linux/fs/stat.c, branch v3.5

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2012-05-24T00:42:39Z

Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...

Merge branch 'vfs-cleanups' (random vfs cleanups)

2012-05-21T15:46:08Z

This teaches vfs_fstat() to use the appropriate f[get|put]_light functions, allowing it to avoid some unnecessary locking for the common case. More noticeably, it also cleans up and simplifies the "getname_flags()" function, which now relies on the architecture strncpy_from_user() doing all the user access checks properly, instead of hacking around the fact that on x86 it didn't use to do it right (see commit 92ae03f2ef99: "x86: merge 32/64-bit versions of 'strncpy_from_user()' and speed it up"). * vfs-cleanups: VFS: make vfs_fstat() use f[get|put]_light() VFS: clean up and simplify getname_flags() x86: make word-at-a-time strncpy_from_user clear bytes at the end

userns: Convert stat to return values mapped from kuids and kgids

2012-05-15T21:08:35Z

- Store uids and gids with kuid_t and kgid_t in struct kstat - Convert uid and gids to userspace usable values with from_kuid and from_kgid Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

vfs: don't force a big memset of stat data just to clear padding fields

2012-05-07T01:02:40Z

Admittedly this is something that the compiler should be able to just do for us, but gcc just isn't that smart. And trying to use a structure initializer (which would get us the right semantics) ends up resulting in gcc allocating stack space for _two_ 'struct stat', and then copying one into the other. So do it by hand - just have a per-architecture macro that initializes the padding fields. And if the architecture doesn't provide one, fall back to the old behavior of just doing the whole memset() first. Signed-off-by: Linus Torvalds

vfs: de-crapify "cp_new_stat()" function

2012-05-07T00:47:30Z

It's an unreadable mess of 32-bit vs 64-bit #ifdef's that mostly follow a rather simple pattern. Make a helper #define to handle that pattern, in the process making the code both shorter and more readable. Signed-off-by: Linus Torvalds

VFS: make vfs_fstat() use f[get|put]_light()

2012-04-28T21:55:17Z

Use the *_light() versions that properly avoid doing the file user count updates when they are unnecessary. Signed-off-by: Linus Torvalds

Merge tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

2012-03-24T17:24:31Z

Pull cleanup of fs/ and lib/ users of module.h from Paul Gortmaker: "Fix up files in fs/ and lib/ dirs to only use module.h if they really need it. These are trivial in scope vs the work done previously. We now have things where any few remaining cleanups can be farmed out to arch or subsystem maintainers, and I have done so when possible. What is remaining here represents the bits that don't clearly lie within a single arch/subsystem boundary, like the fs dir and the lib dir. Some duplicate includes arising from overlapping fixes from independent subsystem maintainer submissions are also quashed." Fix up trivial conflicts due to clashes with other include file cleanups (including some due to the previous bug.h cleanup pull). * tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux: lib: reduce the use of module.h wherever possible fs: reduce the use of module.h wherever possible includecheck: delete any duplicate instances of module.h

switch touch_atime to struct path

2012-03-21T01:29:41Z

Signed-off-by: Al Viro

fs: reduce the use of module.h wherever possible

2012-02-29T00:31:58Z

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker

readlinkat: ensure we return ENOENT for the empty pathname for normal lookups

2011-11-02T11:53:42Z

Since the commit below which added O_PATH support to the *at() calls, the error return for readlink/readlinkat for the empty pathname has switched from ENOENT to EINVAL: commit 65cfc6722361570bfe255698d9cd4dccaf47570d Author: Al Viro Date: Sun Mar 13 15:56:26 2011 -0400 readlinkat(), fchownat() and fstatat() with empty relative pathnames This is both unexpected for userspace and makes readlink/readlinkat inconsistant with all other interfaces; and inconsistant with our stated return for these pathnames. As the readlinkat call does not have a flags parameter we cannot use the AT_EMPTY_PATH approach used in the other calls. Therefore expose whether the original path is infact entry via a new user_path_at_empty() path lookup function. Use this to determine whether to default to EINVAL or ENOENT for failures. Addresses http://bugs.launchpad.net/bugs/817187 [akpm@linux-foundation.org: remove unused getname_flags()] Signed-off-by: Andy Whitcroft Cc: Christoph Hellwig Cc: Al Viro Cc: Cc: Signed-off-by: Andrew Morton Signed-off-by: Christoph Hellwig