proc: fix PAGE_SIZE limit of /proc/$PID/cmdline
/proc/$PID/cmdline truncates output at PAGE_SIZE. It is easy to see with $ cat /proc/self/cmdline $(seq 1037) 2>/dev/null However, command line size was never limited to PAGE_SIZE but to 128 KB and relatively recently limitation was removed altogether. People noticed and ask questions: http://stackoverflow.com/questions/199130/how-do-i-increase-the-proc-pid-cmdline-4096-byte-limit seq file interface is not OK, because it kmalloc's for whole output and open + read(, 1) + sleep will pin arbitrary amounts of kernel memory. To not do that, limit must be imposed which is incompatible with arbitrary sized command lines. I apologize for hairy code, but this it direct consequence of command line layout in memory and hacks to support things like "init [3]". The loops are "unrolled" otherwise it is either macros which hide control flow or functions with 7-8 arguments with equal line count. There should be real setproctitle(2) or something. [akpm@linux-foundation.org: fix a billion min() warnings] Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Tested-by: Jarod Wilson <jarod@redhat.com> Acked-by: Jarod Wilson <jarod@redhat.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Jan Stancek <jstancek@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Alexey Dobriyan
Linus Torvalds
parent
4a00e9df29
commit
c2c0bb4462
205
fs/proc/base.c
205
fs/proc/base.c
|
|
@ -196,18 +196,205 @@ static int proc_root_link(struct dentry *dentry, struct path *path)
|
|||
return result;
|
||||
}
|
||||
|
||||
static int proc_pid_cmdline(struct seq_file *m, struct pid_namespace *ns,
|
||||
struct pid *pid, struct task_struct *task)
|
||||
static ssize_t proc_pid_cmdline_read(struct file *file, char __user *buf,
|
||||
size_t _count, loff_t *pos)
|
||||
{
|
||||
struct task_struct *tsk;
|
||||
struct mm_struct *mm;
|
||||
char *page;
|
||||
unsigned long count = _count;
|
||||
unsigned long arg_start, arg_end, env_start, env_end;
|
||||
unsigned long len1, len2, len;
|
||||
unsigned long p;
|
||||
char c;
|
||||
ssize_t rv;
|
||||
|
||||
BUG_ON(*pos < 0);
|
||||
|
||||
tsk = get_proc_task(file_inode(file));
|
||||
if (!tsk)
|
||||
return -ESRCH;
|
||||
mm = get_task_mm(tsk);
|
||||
put_task_struct(tsk);
|
||||
if (!mm)
|
||||
return 0;
|
||||
/* Check if process spawned far enough to have cmdline. */
|
||||
if (!mm->env_end) {
|
||||
rv = 0;
|
||||
goto out_mmput;
|
||||
}
|
||||
|
||||
page = (char *)__get_free_page(GFP_TEMPORARY);
|
||||
if (!page) {
|
||||
rv = -ENOMEM;
|
||||
goto out_mmput;
|
||||
}
|
||||
|
||||
down_read(&mm->mmap_sem);
|
||||
arg_start = mm->arg_start;
|
||||
arg_end = mm->arg_end;
|
||||
env_start = mm->env_start;
|
||||
env_end = mm->env_end;
|
||||
up_read(&mm->mmap_sem);
|
||||
|
||||
BUG_ON(arg_start > arg_end);
|
||||
BUG_ON(env_start > env_end);
|
||||
|
||||
len1 = arg_end - arg_start;
|
||||
len2 = env_end - env_start;
|
||||
|
||||
/*
|
||||
* Rely on struct seq_operations::show() being called once
|
||||
* per internal buffer allocation. See single_open(), traverse().
|
||||
* Inherently racy -- command line shares address space
|
||||
* with code and data.
|
||||
*/
|
||||
BUG_ON(m->size < PAGE_SIZE);
|
||||
m->count += get_cmdline(task, m->buf, PAGE_SIZE);
|
||||
return 0;
|
||||
rv = access_remote_vm(mm, arg_end - 1, &c, 1, 0);
|
||||
if (rv <= 0)
|
||||
goto out_free_page;
|
||||
|
||||
rv = 0;
|
||||
|
||||
if (c == '\0') {
|
||||
/* Command line (set of strings) occupies whole ARGV. */
|
||||
if (len1 <= *pos)
|
||||
goto out_free_page;
|
||||
|
||||
p = arg_start + *pos;
|
||||
len = len1 - *pos;
|
||||
while (count > 0 && len > 0) {
|
||||
unsigned int _count;
|
||||
int nr_read;
|
||||
|
||||
_count = min3(count, len, PAGE_SIZE);
|
||||
nr_read = access_remote_vm(mm, p, page, _count, 0);
|
||||
if (nr_read < 0)
|
||||
rv = nr_read;
|
||||
if (nr_read <= 0)
|
||||
goto out_free_page;
|
||||
|
||||
if (copy_to_user(buf, page, nr_read)) {
|
||||
rv = -EFAULT;
|
||||
goto out_free_page;
|
||||
}
|
||||
|
||||
p += nr_read;
|
||||
len -= nr_read;
|
||||
buf += nr_read;
|
||||
count -= nr_read;
|
||||
rv += nr_read;
|
||||
}
|
||||
} else {
|
||||
/*
|
||||
* Command line (1 string) occupies ARGV and maybe
|
||||
* extends into ENVP.
|
||||
*/
|
||||
if (len1 + len2 <= *pos)
|
||||
goto skip_argv_envp;
|
||||
if (len1 <= *pos)
|
||||
goto skip_argv;
|
||||
|
||||
p = arg_start + *pos;
|
||||
len = len1 - *pos;
|
||||
while (count > 0 && len > 0) {
|
||||
unsigned int _count, l;
|
||||
int nr_read;
|
||||
bool final;
|
||||
|
||||
_count = min3(count, len, PAGE_SIZE);
|
||||
nr_read = access_remote_vm(mm, p, page, _count, 0);
|
||||
if (nr_read < 0)
|
||||
rv = nr_read;
|
||||
if (nr_read <= 0)
|
||||
goto out_free_page;
|
||||
|
||||
/*
|
||||
* Command line can be shorter than whole ARGV
|
||||
* even if last "marker" byte says it is not.
|
||||
*/
|
||||
final = false;
|
||||
l = strnlen(page, nr_read);
|
||||
if (l < nr_read) {
|
||||
nr_read = l;
|
||||
final = true;
|
||||
}
|
||||
|
||||
if (copy_to_user(buf, page, nr_read)) {
|
||||
rv = -EFAULT;
|
||||
goto out_free_page;
|
||||
}
|
||||
|
||||
p += nr_read;
|
||||
len -= nr_read;
|
||||
buf += nr_read;
|
||||
count -= nr_read;
|
||||
rv += nr_read;
|
||||
|
||||
if (final)
|
||||
goto out_free_page;
|
||||
}
|
||||
skip_argv:
|
||||
/*
|
||||
* Command line (1 string) occupies ARGV and
|
||||
* extends into ENVP.
|
||||
*/
|
||||
if (len1 <= *pos) {
|
||||
p = env_start + *pos - len1;
|
||||
len = len1 + len2 - *pos;
|
||||
} else {
|
||||
p = env_start;
|
||||
len = len2;
|
||||
}
|
||||
while (count > 0 && len > 0) {
|
||||
unsigned int _count, l;
|
||||
int nr_read;
|
||||
bool final;
|
||||
|
||||
_count = min3(count, len, PAGE_SIZE);
|
||||
nr_read = access_remote_vm(mm, p, page, _count, 0);
|
||||
if (nr_read < 0)
|
||||
rv = nr_read;
|
||||
if (nr_read <= 0)
|
||||
goto out_free_page;
|
||||
|
||||
/* Find EOS. */
|
||||
final = false;
|
||||
l = strnlen(page, nr_read);
|
||||
if (l < nr_read) {
|
||||
nr_read = l;
|
||||
final = true;
|
||||
}
|
||||
|
||||
if (copy_to_user(buf, page, nr_read)) {
|
||||
rv = -EFAULT;
|
||||
goto out_free_page;
|
||||
}
|
||||
|
||||
p += nr_read;
|
||||
len -= nr_read;
|
||||
buf += nr_read;
|
||||
count -= nr_read;
|
||||
rv += nr_read;
|
||||
|
||||
if (final)
|
||||
goto out_free_page;
|
||||
}
|
||||
skip_argv_envp:
|
||||
;
|
||||
}
|
||||
|
||||
out_free_page:
|
||||
free_page((unsigned long)page);
|
||||
out_mmput:
|
||||
mmput(mm);
|
||||
if (rv > 0)
|
||||
*pos += rv;
|
||||
return rv;
|
||||
}
|
||||
|
||||
static const struct file_operations proc_pid_cmdline_ops = {
|
||||
.read = proc_pid_cmdline_read,
|
||||
.llseek = generic_file_llseek,
|
||||
};
|
||||
|
||||
static int proc_pid_auxv(struct seq_file *m, struct pid_namespace *ns,
|
||||
struct pid *pid, struct task_struct *task)
|
||||
{
|
||||
|
|
@ -2572,7 +2759,7 @@ static const struct pid_entry tgid_base_stuff[] = {
|
|||
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
|
||||
ONE("syscall", S_IRUSR, proc_pid_syscall),
|
||||
#endif
|
||||
ONE("cmdline", S_IRUGO, proc_pid_cmdline),
|
||||
REG("cmdline", S_IRUGO, proc_pid_cmdline_ops),
|
||||
ONE("stat", S_IRUGO, proc_tgid_stat),
|
||||
ONE("statm", S_IRUGO, proc_pid_statm),
|
||||
REG("maps", S_IRUGO, proc_pid_maps_operations),
|
||||
|
|
@ -2918,7 +3105,7 @@ static const struct pid_entry tid_base_stuff[] = {
|
|||
#ifdef CONFIG_HAVE_ARCH_TRACEHOOK
|
||||
ONE("syscall", S_IRUSR, proc_pid_syscall),
|
||||
#endif
|
||||
ONE("cmdline", S_IRUGO, proc_pid_cmdline),
|
||||
REG("cmdline", S_IRUGO, proc_pid_cmdline_ops),
|
||||
ONE("stat", S_IRUGO, proc_tid_stat),
|
||||
ONE("statm", S_IRUGO, proc_pid_statm),
|
||||
REG("maps", S_IRUGO, proc_tid_maps_operations),
|
||||
|
|
|
|||
Loading…
Reference in New Issue