1004 Commits

Author SHA1 Message Date
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