- 21 10月, 2010 1 次提交
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由 Tetsuo Handa 提交于
We can set default LSM module to DAC (which means "enable no LSM module"). If default LSM module was set to DAC, security_module_enable() must return 0 unless overridden via boot time parameter. Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: NSerge E. Hallyn <serge@hallyn.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 02 8月, 2010 1 次提交
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由 Tetsuo Handa 提交于
When commit be6d3e56 "introduce new LSM hooks where vfsmount is available." was proposed, regarding security_path_truncate(), only "struct file *" argument (which AppArmor wanted to use) was removed. But length and time_attrs arguments are not used by TOMOYO nor AppArmor. Thus, let's remove these arguments. Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: NNick Piggin <npiggin@suse.de> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 28 7月, 2010 1 次提交
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由 Eric Paris 提交于
introduce a new fsnotify hook, fsnotify_perm(), which is called from the security code. This hook is used to allow fsnotify groups to make access control decisions about events on the system. We also must change the generic fsnotify function to return an error code if we intend these hooks to be in any way useful. Signed-off-by: NEric Paris <eparis@redhat.com>
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- 16 7月, 2010 1 次提交
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由 Jiri Slaby 提交于
Add task_struct to task_setrlimit of security_operations to be able to set rlimit of task other than current. Signed-off-by: NJiri Slaby <jirislaby@gmail.com> Acked-by: NEric Paris <eparis@redhat.com> Acked-by: NJames Morris <jmorris@namei.org>
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- 17 5月, 2010 1 次提交
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由 Tetsuo Handa 提交于
register_security() became __init function. So do verify() and security_fixup_ops(). Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 12 4月, 2010 13 次提交
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Eric Paris 提交于
Unused hook. Remove it. Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 03 3月, 2010 1 次提交
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由 wzt.wzt@gmail.com 提交于
LSM framework doesn't allow to load a security module on runtime, it must be loaded on boot time. but in security/security.c: int register_security(struct security_operations *ops) { ... if (security_ops != &default_security_ops) return -EAGAIN; ... } if security_ops == &default_security_ops, it can access to register a security module. If selinux is enabled, other security modules can't register, but if selinux is disabled on boot time, the security_ops was set to default_security_ops, LSM allows other kernel modules to use register_security() to register a not trust security module. For example: disable selinux on boot time(selinux=0). #include <linux/kernel.h> #include <linux/module.h> #include <linux/init.h> #include <linux/version.h> #include <linux/string.h> #include <linux/list.h> #include <linux/security.h> MODULE_LICENSE("GPL"); MODULE_AUTHOR("wzt"); extern int register_security(struct security_operations *ops); int (*new_register_security)(struct security_operations *ops); int rootkit_bprm_check_security(struct linux_binprm *bprm) { return 0; } struct security_operations rootkit_ops = { .bprm_check_security = rootkit_bprm_check_security, }; static int rootkit_init(void) { printk("Load LSM rootkit module.\n"); /* cat /proc/kallsyms | grep register_security */ new_register_security = 0xc0756689; if (new_register_security(&rootkit_ops)) { printk("Can't register rootkit module.\n"); return 0; } printk("Register rootkit module ok.\n"); return 0; } static void rootkit_exit(void) { printk("Unload LSM rootkit module.\n"); } module_init(rootkit_init); module_exit(rootkit_exit); Signed-off-by: NZhitong Wang <zhitong.wangzt@alibaba-inc.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 24 2月, 2010 1 次提交
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由 wzt.wzt@gmail.com 提交于
Enhance the security framework to support resetting the active security module. This eliminates the need for direct use of the security_ops and default_security_ops variables outside of security.c, so make security_ops and default_security_ops static. Also remove the secondary_ops variable as a cleanup since there is no use for that. secondary_ops was originally used by SELinux to call the "secondary" security module (capability or dummy), but that was replaced by direct calls to capability and the only remaining use is to save and restore the original security ops pointer value if SELinux is disabled by early userspace based on /etc/selinux/config. Further, if we support this directly in the security framework, then we can just use &default_security_ops for this purpose since that is now available. Signed-off-by: NZhitong Wang <zhitong.wangzt@alibaba-inc.com> Acked-by: NStephen Smalley <sds@tycho.nsa.gov> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 07 2月, 2010 1 次提交
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由 Al Viro 提交于
Hooks: Just Say No. Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
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- 04 2月, 2010 1 次提交
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由 Kees Cook 提交于
This allows the LSM to distinguish between syslog functions originating from /proc/kmsg access and direct syscalls. By default, the commoncaps will now no longer require CAP_SYS_ADMIN to read an opened /proc/kmsg file descriptor. For example the kernel syslog reader can now drop privileges after opening /proc/kmsg, instead of staying privileged with CAP_SYS_ADMIN. MAC systems that implement security_syslog have unchanged behavior. Signed-off-by: NKees Cook <kees.cook@canonical.com> Acked-by: NSerge Hallyn <serue@us.ibm.com> Acked-by: NJohn Johansen <john.johansen@canonical.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 15 1月, 2010 1 次提交
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由 James Morris 提交于
Currently, the getsecurity and setsecurity operations return zero for kernel private inodes, where xattrs are not available directly to userspace. This confuses some applications, and does not conform to the man page for getxattr(2) etc., which state that these syscalls should return ENOTSUP if xattrs are not supported or disabled. Note that in the listsecurity case, we still need to return zero as we don't know which other xattr handlers may be active. For discussion of userland confusion, see: http://www.mail-archive.com/bug-coreutils@gnu.org/msg17988.html This patch corrects the error returns so that ENOTSUP is reported to userspace as required. Signed-off-by: NJames Morris <jmorris@namei.org> Acked-by: NStephen Smalley <sds@tycho.nsa.gov> Acked-by: NSerge Hallyn <serue@us.ibm.com>
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- 08 12月, 2009 1 次提交
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由 Tetsuo Handa 提交于
include/linux/security.h and security/capability.c are using "struct path *dir" but security/security.c was using "struct path *path" by error. This patch renames "struct path *path" to "struct path *dir". Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 10 11月, 2009 1 次提交
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由 Eric Paris 提交于
For SELinux to do better filtering in userspace we send the name of the module along with the AVC denial when a program is denied module_request. Example output: type=SYSCALL msg=audit(11/03/2009 10:59:43.510:9) : arch=x86_64 syscall=write success=yes exit=2 a0=3 a1=7fc28c0d56c0 a2=2 a3=7fffca0d7440 items=0 ppid=1727 pid=1729 auid=unset uid=root gid=root euid=root suid=root fsuid=root egid=root sgid=root fsgid=root tty=(none) ses=unset comm=rpc.nfsd exe=/usr/sbin/rpc.nfsd subj=system_u:system_r:nfsd_t:s0 key=(null) type=AVC msg=audit(11/03/2009 10:59:43.510:9) : avc: denied { module_request } for pid=1729 comm=rpc.nfsd kmod="net-pf-10" scontext=system_u:system_r:nfsd_t:s0 tcontext=system_u:system_r:kernel_t:s0 tclass=system Signed-off-by: NEric Paris <eparis@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 09 11月, 2009 1 次提交
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由 John Johansen 提交于
The LSM currently requires setting a kernel parameter at boot to select a specific LSM. This adds a config option that allows specifying a default LSM that is used unless overridden with the security= kernel parameter. If the the config option is not set the current behavior of first LSM to register is used. Signed-off-by: NJohn Johansen <john.johansen@canonical.com> Acked-by: NSerge Hallyn <serue@us.ibm.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 25 10月, 2009 1 次提交
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由 Mimi Zohar 提交于
Based on discussions on LKML and LSM, where there are consecutive security_ and ima_ calls in the vfs layer, move the ima_ calls to the existing security_ hooks. Signed-off-by: NMimi Zohar <zohar@us.ibm.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 12 10月, 2009 2 次提交
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由 Tetsuo Handa 提交于
This patch allows pathname based LSM modules to check chroot() operations. This hook is used by TOMOYO. Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 Tetsuo Handa 提交于
This patch allows pathname based LSM modules to check chmod()/chown() operations. Since notify_change() does not receive "struct vfsmount *", we add security_path_chmod() and security_path_chown() to the caller of notify_change(). These hooks are used by TOMOYO. Signed-off-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 10 9月, 2009 1 次提交
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由 David P. Quigley 提交于
This patch introduces three new hooks. The inode_getsecctx hook is used to get all relevant information from an LSM about an inode. The inode_setsecctx is used to set both the in-core and on-disk state for the inode based on a context derived from inode_getsecctx.The final hook inode_notifysecctx will notify the LSM of a change for the in-core state of the inode in question. These hooks are for use in the labeled NFS code and addresses concerns of how to set security on an inode in a multi-xattr LSM. For historical reasons Stephen Smalley's explanation of the reason for these hooks is pasted below. Quote Stephen Smalley inode_setsecctx: Change the security context of an inode. Updates the in core security context managed by the security module and invokes the fs code as needed (via __vfs_setxattr_noperm) to update any backing xattrs that represent the context. Example usage: NFS server invokes this hook to change the security context in its incore inode and on the backing file system to a value provided by the client on a SETATTR operation. inode_notifysecctx: Notify the security module of what the security context of an inode should be. Initializes the incore security context managed by the security module for this inode. Example usage: NFS client invokes this hook to initialize the security context in its incore inode to the value provided by the server for the file when the server returned the file's attributes to the client. Signed-off-by: NDavid P. Quigley <dpquigl@tycho.nsa.gov> Acked-by: NSerge Hallyn <serue@us.ibm.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 02 9月, 2009 1 次提交
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由 David Howells 提交于
Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include <stdio.h> #include <stdlib.h> #include <keyutils.h> #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: NDavid Howells <dhowells@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 01 9月, 2009 1 次提交
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由 Paul Moore 提交于
The TUN driver lacks any LSM hooks which makes it difficult for LSM modules, such as SELinux, to enforce access controls on network traffic generated by TUN users; this is particularly problematic for virtualization apps such as QEMU and KVM. This patch adds three new LSM hooks designed to control the creation and attachment of TUN devices, the hooks are: * security_tun_dev_create() Provides access control for the creation of new TUN devices * security_tun_dev_post_create() Provides the ability to create the necessary socket LSM state for newly created TUN devices * security_tun_dev_attach() Provides access control for attaching to existing, persistent TUN devices and the ability to update the TUN device's socket LSM state as necessary Signed-off-by: NPaul Moore <paul.moore@hp.com> Acked-by: NEric Paris <eparis@parisplace.org> Acked-by: NSerge Hallyn <serue@us.ibm.com> Acked-by: NDavid S. Miller <davem@davemloft.net> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 14 8月, 2009 1 次提交
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由 Eric Paris 提交于
Calling request_module() will trigger a userspace upcall which will load a new module into the kernel. This can be a dangerous event if the process able to trigger request_module() is able to control either the modprobe binary or the module binary. This patch adds a new security hook to request_module() which can be used by an LSM to control a processes ability to call request_module(). Signed-off-by: NEric Paris <eparis@redhat.com> Acked-by: NSerge Hallyn <serue@us.ibm.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 24 6月, 2009 1 次提交
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由 Ingo Molnar 提交于
The ->ptrace_may_access() methods are named confusingly - the real ptrace_may_access() returns a bool, while these security checks have a retval convention. Rename it to ptrace_access_check, to reduce the confusion factor. [ Impact: cleanup, no code changed ] Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 04 6月, 2009 1 次提交
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由 Christoph Lameter 提交于
This patch removes the dependency of mmap_min_addr on CONFIG_SECURITY. It also sets a default mmap_min_addr of 4096. mmapping of addresses below 4096 will only be possible for processes with CAP_SYS_RAWIO. Signed-off-by: NChristoph Lameter <cl@linux-foundation.org> Acked-by: NEric Paris <eparis@redhat.com> Looks-ok-by: NLinus Torvalds <torvalds@linux-foundation.org> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 03 4月, 2009 1 次提交
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由 David Howells 提交于
Export a number of functions for CacheFiles's use. Signed-off-by: NDavid Howells <dhowells@redhat.com> Acked-by: NSteve Dickson <steved@redhat.com> Acked-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Acked-by: NRik van Riel <riel@redhat.com> Acked-by: NAl Viro <viro@zeniv.linux.org.uk> Tested-by: NDaire Byrne <Daire.Byrne@framestore.com>
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- 28 3月, 2009 1 次提交
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由 Paul Moore 提交于
The socket_post_accept() hook is not currently used by any in-tree modules and its existence continues to cause problems by confusing people about what can be safely accomplished using this hook. If a legitimate need for this hook arises in the future it can always be reintroduced. Signed-off-by: NPaul Moore <paul.moore@hp.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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- 07 1月, 2009 2 次提交
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由 David Howells 提交于
Fix a regression in cap_capable() due to: commit 3b11a1de 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: NDavid Howells <dhowells@redhat.com> Tested-by: NJ. Bruce Fields <bfields@citi.umich.edu> Acked-by: NSerge Hallyn <serue@us.ibm.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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由 James Morris 提交于
This reverts commit 14eaddc9. David has a better version to come.
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- 05 1月, 2009 1 次提交
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由 David Howells 提交于
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: NDavid Howells <dhowells@redhat.com> Signed-off-by: NJames Morris <jmorris@namei.org>
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