Commit Graph

830 Commits

Author SHA1 Message Date
Al Viro 8bcb77fabd namei: split off filename_lookupat() with LOOKUP_PARENT
new functions: filename_parentat() and path_parentat() resp.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:20 -04:00
Al Viro b5cd339762 namei: may_follow_link() - lift terminate_walk() on failures into caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:20 -04:00
Al Viro ab10492345 namei: take increment of nd->depth into pick_link()
Makes the situation much more regular - we avoid a strange state
when the element just after the top of stack is used to store
struct path of symlink, but isn't counted in nd->depth.  This
is much more regular, so the normal failure exits, etc., work
fine.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:19 -04:00
Al Viro 1cf2665b5b namei: kill nd->link
Just store it in nd->stack[nd->depth].link right in pick_link().
Now that we make sure of stack expansion in pick_link(), we can
do so...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:19 -04:00
Al Viro fec2fa24e8 may_follow_link(): trim arguments
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:18 -04:00
Al Viro cd179f4468 namei: move bumping the refcount of link->mnt into pick_link()
update the failure cleanup in may_follow_link() to match that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:18 -04:00
Al Viro e8bb73dfb0 namei: fold put_link() into the failure case of complete_walk()
... and don't open-code unlazy_walk() in there - the only reason
for that is to avoid verfication of cached nd->root, which is
trivially avoided by discarding said cached nd->root first.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:17 -04:00
Al Viro fab51e8ab2 namei: take the treatment of absolute symlinks to get_link()
rather than letting the callers handle the jump-to-root part of
semantics, do it right in get_link() and return the rest of the
body for the caller to deal with - at that point it's treated
the same way as relative symlinks would be.  And return NULL
when there's no "rest of the body" - those are treated the same
as pure jump symlink would be.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:17 -04:00
Al Viro 4f697a5e17 namei: simpler treatment of symlinks with nothing other that / in the body
Instead of saving name and branching to OK:, where we'll immediately restore
it, and call walk_component() with WALK_PUT|WALK_GET and nd->last_type being
LAST_BIND, which is equivalent to put_link(nd), err = 0, we can just treat
that the same way we'd treat procfs-style "jump" symlinks - do put_link(nd)
and move on.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:16 -04:00
Al Viro 6920a4405e namei: simplify failure exits in get_link()
when cookie is NULL, put_link() is equivalent to path_put(), so
as soon as we'd set last->cookie to NULL, we can bump nd->depth and
let the normal logics in terminate_walk() to take care of cleanups.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:16 -04:00
Al Viro 6e77137b36 don't pass nameidata to ->follow_link()
its only use is getting passed to nd_jump_link(), which can obtain
it from current->nameidata

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:15 -04:00
Al Viro 8402752ecf namei: simplify the callers of follow_managed()
now that it gets nameidata, no reason to have setting LOOKUP_JUMPED on
mountpoint crossing and calling path_put_conditional() on failures
done in every caller.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:15 -04:00
NeilBrown 756daf263e VFS: replace {, total_}link_count in task_struct with pointer to nameidata
task_struct currently contains two ad-hoc members for use by the VFS:
link_count and total_link_count.  These are only interesting to fs/namei.c,
so exposing them explicitly is poor layering.  Incidentally, link_count
isn't used anymore, so it can just die.

This patches replaces those with a single pointer to 'struct nameidata'.
This structure represents the current filename lookup of which
there can only be one per process, and is a natural place to
store total_link_count.

This will allow the current "nameidata" argument to all
follow_link operations to be removed as current->nameidata
can be used instead in the _very_ few instances that care about
it at all.

As there are occasional circumstances where pathname lookup can
recurse, such as through kern_path_locked, we always save and old
current->nameidata (if there is one) when setting a new value, and
make sure any active link_counts are preserved.

follow_mount and follow_automount now get a 'struct nameidata *'
rather than 'int flags' so that they can directly access
total_link_count, rather than going through 'current'.

Suggested-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:14 -04:00
Al Viro 626de99676 namei: move link count check and stack allocation into pick_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:13 -04:00
Al Viro d63ff28f0f namei: make should_follow_link() store the link in nd->link
... if it decides to follow, that is.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:13 -04:00
Al Viro 4693a547cd namei: new calling conventions for walk_component()
instead of a single flag (!= 0 => we want to follow symlinks) pass
two bits - WALK_GET (want to follow symlinks) and WALK_PUT (put_link()
once we are done looking at the name).  The latter matters only for
success exits - on failure the caller will discard everything anyway.

Suggestions for better variant are welcome; what this thing aims for
is making sure that pending put_link() is done *before* walk_component()
decides to pick a symlink up, rather than between picking it up and
acting upon it.  See the next commit for payoff.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:12 -04:00
Al Viro 8620c238ed link_path_walk: move the OK: inside the loop
fewer labels that way; in particular, resuming after the end of
nested symlink is straight-line.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:12 -04:00
Al Viro 1543972678 namei: have terminate_walk() do put_link() on everything left
All callers of terminate_walk() are followed by more or less
open-coded eqiuvalent of "do put_link() on everything left
in nd->stack".  Better done in terminate_walk() itself, and
when we go for RCU symlink traversal we'll have to do it
there anyway.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:11 -04:00
Al Viro 191d7f73e2 namei: take put_link() into {lookup,mountpoint,do}_last()
rationale: we'll need to have terminate_walk() do put_link() on
everything, which will mean that in some cases ..._last() will do
put_link() anyway.  Easier to have them do it in all cases.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:11 -04:00
Al Viro 1bc4b813e8 namei: lift (open-coded) terminate_walk() into callers of get_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:10 -04:00
Al Viro f0a9ba7021 lift terminate_walk() into callers of walk_component()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:10 -04:00
Al Viro 70291aecc6 namei: lift (open-coded) terminate_walk() in follow_dotdot_rcu() into callers
follow_dotdot_rcu() does an equivalent of terminate_walk() on failure;
shifting it into callers makes for simpler rules and those callers
already have terminate_walk() on other failure exits.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:09 -04:00
Al Viro e269f2a73f namei: we never need more than MAXSYMLINKS entries in nd->stack
The only reason why we needed one more was that purely nested
MAXSYMLINKS symlinks could lead to path_init() using that many
entries in addition to nd->stack[0] which it left unused.

That can't happen now - path_init() starts with entry 0 (and
trailing_symlink() is called only when we'd already encountered
one symlink, so no more than MAXSYMLINKS-1 are left).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:08 -04:00
Al Viro 8eff733a45 link_path_walk: end of nd->depth massage
get rid of orig_depth - we only use it on error exit to tell whether
to stop doing put_link() when depth reaches 0 (call from path_init())
or when it reaches 1 (call from trailing_symlink()).  However, in
the latter case the caller would immediately follow with one more
put_link().  Just keep doing it until the depth reaches zero (and
simplify trailing_symlink() as the result).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:08 -04:00
Al Viro 939724df56 link_path_walk: nd->depth massage, part 10
Get rid of orig_depth checks in OK: logics.  If nd->depth is
zero, we had been called from path_init() and we are done.
If it is greater than 1, we are not done, whether we'd been
called from path_init() or trailing_symlink().  And in
case when it's 1, we might have been called from path_init()
and reached the end of nested symlink (in which case
nd->stack[0].name will point to the rest of pathname and
we are not done) or from trailing_symlink(), in which case
we are done.

Just have trailing_symlink() leave NULL in nd->stack[0].name
and use that to discriminate between those cases.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:06 -04:00
Al Viro dc7af8dc05 link_path_walk: nd->depth massage, part 9
Make link_path_walk() work with any value of nd->depth on entry -
memorize it and use it in tests instead of comparing with 1.
Don't bother with increment/decrement in path_init().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:06 -04:00
Al Viro 21c3003d36 put_link: nd->depth massage, part 8
all calls are preceded by decrement of nd->depth; move it into
put_link() itself.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:05 -04:00
Al Viro 9ea57b72bf trailing_symlink: nd->depth massage, part 7
move decrement of nd->depth on successful returns into the callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:05 -04:00
Al Viro 0fd889d59e get_link: nd->depth massage, part 6
make get_link() increment nd->depth on successful exit

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:04 -04:00
Al Viro f7df08ee05 trailing_symlink: nd->depth massage, part 5
move increment of ->depth to the point where we'd discovered
that get_link() has not returned an error, adjust exits
accordingly.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:04 -04:00
Al Viro ef1a3e7b96 link_path_walk: nd->depth massage, part 4
lift increment/decrement into link_path_walk() callers.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:03 -04:00
Al Viro da4e0be04d link_path_walk: nd->depth massage, part 3
remove decrement/increment surrounding nd_alloc_stack(), adjust the
test in it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:03 -04:00
Al Viro fd4620bbdf link_path_walk: nd->depth massage, part 2
collapse adjacent increment/decrement pairs.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:02 -04:00
Al Viro 071bf50137 link_path_walk: nd->depth massage, part 1
nd->stack[0] is unused until the handling of trailing symlinks and
we want to get rid of that.  Having fucked that transformation up
several times, I went for bloody pedantic series of provably equivalent
transformations.  Sorry.

Step 1: keep nd->depth higher by one in link_path_walk() - increment upon
entry, decrement on exits, adjust the arithmetics inside and surround the
calls of functions that care about nd->depth value (nd_alloc_stack(),
get_link(), put_link()) with decrement/increment pairs.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:02 -04:00
Al Viro 894bc8c466 namei: remove restrictions on nesting depth
The only restriction is that on the total amount of symlinks
crossed; how they are nested does not matter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:01 -04:00
Al Viro 3b2e7f7539 namei: trim the arguments of get_link()
same story as the previous commit

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:01 -04:00
Al Viro b9ff44293c namei: trim redundant arguments of fs/namei.c:put_link()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:00 -04:00
Al Viro 1d8e03d359 namei: trim redundant arguments of trailing_symlink()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:20:00 -04:00
Al Viro 697fc6ca66 namei: move link/cookie pairs into nameidata
Array of MAX_NESTED_LINKS + 1 elements put into nameidata;
what used to be a local array in link_path_walk() occupies
entries 1 .. MAX_NESTED_LINKS in it, link and cookie from
the trailing symlink handling loops - entry 0.

This is _not_ the final arrangement; just an easily verified
incremental step.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:59 -04:00
Al Viro 9e18f10a30 link_path_walk: cleanup - turn goto start; into continue;
Deal with skipping leading slashes before what used to be the
recursive call.  That way we can get rid of that goto completely.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:59 -04:00
Al Viro 07681481b8 link_path_walk: split "return from recursive call" path
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:58 -04:00
Al Viro 32cd74685c link_path_walk: kill the recursion
absolutely straightforward now - the only variables we need to preserve
across the recursive call are name, link and cookie, and recursion depth
is limited (and can is equal to nd->depth).  So arrange an array of
triples to hold instances of those and be done with that.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:58 -04:00
Al Viro bdf6cbf179 link_path_walk: final preparations to killing recursion
reduce the number of returns in there - turn all places
where it returns zero into goto OK and places where it
returns non-zero into goto Err.  The only non-trivial
detail is that all breaks in the loop are guaranteed
to be with non-zero err.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:57 -04:00
Al Viro bb8603f8e1 link_path_walk: get rid of duplication
What we do after the second walk_component() + put_link() + depth
decrement in there is exactly equivalent to what's done right
after the first walk_component().  Easy to verify and not at all
surprising, seeing that there we have just walked the last
component of nested symlink.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:57 -04:00
Al Viro 48c8b0c571 link_path_walk: massage a bit more
Pull the block after the if-else in the end of what used to be do-while
body into all branches there.  We are almost done with the massage...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:56 -04:00
Al Viro d40bcc09ab link_path_walk: turn inner loop into explicit goto
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:56 -04:00
Al Viro 12b0957800 link_path_walk: don't bother with walk_component() after jumping link
... it does nothing if nd->last_type is LAST_BIND.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:55 -04:00
Al Viro b0c24c3bdf link_path_walk: handle get_link() returning ERR_PTR() immediately
If we get ERR_PTR() from get_link(), we are guaranteed to get err != 0
when we break out of do-while, so we are going to hit if (err) return err;
shortly after it.  Pull that into the if (IS_ERR(s)) body.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:55 -04:00
Al Viro 95fa25d9f2 namei: rename follow_link to trailing_symlink, move it down
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:54 -04:00
Al Viro 21fef2176e namei: move the calls of may_follow_link() into follow_link()
All remaining callers of the former are preceded by the latter

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:53 -04:00
Al Viro 172a39a059 namei: expand the call of follow_link() in link_path_walk()
... and strip __always_inline from follow_link() - remaining callers
don't need that.

Now link_path_walk() recursion is a direct one.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:53 -04:00
Al Viro 5a460275ef namei: expand nested_symlink() in its only caller
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:52 -04:00
Al Viro 896475d5bd do_last: move path there from caller's stack frame
We used to need it to feed to follow_link().  No more...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:52 -04:00
Al Viro caa8563443 namei: introduce nameidata->link
shares space with nameidata->next, walk_component() et.al. store
the struct path of symlink instead of returning it into a variable
passed by caller.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:51 -04:00
Al Viro d4dee48bad namei: don't bother with ->follow_link() if ->i_link is set
with new calling conventions it's trivial

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Conflicts:
	fs/namei.c
2015-05-10 22:19:51 -04:00
Al Viro 0a959df54b namei.c: separate the parts of follow_link() that find the link body
Split a piece of fs/namei.c:follow_link() that does obtaining the link
body into a separate function.  follow_link() itself is converted to
calling get_link() and then doing the body traversal (if any).

The next step will expand follow_link() call in link_path_walk()
and this helps to keep the size down...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:50 -04:00
Al Viro 680baacbca new ->follow_link() and ->put_link() calling conventions
a) instead of storing the symlink body (via nd_set_link()) and returning
an opaque pointer later passed to ->put_link(), ->follow_link() _stores_
that opaque pointer (into void * passed by address by caller) and returns
the symlink body.  Returning ERR_PTR() on error, NULL on jump (procfs magic
symlinks) and pointer to symlink body for normal symlinks.  Stored pointer
is ignored in all cases except the last one.

Storing NULL for opaque pointer (or not storing it at all) means no call
of ->put_link().

b) the body used to be passed to ->put_link() implicitly (via nameidata).
Now only the opaque pointer is.  In the cases when we used the symlink body
to free stuff, ->follow_link() now should store it as opaque pointer in addition
to returning it.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:19:45 -04:00
Al Viro 46afd6f61c namei: lift nameidata into filename_mountpoint()
when we go for on-demand allocation of saved state in
link_path_walk(), we'll want nameidata to stay around
for all 3 calls of path_mountpoint().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:33 -04:00
Al Viro f5beed755b name: shift nameidata down into user_path_walk()
that avoids having nameidata on stack during the calls of
->rmdir()/->unlink() and *two* of those during the calls
of ->rename().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:32 -04:00
Al Viro 6a9f40d610 namei: get rid of lookup_hash()
it's a convenient helper, but we'll want to shift nameidata
down the call chain, so it won't be available there...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:32 -04:00
Al Viro a5cfe2d5e1 do_last: regularize the logics around following symlinks
With LOOKUP_FOLLOW we unlazy and return 1; without it we either
fail with ELOOP or, for O_PATH opens, succeed.  No need to mix
those cases...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:31 -04:00
Al Viro fd2805be23 do_last: kill symlink_ok
When O_PATH is present, O_CREAT isn't, so symlink_ok is always equal to
(open_flags & O_PATH) && !(nd->flags & LOOKUP_FOLLOW).

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:30 -04:00
Al Viro f488443d1d namei: take O_NOFOLLOW treatment into do_last()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:30 -04:00
Al Viro 34b128f31c uninline walk_component()
seriously improves the stack *and* I-cache footprint...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:29 -04:00
NeilBrown 37882db054 SECURITY: remove nameidata arg from inode_follow_link.
No ->inode_follow_link() methods use the nameidata arg, and
it is about to become private to namei.c.
So remove from all inode_follow_link() functions.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-10 22:18:29 -04:00
Al Viro f15133df08 path_openat(): fix double fput()
path_openat() jumps to the wrong place after do_tmpfile() - it has
already done path_cleanup() (as part of path_lookupat() called by
do_tmpfile()), so doing that again can lead to double fput().

Cc: stable@vger.kernel.org	# v3.11+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-09 00:12:48 -04:00
Al Viro 766c4cbfac namei: d_is_negative() should be checked before ->d_seq validation
Fetching ->d_inode, verifying ->d_seq and finding d_is_negative() to
be true does *not* mean that inode we'd fetched had been NULL - that
holds only while ->d_seq is still unchanged.

Shift d_is_negative() checks into lookup_fast() prior to ->d_seq
verification.

Reported-by: Steven Rostedt <rostedt@goodmis.org>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-05-09 00:12:35 -04:00
Al Viro 3cab989afd RCU pathwalk breakage when running into a symlink overmounting something
Calling unlazy_walk() in walk_component() and do_last() when we find
a symlink that needs to be followed doesn't acquire a reference to vfsmount.
That's fine when the symlink is on the same vfsmount as the parent directory
(which is almost always the case), but it's not always true - one _can_
manage to bind a symlink on top of something.  And in such cases we end up
with excessive mntput().

Cc: stable@vger.kernel.org # since 2.6.39
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-24 15:52:14 -04:00
David Howells 4bbcbd3b11 VFS: Make pathwalk use d_is_reg() rather than S_ISREG()
Make pathwalk use d_is_reg() rather than S_ISREG() to determine whether to
honour O_TRUNC.  Since this occurs after complete_walk(), the dentry type
field cannot change and the inode pointer cannot change as we hold a ref on
the dentry, so this should be safe.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-15 15:05:30 -04:00
David Howells 698934df8b VFS: Combine inode checks with d_is_negative() and d_is_positive() in pathwalk
Where we have:

    	if (!dentry->d_inode || d_is_negative(dentry)) {

type constructions in pathwalk we should be able to eliminate the check of
d_inode and rely solely on the result of d_is_negative() or d_is_positive().

What we do have to take care to do is to read d_inode after calling a
d_is_xxx() typecheck function to get the barriering right.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-15 15:05:29 -04:00
Al Viro 9e7543e939 remove incorrect comment in lookup_one_len()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:24:30 -04:00
Al Viro 74eb8cc5a5 namei.c: fold do_path_lookup() into both callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:24:30 -04:00
Al Viro fd2f7cb5bc kill struct filename.separate
just make const char iname[] the last member and compare name->name with
name->iname instead of checking name->separate

We need to make sure that out-of-line name doesn't end up allocated adjacent
to struct filename refering to it; fortunately, it's easy to achieve - just
allocate that struct filename with one byte in ->iname[], so that ->iname[0]
will be inside the same object and thus have an address different from that
of out-of-line name [spotted by Boqun Feng <boqun.feng@gmail.com>]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-04-11 22:21:24 -04:00
Al Viro 6e8a1f8741 switch path_init() to struct filename
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-24 17:19:16 -04:00
Al Viro 668696dcbb switch path_mountpoint() to struct filename
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-24 17:19:15 -04:00
Al Viro 5eb6b495c6 switch path_lookupat() to struct filename
all callers were passing it ->name of some struct filename

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-24 17:19:15 -04:00
Al Viro 94b5d2621a getname_flags(): clean up a bit
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-03-24 17:19:14 -04:00
David Howells e36cb0b89c VFS: (Scripted) Convert S_ISLNK/DIR/REG(dentry->d_inode) to d_is_*(dentry)
Convert the following where appropriate:

 (1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).

 (2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).

 (3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry).  This is actually more
     complicated than it appears as some calls should be converted to
     d_can_lookup() instead.  The difference is whether the directory in
     question is a real dir with a ->lookup op or whether it's a fake dir with
     a ->d_automount op.

In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).

Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer.  In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.

However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.

There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE.  Strictly, this was
intended for special directory entry types that don't have attached inodes.

The following perl+coccinelle script was used:

use strict;

my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
    die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
    print "No matches\n";
    exit(0);
}

my @cocci = (
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISLNK(E->d_inode->i_mode)',
    '+ d_is_symlink(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISDIR(E->d_inode->i_mode)',
    '+ d_is_dir(E)',
    '',
    '@@',
    'expression E;',
    '@@',
    '',
    '- S_ISREG(E->d_inode->i_mode)',
    '+ d_is_reg(E)' );

my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);

foreach my $file (@callers) {
    chomp $file;
    print "Processing ", $file, "\n";
    system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
	die "spatch failed";
}

[AV: overlayfs parts skipped]

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-02-22 11:38:41 -05:00
Paul Moore 55422d0bd2 audit: replace getname()/putname() hacks with reference counters
In order to ensure that filenames are not released before the audit
subsystem is done with the strings there are a number of hacks built
into the fs and audit subsystems around getname() and putname().  To
say these hacks are "ugly" would be kind.

This patch removes the filename hackery in favor of a more
conventional reference count based approach.  The diffstat below tells
most of the story; lots of audit/fs specific code is replaced with a
traditional reference count based approach that is easily understood,
even by those not familiar with the audit and/or fs subsystems.

CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:23:58 -05:00
Paul Moore fd3522fdc8 audit: enable filename recording via getname_kernel()
Enable recording of filenames in getname_kernel() and remove the
kludgy workaround in __audit_inode() now that we have proper filename
logging for kernel users.

CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:23:52 -05:00
Al Viro cbaab2db91 simpler calling conventions for filename_mountpoint()
a) make it accept ERR_PTR() as filename (and return its PTR_ERR() in that case)
b) make it putname() the sucker in the end otherwise

simplifies life for callers...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:22:21 -05:00
Paul Moore 5168910413 fs: create proper filename objects using getname_kernel()
There are several areas in the kernel that create temporary filename
objects using the following pattern:

	int func(const char *name)
	{
		struct filename *file = { .name = name };
		...
		return 0;
	}

... which for the most part works okay, but it causes havoc within the
audit subsystem as the filename object does not persist beyond the
lifetime of the function.  This patch converts all of these temporary
filename objects into proper filename objects using getname_kernel()
and putname() which ensure that the filename object persists until the
audit subsystem is finished with it.

Also, a special thanks to Al Viro, Guenter Roeck, and Sabrina Dubroca
for helping resolve a difficult kernel panic on boot related to a
use-after-free problem in kern_path_create(); the thread can be seen
at the link below:

 * https://lkml.org/lkml/2015/1/20/710

This patch includes code that was either based on, or directly written
by Al in the above thread.

CC: viro@zeniv.linux.org.uk
CC: linux@roeck-us.net
CC: sd@queasysnail.net
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:22:20 -05:00
Paul Moore 0851854972 fs: rework getname_kernel to handle up to PATH_MAX sized filenames
In preparation for expanded use in the kernel, make getname_kernel()
more useful by allowing it to handle any legal filename length.

Thanks to Guenter Roeck for his suggestion to substitute memcpy() for
strlcpy().

CC: linux@roeck-us.net
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:22:20 -05:00
Al Viro fa14a0b8d2 cut down the number of do_path_lookup() callers
... and don't bother with new struct filename when we already have one

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2015-01-23 00:22:19 -05:00
Linus Torvalds 603ba7e41b Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pile #2 from Al Viro:
 "Next pile (and there'll be one or two more).

  The large piece in this one is getting rid of /proc/*/ns/* weirdness;
  among other things, it allows to (finally) make nameidata completely
  opaque outside of fs/namei.c, making for easier further cleanups in
  there"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  coda_venus_readdir(): use file_inode()
  fs/namei.c: fold link_path_walk() call into path_init()
  path_init(): don't bother with LOOKUP_PARENT in argument
  fs/namei.c: new helper (path_cleanup())
  path_init(): store the "base" pointer to file in nameidata itself
  make default ->i_fop have ->open() fail with ENXIO
  make nameidata completely opaque outside of fs/namei.c
  kill proc_ns completely
  take the targets of /proc/*/ns/* symlinks to separate fs
  bury struct proc_ns in fs/proc
  copy address of proc_ns_ops into ns_common
  new helpers: ns_alloc_inum/ns_free_inum
  make proc_ns_operations work with struct ns_common * instead of void *
  switch the rest of proc_ns_operations to working with &...->ns
  netns: switch ->get()/->put()/->install()/->inum() to working with &net->ns
  make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns
  common object embedded into various struct ....ns
2014-12-16 15:53:03 -08:00
David Drysdale 51f39a1f0c syscalls: implement execveat() system call
This patchset adds execveat(2) for x86, and is derived from Meredydd
Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528).

The primary aim of adding an execveat syscall is to allow an
implementation of fexecve(3) that does not rely on the /proc filesystem,
at least for executables (rather than scripts).  The current glibc version
of fexecve(3) is implemented via /proc, which causes problems in sandboxed
or otherwise restricted environments.

Given the desire for a /proc-free fexecve() implementation, HPA suggested
(https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be
an appropriate generalization.

Also, having a new syscall means that it can take a flags argument without
back-compatibility concerns.  The current implementation just defines the
AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be
added in future -- for example, flags for new namespaces (as suggested at
https://lkml.org/lkml/2006/7/11/474).

Related history:
 - https://lkml.org/lkml/2006/12/27/123 is an example of someone
   realizing that fexecve() is likely to fail in a chroot environment.
 - http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered
   documenting the /proc requirement of fexecve(3) in its manpage, to
   "prevent other people from wasting their time".
 - https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a
   problem where a process that did setuid() could not fexecve()
   because it no longer had access to /proc/self/fd; this has since
   been fixed.

This patch (of 4):

Add a new execveat(2) system call.  execveat() is to execve() as openat()
is to open(): it takes a file descriptor that refers to a directory, and
resolves the filename relative to that.

In addition, if the filename is empty and AT_EMPTY_PATH is specified,
execveat() executes the file to which the file descriptor refers.  This
replicates the functionality of fexecve(), which is a system call in other
UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/<fd>" (and
so relies on /proc being mounted).

The filename fed to the executed program as argv[0] (or the name of the
script fed to a script interpreter) will be of the form "/dev/fd/<fd>"
(for an empty filename) or "/dev/fd/<fd>/<filename>", effectively
reflecting how the executable was found.  This does however mean that
execution of a script in a /proc-less environment won't work; also, script
execution via an O_CLOEXEC file descriptor fails (as the file will not be
accessible after exec).

Based on patches by Meredydd Luff.

Signed-off-by: David Drysdale <drysdale@google.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@aerifal.cx>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-12-13 12:42:51 -08:00
Al Viro d465887f9d fs/namei.c: fold link_path_walk() call into path_init()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-11 16:27:57 -05:00
Al Viro 980f3ea2f6 path_init(): don't bother with LOOKUP_PARENT in argument
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-11 16:27:57 -05:00
Al Viro 893b7775a7 fs/namei.c: new helper (path_cleanup())
All callers of path_init() proceed to do the identical cleanup when
they are done with nameidata.  Don't open-code it...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-11 16:27:57 -05:00
Al Viro 5e53084d77 path_init(): store the "base" pointer to file in nameidata itself
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-11 16:27:57 -05:00
Al Viro 1f55a6ec94 make nameidata completely opaque outside of fs/namei.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-12-10 21:32:13 -05:00
Linus Torvalds 7e05b807b9 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull VFS fixes from Al Viro:
 "A bunch of assorted fixes, most of them followups to overlayfs merge"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  ovl: initialize ->is_cursor
  Return short read or 0 at end of a raw device, not EIO
  isofs: don't bother with ->d_op for normal case
  isofs_cmp(): we'll never see a dentry for . or ..
  overlayfs: fix lockdep misannotation
  ovl: fix check for cursor
  overlayfs: barriers for opening upper-layer directory
  rcu: Provide counterpart to rcu_dereference() for non-RCU situations
  staging: android: logger: Fix log corruption regression
2014-11-02 10:28:43 -08:00
Eric Rannaud 69a91c237a fs: allow open(dir, O_TMPFILE|..., 0) with mode 0
The man page for open(2) indicates that when O_CREAT is specified, the
'mode' argument applies only to future accesses to the file:

	Note that this mode applies only to future accesses of the newly
	created file; the open() call that creates a read-only file
	may well return a read/write file descriptor.

The man page for open(2) implies that 'mode' is treated identically by
O_CREAT and O_TMPFILE.

O_TMPFILE, however, behaves differently:

	int fd = open("/tmp", O_TMPFILE | O_RDWR, 0);
	assert(fd == -1);
	assert(errno == EACCES);

	int fd = open("/tmp", O_TMPFILE | O_RDWR, 0600);
	assert(fd > 0);

For O_CREAT, do_last() sets acc_mode to MAY_OPEN only:

	if (*opened & FILE_CREATED) {
		/* Don't check for write permission, don't truncate */
		open_flag &= ~O_TRUNC;
		will_truncate = false;
		acc_mode = MAY_OPEN;
		path_to_nameidata(path, nd);
		goto finish_open_created;
	}

But for O_TMPFILE, do_tmpfile() passes the full op->acc_mode to
may_open().

This patch lines up the behavior of O_TMPFILE with O_CREAT. After the
inode is created, may_open() is called with acc_mode = MAY_OPEN, in
do_tmpfile().

A different, but related glibc bug revealed the discrepancy:
https://sourceware.org/bugzilla/show_bug.cgi?id=17523

The glibc lazily loads the 'mode' argument of open() and openat() using
va_arg() only if O_CREAT is present in 'flags' (to support both the 2
argument and the 3 argument forms of open; same idea for openat()).
However, the glibc ignores the 'mode' argument if O_TMPFILE is in
'flags'.

On x86_64, for open(), it magically works anyway, as 'mode' is in
RDX when entering open(), and is still in RDX on SYSCALL, which is where
the kernel looks for the 3rd argument of a syscall.

But openat() is not quite so lucky: 'mode' is in RCX when entering the
glibc wrapper for openat(), while the kernel looks for the 4th argument
of a syscall in R10. Indeed, the syscall calling convention differs from
the regular calling convention in this respect on x86_64. So the kernel
sees mode = 0 when trying to use glibc openat() with O_TMPFILE, and
fails with EACCES.

Signed-off-by: Eric Rannaud <e@nanocritical.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-30 15:50:13 -07:00
Miklos Szeredi d1b72cc6d8 overlayfs: fix lockdep misannotation
In an overlay directory that shadows an empty lower directory, say
/mnt/a/empty102, do:

 	touch /mnt/a/empty102/x
 	unlink /mnt/a/empty102/x
 	rmdir /mnt/a/empty102

It's actually harmless, but needs another level of nesting between
I_MUTEX_CHILD and I_MUTEX_NORMAL.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2014-10-28 18:32:47 -04:00
Miklos Szeredi 0d7a855526 vfs: add RENAME_WHITEOUT
This adds a new RENAME_WHITEOUT flag.  This flag makes rename() create a
whiteout of source.  The whiteout creation is atomic relative to the
rename.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-10-24 00:14:37 +02:00
Miklos Szeredi 787fb6bc96 vfs: add whiteout support
Whiteout isn't actually a new file type, but is represented as a char
device (Linus's idea) with 0/0 device number.

This has several advantages compared to introducing a new whiteout file
type:

 - no userspace API changes (e.g. trivial to make backups of upper layer
   filesystem, without losing whiteouts)

 - no fs image format changes (you can boot an old kernel/fsck without
   whiteout support and things won't break)

 - implementation is trivial

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-10-24 00:14:36 +02:00
Miklos Szeredi cbdf35bcb8 vfs: export check_sticky()
It's already duplicated in btrfs and about to be used in overlayfs too.

Move the sticky bit check to an inline helper and call the out-of-line
helper only in the unlikly case of the sticky bit being set.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-10-24 00:14:36 +02:00
Miklos Szeredi bd5d08569c vfs: export __inode_permission() to modules
We need to be able to check inode permissions (but not filesystem implied
permissions) for stackable filesystems.  Expose this interface for overlayfs.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-10-24 00:14:35 +02:00
Miklos Szeredi 4aa7c6346b vfs: add i_op->dentry_open()
Add a new inode operation i_op->dentry_open().  This is for stacked filesystems
that want to return a struct file from a different filesystem.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
2014-10-24 00:14:35 +02:00
Linus Torvalds 77c688ac87 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs updates from Al Viro:
 "The big thing in this pile is Eric's unmount-on-rmdir series; we
  finally have everything we need for that.  The final piece of prereqs
  is delayed mntput() - now filesystem shutdown always happens on
  shallow stack.

  Other than that, we have several new primitives for iov_iter (Matt
  Wilcox, culled from his XIP-related series) pushing the conversion to
  ->read_iter()/ ->write_iter() a bit more, a bunch of fs/dcache.c
  cleanups and fixes (including the external name refcounting, which
  gives consistent behaviour of d_move() wrt procfs symlinks for long
  and short names alike) and assorted cleanups and fixes all over the
  place.

  This is just the first pile; there's a lot of stuff from various
  people that ought to go in this window.  Starting with
  unionmount/overlayfs mess...  ;-/"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (60 commits)
  fs/file_table.c: Update alloc_file() comment
  vfs: Deduplicate code shared by xattr system calls operating on paths
  reiserfs: remove pointless forward declaration of struct nameidata
  don't need that forward declaration of struct nameidata in dcache.h anymore
  take dname_external() into fs/dcache.c
  let path_init() failures treated the same way as subsequent link_path_walk()
  fix misuses of f_count() in ppp and netlink
  ncpfs: use list_for_each_entry() for d_subdirs walk
  vfs: move getname() from callers to do_mount()
  gfs2_atomic_open(): skip lookups on hashed dentry
  [infiniband] remove pointless assignments
  gadgetfs: saner API for gadgetfs_create_file()
  f_fs: saner API for ffs_sb_create_file()
  jfs: don't hash direct inode
  [s390] remove pointless assignment of ->f_op in vmlogrdr ->open()
  ecryptfs: ->f_op is never NULL
  android: ->f_op is never NULL
  nouveau: __iomem misannotations
  missing annotation in fs/file.c
  fs: namespace: suppress 'may be used uninitialized' warnings
  ...
2014-10-13 11:28:42 +02:00