002345925e
This allows the LSM to distinguish between syslog functions originating from /proc/kmsg access and direct syscalls. By default, the commoncaps will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg file descriptor. For example the kernel syslog reader can now drop privileges after opening /proc/kmsg, instead of staying privileged with CAP_SYS_ADMIN. MAC systems that implement security_syslog have unchanged behavior. Signed-off-by: Kees Cook <kees.cook@canonical.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>
63 lines
1.3 KiB
C
63 lines
1.3 KiB
C
/*
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* linux/fs/proc/kmsg.c
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*
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* Copyright (C) 1992 by Linus Torvalds
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*
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*/
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/time.h>
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#include <linux/kernel.h>
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#include <linux/poll.h>
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#include <linux/proc_fs.h>
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#include <linux/fs.h>
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#include <linux/syslog.h>
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#include <asm/uaccess.h>
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#include <asm/io.h>
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extern wait_queue_head_t log_wait;
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static int kmsg_open(struct inode * inode, struct file * file)
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{
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return do_syslog(1, NULL, 0, SYSLOG_FROM_FILE);
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}
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static int kmsg_release(struct inode * inode, struct file * file)
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{
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(void) do_syslog(0, NULL, 0, SYSLOG_FROM_FILE);
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return 0;
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}
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static ssize_t kmsg_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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if ((file->f_flags & O_NONBLOCK) &&
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!do_syslog(9, NULL, 0, SYSLOG_FROM_FILE))
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return -EAGAIN;
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return do_syslog(2, buf, count, SYSLOG_FROM_FILE);
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}
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static unsigned int kmsg_poll(struct file *file, poll_table *wait)
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{
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poll_wait(file, &log_wait, wait);
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if (do_syslog(9, NULL, 0, SYSLOG_FROM_FILE))
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return POLLIN | POLLRDNORM;
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return 0;
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}
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static const struct file_operations proc_kmsg_operations = {
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.read = kmsg_read,
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.poll = kmsg_poll,
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.open = kmsg_open,
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.release = kmsg_release,
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};
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static int __init proc_kmsg_init(void)
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{
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proc_create("kmsg", S_IRUSR, NULL, &proc_kmsg_operations);
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return 0;
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}
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module_init(proc_kmsg_init);
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