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* LSM: add SafeSetID module that gates setid callsMicah Morton2019-01-251-0/+19
| | | | | | | | | | | | | This change ensures that the set*uid family of syscalls in kernel/sys.c (setreuid, setuid, setresuid, setfsuid) all call ns_capable_common with the CAP_OPT_INSETID flag, so capability checks in the security_capable hook can know whether they are being called from within a set*uid syscall. This change is a no-op by itself, but is needed for the proposed SafeSetID LSM. Signed-off-by: Micah Morton <mortonm@chromium.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.morris@microsoft.com>
* capabilities:: annotate implicit fall throughMathieu Malaterre2019-01-231-3/+1Star
| | | | | | | | | | | | | | | There is a plan to build the kernel with -Wimplicit-fallthrough and this place in the code produced a warning (W=1). In this particular case change put the fall through comment on a single line so as to match the regular expression expected by GCC. This commit remove the following warning: kernel/capability.c:95:3: warning: this statement may fall through [-Wimplicit-fallthrough=] Signed-off-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: James Morris <james.morris@microsoft.com>
* LSM: generalize flag passing to security_capableMicah Morton2019-01-101-9/+13
| | | | | | | | | | | | | | This patch provides a general mechanism for passing flags to the security_capable LSM hook. It replaces the specific 'audit' flag that is used to tell security_capable whether it should log an audit message for the given capability check. The reason for generalizing this flag passing is so we can add an additional flag that signifies whether security_capable is being called by a setid syscall (which is needed by the proposed SafeSetID LSM). Signed-off-by: Micah Morton <mortonm@chromium.org> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.morris@microsoft.com>
* License cleanup: add SPDX GPL-2.0 license identifier to files with no licenseGreg Kroah-Hartman2017-11-021-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* capability: export has_capabilityJike Song2017-01-121-0/+1
| | | | | | | | | | | has_capability() is sometimes needed by modules to test capability for specified task other than current, so export it. Cc: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Jike Song <jike.song@intel.com> Acked-by: Serge Hallyn <serge@hallyn.com> Acked-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
* Replace <asm/uaccess.h> with <linux/uaccess.h> globallyLinus Torvalds2016-12-241-1/+1
| | | | | | | | | | | | | This was entirely automated, using the script by Al: PATT='^[[:blank:]]*#[[:blank:]]*include[[:blank:]]*<asm/uaccess.h>' sed -i -e "s!$PATT!#include <linux/uaccess.h>!" \ $(git grep -l "$PATT"|grep -v ^include/linux/uaccess.h) to do the replacement at the end of the merge window. Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* exec: Ensure mm->user_ns contains the execed filesEric W. Biederman2016-11-221-2/+14
| | | | | | | | | | | | | | | | | | | | When the user namespace support was merged the need to prevent ptrace from revealing the contents of an unreadable executable was overlooked. Correct this oversight by ensuring that the executed file or files are in mm->user_ns, by adjusting mm->user_ns. Use the new function privileged_wrt_inode_uidgid to see if the executable is a member of the user namespace, and as such if having CAP_SYS_PTRACE in the user namespace should allow tracing the executable. If not update mm->user_ns to the parent user namespace until an appropriate parent is found. Cc: stable@vger.kernel.org Reported-by: Jann Horn <jann@thejh.net> Fixes: 9e4a36ece652 ("userns: Fail exec for suid and sgid binaries with ids outside our user namespace.") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* ptrace: Capture the ptracer's creds not PT_PTRACE_CAPEric W. Biederman2016-11-221-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | When the flag PT_PTRACE_CAP was added the PTRACE_TRACEME path was overlooked. This can result in incorrect behavior when an application like strace traces an exec of a setuid executable. Further PT_PTRACE_CAP does not have enough information for making good security decisions as it does not report which user namespace the capability is in. This has already allowed one mistake through insufficient granulariy. I found this issue when I was testing another corner case of exec and discovered that I could not get strace to set PT_PTRACE_CAP even when running strace as root with a full set of caps. This change fixes the above issue with strace allowing stracing as root a setuid executable without disabling setuid. More fundamentaly this change allows what is allowable at all times, by using the correct information in it's decision. Cc: stable@vger.kernel.org Fixes: 4214e42f96d4 ("v2.4.9.11 -> v2.4.9.12") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* kernel: Add noaudit variant of ns_capable()Tyler Hicks2016-06-061-10/+36
| | | | | | | | | | | | | | | When checking the current cred for a capability in a specific user namespace, it isn't always desirable to have the LSMs audit the check. This patch adds a noaudit variant of ns_capable() for when those situations arise. The common logic between ns_capable() and the new ns_capable_noaudit() is moved into a single, shared function to keep duplicated code to a minimum and ease maintainability. Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
* kernel: conditionally support non-root users, groups and capabilitiesIulia Manda2015-04-161-16/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are a lot of embedded systems that run most or all of their functionality in init, running as root:root. For these systems, supporting multiple users is not necessary. This patch adds a new symbol, CONFIG_MULTIUSER, that makes support for non-root users, non-root groups, and capabilities optional. It is enabled under CONFIG_EXPERT menu. When this symbol is not defined, UID and GID are zero in any possible case and processes always have all capabilities. The following syscalls are compiled out: setuid, setregid, setgid, setreuid, setresuid, getresuid, setresgid, getresgid, setgroups, getgroups, setfsuid, setfsgid, capget, capset. Also, groups.c is compiled out completely. In kernel/capability.c, capable function was moved in order to avoid adding two ifdef blocks. This change saves about 25 KB on a defconfig build. The most minimal kernels have total text sizes in the high hundreds of kB rather than low MB. (The 25k goes down a bit with allnoconfig, but not that much. The kernel was booted in Qemu. All the common functionalities work. Adding users/groups is not possible, failing with -ENOSYS. Bloat-o-meter output: add/remove: 7/87 grow/shrink: 19/397 up/down: 1675/-26325 (-24650) [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Iulia Manda <iulia.manda21@gmail.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> Tested-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* CAPABILITIES: remove undefined caps from all processesEric Paris2014-07-241-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This is effectively a revert of 7b9a7ec565505699f503b4fcf61500dceb36e744 plus fixing it a different way... We found, when trying to run an application from an application which had dropped privs that the kernel does security checks on undefined capability bits. This was ESPECIALLY difficult to debug as those undefined bits are hidden from /proc/$PID/status. Consider a root application which drops all capabilities from ALL 4 capability sets. We assume, since the application is going to set eff/perm/inh from an array that it will clear not only the defined caps less than CAP_LAST_CAP, but also the higher 28ish bits which are undefined future capabilities. The BSET gets cleared differently. Instead it is cleared one bit at a time. The problem here is that in security/commoncap.c::cap_task_prctl() we actually check the validity of a capability being read. So any task which attempts to 'read all things set in bset' followed by 'unset all things set in bset' will not even attempt to unset the undefined bits higher than CAP_LAST_CAP. So the 'parent' will look something like: CapInh: 0000000000000000 CapPrm: 0000000000000000 CapEff: 0000000000000000 CapBnd: ffffffc000000000 All of this 'should' be fine. Given that these are undefined bits that aren't supposed to have anything to do with permissions. But they do... So lets now consider a task which cleared the eff/perm/inh completely and cleared all of the valid caps in the bset (but not the invalid caps it couldn't read out of the kernel). We know that this is exactly what the libcap-ng library does and what the go capabilities library does. They both leave you in that above situation if you try to clear all of you capapabilities from all 4 sets. If that root task calls execve() the child task will pick up all caps not blocked by the bset. The bset however does not block bits higher than CAP_LAST_CAP. So now the child task has bits in eff which are not in the parent. These are 'meaningless' undefined bits, but still bits which the parent doesn't have. The problem is now in cred_cap_issubset() (or any operation which does a subset test) as the child, while a subset for valid cap bits, is not a subset for invalid cap bits! So now we set durring commit creds that the child is not dumpable. Given it is 'more priv' than its parent. It also means the parent cannot ptrace the child and other stupidity. The solution here: 1) stop hiding capability bits in status This makes debugging easier! 2) stop giving any task undefined capability bits. it's simple, it you don't put those invalid bits in CAP_FULL_SET you won't get them in init and you won't get them in any other task either. This fixes the cap_issubset() tests and resulting fallout (which made the init task in a docker container untraceable among other things) 3) mask out undefined bits when sys_capset() is called as it might use ~0, ~0 to denote 'all capabilities' for backward/forward compatibility. This lets 'capsh --caps="all=eip" -- -c /bin/bash' run. 4) mask out undefined bit when we read a file capability off of disk as again likely all bits are set in the xattr for forward/backward compatibility. This lets 'setcap all+pe /bin/bash; /bin/bash' run Signed-off-by: Eric Paris <eparis@redhat.com> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Andrew Vagin <avagin@openvz.org> Cc: Andrew G. Morgan <morgan@kernel.org> Cc: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: Kees Cook <keescook@chromium.org> Cc: Steve Grubb <sgrubb@redhat.com> Cc: Dan Walsh <dwalsh@redhat.com> Cc: stable@vger.kernel.org Signed-off-by: James Morris <james.l.morris@oracle.com>
* fs,userns: Change inode_capable to capable_wrt_inode_uidgidAndy Lutomirski2014-06-101-12/+8Star
| | | | | | | | | | | | | | | | | | | | The kernel has no concept of capabilities with respect to inodes; inodes exist independently of namespaces. For example, inode_capable(inode, CAP_LINUX_IMMUTABLE) would be nonsense. This patch changes inode_capable to check for uid and gid mappings and renames it to capable_wrt_inode_uidgid, which should make it more obvious what it does. Fixes CVE-2014-4014. Cc: Theodore Ts'o <tytso@mit.edu> Cc: Serge Hallyn <serge.hallyn@ubuntu.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Dave Chinner <david@fromorbit.com> Cc: stable@vger.kernel.org Signed-off-by: Andy Lutomirski <luto@amacapital.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* kernel/capability.c: code clean-upFabian Frederick2014-06-051-3/+3
| | | | | | | | | | | | | - EXPORT_SYMBOL - typo: unexpectidly->unexpectedly - function prototype over 80 characters Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of ↵Linus Torvalds2014-04-031-19/+10Star
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security Pull security subsystem updates from James Morris: "Apart from reordering the SELinux mmap code to ensure DAC is called before MAC, these are minor maintenance updates" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (23 commits) selinux: correctly label /proc inodes in use before the policy is loaded selinux: put the mmap() DAC controls before the MAC controls selinux: fix the output of ./scripts/get_maintainer.pl for SELinux evm: enable key retention service automatically ima: skip memory allocation for empty files evm: EVM does not use MD5 ima: return d_name.name if d_path fails integrity: fix checkpatch errors ima: fix erroneous removal of security.ima xattr security: integrity: Use a more current logging style MAINTAINERS: email updates and other misc. changes ima: reduce memory usage when a template containing the n field is used ima: restore the original behavior for sending data with ima template Integrity: Pass commname via get_task_comm() fs: move i_readcount ima: use static const char array definitions security: have cap_dentry_init_security return error ima: new helper: file_inode(file) kernel: Mark function as static in kernel/seccomp.c capability: Use current logging styles ...
| * capability: Use current logging stylesJoe Perches2014-02-241-19/+10Star
| | | | | | | | | | | | | | | | | | | | | | Prefix logging output with "capability: " via pr_fmt. Convert printks to pr_<level>. Use pr_<level>_once instead of guard flags. Coalesce formats. Signed-off-by: Joe Perches <joe@perches.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com> Signed-off-by: James Morris <james.l.morris@oracle.com>
* | audit: Simplify and correct audit_log_capsetEric W. Biederman2014-01-141-1/+1
|/ | | | | | | | | | | | | | | | - Always report the current process as capset now always only works on the current process. This prevents reporting 0 or a random pid in a random pid namespace. - Don't bother to pass the pid as is available. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> (cherry picked from commit bcc85f0af31af123e32858069eb2ad8f39f90e67) (cherry picked from commit f911cac4556a7a23e0b3ea850233d13b32328692) Signed-off-by: Richard Guy Briggs <rgb@redhat.com> [eparis: fix build error when audit disabled] Signed-off-by: Eric Paris <eparis@redhat.com>
* Merge tag 'xfs-for-linus-v3.12-rc1' of git://oss.sgi.com/xfs/xfsLinus Torvalds2013-09-091-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull xfs updates from Ben Myers: "For 3.12-rc1 there are a number of bugfixes in addition to work to ease usage of shared code between libxfs and the kernel, the rest of the work to enable project and group quotas to be used simultaneously, performance optimisations in the log and the CIL, directory entry file type support, fixes for log space reservations, some spelling/grammar cleanups, and the addition of user namespace support. - introduce readahead to log recovery - add directory entry file type support - fix a number of spelling errors in comments - introduce new Q_XGETQSTATV quotactl for project quotas - add USER_NS support - log space reservation rework - CIL optimisations - kernel/userspace libxfs rework" * tag 'xfs-for-linus-v3.12-rc1' of git://oss.sgi.com/xfs/xfs: (112 commits) xfs: XFS_MOUNT_QUOTA_ALL needed by userspace xfs: dtype changed xfs_dir2_sfe_put_ino to xfs_dir3_sfe_put_ino Fix wrong flag ASSERT in xfs_attr_shortform_getvalue xfs: finish removing IOP_* macros. xfs: inode log reservations are too small xfs: check correct status variable for xfs_inobt_get_rec() call xfs: inode buffers may not be valid during recovery readahead xfs: check LSN ordering for v5 superblocks during recovery xfs: btree block LSN escaping to disk uninitialised XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568 xfs: fix bad dquot buffer size in log recovery readahead xfs: don't account buffer cancellation during log recovery readahead xfs: check for underflow in xfs_iformat_fork() xfs: xfs_dir3_sfe_put_ino can be static xfs: introduce object readahead to log recovery xfs: Simplify xfs_ail_min() with list_first_entry_or_null() xfs: Register hotcpu notifier after initialization xfs: add xfs sb v4 support for dirent filetype field xfs: Add write support for dirent filetype field xfs: Add read-only support for dirent filetype field ...
| * xfs: ioctl check for capabilities in the current user namespaceDwight Engen2013-08-151-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Use inode_capable() to check if SUID|SGID bits should be cleared to match similar check in inode_change_ok(). The check for CAP_LINUX_IMMUTABLE was not modified since all other file systems also check against init_user_ns rather than current_user_ns. Only allow changing of projid from init_user_ns. Reviewed-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Gao feng <gaofeng@cn.fujitsu.com> Signed-off-by: Dwight Engen <dwight.engen@oracle.com> Signed-off-by: Ben Myers <bpm@sgi.com>
* | userns: Kill nsown_capable it makes the wrong thing easyEric W. Biederman2013-08-311-12/+0Star
|/ | | | | | | | | | nsown_capable is a special case of ns_capable essentially for just CAP_SETUID and CAP_SETGID. For the existing users it doesn't noticably simplify things and from the suggested patches I have seen it encourages people to do the wrong thing. So remove nsown_capable. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* Add file_ns_capable() helper function for open-time capability checkingLinus Torvalds2013-04-141-0/+24
| | | | | | | | | | Nothing is using it yet, but this will allow us to delay the open-time checks to use time, without breaking the normal UNIX permission semantics where permissions are determined by the opener (and the file descriptor can then be passed to a different process, or the process can drop capabilities). Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userns: Teach inode_capable to understand inodes whose uids map to other ↵Eric W. Biederman2012-05-151-2/+4
| | | | | | | namespaces. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* userns: Replace the hard to write inode_userns with inode_capable.Eric W. Biederman2012-04-081-0/+19
| | | | | | | | | | | | | | | | | | | | | This represents a change in strategy of how to handle user namespaces. Instead of tagging everything explicitly with a user namespace and bulking up all of the comparisons of uids and gids in the kernel, all uids and gids in use will have a mapping to a flat kuid and kgid spaces respectively. This allows much more of the existing logic to be preserved and in general allows for faster code. In this new and improved world we allow someone to utiliize capabilities over an inode if the inodes owner mapps into the capabilities holders user namespace and the user has capabilities in their user namespace. Which is simple and efficient. Moving the fs uid comparisons to be comparisons in a flat kuid space follows in later patches, something that is only significant if you are using user namespaces. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
* Revert "capabitlies: ns_capable can use the cap helpers rather than lsm call"Linus Torvalds2012-01-171-1/+1
| | | | | | | | | | | | | | | | | | | | | | | This reverts commit d2a7009f0bb03fa22ad08dd25472efa0568126b9. J. R. Okajima explains: "After this commit, I am afraid access(2) on NFS may not work correctly. The scenario based upon my guess. - access(2) overrides the credentials. - calls inode_permission() -- ... -- generic_permission() -- ns_capable(). - while the old ns_capable() calls security_capable(current_cred()), the new ns_capable() calls has_ns_capability(current) -- security_capable(__task_cred(t)). current_cred() returns current->cred which is effective (overridden) credentials, but __task_cred(current) returns current->real_cred (the NFSD's credential). And the overridden credentials by access(2) lost." Requested-by: J. R. Okajima <hooanon05@yahoo.co.jp> Acked-by: Eric Paris <eparis@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-linus' of git://selinuxproject.org/~jmorris/linux-securityLinus Torvalds2012-01-151-34/+46
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * 'for-linus' of git://selinuxproject.org/~jmorris/linux-security: capabilities: remove __cap_full_set definition security: remove the security_netlink_recv hook as it is equivalent to capable() ptrace: do not audit capability check when outputing /proc/pid/stat capabilities: remove task_ns_* functions capabitlies: ns_capable can use the cap helpers rather than lsm call capabilities: style only - move capable below ns_capable capabilites: introduce new has_ns_capabilities_noaudit capabilities: call has_ns_capability from has_capability capabilities: remove all _real_ interfaces capabilities: introduce security_capable_noaudit capabilities: reverse arguments to security_capable capabilities: remove the task from capable LSM hook entirely selinux: sparse fix: fix several warnings in the security server cod selinux: sparse fix: fix warnings in netlink code selinux: sparse fix: eliminate warnings for selinuxfs selinux: sparse fix: declare selinux_disable() in security.h selinux: sparse fix: move selinux_complete_init selinux: sparse fix: make selinux_secmark_refcount static SELinux: Fix RCU deref check warning in sel_netport_insert() Manually fix up a semantic mis-merge wrt security_netlink_recv(): - the interface was removed in commit fd7784615248 ("security: remove the security_netlink_recv hook as it is equivalent to capable()") - a new user of it appeared in commit a38f7907b926 ("crypto: Add userspace configuration API") causing no automatic merge conflict, but Eric Paris pointed out the issue.
| * capabilities: remove task_ns_* functionsEric Paris2012-01-061-14/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | task_ in the front of a function, in the security subsystem anyway, means to me at least, that we are operating with that task as the subject of the security decision. In this case what it means is that we are using current as the subject but we use the task to get the right namespace. Who in the world would ever realize that's what task_ns_capability means just by the name? This patch eliminates the task_ns functions entirely and uses the has_ns_capability function instead. This means we explicitly open code the ns in question in the caller. I think it makes the caller a LOT more clear what is going on. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabitlies: ns_capable can use the cap helpers rather than lsm callEric Paris2012-01-061-1/+1
| | | | | | | | | | | | | | | | Just to reduce the number of places to change if we every change the LSM hook, use the capability helpers internally when possible. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabilities: style only - move capable below ns_capableEric Paris2012-01-061-16/+16
| | | | | | | | | | | | | | | | | | Although the current code is fine for consistency this moves the capable code below the function it calls in the c file. It doesn't actually change code. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabilites: introduce new has_ns_capabilities_noauditEric Paris2012-01-061-5/+25
| | | | | | | | | | | | | | | | | | | | For consistency in interfaces, introduce a new interface called has_ns_capabilities_noaudit. It checks if the given task has the given capability in the given namespace. Use this new function by has_capabilities_noaudit. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabilities: call has_ns_capability from has_capabilityEric Paris2012-01-061-16/+10Star
| | | | | | | | | | | | | | | | | | | | Declare the more specific has_ns_capability first in the code and then call it from has_capability. The declaration reversal isn't stricty necessary since they are both declared in header files, but it just makes sense to put more specific functions first in the code. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabilities: remove all _real_ interfacesEric Paris2012-01-061-3/+15
| | | | | | | | | | | | | | | | | | The name security_real_capable and security_real_capable_noaudit just don't make much sense to me. Convert them to use security_capable and security_capable_noaudit. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
| * capabilities: reverse arguments to security_capableEric Paris2012-01-061-1/+1
| | | | | | | | | | | | | | | | | | | | security_capable takes ns, cred, cap. But the LSM capable() hook takes cred, ns, cap. The capability helper functions also take cred, ns, cap. Rather than flip argument order just to flip it back, leave them alone. Heck, this should be a little faster since argument will be in the right place! Signed-off-by: Eric Paris <eparis@redhat.com>
* | kernel: Map most files to use export.h instead of module.hPaul Gortmaker2011-10-311-1/+1
|/ | | | | | | | | | | | | | | | The changed files were only including linux/module.h for the EXPORT_SYMBOL infrastructure, and nothing else. Revector them onto the isolated export header for faster compile times. Nothing to see here but a whole lot of instances of: -#include <linux/module.h> +#include <linux/export.h> This commit is only changing the kernel dir; next targets will probably be mm, fs, the arch dirs, etc. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
* Merge branch 'master' into nextJames Morris2011-05-191-0/+12
|\ | | | | | | | | | | | | | | | | Conflicts: include/linux/capability.h Manually resolve merge conflict w/ thanks to Stephen Rothwell. Signed-off-by: James Morris <jmorris@namei.org>
| * Cache user_ns in struct credSerge E. Hallyn2011-05-131-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If !CONFIG_USERNS, have current_user_ns() defined to (&init_user_ns). Get rid of _current_user_ns. This requires nsown_capable() to be defined in capability.c rather than as static inline in capability.h, so do that. Request_key needs init_user_ns defined at current_user_ns if !CONFIG_USERNS, so forward-declare that in cred.h if !CONFIG_USERNS at current_user_ns() define. Compile-tested with and without CONFIG_USERNS. Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> [ This makes a huge performance difference for acl_permission_check(), up to 30%. And that is one of the hottest kernel functions for loads that are pathname-lookup heavy. ] Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | capabilities: delete unused cap_set_fullEric Paris2011-04-041-2/+0Star
| | | | | | | | | | | | | | | | | | unused code. Clean it up. Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: David Howells <dhowells@redhat.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
* | capabilities: do not drop CAP_SETPCAP from the initial taskEric Paris2011-04-041-2/+0Star
|/ | | | | | | | | | | In olden' days of yore CAP_SETPCAP had special meaning for the init task. We actually have code to make sure that CAP_SETPCAP wasn't in pE of things using the init_cred. But CAP_SETPCAP isn't so special any more and we don't have a reason to special case dropping it for init or kthreads.... Signed-off-by: Eric Paris <eparis@redhat.com> Acked-by: Andrew G. Morgan <morgan@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
* userns: make has_capability* into real functionsSerge E. Hallyn2011-03-241-0/+54
| | | | | | | | | | | | | So we can let type safety keep things sane, and as a bonus we can remove the declaration of init_user_ns in capability.h. Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Daniel Lezcano <daniel.lezcano@free.fr> Cc: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* userns: security: make capabilities relative to the user namespaceSerge E. Hallyn2011-03-241-5/+37
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Introduce ns_capable to test for a capability in a non-default user namespace. - Teach cap_capable to handle capabilities in a non-default user namespace. The motivation is to get to the unprivileged creation of new namespaces. It looks like this gets us 90% of the way there, with only potential uid confusion issues left. I still need to handle getting all caps after creation but otherwise I think I have a good starter patch that achieves all of your goals. Changelog: 11/05/2010: [serge] add apparmor 12/14/2010: [serge] fix capabilities to created user namespaces Without this, if user serge creates a user_ns, he won't have capabilities to the user_ns he created. THis is because we were first checking whether his effective caps had the caps he needed and returning -EPERM if not, and THEN checking whether he was the creator. Reverse those checks. 12/16/2010: [serge] security_real_capable needs ns argument in !security case 01/11/2011: [serge] add task_ns_capable helper 01/11/2011: [serge] add nsown_capable() helper per Bastian Blank suggestion 02/16/2011: [serge] fix a logic bug: the root user is always creator of init_user_ns, but should not always have capabilities to it! Fix the check in cap_capable(). 02/21/2011: Add the required user_ns parameter to security_capable, fixing a compile failure. 02/23/2011: Convert some macros to functions as per akpm comments. Some couldn't be converted because we can't easily forward-declare them (they are inline if !SECURITY, extern if SECURITY). Add a current_user_ns function so we can use it in capability.h without #including cred.h. Move all forward declarations together to the top of the #ifdef __KERNEL__ section, and use kernel-doc format. 02/23/2011: Per dhowells, clean up comment in cap_capable(). 02/23/2011: Per akpm, remove unreachable 'return -EPERM' in cap_capable. (Original written and signed off by Eric; latest, modified version acked by him) [akpm@linux-foundation.org: fix build] [akpm@linux-foundation.org: export current_user_ns() for ecryptfs] [serge.hallyn@canonical.com: remove unneeded extra argument in selinux's task_has_capability] Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Daniel Lezcano <daniel.lezcano@free.fr> Acked-by: David Howells <dhowells@redhat.com> Cc: James Morris <jmorris@namei.org> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* security: add cred argument to security_capable()Chris Wright2011-02-111-1/+1
| | | | | | | | | Expand security_capable() to include cred, so that it can be usable in a wider range of call sites. Signed-off-by: Chris Wright <chrisw@sous-sol.org> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: James Morris <jmorris@namei.org>
* sched: Remove remaining USER_SCHED codeLi Zefan2010-04-021-1/+0Star
| | | | | | | | | | | This is left over from commit 7c9414385e ("sched: Remove USER_SCHED"") Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Dhaval Giani <dhaval.giani@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: David Howells <dhowells@redhat.com> LKML-Reference: <4BA9A05F.7010407@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* capabilities: Use RCU to protect task lookup in sys_capgetThomas Gleixner2009-12-091-2/+2
| | | | | | | | | | | | | cap_get_target_pid() protects the task lookup with tasklist_lock. security_capget() is called under tasklist_lock as well but tasklist_lock does not protect anything there. The capabilities are protected by RCU already. So tasklist_lock only protects the lookup and prevents the task going away, which can be done with rcu_read_lock() as well. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: James Morris <jmorris@namei.org>
* remove CONFIG_SECURITY_FILE_CAPABILITIES compile optionSerge E. Hallyn2009-11-241-2/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | As far as I know, all distros currently ship kernels with default CONFIG_SECURITY_FILE_CAPABILITIES=y. Since having the option on leaves a 'no_file_caps' option to boot without file capabilities, the main reason to keep the option is that turning it off saves you (on my s390x partition) 5k. In particular, vmlinux sizes came to: without patch fscaps=n: 53598392 without patch fscaps=y: 53603406 with this patch applied: 53603342 with the security-next tree. Against this we must weigh the fact that there is no simple way for userspace to figure out whether file capabilities are supported, while things like per-process securebits, capability bounding sets, and adding bits to pI if CAP_SETPCAP is in pE are not supported with SECURITY_FILE_CAPABILITIES=n, leaving a bit of a problem for applications wanting to know whether they can use them and/or why something failed. It also adds another subtly different set of semantics which we must maintain at the risk of severe security regressions. So this patch removes the SECURITY_FILE_CAPABILITIES compile option. It drops the kernel size by about 50k over the stock SECURITY_FILE_CAPABILITIES=y kernel, by removing the cap_limit_ptraced_target() function. Changelog: Nov 20: remove cap_limit_ptraced_target() as it's logic was ifndef'ed. Signed-off-by: Serge E. Hallyn <serue@us.ibm.com> Acked-by: Andrew G. Morgan" <morgan@kernel.org> Signed-off-by: James Morris <jmorris@namei.org>
* Silence the existing API for capability version compatibility check.Andrew G. Morgan2009-11-231-2/+2
| | | | | | | | | | | | | | | | | | | | | | When libcap, or other libraries attempt to confirm/determine the supported capability version magic, they generally supply a NULL dataptr to capget(). In this case, while returning the supported/preferred magic (via a modified header content), the return code of this system call may be 0, -EINVAL, or -EFAULT. No libcap code depends on the previous -EINVAL etc. return code, and all of the above three return codes can accompany a valid (successful) attempt to determine the requested magic value. This patch cleans up the system call to return 0, if the call is successfully being used to determine the supported/preferred capability magic value. Signed-off-by: Andrew G. Morgan <morgan@kernel.org> Acked-by: Steve Grubb <sgrubb@redhat.com> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
* capabilities: simplify bound checks for copy_from_user()Arjan van de Ven2009-10-131-3/+6
| | | | | | | | | | | | | The capabilities syscall has a copy_from_user() call where gcc currently cannot prove to itself that the copy is always within bounds. This patch adds a very explicity bound check to prove to gcc that this copy_from_user cannot overflow its destination buffer. Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Acked-by: James Morris <jmorris@namei.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: James Morris <jmorris@namei.org>
* [CVE-2009-0029] System call wrappers part 04Heiko Carstens2009-01-141-2/+2
| | | | Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
* Merge branch 'next' into for-linusJames Morris2009-01-061-1/+1
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| * CRED: Fix regression in cap_capable() as shown up by sys_faccessat() [ver #3]David Howells2009-01-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix a regression in cap_capable() due to: commit 3b11a1decef07c19443d24ae926982bc8ec9f4c0 Author: David Howells <dhowells@redhat.com> Date: Fri Nov 14 10:39:26 2008 +1100 CRED: Differentiate objective and effective subjective credentials on a task The problem is that the above patch allows a process to have two sets of credentials, and for the most part uses the subjective credentials when accessing current's creds. There is, however, one exception: cap_capable(), and thus capable(), uses the real/objective credentials of the target task, whether or not it is the current task. Ordinarily this doesn't matter, since usually the two cred pointers in current point to the same set of creds. However, sys_faccessat() makes use of this facility to override the credentials of the calling process to make its test, without affecting the creds as seen from other processes. One of the things sys_faccessat() does is to make an adjustment to the effective capabilities mask, which cap_capable(), as it stands, then ignores. The affected capability check is in generic_permission(): if (!(mask & MAY_EXEC) || execute_ok(inode)) if (capable(CAP_DAC_OVERRIDE)) return 0; This change passes the set of credentials to be tested down into the commoncap and SELinux code. The security functions called by capable() and has_capability() select the appropriate set of credentials from the process being checked. This can be tested by compiling the following program from the XFS testsuite: /* * t_access_root.c - trivial test program to show permission bug. * * Written by Michael Kerrisk - copyright ownership not pursued. * Sourced from: http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/6030.html */ #include <limits.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/stat.h> #define UID 500 #define GID 100 #define PERM 0 #define TESTPATH "/tmp/t_access" static void errExit(char *msg) { perror(msg); exit(EXIT_FAILURE); } /* errExit */ static void accessTest(char *file, int mask, char *mstr) { printf("access(%s, %s) returns %d\n", file, mstr, access(file, mask)); } /* accessTest */ int main(int argc, char *argv[]) { int fd, perm, uid, gid; char *testpath; char cmd[PATH_MAX + 20]; testpath = (argc > 1) ? argv[1] : TESTPATH; perm = (argc > 2) ? strtoul(argv[2], NULL, 8) : PERM; uid = (argc > 3) ? atoi(argv[3]) : UID; gid = (argc > 4) ? atoi(argv[4]) : GID; unlink(testpath); fd = open(testpath, O_RDWR | O_CREAT, 0); if (fd == -1) errExit("open"); if (fchown(fd, uid, gid) == -1) errExit("fchown"); if (fchmod(fd, perm) == -1) errExit("fchmod"); close(fd); snprintf(cmd, sizeof(cmd), "ls -l %s", testpath); system(cmd); if (seteuid(uid) == -1) errExit("seteuid"); accessTest(testpath, 0, "0"); accessTest(testpath, R_OK, "R_OK"); accessTest(testpath, W_OK, "W_OK"); accessTest(testpath, X_OK, "X_OK"); accessTest(testpath, R_OK | W_OK, "R_OK | W_OK"); accessTest(testpath, R_OK | X_OK, "R_OK | X_OK"); accessTest(testpath, W_OK | X_OK, "W_OK | X_OK"); accessTest(testpath, R_OK | W_OK | X_OK, "R_OK | W_OK | X_OK"); exit(EXIT_SUCCESS); } /* main */ This can be run against an Ext3 filesystem as well as against an XFS filesystem. If successful, it will show: [root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043 ---------- 1 dhowells dhowells 0 2008-12-31 03:00 /tmp/xxx access(/tmp/xxx, 0) returns 0 access(/tmp/xxx, R_OK) returns 0 access(/tmp/xxx, W_OK) returns 0 access(/tmp/xxx, X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK) returns 0 access(/tmp/xxx, R_OK | X_OK) returns -1 access(/tmp/xxx, W_OK | X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1 If unsuccessful, it will show: [root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043 ---------- 1 dhowells dhowells 0 2008-12-31 02:56 /tmp/xxx access(/tmp/xxx, 0) returns 0 access(/tmp/xxx, R_OK) returns -1 access(/tmp/xxx, W_OK) returns -1 access(/tmp/xxx, X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK) returns -1 access(/tmp/xxx, R_OK | X_OK) returns -1 access(/tmp/xxx, W_OK | X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1 I've also tested the fix with the SELinux and syscalls LTP testsuites. Signed-off-by: David Howells <dhowells@redhat.com> Tested-by: J. Bruce Fields <bfields@citi.umich.edu> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
| * Revert "CRED: Fix regression in cap_capable() as shown up by sys_faccessat() ↵James Morris2009-01-061-1/+1
| | | | | | | | | | | | | | | | [ver #2]" This reverts commit 14eaddc967b16017d4a1a24d2be6c28ecbe06ed8. David has a better version to come.
| * CRED: Fix regression in cap_capable() as shown up by sys_faccessat() [ver #2]David Howells2009-01-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix a regression in cap_capable() due to: commit 5ff7711e635b32f0a1e558227d030c7e45b4a465 Author: David Howells <dhowells@redhat.com> Date: Wed Dec 31 02:52:28 2008 +0000 CRED: Differentiate objective and effective subjective credentials on a task The problem is that the above patch allows a process to have two sets of credentials, and for the most part uses the subjective credentials when accessing current's creds. There is, however, one exception: cap_capable(), and thus capable(), uses the real/objective credentials of the target task, whether or not it is the current task. Ordinarily this doesn't matter, since usually the two cred pointers in current point to the same set of creds. However, sys_faccessat() makes use of this facility to override the credentials of the calling process to make its test, without affecting the creds as seen from other processes. One of the things sys_faccessat() does is to make an adjustment to the effective capabilities mask, which cap_capable(), as it stands, then ignores. The affected capability check is in generic_permission(): if (!(mask & MAY_EXEC) || execute_ok(inode)) if (capable(CAP_DAC_OVERRIDE)) return 0; This change splits capable() from has_capability() down into the commoncap and SELinux code. The capable() security op now only deals with the current process, and uses the current process's subjective creds. A new security op - task_capable() - is introduced that can check any task's objective creds. strictly the capable() security op is superfluous with the presence of the task_capable() op, however it should be faster to call the capable() op since two fewer arguments need be passed down through the various layers. This can be tested by compiling the following program from the XFS testsuite: /* * t_access_root.c - trivial test program to show permission bug. * * Written by Michael Kerrisk - copyright ownership not pursued. * Sourced from: http://linux.derkeiler.com/Mailing-Lists/Kernel/2003-10/6030.html */ #include <limits.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <fcntl.h> #include <sys/stat.h> #define UID 500 #define GID 100 #define PERM 0 #define TESTPATH "/tmp/t_access" static void errExit(char *msg) { perror(msg); exit(EXIT_FAILURE); } /* errExit */ static void accessTest(char *file, int mask, char *mstr) { printf("access(%s, %s) returns %d\n", file, mstr, access(file, mask)); } /* accessTest */ int main(int argc, char *argv[]) { int fd, perm, uid, gid; char *testpath; char cmd[PATH_MAX + 20]; testpath = (argc > 1) ? argv[1] : TESTPATH; perm = (argc > 2) ? strtoul(argv[2], NULL, 8) : PERM; uid = (argc > 3) ? atoi(argv[3]) : UID; gid = (argc > 4) ? atoi(argv[4]) : GID; unlink(testpath); fd = open(testpath, O_RDWR | O_CREAT, 0); if (fd == -1) errExit("open"); if (fchown(fd, uid, gid) == -1) errExit("fchown"); if (fchmod(fd, perm) == -1) errExit("fchmod"); close(fd); snprintf(cmd, sizeof(cmd), "ls -l %s", testpath); system(cmd); if (seteuid(uid) == -1) errExit("seteuid"); accessTest(testpath, 0, "0"); accessTest(testpath, R_OK, "R_OK"); accessTest(testpath, W_OK, "W_OK"); accessTest(testpath, X_OK, "X_OK"); accessTest(testpath, R_OK | W_OK, "R_OK | W_OK"); accessTest(testpath, R_OK | X_OK, "R_OK | X_OK"); accessTest(testpath, W_OK | X_OK, "W_OK | X_OK"); accessTest(testpath, R_OK | W_OK | X_OK, "R_OK | W_OK | X_OK"); exit(EXIT_SUCCESS); } /* main */ This can be run against an Ext3 filesystem as well as against an XFS filesystem. If successful, it will show: [root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043 ---------- 1 dhowells dhowells 0 2008-12-31 03:00 /tmp/xxx access(/tmp/xxx, 0) returns 0 access(/tmp/xxx, R_OK) returns 0 access(/tmp/xxx, W_OK) returns 0 access(/tmp/xxx, X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK) returns 0 access(/tmp/xxx, R_OK | X_OK) returns -1 access(/tmp/xxx, W_OK | X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1 If unsuccessful, it will show: [root@andromeda src]# ./t_access_root /tmp/xxx 0 4043 4043 ---------- 1 dhowells dhowells 0 2008-12-31 02:56 /tmp/xxx access(/tmp/xxx, 0) returns 0 access(/tmp/xxx, R_OK) returns -1 access(/tmp/xxx, W_OK) returns -1 access(/tmp/xxx, X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK) returns -1 access(/tmp/xxx, R_OK | X_OK) returns -1 access(/tmp/xxx, W_OK | X_OK) returns -1 access(/tmp/xxx, R_OK | W_OK | X_OK) returns -1 I've also tested the fix with the SELinux and syscalls LTP testsuites. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
* | sanitize audit_log_capset()Al Viro2009-01-041-3/+1Star
|/ | | | | | | | * no allocations * return void * don't duplicate checked for dummy context Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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