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6b2553918d
new method: ->get_link(); replacement of ->follow_link(). The differences are: * inode and dentry are passed separately * might be called both in RCU and non-RCU mode; the former is indicated by passing it a NULL dentry. * when called that way it isn't allowed to block and should return ERR_PTR(-ECHILD) if it needs to be called in non-RCU mode. It's a flagday change - the old method is gone, all in-tree instances converted. Conversion isn't hard; said that, so far very few instances do not immediately bail out when called in RCU mode. That'll change in the next commits. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/pid_namespace.h>
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#include "internal.h"
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/*
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* /proc/self:
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*/
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static int proc_self_readlink(struct dentry *dentry, char __user *buffer,
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int buflen)
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{
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struct pid_namespace *ns = dentry->d_sb->s_fs_info;
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pid_t tgid = task_tgid_nr_ns(current, ns);
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char tmp[PROC_NUMBUF];
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if (!tgid)
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return -ENOENT;
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sprintf(tmp, "%d", tgid);
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return readlink_copy(buffer, buflen, tmp);
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}
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static const char *proc_self_get_link(struct dentry *dentry,
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struct inode *inode, void **cookie)
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{
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struct pid_namespace *ns = inode->i_sb->s_fs_info;
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pid_t tgid = task_tgid_nr_ns(current, ns);
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char *name;
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if (!dentry)
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return ERR_PTR(-ECHILD);
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if (!tgid)
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return ERR_PTR(-ENOENT);
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/* 11 for max length of signed int in decimal + NULL term */
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name = kmalloc(12, GFP_KERNEL);
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if (!name)
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return ERR_PTR(-ENOMEM);
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sprintf(name, "%d", tgid);
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return *cookie = name;
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}
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static const struct inode_operations proc_self_inode_operations = {
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.readlink = proc_self_readlink,
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.get_link = proc_self_get_link,
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.put_link = kfree_put_link,
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};
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static unsigned self_inum;
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int proc_setup_self(struct super_block *s)
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{
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struct inode *root_inode = d_inode(s->s_root);
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struct pid_namespace *ns = s->s_fs_info;
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struct dentry *self;
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mutex_lock(&root_inode->i_mutex);
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self = d_alloc_name(s->s_root, "self");
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if (self) {
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struct inode *inode = new_inode_pseudo(s);
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if (inode) {
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inode->i_ino = self_inum;
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inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
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inode->i_mode = S_IFLNK | S_IRWXUGO;
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inode->i_uid = GLOBAL_ROOT_UID;
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inode->i_gid = GLOBAL_ROOT_GID;
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inode->i_op = &proc_self_inode_operations;
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d_add(self, inode);
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} else {
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dput(self);
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self = ERR_PTR(-ENOMEM);
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}
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} else {
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self = ERR_PTR(-ENOMEM);
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}
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mutex_unlock(&root_inode->i_mutex);
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if (IS_ERR(self)) {
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pr_err("proc_fill_super: can't allocate /proc/self\n");
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return PTR_ERR(self);
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}
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ns->proc_self = self;
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return 0;
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}
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void __init proc_self_init(void)
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{
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proc_alloc_inum(&self_inum);
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}
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