linux/fs/proc/self.c
Deepa Dinamani 078cd8279e fs: Replace CURRENT_TIME with current_time() for inode timestamps
CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_time() instead.

CURRENT_TIME is also not y2038 safe.

This is also in preparation for the patch that transitions
vfs timestamps to use 64 bit time and hence make them
y2038 safe. As part of the effort current_time() will be
extended to do range checks. Hence, it is necessary for all
file system timestamps to use current_time(). Also,
current_time() will be transitioned along with vfs to be
y2038 safe.

Note that whenever a single call to current_time() is used
to change timestamps in different inodes, it is because they
share the same time granularity.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felipe Balbi <balbi@kernel.org>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-27 21:06:21 -04:00

85 lines
2.0 KiB
C

#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/pid_namespace.h>
#include "internal.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 readlink_copy(buffer, buflen, tmp);
}
static const char *proc_self_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
struct pid_namespace *ns = inode->i_sb->s_fs_info;
pid_t tgid = task_tgid_nr_ns(current, ns);
char *name;
if (!tgid)
return ERR_PTR(-ENOENT);
/* 11 for max length of signed int in decimal + NULL term */
name = kmalloc(12, dentry ? GFP_KERNEL : GFP_ATOMIC);
if (unlikely(!name))
return dentry ? ERR_PTR(-ENOMEM) : ERR_PTR(-ECHILD);
sprintf(name, "%d", tgid);
set_delayed_call(done, kfree_link, name);
return name;
}
static const struct inode_operations proc_self_inode_operations = {
.readlink = proc_self_readlink,
.get_link = proc_self_get_link,
};
static unsigned self_inum;
int proc_setup_self(struct super_block *s)
{
struct inode *root_inode = d_inode(s->s_root);
struct pid_namespace *ns = s->s_fs_info;
struct dentry *self;
inode_lock(root_inode);
self = d_alloc_name(s->s_root, "self");
if (self) {
struct inode *inode = new_inode_pseudo(s);
if (inode) {
inode->i_ino = self_inum;
inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
inode->i_mode = S_IFLNK | S_IRWXUGO;
inode->i_uid = GLOBAL_ROOT_UID;
inode->i_gid = GLOBAL_ROOT_GID;
inode->i_op = &proc_self_inode_operations;
d_add(self, inode);
} else {
dput(self);
self = ERR_PTR(-ENOMEM);
}
} else {
self = ERR_PTR(-ENOMEM);
}
inode_unlock(root_inode);
if (IS_ERR(self)) {
pr_err("proc_fill_super: can't allocate /proc/self\n");
return PTR_ERR(self);
}
ns->proc_self = self;
return 0;
}
void __init proc_self_init(void)
{
proc_alloc_inum(&self_inum);
}