- 15 Mar, 2011 16 commits
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Al Viro authored
new helper: walk_component(). Handles everything except symlinks; returns negative on error, 0 on success and 1 on symlinks we decided to follow. Drops out of RCU mode on such symlinks. link_path_walk() and do_last() switched to using that. Signed-off-by:Al Viro <viro@zeniv.linux.org.uk>
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Aneesh Kumar K.V authored
We don't want to allow creation of private hardlinks by different application using the fd passed to them via SCM_RIGHTS. So limit the null relative name usage in linkat syscall to CAP_DAC_READ_SEARCH Signed-off-by:Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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Al Viro authored
Just need to make sure that AF_UNIX garbage collector won't confuse O_PATHed socket on filesystem for real AF_UNIX opened socket. Signed-off-by: -
Al Viro authored
For readlinkat() we simply allow empty pathname; it will fail unless we have dfd equal to O_PATH-opened symlink, so we are outside of POSIX scope here. For fchownat() and fstatat() we allow AT_EMPTY_PATH; let the caller explicitly ask for such behaviour. Signed-off-by: -
Al Viro authored
At that point we can't do almost nothing with them. They can be opened with O_PATH, we can manipulate such descriptors with dup(), etc. and we can see them in /proc/*/{fd,fdinfo}/*. We can't (and won't be able to) follow /proc/*/fd/* symlinks for those; there's simply not enough information for pathname resolution to go on from such point - to resolve a symlink we need to know which directory does it live in. We will be able to do useful things with them after the next commit, though - readlinkat() and fchownat() will be possible to use with dfd being an O_PATH-opened symlink and empty relative pathname. Combined with open_by_handle() it'll give us a way to do realink-by-handle and lchown-by-handle without messing with more redundant syscalls. Signed-off-by: -
Al Viro authored
New flag for open(2) - O_PATH. Semantics: * pathname is resolved, but the file itself is _NOT_ opened as far as filesystem is concerned. * almost all operations on the resulting descriptors shall fail with -EBADF. Exceptions are: 1) operations on descriptors themselves (i.e. close(), dup(), dup2(), dup3(), fcntl(fd, F_DUPFD), fcntl(fd, F_DUPFD_CLOEXEC, ...), fcntl(fd, F_GETFD), fcntl(fd, F_SETFD, ...)) 2) fcntl(fd, F_GETFL), for a common non-destructive way to check if descriptor is open 3) "dfd" arguments of ...at(2) syscalls, i.e. the starting points of pathname resolution * closing such descriptor does *NOT* affect dnotify or posix locks. * permissions are checked as usual along the way to file; no permission checks are applied to the file itself. Of course, giving such thing to syscall will result in permission checks (at the moment it means checking that starting point of ....at() is a directory and caller has exec permissions on it). fget() and fget_light() return NULL on such descriptors; use of fget_raw() and fget_raw_light() is needed to get them. That protects existing code from dealing with those things. There are two things still missing (they come in the next commits): one is handling of symlinks (right now we refuse to open them that way; see the next commit for semantics related to those) and another is descriptor passing via SCM_RIGHTS datagrams. Signed-off-by: -
Aneesh Kumar K.V authored
File system UUID is made available to application via /proc/<pid>/mountinfo Signed-off-by:
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Aneesh Kumar K.V authored
File system UUID is made available to application via /proc/<pid>/mountinfo Signed-off-by:
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Aneesh Kumar K.V authored
We add a per superblock uuid field. File systems should update the uuid in the fill_super callback Signed-off-by:
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Aneesh Kumar K.V authored
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Aneesh Kumar K.V authored
This patch add new syscalls to x86_64 Signed-off-by:
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Aneesh Kumar K.V authored
This patch adds new syscalls to x86_32 Signed-off-by:
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Aneesh Kumar K.V authored
Now that VFS check for inode->i_nlink == 0 and returns proper error, remove similar check from file system Signed-off-by:
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Aneesh Kumar K.V authored
Add inode->i_nlink == 0 check in VFS. Some of the file systems do this internally. A followup patch will remove those instance. This is needed to ensure that with link by handle we don't allow to create hardlink of an unlinked file. The check also prevent a race between unlink and link Signed-off-by:
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Aneesh Kumar K.V authored
[AV: duplicate of open() guts removed; file_open_root() used instead] Signed-off-by:
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Aneesh Kumar K.V authored
The syscall also return mount id which can be used to lookup file system specific information such as uuid in /proc/<pid>/mountinfo Signed-off-by:
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- 14 Mar, 2011 24 commits
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Al Viro authored
For name_to_handle_at(2) we'll want both ...at()-style syscall that would be usable for non-directory descriptors (with empty relative pathname). Introduce new flag (AT_EMPTY_PATH) to deal with that and corresponding LOOKUP_EMPTY; teach user_path_at() and path_init() to deal with the latter. Signed-off-by: -
Aneesh Kumar K.V authored
The exportfs encode handle function should return the minimum required handle size. This helps user to find out the handle size by passing 0 handle size in the first step and then redoing to the call again with the returned handle size value. Acked-by:
Serge Hallyn <serue@us.ibm.com> Signed-off-by:
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Al Viro authored
New helpers: user_statfs() and fd_statfs(), taking userland pathname and descriptor resp. and filling struct kstatfs. Syscalls of statfs family (native, compat and foreign - osf and hpux on alpha and parisc resp.) switched to those. Removes some boilerplate code, simplifies cleanup on errors... Signed-off-by: -
Al Viro authored
new function: file_open_root(dentry, mnt, name, flags) opens the file vfs_path_lookup would arrive to. Note that name can be empty; in that case the usual requirement that dentry should be a directory is lifted. open-coded equivalents switched to it, may_open() got down exactly one caller and became static. Signed-off-by: -
Al Viro authored
New lookup flag: LOOKUP_ROOT. nd->root is set (and held) by caller, path_init() starts walking from that place and all pathname resolution machinery never drops nd->root if that flag is set. That turns vfs_path_lookup() into a special case of do_path_lookup() *and* gets us down to 3 callers of link_path_walk(), making it finally feasible to rip the handling of trailing symlink out of link_path_walk(). That will not only simply the living hell out of it, but make life much simpler for unionfs merge. Trailing symlink handling will become iterative, which is a good thing for stack footprint in a lot of situations as well. Signed-off-by: -
Al Viro authored
That thing has devolved into rats nest of gotos; sane use of unlikely() gets rid of that horror and gives much more readable structure: * make a fast attempt to find a dentry; false negatives are OK. In RCU mode if everything went fine, we are done, otherwise just drop out of RCU. If we'd done (RCU) ->d_revalidate() and it had not refused outright (i.e. didn't give us -ECHILD), remember its result. * now we are not in RCU mode and hopefully have a dentry. If we do not, lock parent, do full d_lookup() and if that has not found anything, allocate and call ->lookup(). If we'd done that ->lookup(), remember that dentry is good and we don't need to revalidate it. * now we have a dentry. If it has ->d_revalidate() and we can't skip it, call it. * hopefully dentry is good; if not, either fail (in case of error) or try to invalidate it. If d_invalidate() has succeeded, drop it and retry everything as if original attempt had not found a dentry. * now we can finish it up - deal with mountpoint crossing and automount. Signed-off-by: -
Al Viro authored
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Al Viro authored
There used to be time when ->d_revalidate() couldn't return an error. So intents code had lookup_instantiate_filp() stash ERR_PTR(error) in nd->intent.open.filp and had it checked after lookup_hash(), to catch the otherwise silent failures. That had been introduced by commit 4af4c52f. These days ->d_revalidate() can and does propagate errors back to callers explicitly, so this check isn't needed anymore. Signed-off-by:
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Al Viro authored
... and clean up a bit more Signed-off-by: -
Al Viro authored
We have a bunch of diverging codepaths in do_last(); some of them converge, but the case of having to create a new file duplicates large part of common tail of the rest and exits separately. Massage them so that they could be merged. Signed-off-by: -
Al Viro authored
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Al Viro authored
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Al Viro authored
Lift it to lookup_one_len() and link_path_walk() resp. into the same place where we calculated default hash function of the same name. Signed-off-by: -
Al Viro authored
only one caller left Signed-off-by: -
Al Viro authored
Instead of path_lookupat() doing trailing symlink resolution, use the same scheme as on the O_CREAT side. Walk with LOOKUP_PARENT, then (in do_last()) look the final component up, then either open it or return error or, if it's a symlink, give the symlink back to path_openat() to be resolved there. The really messy complication here is RCU. We don't want to drop out of RCU mode before the final lookup, since we don't want to bounce parent directory ->d_count without a good reason. Result is _not_ pretty; later in the series we'll clean it up. For now we are roughly back where we'd been before the revert done by Nick's series - top-level logics of path_openat() is cleaned up, do_last() does actual opening, symlink resolution is done uniformly. Signed-off-by: -
Al Viro authored
Don't stash the struct file * used as starting point of walk in nameidata; pass file ** to path_init() instead. Signed-off-by: -
Al Viro authored
New helper: terminate_walk(). An error has happened during pathname resolution and we either drop nd->path or terminate RCU, depending the mode we had been in. After that, nd is essentially empty. Switch link_path_walk() to using that for cleanup. Now the top-level logics in link_path_walk() is back to sanity. RCU dependencies are in the lower-level functions. Signed-off-by: -
Al Viro authored
Now we have do_follow_link() guaranteed to leave without dangling RCU and the next step will get LOOKUP_RCU logics completely out of link_path_walk(). Signed-off-by: -
Al Viro authored
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Al Viro authored
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Al Viro authored
getting LOOKUP_RCU checks out of link_path_walk()... Signed-off-by: -
Al Viro authored
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Al Viro authored
new helper: path_openat(). Does what do_filp_open() does, except that it tries only the walk mode (RCU/normal/force revalidation) it had been told to. Both create and non-create branches are using path_lookupat() now. Fixed the double audit_inode() in non-create branch. Signed-off-by: -
Al Viro authored
take calculation of open_flags by open(2) arguments into new helper in fs/open.c, move filp_open() over there, have it and do_sys_open() use that helper, switch exec.c callers of do_filp_open() to explicit (and constant) struct open_flags. Signed-off-by:
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