
if (ret != -1 && ret2 == -1)
ret = ret2;
return ret;
invalid_arg:
errno = EINVAL;
return -1;
}
static long afs(long function, long b, long c, long d, long e, long f)
{
if (function == AFS_PIOCTL) {
return pioctl((const char *) b,
(int) c,
(struct ViceIoctl *) d,
(int) e);
} else {
printf("afs(%ld,%lx)\n", function, b);
errno = ENOSYS;
return -1;
}
}
long syscall(int number, long a, long b, long c, long d, long e, long f)
{
long ret;
if (!libc_syscall) {
libc_syscall = dlsym(RTLD_NEXT, "syscall");
if (!libc_syscall) {
fprintf(stderr, "Cannot get syscall\n");
abort();
}
}
ret = libc_syscall(number, a, b, c, d, e, f);
if (ret != -1)
return ret;
if (errno == ENOSYS && number == SYS_afs_syscall)
return afs(a, b, c, d, e, f);
return -1;
}
This can be tested like this:
gcc -gstabs+ -fpic -Wall -c -o pioctl.o pioctl.c
gcc -shared -o libpioctl.so pioctl.o -ldl -lc
[root@andromeda ~]# LD_PRELOAD=/tmp/libpioctl.so fs getfid /afs
pioctl(/afs,16,0x7fffdadc6560,1)
File /afs (1.0.0) contained in volume 1
Signed-off-by: David Howells <dhowells RemoveThis @redhat.com>
---
fs/afs/Makefile | 3 +
fs/afs/dir.c | 2 +
fs/afs/file.c | 2 +
fs/afs/inode.c | 8 +++
fs/afs/internal.h | 5 ++
fs/afs/mntpt.c | 2 +
fs/afs/security.c | 18 ++++--
fs/afs/xattr.c | 162 +++++++++++++++++++++++++++++++++++++++++++++++++++
security/security.c | 1
9 files changed, 197 insertions(+), 6 deletions(-)
create mode 100644 fs/afs/xattr.c
diff --git a/fs/afs/Makefile b/fs/afs/Makefile
index 4f64b95..095c541 100644
--- a/fs/afs/Makefile
+++ b/fs/afs/Makefile
@@ -27,6 +27,7 @@ kafs-objs := \
vlocation.o \
vnode.o \
volume.o \
- write.o
+ write.o \
+ xattr.o
obj-$(CONFIG_AFS_FS) := kafs.o
diff --git a/fs/afs/dir.c b/fs/afs/dir.c
index 9bd7577..5272872 100644
--- a/fs/afs/dir.c
+++ b/fs/afs/dir.c
@@ -60,6 +60,8 @@ const struct inode_operations afs_dir_inode_operations = {
.permission = afs_permission,
.getattr = afs_getattr,
.setattr = afs_setattr,
+ .getxattr = afs_getxattr,
+ .listxattr = afs_listxattr,
};
static const struct dentry_operations afs_fs_dentry_operations = {
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 0149dab..1586496 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -45,6 +45,8 @@ const struct inode_operations afs_file_inode_operations = {
.getattr = afs_getattr,
.setattr = afs_setattr,
.permission = afs_permission,
+ .getxattr = afs_getxattr,
+ .listxattr = afs_listxattr,
};
const struct address_space_operations afs_fs_aops = {
diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index c048f06..8fe6192 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -27,6 +27,14 @@ struct afs_iget_data {
struct afs_volume *volume; /* volume on which resides */
};
+const struct inode_operations afs_symlink_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = page_follow_link_light,
+ .put_link = page_put_link,
+ .getxattr = afs_getxattr,
+ .listxattr = afs_listxattr,
+};
+
/*
* map the AFS file status to the inode member variables
*/
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 59049b0..5a815e8 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -741,6 +741,11 @@ extern ssize_t afs_file_write(struct kiocb *, const struct iovec *,
extern int afs_writeback_all(struct afs_vnode *);
extern int afs_fsync(struct file *, struct dentry *, int);
+/*
+ * xattr.c
+ */
+extern ssize_t afs_listxattr(struct dentry *, char *, size_t);
+extern ssize_t afs_getxattr(struct dentry *, const char *, void *, size_t);
/*****************************************************************************/
/*
diff --git a/fs/afs/mntpt.c b/fs/afs/mntpt.c
index c52be53..994f75d 100644
--- a/fs/afs/mntpt.c
+++ b/fs/afs/mntpt.c
@@ -37,6 +37,8 @@ const struct inode_operations afs_mntpt_inode_operations = {
.follow_link = afs_mntpt_follow_link,
.readlink = page_readlink,
.getattr = afs_getattr,
+ .getxattr = afs_getxattr,
+ .listxattr = afs_listxattr,
};
static LIST_HEAD(afs_vfsmounts);
diff --git a/fs/afs/security.c b/fs/afs/security.c
index 3ef5043..6c9e011 100644
--- a/fs/afs/security.c
+++ b/fs/afs/security.c
@@ -291,7 +291,7 @@ int afs_permission(struct inode *inode, int mask)
struct key *key;
int ret;
- _enter("{{%x:%u},%lx},%x,",
+ kenter("{{%x:%u},%lx},%x,",
vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
key = afs_request_key(vnode->volume->cell);
@@ -315,7 +315,7 @@ int afs_permission(struct inode *inode, int mask)
goto error;
/* interpret the access mask */
- _debug("REQ %x ACC %x on %s",
+ kdebug("REQ %x ACC %x on %s",
mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
if (S_ISDIR(inode->i_mode)) {
@@ -330,8 +330,11 @@ int afs_permission(struct inode *inode, int mask)
AFS_ACE_INSERT | /* create, mkdir, symlink, rename to */
AFS_ACE_WRITE))) /* chmod */
goto permission_denied;
+ } else if (mask & MAY_OPEN) {
} else {
- BUG();
+ printk(KERN_WARNING "AFS: Unhandled perm mask %x\n",
+ mask);
+ goto permission_denied;
}
} else {
if (!(access & AFS_ACE_LOOKUP))
@@ -342,18 +345,23 @@ int afs_permission(struct inode *inode, int mask)
} else if (mask & MAY_WRITE) {
if (!(access & AFS_ACE_WRITE))
goto permission_denied;
+ } else if (mask & MAY_OPEN) {
+ } else {
+ printk(KERN_WARNING "AFS: Unhandled perm mask %x\n",
+ mask);
+ goto permission_denied;
}
}
key_put(key);
ret = generic_permission(inode, mask, NULL);
- _leave(" = %d", ret);
+ kleave(" = %d", ret);
return ret;
permission_denied:
ret = -EACCES;
error:
key_put(key);
- _leave(" = %d", ret);
+ kleave(" = %d [error]", ret);
return ret;
}
diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
new file mode 100644
index 0000000..6e9d832
--- /dev/null
+++ b/fs/afs/xattr.c
@@ -0,0 +1,162 @@
+/* AFS extended attribute support
+ *
+ * Copyright (C) 2009 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/xattr.h>
+#include <linux/security.h>
+#include "internal.h"
+
+static const char afs_xattr_prefix[] = XATTR_SYSTEM_PREFIX "afs.";
+
+typedef ssize_t (*afs_xattr_get_t)(struct afs_vnode *vnode, struct key *key,
+ void *value, size_t size);
+
+struct afs_xattr {
+ const char *name;
+ afs_xattr_get_t get;
+};
+
+/*
+ * Get the AFS file identifier of a file
+ */
+static ssize_t afs_xattr_get_fid(struct afs_vnode *vnode, struct key *key,
+ void *value, size_t size)
+{
+ ssize_t ret;
+
+ _enter("");
+
+ ret = snprintf(value, size, "%08x:%08x:%08x",
+ vnode->fid.vid, vnode->fid.vnode, vnode->fid.unique);
+
+ _leave(" = %zd", ret);
+ return ret;
+}
+
+/*
+ * Get the AFS cell name of a file
+ */
+static ssize_t afs_xattr_get_cell(struct afs_vnode *vnode, struct key *key,
+ void *value, size_t size)
+{
+ ssize_t ret;
+
+ _enter("");
+
+ ret = snprintf(value, size, "%s", vnode->volume->vlocation->cell->name);
+
+ _leave(" = %zd", ret);
+ return ret;
+}
+
+/*
+ * ordered list of AFS attributes
+ */
+static const struct afs_xattr afs_xattrs[] = {
+ { "cell", afs_xattr_get_cell },
+ { "fid", afs_xattr_get_fid },
+ { NULL }
+};
+
+/*
+ * list extended attributes for an AFS file
+ */
+ssize_t afs_listxattr(struct dentry *dentry, char *list, size_t size)
+{
+ const struct afs_xattr *p;
+ struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
+ struct key *key;
+ ssize_t total, nlen, len, plen, ret;
+ char *to = list;
+
+ _enter(",%p,%zu", list, size);
+
+ key = afs_request_key(vnode->volume->cell);
+ if (IS_ERR(key)) {
+ ret = PTR_ERR(key);
+ _leave(" = %ld [no key]", ret);
+ return ret;
+ }
+
+ /* list the AFS attributes */
+ _debug("afs attr");
+ plen = sizeof(afs_xattr_prefix);
+ total = 0;
+ for (p = afs_xattrs; p->name; p++) {
+ nlen = strlen(p->name);
+ len = nlen + sizeof(afs_xattr_prefix);
+ total += len;
+ if (len <= size && list) {
+ size -= len;
+ memcpy(to, afs_xattr_prefix, plen - 1);
+ to += plen - 1;
+ memcpy(to, p->name, nlen + 1);
+ to += nlen + 1;
+ }
+ }
+
+ /* TODO: tag on user attributes when they become available */
+ _debug("user attr");
+
+ /* tag on the security subsys's attributes */
+ _debug("sec attr");
+ len = security_inode_listsecurity(dentry->d_inode, to, size);
+ if (IS_ERR_VALUE(len))
+ total = len;
+ else
+ total += len;
+
+ key_put(key);
+ _leave(" = %zd [%zd]", total, to - list);
+ return total;
+}
+
+/*
+ * get extended attributes for an AFS file
+ */
+ssize_t afs_getxattr(struct dentry *dentry, const char *name,
+ void *value, size_t size)
+{
+ const struct afs_xattr *p;
+ struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
+ struct key *key;
+ ssize_t ret;
+
+ _enter(",%s,,%zu", name, size);
+
+ key = afs_request_key(vnode->volume->cell);
+ if (IS_ERR(key)) {
+ ret = PTR_ERR(key);
+ _leave(" = %ld [no key]", ret);
+ return ret;
+ }
+
+ /* get AFS attributes */
+ if (memcmp(name, afs_xattr_prefix, sizeof(afs_xattr_prefix) - 1) == 0) {
+ name += sizeof(afs_xattr_prefix) - 1;
+
+ for (p = afs_xattrs; p->name; p++) {
+ if (strcmp(name, p->name) == 0) {
+ ret = p->get(vnode, key, value, size);
+ goto out;
+ }
+ }
+ goto noattr;
+ }
+
+ /* TODO: get user attributes when they become available */
+
+noattr:
+ ret = -ENODATA;
+out:
+ key_put(key);
+ _leave(" = %zd", ret);
+ return ret;
+}
diff --git a/security/security.c b/security/security.c
index dc7674f..fe6b812 100644
--- a/security/security.c
+++ b/security/security.c
@@ -609,6 +609,7 @@ int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer
return 0;
return security_ops->inode_listsecurity(inode, buffer, buffer_size);
}
+EXPORT_SYMBOL(security_inode_listsecurity);
void security_inode_getsecid(const struct inode *inode, u32 *secid)
{
--
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