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Commit 1d1221f3 authored by Vasiliy Kulikov's avatar Vasiliy Kulikov Committed by Linus Torvalds
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proc: restrict access to /proc/PID/io 



/proc/PID/io may be used for gathering private information.  E.g.  for
openssh and vsftpd daemons wchars/rchars may be used to learn the
precise password length.  Restrict it to processes being able to ptrace
the target process.

ptrace_may_access() is needed to prevent keeping open file descriptor of
"io" file, executing setuid binary and gathering io information of the
setuid'ed process.

Signed-off-by: default avatarVasiliy Kulikov <segoon@openwall.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b0af8dfd

fs/proc/base.c

+5 −2
Original line number Diff line number Diff line
@@ -2708,6 +2708,9 @@ static int do_io_accounting(struct task_struct *task, char *buffer, int whole) 
	struct task_io_accounting acct = task->ioac;

	unsigned long flags;



	if (!ptrace_may_access(task, PTRACE_MODE_READ))

		return -EACCES;



	if (whole && lock_task_sighand(task, &flags)) {

		struct task_struct *t = task;
@@ -2839,7 +2842,7 @@ static const struct pid_entry tgid_base_stuff[] = { 
	REG("coredump_filter", S_IRUGO|S_IWUSR, proc_coredump_filter_operations),

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	INF("io",	S_IRUGO, proc_tgid_io_accounting),

	INF("io",	S_IRUSR, proc_tgid_io_accounting),

#endif

#ifdef CONFIG_HARDWALL

	INF("hardwall",   S_IRUGO, proc_pid_hardwall),
@@ -3181,7 +3184,7 @@ static const struct pid_entry tid_base_stuff[] = { 
	REG("make-it-fail", S_IRUGO|S_IWUSR, proc_fault_inject_operations),

#endif

#ifdef CONFIG_TASK_IO_ACCOUNTING

	INF("io",	S_IRUGO, proc_tid_io_accounting),

	INF("io",	S_IRUSR, proc_tid_io_accounting),

#endif

#ifdef CONFIG_HARDWALL

	INF("hardwall",   S_IRUGO, proc_pid_hardwall),