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author | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-23 17:42:39 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-05-23 17:42:39 -0700 |
commit | 644473e9c60c1ff4f6351fed637a6e5551e3dce7 (patch) | |
tree | 10316518bedc735a2c6552886658d69dfd9f1eb0 /kernel/sys.c | |
parent | fb827ec68446c83e9e8754fa9b55aed27ecc4661 (diff) | |
parent | 4b06a81f1daee668fbd6de85557bfb36dd36078f (diff) | |
download | linux-644473e9c60c1ff4f6351fed637a6e5551e3dce7.tar.gz linux-644473e9c60c1ff4f6351fed637a6e5551e3dce7.tar.bz2 linux-644473e9c60c1ff4f6351fed637a6e5551e3dce7.zip |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace enhancements from Eric Biederman:
"This is a course correction for the user namespace, so that we can
reach an inexpensive, maintainable, and reasonably complete
implementation.
Highlights:
- Config guards make it impossible to enable the user namespace and
code that has not been converted to be user namespace safe.
- Use of the new kuid_t type ensures the if you somehow get past the
config guards the kernel will encounter type errors if you enable
user namespaces and attempt to compile in code whose permission
checks have not been updated to be user namespace safe.
- All uids from child user namespaces are mapped into the initial
user namespace before they are processed. Removing the need to add
an additional check to see if the user namespace of the compared
uids remains the same.
- With the user namespaces compiled out the performance is as good or
better than it is today.
- For most operations absolutely nothing changes performance or
operationally with the user namespace enabled.
- The worst case performance I could come up with was timing 1
billion cache cold stat operations with the user namespace code
enabled. This went from 156s to 164s on my laptop (or 156ns to
164ns per stat operation).
- (uid_t)-1 and (gid_t)-1 are reserved as an internal error value.
Most uid/gid setting system calls treat these value specially
anyway so attempting to use -1 as a uid would likely cause
entertaining failures in userspace.
- If setuid is called with a uid that can not be mapped setuid fails.
I have looked at sendmail, login, ssh and every other program I
could think of that would call setuid and they all check for and
handle the case where setuid fails.
- If stat or a similar system call is called from a context in which
we can not map a uid we lie and return overflowuid. The LFS
experience suggests not lying and returning an error code might be
better, but the historical precedent with uids is different and I
can not think of anything that would break by lying about a uid we
can't map.
- Capabilities are localized to the current user namespace making it
safe to give the initial user in a user namespace all capabilities.
My git tree covers all of the modifications needed to convert the core
kernel and enough changes to make a system bootable to runlevel 1."
Fix up trivial conflicts due to nearby independent changes in fs/stat.c
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits)
userns: Silence silly gcc warning.
cred: use correct cred accessor with regards to rcu read lock
userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq
userns: Convert cgroup permission checks to use uid_eq
userns: Convert tmpfs to use kuid and kgid where appropriate
userns: Convert sysfs to use kgid/kuid where appropriate
userns: Convert sysctl permission checks to use kuid and kgids.
userns: Convert proc to use kuid/kgid where appropriate
userns: Convert ext4 to user kuid/kgid where appropriate
userns: Convert ext3 to use kuid/kgid where appropriate
userns: Convert ext2 to use kuid/kgid where appropriate.
userns: Convert devpts to use kuid/kgid where appropriate
userns: Convert binary formats to use kuid/kgid where appropriate
userns: Add negative depends on entries to avoid building code that is userns unsafe
userns: signal remove unnecessary map_cred_ns
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
userns: Fail exec for suid and sgid binaries with ids outside our user namespace.
userns: Convert stat to return values mapped from kuids and kgids
userns: Convert user specfied uids and gids in chown into kuids and kgid
userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
...
Diffstat (limited to 'kernel/sys.c')
-rw-r--r-- | kernel/sys.c | 266 |
1 files changed, 174 insertions, 92 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index ba0ae8eea6fb..6df42624e454 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -93,10 +93,8 @@ int overflowuid = DEFAULT_OVERFLOWUID; int overflowgid = DEFAULT_OVERFLOWGID; -#ifdef CONFIG_UID16 EXPORT_SYMBOL(overflowuid); EXPORT_SYMBOL(overflowgid); -#endif /* * the same as above, but for filesystems which can only store a 16-bit @@ -133,11 +131,10 @@ static bool set_one_prio_perm(struct task_struct *p) { const struct cred *cred = current_cred(), *pcred = __task_cred(p); - if (pcred->user->user_ns == cred->user->user_ns && - (pcred->uid == cred->euid || - pcred->euid == cred->euid)) + if (uid_eq(pcred->uid, cred->euid) || + uid_eq(pcred->euid, cred->euid)) return true; - if (ns_capable(pcred->user->user_ns, CAP_SYS_NICE)) + if (ns_capable(pcred->user_ns, CAP_SYS_NICE)) return true; return false; } @@ -177,6 +174,7 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) const struct cred *cred = current_cred(); int error = -EINVAL; struct pid *pgrp; + kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) goto out; @@ -209,18 +207,19 @@ SYSCALL_DEFINE3(setpriority, int, which, int, who, int, niceval) } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); break; case PRIO_USER: - user = (struct user_struct *) cred->user; + uid = make_kuid(cred->user_ns, who); + user = cred->user; if (!who) - who = cred->uid; - else if ((who != cred->uid) && - !(user = find_user(who))) + uid = cred->uid; + else if (!uid_eq(uid, cred->uid) && + !(user = find_user(uid))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) { - if (__task_cred(p)->uid == who) + if (uid_eq(task_uid(p), uid)) error = set_one_prio(p, niceval, error); } while_each_thread(g, p); - if (who != cred->uid) + if (!uid_eq(uid, cred->uid)) free_uid(user); /* For find_user() */ break; } @@ -244,6 +243,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who) const struct cred *cred = current_cred(); long niceval, retval = -ESRCH; struct pid *pgrp; + kuid_t uid; if (which > PRIO_USER || which < PRIO_PROCESS) return -EINVAL; @@ -274,21 +274,22 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who) } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); break; case PRIO_USER: - user = (struct user_struct *) cred->user; + uid = make_kuid(cred->user_ns, who); + user = cred->user; if (!who) - who = cred->uid; - else if ((who != cred->uid) && - !(user = find_user(who))) + uid = cred->uid; + else if (!uid_eq(uid, cred->uid) && + !(user = find_user(uid))) goto out_unlock; /* No processes for this user */ do_each_thread(g, p) { - if (__task_cred(p)->uid == who) { + if (uid_eq(task_uid(p), uid)) { niceval = 20 - task_nice(p); if (niceval > retval) retval = niceval; } } while_each_thread(g, p); - if (who != cred->uid) + if (!uid_eq(uid, cred->uid)) free_uid(user); /* for find_user() */ break; } @@ -553,9 +554,19 @@ void ctrl_alt_del(void) */ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kgid_t krgid, kegid; + + krgid = make_kgid(ns, rgid); + kegid = make_kgid(ns, egid); + + if ((rgid != (gid_t) -1) && !gid_valid(krgid)) + return -EINVAL; + if ((egid != (gid_t) -1) && !gid_valid(kegid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -564,25 +575,25 @@ SYSCALL_DEFINE2(setregid, gid_t, rgid, gid_t, egid) retval = -EPERM; if (rgid != (gid_t) -1) { - if (old->gid == rgid || - old->egid == rgid || + if (gid_eq(old->gid, krgid) || + gid_eq(old->egid, krgid) || nsown_capable(CAP_SETGID)) - new->gid = rgid; + new->gid = krgid; else goto error; } if (egid != (gid_t) -1) { - if (old->gid == egid || - old->egid == egid || - old->sgid == egid || + if (gid_eq(old->gid, kegid) || + gid_eq(old->egid, kegid) || + gid_eq(old->sgid, kegid) || nsown_capable(CAP_SETGID)) - new->egid = egid; + new->egid = kegid; else goto error; } if (rgid != (gid_t) -1 || - (egid != (gid_t) -1 && egid != old->gid)) + (egid != (gid_t) -1 && !gid_eq(kegid, old->gid))) new->sgid = new->egid; new->fsgid = new->egid; @@ -600,9 +611,15 @@ error: */ SYSCALL_DEFINE1(setgid, gid_t, gid) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kgid_t kgid; + + kgid = make_kgid(ns, gid); + if (!gid_valid(kgid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -611,9 +628,9 @@ SYSCALL_DEFINE1(setgid, gid_t, gid) retval = -EPERM; if (nsown_capable(CAP_SETGID)) - new->gid = new->egid = new->sgid = new->fsgid = gid; - else if (gid == old->gid || gid == old->sgid) - new->egid = new->fsgid = gid; + new->gid = new->egid = new->sgid = new->fsgid = kgid; + else if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->sgid)) + new->egid = new->fsgid = kgid; else goto error; @@ -631,7 +648,7 @@ static 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->uid); if (!new_user) return -EAGAIN; @@ -670,9 +687,19 @@ static int set_user(struct cred *new) */ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kuid_t kruid, keuid; + + kruid = make_kuid(ns, ruid); + keuid = make_kuid(ns, euid); + + if ((ruid != (uid_t) -1) && !uid_valid(kruid)) + return -EINVAL; + if ((euid != (uid_t) -1) && !uid_valid(keuid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -681,29 +708,29 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid) retval = -EPERM; if (ruid != (uid_t) -1) { - new->uid = ruid; - if (old->uid != ruid && - old->euid != ruid && + new->uid = kruid; + if (!uid_eq(old->uid, kruid) && + !uid_eq(old->euid, kruid) && !nsown_capable(CAP_SETUID)) goto error; } if (euid != (uid_t) -1) { - new->euid = euid; - if (old->uid != euid && - old->euid != euid && - old->suid != euid && + new->euid = keuid; + if (!uid_eq(old->uid, keuid) && + !uid_eq(old->euid, keuid) && + !uid_eq(old->suid, keuid) && !nsown_capable(CAP_SETUID)) goto error; } - if (new->uid != old->uid) { + if (!uid_eq(new->uid, old->uid)) { retval = set_user(new); if (retval < 0) goto error; } if (ruid != (uid_t) -1 || - (euid != (uid_t) -1 && euid != old->uid)) + (euid != (uid_t) -1 && !uid_eq(keuid, old->uid))) new->suid = new->euid; new->fsuid = new->euid; @@ -731,9 +758,15 @@ error: */ SYSCALL_DEFINE1(setuid, uid_t, uid) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kuid_t kuid; + + kuid = make_kuid(ns, uid); + if (!uid_valid(kuid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -742,17 +775,17 @@ SYSCALL_DEFINE1(setuid, uid_t, uid) retval = -EPERM; if (nsown_capable(CAP_SETUID)) { - new->suid = new->uid = uid; - if (uid != old->uid) { + new->suid = new->uid = kuid; + if (!uid_eq(kuid, old->uid)) { retval = set_user(new); if (retval < 0) goto error; } - } else if (uid != old->uid && uid != new->suid) { + } else if (!uid_eq(kuid, old->uid) && !uid_eq(kuid, new->suid)) { goto error; } - new->fsuid = new->euid = uid; + new->fsuid = new->euid = kuid; retval = security_task_fix_setuid(new, old, LSM_SETID_ID); if (retval < 0) @@ -772,9 +805,24 @@ error: */ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kuid_t kruid, keuid, ksuid; + + kruid = make_kuid(ns, ruid); + keuid = make_kuid(ns, euid); + ksuid = make_kuid(ns, suid); + + if ((ruid != (uid_t) -1) && !uid_valid(kruid)) + return -EINVAL; + + if ((euid != (uid_t) -1) && !uid_valid(keuid)) + return -EINVAL; + + if ((suid != (uid_t) -1) && !uid_valid(ksuid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -784,29 +832,29 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid) retval = -EPERM; if (!nsown_capable(CAP_SETUID)) { - if (ruid != (uid_t) -1 && ruid != old->uid && - ruid != old->euid && ruid != old->suid) + if (ruid != (uid_t) -1 && !uid_eq(kruid, old->uid) && + !uid_eq(kruid, old->euid) && !uid_eq(kruid, old->suid)) goto error; - if (euid != (uid_t) -1 && euid != old->uid && - euid != old->euid && euid != old->suid) + if (euid != (uid_t) -1 && !uid_eq(keuid, old->uid) && + !uid_eq(keuid, old->euid) && !uid_eq(keuid, old->suid)) goto error; - if (suid != (uid_t) -1 && suid != old->uid && - suid != old->euid && suid != old->suid) + if (suid != (uid_t) -1 && !uid_eq(ksuid, old->uid) && + !uid_eq(ksuid, old->euid) && !uid_eq(ksuid, old->suid)) goto error; } if (ruid != (uid_t) -1) { - new->uid = ruid; - if (ruid != old->uid) { + new->uid = kruid; + if (!uid_eq(kruid, old->uid)) { retval = set_user(new); if (retval < 0) goto error; } } if (euid != (uid_t) -1) - new->euid = euid; + new->euid = keuid; if (suid != (uid_t) -1) - new->suid = suid; + new->suid = ksuid; new->fsuid = new->euid; retval = security_task_fix_setuid(new, old, LSM_SETID_RES); @@ -820,14 +868,19 @@ error: return retval; } -SYSCALL_DEFINE3(getresuid, uid_t __user *, ruid, uid_t __user *, euid, uid_t __user *, suid) +SYSCALL_DEFINE3(getresuid, uid_t __user *, ruidp, uid_t __user *, euidp, uid_t __user *, suidp) { const struct cred *cred = current_cred(); int retval; + uid_t ruid, euid, suid; + + ruid = from_kuid_munged(cred->user_ns, cred->uid); + euid = from_kuid_munged(cred->user_ns, cred->euid); + suid = from_kuid_munged(cred->user_ns, cred->suid); - if (!(retval = put_user(cred->uid, ruid)) && - !(retval = put_user(cred->euid, euid))) - retval = put_user(cred->suid, suid); + if (!(retval = put_user(ruid, ruidp)) && + !(retval = put_user(euid, euidp))) + retval = put_user(suid, suidp); return retval; } @@ -837,9 +890,22 @@ 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) { + struct user_namespace *ns = current_user_ns(); const struct cred *old; struct cred *new; int retval; + kgid_t krgid, kegid, ksgid; + + krgid = make_kgid(ns, rgid); + kegid = make_kgid(ns, egid); + ksgid = make_kgid(ns, sgid); + + if ((rgid != (gid_t) -1) && !gid_valid(krgid)) + return -EINVAL; + if ((egid != (gid_t) -1) && !gid_valid(kegid)) + return -EINVAL; + if ((sgid != (gid_t) -1) && !gid_valid(ksgid)) + return -EINVAL; new = prepare_creds(); if (!new) @@ -848,23 +914,23 @@ SYSCALL_DEFINE3(setresgid, gid_t, rgid, gid_t, egid, gid_t, sgid) retval = -EPERM; if (!nsown_capable(CAP_SETGID)) { - if (rgid != (gid_t) -1 && rgid != old->gid && - rgid != old->egid && rgid != old->sgid) + if (rgid != (gid_t) -1 && !gid_eq(krgid, old->gid) && + !gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid)) goto error; - if (egid != (gid_t) -1 && egid != old->gid && - egid != old->egid && egid != old->sgid) + if (egid != (gid_t) -1 && !gid_eq(kegid, old->gid) && + !gid_eq(kegid, old->egid) && !gid_eq(kegid, old->sgid)) goto error; - if (sgid != (gid_t) -1 && sgid != old->gid && - sgid != old->egid && sgid != old->sgid) + if (sgid != (gid_t) -1 && !gid_eq(ksgid, old->gid) && + !gid_eq(ksgid, old->egid) && !gid_eq(ksgid, old->sgid)) goto error; } if (rgid != (gid_t) -1) - new->gid = rgid; + new->gid = krgid; if (egid != (gid_t) -1) - new->egid = egid; + new->egid = kegid; if (sgid != (gid_t) -1) - new->sgid = sgid; + new->sgid = ksgid; new->fsgid = new->egid; return commit_creds(new); @@ -874,14 +940,19 @@ error: return retval; } -SYSCALL_DEFINE3(getresgid, gid_t __user *, rgid, gid_t __user *, egid, gid_t __user *, sgid) +SYSCALL_DEFINE3(getresgid, gid_t __user *, rgidp, gid_t __user *, egidp, gid_t __user *, sgidp) { const struct cred *cred = current_cred(); int retval; + gid_t rgid, egid, sgid; + + rgid = from_kgid_munged(cred->user_ns, cred->gid); + egid = from_kgid_munged(cred->user_ns, cred->egid); + sgid = from_kgid_munged(cred->user_ns, cred->sgid); - if (!(retval = put_user(cred->gid, rgid)) && - !(retval = put_user(cred->egid, egid))) - retval = put_user(cred->sgid, sgid); + if (!(retval = put_user(rgid, rgidp)) && + !(retval = put_user(egid, egidp))) + retval = put_user(sgid, sgidp); return retval; } @@ -898,18 +969,24 @@ SYSCALL_DEFINE1(setfsuid, uid_t, uid) const struct cred *old; struct cred *new; uid_t old_fsuid; + kuid_t kuid; + + old = current_cred(); + old_fsuid = from_kuid_munged(old->user_ns, old->fsuid); + + kuid = make_kuid(old->user_ns, uid); + if (!uid_valid(kuid)) + return old_fsuid; new = prepare_creds(); if (!new) - return current_fsuid(); - old = current_cred(); - old_fsuid = old->fsuid; + return old_fsuid; - if (uid == old->uid || uid == old->euid || - uid == old->suid || uid == old->fsuid || + if (uid_eq(kuid, old->uid) || uid_eq(kuid, old->euid) || + uid_eq(kuid, old->suid) || uid_eq(kuid, old->fsuid) || nsown_capable(CAP_SETUID)) { - if (uid != old_fsuid) { - new->fsuid = uid; + if (!uid_eq(kuid, old->fsuid)) { + new->fsuid = kuid; if (security_task_fix_setuid(new, old, LSM_SETID_FS) == 0) goto change_okay; } @@ -931,18 +1008,24 @@ SYSCALL_DEFINE1(setfsgid, gid_t, gid) const struct cred *old; struct cred *new; gid_t old_fsgid; + kgid_t kgid; + + old = current_cred(); + old_fsgid = from_kgid_munged(old->user_ns, old->fsgid); + + kgid = make_kgid(old->user_ns, gid); + if (!gid_valid(kgid)) + return old_fsgid; new = prepare_creds(); if (!new) - return current_fsgid(); - old = current_cred(); - old_fsgid = old->fsgid; + return old_fsgid; - if (gid == old->gid || gid == old->egid || - gid == old->sgid || gid == old->fsgid || + if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->egid) || + gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) || nsown_capable(CAP_SETGID)) { - if (gid != old_fsgid) { - new->fsgid = gid; + if (!gid_eq(kgid, old->fsgid)) { + new->fsgid = kgid; goto change_okay; } } @@ -1498,15 +1581,14 @@ static int check_prlimit_permission(struct task_struct *task) return 0; tcred = __task_cred(task); - if (cred->user->user_ns == tcred->user->user_ns && - (cred->uid == tcred->euid && - cred->uid == tcred->suid && - cred->uid == tcred->uid && - cred->gid == tcred->egid && - cred->gid == tcred->sgid && - cred->gid == tcred->gid)) + if (uid_eq(cred->uid, tcred->euid) && + uid_eq(cred->uid, tcred->suid) && + uid_eq(cred->uid, tcred->uid) && + gid_eq(cred->gid, tcred->egid) && + gid_eq(cred->gid, tcred->sgid) && + gid_eq(cred->gid, tcred->gid)) return 0; - if (ns_capable(tcred->user->user_ns, CAP_SYS_RESOURCE)) + if (ns_capable(tcred->user_ns, CAP_SYS_RESOURCE)) return 0; return -EPERM; |