Commit e656d8a6 authored by Eric W. Biederman's avatar Eric W. Biederman
Browse files

procfs: Use the proc generic infrastructure for proc/self. 



I had visions at one point of splitting proc into two filesystems.  If
that had happened proc/self being the the part of proc that actually deals
with pids would have been a nice cleanup.  As it is proc/self requires
a lot of unnecessary infrastructure for a single file.

The only user visible change is that a mounted /proc for a pid namespace
that is dead now shows a broken proc symlink, instead of being completely
invisible.  I don't think anyone will notice or care.

Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent dd34ad35

fs/proc/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ proc-y += uptime.o 
proc-y	+= version.o

proc-y	+= softirqs.o

proc-y	+= namespaces.o

proc-y	+= self.o

proc-$(CONFIG_PROC_SYSCTL)	+= proc_sysctl.o

proc-$(CONFIG_NET)		+= proc_net.o

proc-$(CONFIG_PROC_KCORE)	+= kcore.o

fs/proc/base.c

+2 −152
Original line number Diff line number Diff line
@@ -2237,146 +2237,6 @@ static const struct file_operations proc_coredump_filter_operations = { 
};

#endif



/*

 * /proc/self:

 */

static int proc_self_readlink(struct dentry *dentry, char __user *buffer,

			      int buflen)

{

	struct pid_namespace *ns = dentry->d_sb->s_fs_info;

	pid_t tgid = task_tgid_nr_ns(current, ns);

	char tmp[PROC_NUMBUF];

	if (!tgid)

		return -ENOENT;

	sprintf(tmp, "%d", tgid);

	return vfs_readlink(dentry,buffer,buflen,tmp);

}



static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)

{

	struct pid_namespace *ns = dentry->d_sb->s_fs_info;

	pid_t tgid = task_tgid_nr_ns(current, ns);

	char *name = ERR_PTR(-ENOENT);

	if (tgid) {

		/* 11 for max length of signed int in decimal + NULL term */

		name = kmalloc(12, GFP_KERNEL);

		if (!name)

			name = ERR_PTR(-ENOMEM);

		else

			sprintf(name, "%d", tgid);

	}

	nd_set_link(nd, name);

	return NULL;

}



static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,

				void *cookie)

{

	char *s = nd_get_link(nd);

	if (!IS_ERR(s))

		kfree(s);

}



static const struct inode_operations proc_self_inode_operations = {

	.readlink	= proc_self_readlink,

	.follow_link	= proc_self_follow_link,

	.put_link	= proc_self_put_link,

};



/*

 * proc base

 *

 * These are the directory entries in the root directory of /proc

 * that properly belong to the /proc filesystem, as they describe

 * describe something that is process related.

 */

static const struct pid_entry proc_base_stuff[] = {

	NOD("self", S_IFLNK|S_IRWXUGO,

		&proc_self_inode_operations, NULL, {}),

};



static struct dentry *proc_base_instantiate(struct inode *dir,

	struct dentry *dentry, struct task_struct *task, const void *ptr)

{

	const struct pid_entry *p = ptr;

	struct inode *inode;

	struct proc_inode *ei;

	struct dentry *error;



	/* Allocate the inode */

	error = ERR_PTR(-ENOMEM);

	inode = new_inode(dir->i_sb);

	if (!inode)

		goto out;



	/* Initialize the inode */

	ei = PROC_I(inode);

	inode->i_ino = get_next_ino();

	inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;



	/*

	 * grab the reference to the task.

	 */

	ei->pid = get_task_pid(task, PIDTYPE_PID);

	if (!ei->pid)

		goto out_iput;



	inode->i_mode = p->mode;

	if (S_ISDIR(inode->i_mode))

		set_nlink(inode, 2);

	if (S_ISLNK(inode->i_mode))

		inode->i_size = 64;

	if (p->iop)

		inode->i_op = p->iop;

	if (p->fop)

		inode->i_fop = p->fop;

	ei->op = p->op;

	d_add(dentry, inode);

	error = NULL;

out:

	return error;

out_iput:

	iput(inode);

	goto out;

}



static struct dentry *proc_base_lookup(struct inode *dir, struct dentry *dentry)

{

	struct dentry *error;

	struct task_struct *task = get_proc_task(dir);

	const struct pid_entry *p, *last;



	error = ERR_PTR(-ENOENT);



	if (!task)

		goto out_no_task;



	/* Lookup the directory entry */

	last = &proc_base_stuff[ARRAY_SIZE(proc_base_stuff) - 1];

	for (p = proc_base_stuff; p <= last; p++) {

		if (p->len != dentry->d_name.len)

			continue;

		if (!memcmp(dentry->d_name.name, p->name, p->len))

			break;

	}

	if (p > last)

		goto out;



	error = proc_base_instantiate(dir, dentry, task, p);



out:

	put_task_struct(task);

out_no_task:

	return error;

}



static int proc_base_fill_cache(struct file *filp, void *dirent,

	filldir_t filldir, struct task_struct *task, const struct pid_entry *p)

{

	return proc_fill_cache(filp, dirent, filldir, p->name, p->len,

				proc_base_instantiate, task, p);

}



#ifdef CONFIG_TASK_IO_ACCOUNTING

static int do_io_accounting(struct task_struct *task, char *buffer, int whole)

{
@@ -2767,15 +2627,11 @@ out: 


struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags)

{

	struct dentry *result;

	struct dentry *result = NULL;

	struct task_struct *task;

	unsigned tgid;

	struct pid_namespace *ns;



	result = proc_base_lookup(dir, dentry);

	if (!IS_ERR(result) || PTR_ERR(result) != -ENOENT)

		goto out;



	tgid = name_to_int(dentry);

	if (tgid == ~0U)

		goto out;
@@ -2838,7 +2694,7 @@ retry: 
	return iter;

}



#define TGID_OFFSET (FIRST_PROCESS_ENTRY + ARRAY_SIZE(proc_base_stuff))

#define TGID_OFFSET (FIRST_PROCESS_ENTRY)



static int proc_pid_fill_cache(struct file *filp, void *dirent, filldir_t filldir,

	struct tgid_iter iter)
@@ -2872,12 +2728,6 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir) 
	if (!reaper)

		goto out_no_task;



	for (; nr < ARRAY_SIZE(proc_base_stuff); filp->f_pos++, nr++) {

		const struct pid_entry *p = &proc_base_stuff[nr];

		if (proc_base_fill_cache(filp, dirent, filldir, reaper, p) < 0)

			goto out;

	}



	ns = filp->f_dentry->d_sb->s_fs_info;

	iter.task = NULL;

	iter.tgid = filp->f_pos - TGID_OFFSET;

fs/proc/internal.h

+1 −0
Original line number Diff line number Diff line
@@ -15,6 +15,7 @@ struct ctl_table_header; 
struct  mempolicy;



extern struct proc_dir_entry proc_root;

extern void proc_self_init(void);

#ifdef CONFIG_PROC_SYSCTL

extern int proc_sys_init(void);

extern void sysctl_head_put(struct ctl_table_header *head);

fs/proc/root.c

+1 −0
Original line number Diff line number Diff line
@@ -169,6 +169,7 @@ void __init proc_root_init(void) 
		return;

	}



	proc_self_init();

	proc_symlink("mounts", NULL, "self/mounts");



	proc_net_init();

fs/proc/self.c

0 → 100644
+59 −0
Original line number Diff line number Diff line 
#include <linux/proc_fs.h>

#include <linux/sched.h>

#include <linux/namei.h>



/*

 * /proc/self:

 */

static int proc_self_readlink(struct dentry *dentry, char __user *buffer,

			      int buflen)

{

	struct pid_namespace *ns = dentry->d_sb->s_fs_info;

	pid_t tgid = task_tgid_nr_ns(current, ns);

	char tmp[PROC_NUMBUF];

	if (!tgid)

		return -ENOENT;

	sprintf(tmp, "%d", tgid);

	return vfs_readlink(dentry,buffer,buflen,tmp);

}



static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)

{

	struct pid_namespace *ns = dentry->d_sb->s_fs_info;

	pid_t tgid = task_tgid_nr_ns(current, ns);

	char *name = ERR_PTR(-ENOENT);

	if (tgid) {

		/* 11 for max length of signed int in decimal + NULL term */

		name = kmalloc(12, GFP_KERNEL);

		if (!name)

			name = ERR_PTR(-ENOMEM);

		else

			sprintf(name, "%d", tgid);

	}

	nd_set_link(nd, name);

	return NULL;

}



static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,

				void *cookie)

{

	char *s = nd_get_link(nd);

	if (!IS_ERR(s))

		kfree(s);

}



static const struct inode_operations proc_self_inode_operations = {

	.readlink	= proc_self_readlink,

	.follow_link	= proc_self_follow_link,

	.put_link	= proc_self_put_link,

};



void __init proc_self_init(void)

{

	struct proc_dir_entry *proc_self_symlink;

	mode_t mode;



	mode = S_IFLNK | S_IRWXUGO;

	proc_self_symlink = proc_create("self", mode, NULL, NULL );

	proc_self_symlink->proc_iops = &proc_self_inode_operations;

}

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