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locks: only validate the lock vs. f_mode in F_SETLK codepaths 

v2: replace missing break in switch statement (as pointed out by Dave
    Jones)

commit bce7560d49 (locks: consolidate checks for compatible
filp->f_mode values in setlk handlers) introduced a regression in the
F_GETLK handler.

flock64_to_posix_lock is a shared codepath between F_GETLK and F_SETLK,
but the f_mode checks should only be applicable to the F_SETLK codepaths
according to POSIX.

Instead of just reverting the patch, add a new function to do this
checking and have the F_SETLK handlers call it.

Cc: Dave Jones <davej@redhat.com>
Reported-and-Tested-by: Reuben Farrelly <reuben@reub.net>
Signed-off-by: Jeff Layton <jlayton@poochiereds.net>
This commit is contained in:
Jeff Layton 2014-05-09 11:41:54 -04:00
parent afcf0a2d92
commit cf01f4eef9
1 changed files with 24 additions and 12 deletions
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36
fs/locks.c
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@ -389,18 +389,6 @@ static int flock64_to_posix_lock(struct file *filp, struct file_lock *fl,
fl->fl_ops = NULL;
fl->fl_lmops = NULL;
/* Ensure that fl->fl_filp has compatible f_mode */
switch (l->l_type) {
case F_RDLCK:
if (!(filp->f_mode & FMODE_READ))
return -EBADF;
break;
case F_WRLCK:
if (!(filp->f_mode & FMODE_WRITE))
return -EBADF;
break;
}
return assign_type(fl, l->l_type);
}
@ -2034,6 +2022,22 @@ static int do_lock_file_wait(struct file *filp, unsigned int cmd,
return error;
}
/* Ensure that fl->fl_filp has compatible f_mode for F_SETLK calls */
static int
check_fmode_for_setlk(struct file_lock *fl)
{
switch (fl->fl_type) {
case F_RDLCK:
if (!(fl->fl_file->f_mode & FMODE_READ))
return -EBADF;
break;
case F_WRLCK:
if (!(fl->fl_file->f_mode & FMODE_WRITE))
return -EBADF;
}
return 0;
}
/* Apply the lock described by l to an open file descriptor.
* This implements both the F_SETLK and F_SETLKW commands of fcntl().
*/
@ -2071,6 +2075,10 @@ again:
if (error)
goto out;
error = check_fmode_for_setlk(file_lock);
if (error)
goto out;
/*
* If the cmd is requesting file-private locks, then set the
* FL_OFDLCK flag and override the owner.
@ -2206,6 +2214,10 @@ again:
if (error)
goto out;
error = check_fmode_for_setlk(file_lock);
if (error)
goto out;
/*
* If the cmd is requesting file-private locks, then set the
* FL_OFDLCK flag and override the owner.