sysctl: allow to change limits for posix messages queues
[ Upstream commit f9436a5d0497f759330d07e1189565edd4456be8 ] All parameters of posix messages queues (queues_max/msg_max/msgsize_max) end up being limited by RLIMIT_MSGQUEUE. The code in mqueue_get_inode is where that limiting happens. The RLIMIT_MSGQUEUE is bound to the user namespace and is counted hierarchically. We can allow root in the user namespace to modify the posix messages queues parameters. Link: https://lkml.kernel.org/r/6ad67f23d1459a4f4339f74aa73bac0ecf3995e1.1705333426.git.legion@kernel.org Signed-off-by: Alexey Gladkov <legion@kernel.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Link: https://lkml.kernel.org/r/7eb21211c8622e91d226e63416b1b93c079f60ee.1663756794.git.legion@kernel.org Cc: Christian Brauner <brauner@kernel.org> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Joel Granados <joel.granados@gmail.com> Cc: Kees Cook <keescook@chromium.org> Cc: Luis Chamberlain <mcgrof@kernel.org> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Stable-dep-of: 98ca62ba9e2b ("sysctl: always initialize i_uid/i_gid") Signed-off-by: Sasha Levin <sashal@kernel.org>
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@ -12,6 +12,7 @@
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#include <linux/stat.h>
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#include <linux/capability.h>
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#include <linux/slab.h>
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#include <linux/cred.h>
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static int msg_max_limit_min = MIN_MSGMAX;
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static int msg_max_limit_max = HARD_MSGMAX;
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@ -76,8 +77,43 @@ static int set_is_seen(struct ctl_table_set *set)
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return ¤t->nsproxy->ipc_ns->mq_set == set;
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}
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static void mq_set_ownership(struct ctl_table_header *head,
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struct ctl_table *table,
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kuid_t *uid, kgid_t *gid)
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{
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struct ipc_namespace *ns =
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container_of(head->set, struct ipc_namespace, mq_set);
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kuid_t ns_root_uid = make_kuid(ns->user_ns, 0);
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kgid_t ns_root_gid = make_kgid(ns->user_ns, 0);
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*uid = uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID;
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*gid = gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID;
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}
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static int mq_permissions(struct ctl_table_header *head, struct ctl_table *table)
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{
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int mode = table->mode;
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kuid_t ns_root_uid;
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kgid_t ns_root_gid;
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mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid);
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if (uid_eq(current_euid(), ns_root_uid))
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mode >>= 6;
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else if (in_egroup_p(ns_root_gid))
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mode >>= 3;
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mode &= 7;
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return (mode << 6) | (mode << 3) | mode;
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}
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static struct ctl_table_root set_root = {
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.lookup = set_lookup,
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.permissions = mq_permissions,
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.set_ownership = mq_set_ownership,
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};
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bool setup_mq_sysctls(struct ipc_namespace *ns)
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