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e656d8a6f7
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: Eric W. Biederman <ebiederm@xmission.com>
60 lines
1.4 KiB
C
60 lines
1.4 KiB
C
#include <linux/proc_fs.h>
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#include <linux/sched.h>
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#include <linux/namei.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 vfs_readlink(dentry,buffer,buflen,tmp);
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}
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static void *proc_self_follow_link(struct dentry *dentry, struct nameidata *nd)
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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 *name = ERR_PTR(-ENOENT);
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if (tgid) {
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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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name = ERR_PTR(-ENOMEM);
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else
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sprintf(name, "%d", tgid);
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}
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nd_set_link(nd, name);
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return NULL;
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}
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static void proc_self_put_link(struct dentry *dentry, struct nameidata *nd,
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void *cookie)
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{
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char *s = nd_get_link(nd);
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if (!IS_ERR(s))
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kfree(s);
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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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.follow_link = proc_self_follow_link,
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.put_link = proc_self_put_link,
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};
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void __init proc_self_init(void)
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{
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struct proc_dir_entry *proc_self_symlink;
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mode_t mode;
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mode = S_IFLNK | S_IRWXUGO;
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proc_self_symlink = proc_create("self", mode, NULL, NULL );
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proc_self_symlink->proc_iops = &proc_self_inode_operations;
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}
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