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SubjectRe: [PATCH] Process Attribute API for Security Modules 2.5.69
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Date
On Wed, 2003-05-07 at 06:50, viro@parcelfarce.linux.theplanet.co.uk
wrote:
> Umm... How about having it merged with proc_base_readdir()? I.e.
> have both call the common helper. Ditto for lookups.
>
> Other than that (and missing check for copy_to_user() return value in
> ->read()) I don't see any problems here.

This updated patch against 2.5.69 merges the readdir and lookup routines
for proc_base and proc_attr, fixes the copy_to_user call in
proc_attr_read and proc_info_read, moves the new data and code within
CONFIG_SECURITY, and uses ARRAY_SIZE, per the comments from Al Viro and
Andrew Morton. As before, this patch implements a process attribute API
for security modules via a set of nodes in a /proc/pid/attr directory.
Credit for the idea of implementing this API via /proc/pid/attr nodes
goes to Al Viro. Jan Harkes provided a nice cleanup of the
implementation to reduce the code bloat.

fs/proc/base.c | 172 +++++++++++++++++++++++++++++++++++++++++++----
include/linux/security.h | 23 ++++++
security/dummy.c | 12 +++
3 files changed, 196 insertions(+), 11 deletions(-)
Index: linux-2.5/fs/proc/base.c
diff -u linux-2.5/fs/proc/base.c:1.1.1.3 linux-2.5/fs/proc/base.c:1.10
--- linux-2.5/fs/proc/base.c:1.1.1.3 Mon Apr 21 10:15:46 2003
+++ linux-2.5/fs/proc/base.c Wed May 7 10:53:05 2003
@@ -58,6 +58,13 @@
PROC_PID_MAPS,
PROC_PID_MOUNTS,
PROC_PID_WCHAN,
+#ifdef CONFIG_SECURITY
+ PROC_PID_ATTR,
+ PROC_PID_ATTR_CURRENT,
+ PROC_PID_ATTR_PREV,
+ PROC_PID_ATTR_EXEC,
+ PROC_PID_ATTR_FSCREATE,
+#endif
PROC_PID_FD_DIR = 0x8000, /* 0x8000-0xffff */
};

@@ -82,11 +89,23 @@
E(PROC_PID_ROOT, "root", S_IFLNK|S_IRWXUGO),
E(PROC_PID_EXE, "exe", S_IFLNK|S_IRWXUGO),
E(PROC_PID_MOUNTS, "mounts", S_IFREG|S_IRUGO),
+#ifdef CONFIG_SECURITY
+ E(PROC_PID_ATTR, "attr", S_IFDIR|S_IRUGO|S_IXUGO),
+#endif
#ifdef CONFIG_KALLSYMS
E(PROC_PID_WCHAN, "wchan", S_IFREG|S_IRUGO),
#endif
{0,0,NULL,0}
};
+#ifdef CONFIG_SECURITY
+static struct pid_entry attr_stuff[] = {
+ E(PROC_PID_ATTR_CURRENT, "current", S_IFREG|S_IRUGO|S_IWUSR),
+ E(PROC_PID_ATTR_PREV, "prev", S_IFREG|S_IRUGO|S_IWUSR),
+ E(PROC_PID_ATTR_EXEC, "exec", S_IFREG|S_IRUGO|S_IWUSR),
+ E(PROC_PID_ATTR_FSCREATE, "fscreate", S_IFREG|S_IRUGO|S_IWUSR),
+ {0,0,NULL,0}
+};
+#endif
#undef E

static inline struct task_struct *proc_task(struct inode *inode)
@@ -409,8 +428,10 @@
if (count + *ppos > length)
count = length - *ppos;
end = count + *ppos;
- copy_to_user(buf, (char *) page + *ppos, count);
- *ppos = end;
+ if (copy_to_user(buf, (char *) page + *ppos, count))
+ count = -EFAULT;
+ else
+ *ppos = end;
free_page(page);
return count;
}
@@ -687,14 +708,17 @@
return retval;
}

-static int proc_base_readdir(struct file * filp,
- void * dirent, filldir_t filldir)
+static int proc_pident_readdir(struct file * filp,
+ void * dirent, filldir_t filldir,
+ struct pid_entry *ents, unsigned int nents)
{
int i;
int pid;
- struct inode *inode = filp->f_dentry->d_inode;
+ struct dentry *dentry = filp->f_dentry;
+ struct inode *inode = dentry->d_inode;
struct pid_entry *p;
int ret = 0;
+ ino_t ino;

lock_kernel();

@@ -706,24 +730,26 @@
i = filp->f_pos;
switch (i) {
case 0:
- if (filldir(dirent, ".", 1, i, inode->i_ino, DT_DIR) < 0)
+ ino = inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
goto out;
i++;
filp->f_pos++;
/* fall through */
case 1:
- if (filldir(dirent, "..", 2, i, PROC_ROOT_INO, DT_DIR) < 0)
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
goto out;
i++;
filp->f_pos++;
/* fall through */
default:
i -= 2;
- if (i>=sizeof(base_stuff)/sizeof(base_stuff[0])) {
+ if (i>=nents) {
ret = 1;
goto out;
}
- p = base_stuff + i;
+ p = ents + i;
while (p->name) {
if (filldir(dirent, p->name, p->len, filp->f_pos,
fake_ino(pid, p->type), p->mode >> 12) < 0)
@@ -739,6 +765,13 @@
return ret;
}

+static int proc_base_readdir(struct file * filp,
+ void * dirent, filldir_t filldir)
+{
+ return proc_pident_readdir(filp,dirent,filldir,
+ base_stuff,ARRAY_SIZE(base_stuff));
+}
+
/* building an inode */

static int task_dumpable(struct task_struct *task)
@@ -961,8 +994,86 @@
.permission = proc_permission,
};

+#ifdef CONFIG_SECURITY
+static ssize_t proc_pid_attr_read(struct file * file, char * buf,
+ size_t count, loff_t *ppos)
+{
+ struct inode * inode = file->f_dentry->d_inode;
+ unsigned long page;
+ ssize_t length;
+ ssize_t end;
+ struct task_struct *task = proc_task(inode);
+
+ if (count > PAGE_SIZE)
+ count = PAGE_SIZE;
+ if (!(page = __get_free_page(GFP_KERNEL)))
+ return -ENOMEM;
+
+ length = security_getprocattr(task,
+ (char*)file->f_dentry->d_name.name,
+ (void*)page, count);
+ if (length < 0) {
+ free_page(page);
+ return length;
+ }
+ /* Static 4kB (or whatever) block capacity */
+ if (*ppos >= length) {
+ free_page(page);
+ return 0;
+ }
+ if (count + *ppos > length)
+ count = length - *ppos;
+ end = count + *ppos;
+ if (copy_to_user(buf, (char *) page + *ppos, count))
+ count = -EFAULT;
+ else
+ *ppos = end;
+ free_page(page);
+ return count;
+}
+
+static ssize_t proc_pid_attr_write(struct file * file, const char * buf,
+ size_t count, loff_t *ppos)
+{
+ struct inode * inode = file->f_dentry->d_inode;
+ char *page;
+ ssize_t length;
+ struct task_struct *task = proc_task(inode);
+
+ if (count > PAGE_SIZE)
+ count = PAGE_SIZE;
+ if (*ppos != 0) {
+ /* No partial writes. */
+ return -EINVAL;
+ }
+ page = (char*)__get_free_page(GFP_USER);
+ if (!page)
+ return -ENOMEM;
+ length = -EFAULT;
+ if (copy_from_user(page, buf, count))
+ goto out;
+
+ length = security_setprocattr(task,
+ (char*)file->f_dentry->d_name.name,
+ (void*)page, count);
+out:
+ free_page((unsigned long) page);
+ return length;
+}
+
+static struct file_operations proc_pid_attr_operations = {
+ .read = proc_pid_attr_read,
+ .write = proc_pid_attr_write,
+};
+
+static struct file_operations proc_attr_operations;
+static struct inode_operations proc_attr_inode_operations;
+#endif
+
/* SMP-safe */
-static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)
+static struct dentry *proc_pident_lookup(struct inode *dir,
+ struct dentry *dentry,
+ struct pid_entry *ents)
{
struct inode *inode;
int error;
@@ -973,7 +1084,7 @@
error = -ENOENT;
inode = NULL;

- for (p = base_stuff; p->name; p++) {
+ for (p = ents; p->name; p++) {
if (p->len != dentry->d_name.len)
continue;
if (!memcmp(dentry->d_name.name, p->name, p->len))
@@ -1041,6 +1152,19 @@
case PROC_PID_MOUNTS:
inode->i_fop = &proc_mounts_operations;
break;
+#ifdef CONFIG_SECURITY
+ case PROC_PID_ATTR:
+ inode->i_nlink = 2;
+ inode->i_op = &proc_attr_inode_operations;
+ inode->i_fop = &proc_attr_operations;
+ break;
+ case PROC_PID_ATTR_CURRENT:
+ case PROC_PID_ATTR_PREV:
+ case PROC_PID_ATTR_EXEC:
+ case PROC_PID_ATTR_FSCREATE:
+ inode->i_fop = &proc_pid_attr_operations;
+ break;
+#endif
#ifdef CONFIG_KALLSYMS
case PROC_PID_WCHAN:
inode->i_fop = &proc_info_file_operations;
@@ -1062,6 +1186,10 @@
return ERR_PTR(error);
}

+static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry){
+ return proc_pident_lookup(dir, dentry, base_stuff);
+}
+
static struct file_operations proc_base_operations = {
.read = generic_read_dir,
.readdir = proc_base_readdir,
@@ -1070,6 +1198,28 @@
static struct inode_operations proc_base_inode_operations = {
.lookup = proc_base_lookup,
};
+
+#ifdef CONFIG_SECURITY
+static int proc_attr_readdir(struct file * filp,
+ void * dirent, filldir_t filldir)
+{
+ return proc_pident_readdir(filp,dirent,filldir,
+ attr_stuff,ARRAY_SIZE(attr_stuff));
+}
+
+static struct file_operations proc_attr_operations = {
+ .read = generic_read_dir,
+ .readdir = proc_attr_readdir,
+};
+
+static struct dentry *proc_attr_lookup(struct inode *dir, struct dentry *dentry){
+ return proc_pident_lookup(dir, dentry, attr_stuff);
+}
+
+static struct inode_operations proc_attr_inode_operations = {
+ .lookup = proc_attr_lookup,
+};
+#endif

/*
* /proc/self:
Index: linux-2.5/include/linux/security.h
diff -u linux-2.5/include/linux/security.h:1.1.1.2 linux-2.5/include/linux/security.h:1.16
--- linux-2.5/include/linux/security.h:1.1.1.2 Wed Mar 19 09:54:58 2003
+++ linux-2.5/include/linux/security.h Fri Apr 18 11:17:19 2003
@@ -1123,6 +1128,9 @@

void (*d_instantiate) (struct dentry *dentry, struct inode *inode);

+ int (*getprocattr)(struct task_struct *p, char *name, void *value, size_t size);
+ int (*setprocattr)(struct task_struct *p, char *name, void *value, size_t size);
+
#ifdef CONFIG_SECURITY_NETWORK
int (*unix_stream_connect) (struct socket * sock,
struct socket * other, struct sock * newsk);
@@ -1755,6 +1769,16 @@
security_ops->d_instantiate (dentry, inode);
}

+static inline int security_getprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return security_ops->getprocattr(p, name, value, size);
+}
+
+static inline int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return security_ops->setprocattr(p, name, value, size);
+}
+
static inline int security_netlink_send(struct sk_buff * skb)
{
return security_ops->netlink_send(skb);
@@ -2339,6 +2367,16 @@

static inline void security_d_instantiate (struct dentry *dentry, struct inode *inode)
{ }
+
+static inline int security_getprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return -EINVAL;
+}
+
+static inline int security_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return -EINVAL;
+}

/*
* The netlink capability defaults need to be used inline by default
Index: linux-2.5/security/dummy.c
diff -u linux-2.5/security/dummy.c:1.1.1.2 linux-2.5/security/dummy.c:1.14
--- linux-2.5/security/dummy.c:1.1.1.2 Wed Mar 19 09:59:17 2003
+++ linux-2.5/security/dummy.c Fri Apr 18 11:17:20 2003
@@ -736,6 +741,16 @@
return;
}

+static int dummy_getprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return -EINVAL;
+}
+
+static int dummy_setprocattr(struct task_struct *p, char *name, void *value, size_t size)
+{
+ return -EINVAL;
+}
+

struct security_operations dummy_security_ops;

@@ -860,6 +876,8 @@
set_to_dummy_if_null(ops, register_security);
set_to_dummy_if_null(ops, unregister_security);
set_to_dummy_if_null(ops, d_instantiate);
+ set_to_dummy_if_null(ops, getprocattr);
+ set_to_dummy_if_null(ops, setprocattr);
#ifdef CONFIG_SECURITY_NETWORK
set_to_dummy_if_null(ops, unix_stream_connect);
set_to_dummy_if_null(ops, unix_may_send);

--
Stephen Smalley <sds@epoch.ncsc.mil>
National Security Agency

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