[<prev] [next>] [thread-next>] [day] [month] [year] [list]
Message-ID: <20100421012749.GA21338@us.ibm.com>
Date: Tue, 20 Apr 2010 20:27:49 -0500
From: "Serge E. Hallyn" <serue@...ibm.com>
To: lkml <linux-kernel@...r.kernel.org>
Cc: David Howells <dhowells@...hat.com>,
Ashwin Ganti <ashwin.ganti@...il.com>,
Greg KH <greg@...ah.com>, rsc@...ch.com, ericvh@...il.com,
linux-security-module@...r.kernel.org,
Ron Minnich <rminnich@...il.com>, jt.beard@...il.com,
Andrew Morton <akpm@...ux-foundation.org>,
Andrew Morgan <morgan@...nel.org>, oleg@...ibm.com,
Eric Paris <eparis@...hat.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 1/3] p9auth: split core function out of some set*{u,g}id
functions
Break the core functionality of set{fs,res}{u,g}id into cred_setX
which performs the access checks based on current_cred(), but performs
the requested change on a passed-in cred.
Export the helpers, since p9auth can be compiled as a module. It
might be worth not allowing modular p9auth to avoid having to export
them.
Really the setfs{u,g}id helper isn't needed, but move it as
well to keep the code consistent.
This patch also changes set_user() to use new->user->user_ns. While
technically not needed as all callers should have new->user->user_ns
equal to current_userns(), it is more correct and may prevent surprises
in the future.
Signed-off-by: Serge E. Hallyn <serue@...ibm.com>
---
include/linux/cred.h | 12 +++++
kernel/cred.c | 119 +++++++++++++++++++++++++++++++++++++++++++++
kernel/sys.c | 131 ++++++++------------------------------------------
3 files changed, 151 insertions(+), 111 deletions(-)
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 52507c3..0ce7a50 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -22,6 +22,9 @@ struct user_struct;
struct cred;
struct inode;
+/* defined in sys.c, used in cred_setresuid */
+extern int set_user(struct cred *new);
+
/*
* COW Supplementary groups list
*/
@@ -396,4 +399,13 @@ do { \
*(_fsgid) = __cred->fsgid; \
} while(0)
+#define CRED_SETID_NOFORCE 0
+#define CRED_SETID_FORCE 1
+int cred_setresuid(struct cred *new, uid_t ruid, uid_t euid, uid_t suid,
+ int force);
+int cred_setresgid(struct cred *new, gid_t rgid, gid_t egid, gid_t sgid,
+ int force);
+int cred_setfsuid(struct cred *new, uid_t uid, uid_t *old_fsuid);
+int cred_setfsgid(struct cred *new, gid_t gid, gid_t *old_fsgid);
+
#endif /* _LINUX_CRED_H */
diff --git a/kernel/cred.c b/kernel/cred.c
index e1dbe9e..4fc3284 100644
--- a/kernel/cred.c
+++ b/kernel/cred.c
@@ -785,6 +785,125 @@ int set_create_files_as(struct cred *new, struct inode *inode)
}
EXPORT_SYMBOL(set_create_files_as);
+int cred_setresuid(struct cred *new, uid_t ruid, uid_t euid, uid_t suid,
+ int force)
+{
+ int retval;
+ const struct cred *old;
+
+ retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES);
+ if (retval)
+ return retval;
+ old = current_cred();
+
+ if (!force && !capable(CAP_SETUID)) {
+ if (ruid != (uid_t) -1 && ruid != old->uid &&
+ ruid != old->euid && ruid != old->suid)
+ return -EPERM;
+ if (euid != (uid_t) -1 && euid != old->uid &&
+ euid != old->euid && euid != old->suid)
+ return -EPERM;
+ if (suid != (uid_t) -1 && suid != old->uid &&
+ suid != old->euid && suid != old->suid)
+ return -EPERM;
+ }
+
+ if (ruid != (uid_t) -1) {
+ new->uid = ruid;
+ if (ruid != old->uid) {
+ retval = set_user(new);
+ if (retval < 0)
+ return retval;
+ }
+ }
+ if (euid != (uid_t) -1)
+ new->euid = euid;
+ if (suid != (uid_t) -1)
+ new->suid = suid;
+ new->fsuid = new->euid;
+
+ return security_task_fix_setuid(new, old, LSM_SETID_RES);
+}
+EXPORT_SYMBOL_GPL(cred_setresuid);
+
+int cred_setresgid(struct cred *new, gid_t rgid, gid_t egid, gid_t sgid,
+ int force)
+{
+ const struct cred *old = current_cred();
+ int retval;
+
+ retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES);
+ if (retval)
+ return retval;
+
+ if (!force && !capable(CAP_SETGID)) {
+ if (rgid != (gid_t) -1 && rgid != old->gid &&
+ rgid != old->egid && rgid != old->sgid)
+ return -EPERM;
+ if (egid != (gid_t) -1 && egid != old->gid &&
+ egid != old->egid && egid != old->sgid)
+ return -EPERM;
+ if (sgid != (gid_t) -1 && sgid != old->gid &&
+ sgid != old->egid && sgid != old->sgid)
+ return -EPERM;
+ }
+
+ if (rgid != (gid_t) -1)
+ new->gid = rgid;
+ if (egid != (gid_t) -1)
+ new->egid = egid;
+ if (sgid != (gid_t) -1)
+ new->sgid = sgid;
+ new->fsgid = new->egid;
+ return 0;
+}
+EXPORT_SYMBOL_GPL(cred_setresgid);
+
+int cred_setfsuid(struct cred *new, uid_t uid, uid_t *old_fsuid)
+{
+ const struct cred *old;
+
+ old = current_cred();
+ *old_fsuid = old->fsuid;
+
+ if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS) < 0)
+ return -EPERM;
+
+ if (uid == old->uid || uid == old->euid ||
+ uid == old->suid || uid == old->fsuid ||
+ capable(CAP_SETUID)) {
+ if (uid != *old_fsuid) {
+ new->fsuid = uid;
+ if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
+ return 0;
+ }
+ }
+ return -EPERM;
+}
+EXPORT_SYMBOL_GPL(cred_setfsuid);
+
+int cred_setfsgid(struct cred *new, gid_t gid, gid_t *old_fsgid)
+{
+ const struct cred *old;
+
+ old = current_cred();
+ *old_fsgid = old->fsgid;
+
+ if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
+ return -EPERM;
+
+ if (gid == old->gid || gid == old->egid ||
+ gid == old->sgid || gid == old->fsgid ||
+ capable(CAP_SETGID)) {
+ if (gid != *old_fsgid) {
+ new->fsgid = gid;
+ return 0;
+ }
+ }
+ return -EPERM;
+}
+EXPORT_SYMBOL_GPL(cred_setfsgid);
+
#ifdef CONFIG_DEBUG_CREDENTIALS
bool creds_are_invalid(const struct cred *cred)
diff --git a/kernel/sys.c b/kernel/sys.c
index 6d1a7e0..78f32eb 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -565,11 +565,11 @@ error:
/*
* change the user struct in a credentials set to match the new UID
*/
-static int set_user(struct cred *new)
+int set_user(struct cred *new)
{
struct user_struct *new_user;
- new_user = alloc_uid(current_user_ns(), new->uid);
+ new_user = alloc_uid(new->user->user_ns, new->uid);
if (!new_user)
return -EAGAIN;
@@ -711,7 +711,6 @@ error:
*/
SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
{
- const struct cred *old;
struct cred *new;
int retval;
@@ -719,45 +718,10 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
if (!new)
return -ENOMEM;
- retval = security_task_setuid(ruid, euid, suid, LSM_SETID_RES);
- if (retval)
- goto error;
- old = current_cred();
+ retval = cred_setresuid(new, ruid, euid, suid, CRED_SETID_NOFORCE);
+ if (retval == 0)
+ return commit_creds(new);
- retval = -EPERM;
- if (!capable(CAP_SETUID)) {
- if (ruid != (uid_t) -1 && ruid != old->uid &&
- ruid != old->euid && ruid != old->suid)
- goto error;
- if (euid != (uid_t) -1 && euid != old->uid &&
- euid != old->euid && euid != old->suid)
- goto error;
- if (suid != (uid_t) -1 && suid != old->uid &&
- suid != old->euid && suid != old->suid)
- goto error;
- }
-
- if (ruid != (uid_t) -1) {
- new->uid = ruid;
- if (ruid != old->uid) {
- retval = set_user(new);
- if (retval < 0)
- goto error;
- }
- }
- if (euid != (uid_t) -1)
- new->euid = euid;
- if (suid != (uid_t) -1)
- new->suid = suid;
- new->fsuid = new->euid;
-
- retval = security_task_fix_setuid(new, old, LSM_SETID_RES);
- if (retval < 0)
- goto error;
-
- return commit_creds(new);
-
-error:
abort_creds(new);
return retval;
}
@@ -779,43 +743,17 @@ SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __u
*/
SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid)
{
- const struct cred *old;
struct cred *new;
int retval;
new = prepare_creds();
if (!new)
return -ENOMEM;
- old = current_cred();
- retval = security_task_setgid(rgid, egid, sgid, LSM_SETID_RES);
- if (retval)
- goto error;
+ retval = cred_setresgid(new, rgid, egid, sgid, CRED_SETID_NOFORCE);
+ if (retval == 0)
+ return commit_creds(new);
- retval = -EPERM;
- if (!capable(CAP_SETGID)) {
- if (rgid != (gid_t) -1 && rgid != old->gid &&
- rgid != old->egid && rgid != old->sgid)
- goto error;
- if (egid != (gid_t) -1 && egid != old->gid &&
- egid != old->egid && egid != old->sgid)
- goto error;
- if (sgid != (gid_t) -1 && sgid != old->gid &&
- sgid != old->egid && sgid != old->sgid)
- goto error;
- }
-
- if (rgid != (gid_t) -1)
- new->gid = rgid;
- if (egid != (gid_t) -1)
- new->egid = egid;
- if (sgid != (gid_t) -1)
- new->sgid = sgid;
- new->fsgid = new->egid;
-
- return commit_creds(new);
-
-error:
abort_creds(new);
return retval;
}
@@ -841,35 +779,20 @@ SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __u
*/
SYSCALL_DEFINE1(setfsuid, uid_t, uid)
{
- const struct cred *old;
struct cred *new;
uid_t old_fsuid;
+ int retval;
new = prepare_creds();
if (!new)
return current_fsuid();
- old = current_cred();
- old_fsuid = old->fsuid;
-
- if (security_task_setuid(uid, (uid_t)-1, (uid_t)-1, LSM_SETID_FS) < 0)
- goto error;
-
- if (uid == old->uid || uid == old->euid ||
- uid == old->suid || uid == old->fsuid ||
- capable(CAP_SETUID)) {
- if (uid != old_fsuid) {
- new->fsuid = uid;
- if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0)
- goto change_okay;
- }
- }
-error:
- abort_creds(new);
- return old_fsuid;
+ retval = cred_setfsuid(new, uid, &old_fsuid);
+ if (retval == 0)
+ commit_creds(new);
+ else
+ abort_creds(new);
-change_okay:
- commit_creds(new);
return old_fsuid;
}
@@ -878,34 +801,20 @@ change_okay:
*/
SYSCALL_DEFINE1(setfsgid, gid_t, gid)
{
- const struct cred *old;
struct cred *new;
gid_t old_fsgid;
+ int retval;
new = prepare_creds();
if (!new)
return current_fsgid();
- old = current_cred();
- old_fsgid = old->fsgid;
-
- if (security_task_setgid(gid, (gid_t)-1, (gid_t)-1, LSM_SETID_FS))
- goto error;
-
- if (gid == old->gid || gid == old->egid ||
- gid == old->sgid || gid == old->fsgid ||
- capable(CAP_SETGID)) {
- if (gid != old_fsgid) {
- new->fsgid = gid;
- goto change_okay;
- }
- }
-error:
- abort_creds(new);
- return old_fsgid;
+ retval = cred_setfsgid(new, gid, &old_fsgid);
+ if (retval == 0)
+ commit_creds(new);
+ else
+ abort_creds(new);
-change_okay:
- commit_creds(new);
return old_fsgid;
}
--
1.7.0.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists