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2015-05-12LSM: Switch to lists of hooksCasey Schaufler1-11/+3
Instead of using a vector of security operations with explicit, special case stacking of the capability and yama hooks use lists of hooks with capability and yama hooks included as appropriate. The security_operations structure is no longer required. Instead, there is a union of the function pointers that allows all the hooks lists to use a common mechanism for list management while retaining typing. Each module supplies an array describing the hooks it provides instead of a sparsely populated security_operations structure. The description includes the element that gets put on the hook list, avoiding the issues surrounding individual element allocation. The method for registering security modules is changed to reflect the information available. The method for removing a module, currently only used by SELinux, has also changed. It should be generic now, however if there are potential race conditions based on ordering of hook removal that needs to be addressed by the calling module. The security hooks are called from the lists and the first failure is returned. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-05-12LSM: Add security module hook list headsCasey Schaufler1-29/+29
Add a list header for each security hook. They aren't used until later in the patch series. They are grouped together in a structure so that there doesn't need to be an external address for each. Macro-ize the initialization of the security_operations for each security module in anticipation of changing out the security_operations structure. Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-05-12LSM: Split security.hCasey Schaufler1-1/+1
The security.h header file serves two purposes, interfaces for users of the security modules and interfaces for security modules. Users of the security modules don't need to know about what's in the security_operations structure, so pull it out into it's own header, lsm_hooks.h Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: John Johansen <john.johansen@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Acked-by: Paul Moore <paul@paul-moore.com> Acked-by: Stephen Smalley <sds@tycho.nsa.gov> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <james.l.morris@oracle.com>
2015-04-11switch security_inode_getattr() to struct path *Al Viro1-3/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2013-03-18tomoyo: use DEFINE_SRCU() to define tomoyo_ssLai Jiangshan1-3/+2
DEFINE_STATIC_SRCU() defines srcu struct and do init at build time. Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <james.l.morris@oracle.com>
2012-10-11consitify do_mount() argumentsAl Viro1-2/+2
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-09-21userns: Teach security_path_chown to take kuids and kgidsEric W. Biederman1-5/+7
Don't make the security modules deal with raw user space uid and gids instead pass in a kuid_t and a kgid_t so that security modules only have to deal with internal kernel uids and gids. Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: James Morris <james.l.morris@oracle.com> Cc: John Johansen <john.johansen@canonical.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2012-04-09SELinux: rename dentry_open to file_openEric Paris1-3/+3
dentry_open takes a file, rename it to file_open Signed-off-by: Eric Paris <eparis@redhat.com>
2012-01-06switch security_path_chmod() to struct path *Al Viro1-7/+4
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch ->path_mknod() to umode_tAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch ->path_mkdir() to umode_tAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-03switch security_path_chmod() to umode_tAl Viro1-1/+1
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2011-09-14TOMOYO: Add socket operation restriction support.Tetsuo Handa1-0/+62
This patch adds support for permission checks for PF_INET/PF_INET6/PF_UNIX socket's bind()/listen()/connect()/send() operations. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2011-07-14TOMOYO: Update kernel-doc.Tetsuo Handa1-4/+206
Update comments for scripts/kernel-doc and fix some of errors reported by scripts/checkpatch.pl . Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2011-07-11TOMOYO: Enable conditional ACL.Tetsuo Handa1-7/+7
Enable conditional ACL by passing object's pointers. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2011-06-30TOMOYO: Fix build error with CONFIG_SECURITY_TOMOYO_OMIT_USERSPACE_LOADER=y .Tetsuo Handa1-0/+2
I forgot to add #ifndef in commit 0e4ae0e0 "TOMOYO: Make several options configurable.", resulting security/built-in.o: In function `tomoyo_bprm_set_creds': tomoyo.c:(.text+0x4698e): undefined reference to `tomoyo_load_policy' error. Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2011-06-29TOMOYO: Cleanup part 1.Tetsuo Handa1-3/+11
In order to synchronize with TOMOYO 1.8's syntax, (1) Remove special handling for allow_read/write permission. (2) Replace deny_rewrite/allow_rewrite permission with allow_append permission. (3) Remove file_pattern keyword. (4) Remove allow_read permission from exception policy. (5) Allow creating domains in enforcing mode without calling supervisor. (6) Add permission check for opening directory for reading. (7) Add permission check for stat() operation. (8) Make "cat < /sys/kernel/security/tomoyo/self_domain" behave as if "cat /sys/kernel/security/tomoyo/self_domain". Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02TOMOYO: Rename symbols.Tetsuo Handa1-1/+1
Use shorter name in order to make it easier to fix 80 columns limit. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02LSM: Remove unused arguments from security_path_truncate().Tetsuo Handa1-2/+1
When commit be6d3e56a6b9b3a4ee44a0685e39e595073c6f0d "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: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Nick Piggin <npiggin@suse.de> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02TOMOYO: Split files into some pieces.Tetsuo Handa1-5/+2
security/tomoyo/common.c became too large to read. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02TOMOYO: Add mount restriction.Tetsuo Handa1-1/+1
mount(2) has three string and one numeric parameters. Split mount restriction code from security/tomoyo/file.c . Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02TOMOYO: Split file access control functions by type of parameters.Tetsuo Handa1-6/+15
Check numeric parameters for operations that deal them (e.g. chmod/chown/ioctl). Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-08-02TOMOYO: Use structure for passing common arguments.Tetsuo Handa1-1/+1
Use "struct tomoyo_request_info" instead of passing individual arguments. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-03-01Merge branch 'next' into for-linusJames Morris1-44/+98
2010-02-16TOMOYO: Remove unneeded parameter.Tetsuo Handa1-23/+17
tomoyo_path_perm() tomoyo_path2_perm() and tomoyo_check_rewrite_permission() always receive tomoyo_domain(). We can move it from caller to callee. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-02-16TOMOYO: Use shorter names.Tetsuo Handa1-45/+27
Use shorter name to reduce newlines needed for 80 columns limit. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2010-02-15TOMOYO: Add refcounter on domain structure.Tetsuo Handa1-16/+21
Add refcounter to "struct tomoyo_domain_info" since garbage collector needs to determine whether this struct is referred by "struct cred"->security or not. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-02-15TOMOYO: Merge headers.Tetsuo Handa1-2/+0
Gather structures and constants scattered around security/tomoyo/ directory. This is for preparation for adding garbage collector since garbage collector needs to know structures and constants which TOMOYO uses. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2010-01-14Fix ACC_MODE() for realAl Viro1-6/+1
commit 5300990c0370e804e49d9a59d928c5d53fb73487 had stepped on a rather nasty mess: definitions of ACC_MODE used to be different. Fixed the resulting breakage, converting them to variant that takes O_... value; all callers have that and it actually simplifies life (see tomoyo part of changes). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2009-12-15TOMOYO: Use RCU primitives for list operationTetsuo Handa1-3/+17
Replace list operation with RCU primitives and replace down_read()/up_read() with srcu_read_lock()/srcu_read_unlock(). Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Serge Hallyn <serue@us.ibm.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-12-09Merge branch 'master' into nextJames Morris1-80/+0
2009-12-08TOMOYO: Add rest of file operation restrictions.Tetsuo Handa1-0/+61
LSM hooks for chmod()/chown()/chroot() are now ready. This patch utilizes these hooks. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-11-20security/tomoyo: Remove now unnecessary handling of security_sysctl.Eric W. Biederman1-72/+0
Now that sys_sysctl is an emulation on top of proc sys all sysctl operations look like normal filesystem operations and we don't need to use the special sysctl hook to authenticate them. Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2009-11-12sysctl security/tomoyo: Don't look at ctl_nameTetsuo Handa1-9/+1
ctl_name field was removed. Always use procname field. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2009-09-02KEYS: Add a keyctl to install a process's session keyring on its parent [try #6]David Howells1-0/+17
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: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
2009-06-19TOMOYO: Remove next_domain from tomoyo_find_next_domain().Tetsuo Handa1-8/+2
We can update bprm->cred->security inside tomoyo_find_next_domain(). Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-06-09TOMOYO: Add description of lists and structures.Tetsuo Handa1-0/+4
This patch adds some descriptions of lists and structures. This patch contains no code changes. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-05-27tomoyo: add missing call to cap_bprm_set_credsHerton Ronaldo Krzesinski1-0/+6
cap_bprm_set_creds() has to be called from security_bprm_set_creds(). TOMOYO forgot to call cap_bprm_set_creds() from tomoyo_bprm_set_creds() and suid executables were not being working. Make sure we call cap_bprm_set_creds() with TOMOYO, to set credentials properly inside tomoyo_bprm_set_creds(). Signed-off-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br> Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-04-14tomoyo: version bump to 2.2.0.Tetsuo Handa1-1/+1
Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-23TOMOYO: Do not call tomoyo_realpath_init unless registered.Tetsuo Handa1-0/+1
tomoyo_realpath_init() is unconditionally called by security_initcall(). But nobody will use realpath related functions if TOMOYO is not registered. So, let tomoyo_init() call tomoyo_realpath_init(). This patch saves 4KB of memory allocation if TOMOYO is not registered. Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-12tomoyo: fix sparse warningTetsuo Handa1-4/+4
Fix sparse warning. $ make C=2 SUBDIRS=security/tomoyo CF="-D__cold__=" CHECK security/tomoyo/common.c CHECK security/tomoyo/realpath.c CHECK security/tomoyo/tomoyo.c security/tomoyo/tomoyo.c:110:8: warning: symbol 'buf' shadows an earlier one security/tomoyo/tomoyo.c:100:7: originally declared here Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
2009-02-12LSM adapter functions.Kentaro Takeda1-0/+293
DAC's permissions and TOMOYO's permissions are not one-to-one mapping. Regarding DAC, there are "read", "write", "execute" permissions. Regarding TOMOYO, there are "allow_read", "allow_write", "allow_read/write", "allow_execute", "allow_create", "allow_unlink", "allow_mkdir", "allow_rmdir", "allow_mkfifo", "allow_mksock", "allow_mkblock", "allow_mkchar", "allow_truncate", "allow_symlink", "allow_rewrite", "allow_link", "allow_rename" permissions. +----------------------------------+----------------------------------+ | requested operation | required TOMOYO's permission | +----------------------------------+----------------------------------+ | sys_open(O_RDONLY) | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_WRONLY) | allow_write | +----------------------------------+----------------------------------+ | sys_open(O_RDWR) | allow_read/write | +----------------------------------+----------------------------------+ | open_exec() from do_execve() | allow_execute | +----------------------------------+----------------------------------+ | open_exec() from !do_execve() | allow_read | +----------------------------------+----------------------------------+ | sys_read() | (none) | +----------------------------------+----------------------------------+ | sys_write() | (none) | +----------------------------------+----------------------------------+ | sys_mmap() | (none) | +----------------------------------+----------------------------------+ | sys_uselib() | allow_read | +----------------------------------+----------------------------------+ | sys_open(O_CREAT) | allow_create | +----------------------------------+----------------------------------+ | sys_open(O_TRUNC) | allow_truncate | +----------------------------------+----------------------------------+ | sys_truncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_ftruncate() | allow_truncate | +----------------------------------+----------------------------------+ | sys_open() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | setfl() without O_APPEND | allow_rewrite | +----------------------------------+----------------------------------+ | sys_sysctl() for writing | allow_write | +----------------------------------+----------------------------------+ | sys_sysctl() for reading | allow_read | +----------------------------------+----------------------------------+ | sys_unlink() | allow_unlink | +----------------------------------+----------------------------------+ | sys_mknod(S_IFREG) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(0) | allow_create | +----------------------------------+----------------------------------+ | sys_mknod(S_IFIFO) | allow_mkfifo | +----------------------------------+----------------------------------+ | sys_mknod(S_IFSOCK) | allow_mksock | +----------------------------------+----------------------------------+ | sys_bind(AF_UNIX) | allow_mksock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFBLK) | allow_mkblock | +----------------------------------+----------------------------------+ | sys_mknod(S_IFCHR) | allow_mkchar | +----------------------------------+----------------------------------+ | sys_symlink() | allow_symlink | +----------------------------------+----------------------------------+ | sys_mkdir() | allow_mkdir | +----------------------------------+----------------------------------+ | sys_rmdir() | allow_rmdir | +----------------------------------+----------------------------------+ | sys_link() | allow_link | +----------------------------------+----------------------------------+ | sys_rename() | allow_rename | +----------------------------------+----------------------------------+ TOMOYO requires "allow_execute" permission of a pathname passed to do_execve() but does not require "allow_read" permission of that pathname. Let's consider 3 patterns (statically linked, dynamically linked, shell script). This description is to some degree simplified. $ cat hello.c #include <stdio.h> int main() { printf("Hello\n"); return 0; } $ cat hello.sh #! /bin/sh echo "Hello" $ gcc -static -o hello-static hello.c $ gcc -o hello-dynamic hello.c $ chmod 755 hello.sh Case 1 -- Executing hello-static from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-static"). (2) The kernel checks "allow_execute hello-static" from "bash" domain. (3) The kernel calculates "bash hello-static" as the domain to transit to. (4) The kernel overwrites the child process by "hello-static". (5) The child process transits to "bash hello-static" domain. (6) The "hello-static" starts and finishes. Case 2 -- Executing hello-dynamic from bash. (1) The bash process calls fork() and the child process requests do_execve("hello-dynamic"). (2) The kernel checks "allow_execute hello-dynamic" from "bash" domain. (3) The kernel calculates "bash hello-dynamic" as the domain to transit to. (4) The kernel checks "allow_read ld-linux.so" from "bash hello-dynamic" domain. I think permission to access ld-linux.so should be charged hello-dynamic program, for "hello-dynamic needs ld-linux.so" is not a fault of bash program. (5) The kernel overwrites the child process by "hello-dynamic". (6) The child process transits to "bash hello-dynamic" domain. (7) The "hello-dynamic" starts and finishes. Case 3 -- Executing hello.sh from bash. (1) The bash process calls fork() and the child process requests do_execve("hello.sh"). (2) The kernel checks "allow_execute hello.sh" from "bash" domain. (3) The kernel calculates "bash hello.sh" as the domain to transit to. (4) The kernel checks "allow_read /bin/sh" from "bash hello.sh" domain. I think permission to access /bin/sh should be charged hello.sh program, for "hello.sh needs /bin/sh" is not a fault of bash program. (5) The kernel overwrites the child process by "/bin/sh". (6) The child process transits to "bash hello.sh" domain. (7) The "/bin/sh" requests open("hello.sh"). (8) The kernel checks "allow_read hello.sh" from "bash hello.sh" domain. (9) The "/bin/sh" starts and finishes. Whether a file is interpreted as a program or not depends on an application. The kernel cannot know whether the file is interpreted as a program or not. Thus, TOMOYO treats "hello-static" "hello-dynamic" "ld-linux.so" "hello.sh" "/bin/sh" equally as merely files; no distinction between executable and non-executable. Therefore, TOMOYO doesn't check DAC's execute permission. TOMOYO checks "allow_read" permission instead. Calling do_execve() is a bold gesture that an old program's instance (i.e. current process) is ready to be overwritten by a new program and is ready to transfer control to the new program. To split purview of programs, TOMOYO requires "allow_execute" permission of the new program against the old program's instance and performs domain transition. If do_execve() succeeds, the old program is no longer responsible against the consequence of the new program's behavior. Only the new program is responsible for all consequences. But TOMOYO doesn't require "allow_read" permission of the new program. If TOMOYO requires "allow_read" permission of the new program, TOMOYO will allow an attacker (who hijacked the old program's instance) to open the new program and steal data from the new program. Requiring "allow_read" permission will widen purview of the old program. Not requiring "allow_read" permission of the new program against the old program's instance is my design for reducing purview of the old program. To be able to know whether the current process is in do_execve() or not, I want to add in_execve flag to "task_struct". Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Signed-off-by: Toshiharu Harada <haradats@nttdata.co.jp> Signed-off-by: James Morris <jmorris@namei.org>
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