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authorThomas Cedeno <thomascedeno@google.com>2020-07-16 19:13:57 +0000
committerMicah Morton <mortonm@chromium.org>2020-10-13 09:17:34 -0700
commit111767c1d86bd9661f8b72ace50cbcb13507a1bf (patch)
treeeb61e1cd69c7b43ce363d8cde1c67ae0751eeb37 /kernel
parentbbf5c979011a099af5dc76498918ed7df445635b (diff)
LSM: Signal to SafeSetID when setting group IDs
For SafeSetID to properly gate set*gid() calls, it needs to know whether ns_capable() is being called from within a sys_set*gid() function or is being called from elsewhere in the kernel. This allows SafeSetID to deny CAP_SETGID to restricted groups when they are attempting to use the capability for code paths other than updating GIDs (e.g. setting up userns GID mappings). This is the identical approach to what is currently done for CAP_SETUID. NOTE: We also add signaling to SafeSetID from the setgroups() syscall, as we have future plans to restrict a process' ability to set supplementary groups in addition to what is added in this series for restricting setting of the primary group. Signed-off-by: Thomas Cedeno <thomascedeno@google.com> Signed-off-by: Micah Morton <mortonm@chromium.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/capability.c2
-rw-r--r--kernel/groups.c2
-rw-r--r--kernel/sys.c10
3 files changed, 7 insertions, 7 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index 7c59b096c98a..de7eac903a2a 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -418,7 +418,7 @@ EXPORT_SYMBOL(ns_capable_noaudit);
/**
* ns_capable_setid - Determine if the current task has a superior capability
* in effect, while signalling that this check is being done from within a
- * setid syscall.
+ * setid or setgroups syscall.
* @ns: The usernamespace we want the capability in
* @cap: The capability to be tested for
*
diff --git a/kernel/groups.c b/kernel/groups.c
index 6ee6691f6839..fe7e6385530e 100644
--- a/kernel/groups.c
+++ b/kernel/groups.c
@@ -178,7 +178,7 @@ bool may_setgroups(void)
{
struct user_namespace *user_ns = current_user_ns();
- return ns_capable(user_ns, CAP_SETGID) &&
+ return ns_capable_setid(user_ns, CAP_SETGID) &&
userns_may_setgroups(user_ns);
}
diff --git a/kernel/sys.c b/kernel/sys.c
index ab6c409b1159..ad80f9767f27 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -373,7 +373,7 @@ long __sys_setregid(gid_t rgid, gid_t egid)
if (rgid != (gid_t) -1) {
if (gid_eq(old->gid, krgid) ||
gid_eq(old->egid, krgid) ||
- ns_capable(old->user_ns, CAP_SETGID))
+ ns_capable_setid(old->user_ns, CAP_SETGID))
new->gid = krgid;
else
goto error;
@@ -382,7 +382,7 @@ long __sys_setregid(gid_t rgid, gid_t egid)
if (gid_eq(old->gid, kegid) ||
gid_eq(old->egid, kegid) ||
gid_eq(old->sgid, kegid) ||
- ns_capable(old->user_ns, CAP_SETGID))
+ ns_capable_setid(old->user_ns, CAP_SETGID))
new->egid = kegid;
else
goto error;
@@ -432,7 +432,7 @@ long __sys_setgid(gid_t gid)
old = current_cred();
retval = -EPERM;
- if (ns_capable(old->user_ns, CAP_SETGID))
+ if (ns_capable_setid(old->user_ns, CAP_SETGID))
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;
@@ -744,7 +744,7 @@ long __sys_setresgid(gid_t rgid, gid_t egid, gid_t sgid)
old = current_cred();
retval = -EPERM;
- if (!ns_capable(old->user_ns, CAP_SETGID)) {
+ if (!ns_capable_setid(old->user_ns, CAP_SETGID)) {
if (rgid != (gid_t) -1 && !gid_eq(krgid, old->gid) &&
!gid_eq(krgid, old->egid) && !gid_eq(krgid, old->sgid))
goto error;
@@ -871,7 +871,7 @@ long __sys_setfsgid(gid_t gid)
if (gid_eq(kgid, old->gid) || gid_eq(kgid, old->egid) ||
gid_eq(kgid, old->sgid) || gid_eq(kgid, old->fsgid) ||
- ns_capable(old->user_ns, CAP_SETGID)) {
+ ns_capable_setid(old->user_ns, CAP_SETGID)) {
if (!gid_eq(kgid, old->fsgid)) {
new->fsgid = kgid;
if (security_task_fix_setgid(new,old,LSM_SETID_FS) == 0)

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