5.4-stable patches

added patches:
	bpf-add-kconfig-knob-for-disabling-unpriv-bpf-by-default.patch

diff --git a/queue-5.4/bpf-add-kconfig-knob-for-disabling-unpriv-bpf-by-default.patch b/queue-5.4/bpf-add-kconfig-knob-for-disabling-unpriv-bpf-by-default.patch
new file mode 100644 (file)
index 0000000..c6f6f7e
--- /dev/null
+++ b/queue-5.4/bpf-add-kconfig-knob-for-disabling-unpriv-bpf-by-default.patch
@@ -0,0 +1,141 @@
+From 08389d888287c3823f80b0216766b71e17f0aba5 Mon Sep 17 00:00:00 2001
+From: Daniel Borkmann <daniel@iogearbox.net>
+Date: Tue, 11 May 2021 22:35:17 +0200
+Subject: bpf: Add kconfig knob for disabling unpriv bpf by default
+
+From: Daniel Borkmann <daniel@iogearbox.net>
+
+commit 08389d888287c3823f80b0216766b71e17f0aba5 upstream.
+
+Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
+If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.
+
+This still allows a transition of 2 -> {0,1} through an admin. Similarly,
+this also still keeps 1 -> {1} behavior intact, so that once set to permanently
+disabled, it cannot be undone aside from a reboot.
+
+We've also added extra2 with max of 2 for the procfs handler, so that an admin
+still has a chance to toggle between 0 <-> 2.
+
+Either way, as an additional alternative, applications can make use of CAP_BPF
+that we added a while ago.
+
+Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
+Signed-off-by: Alexei Starovoitov <ast@kernel.org>
+Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
+[fllinden@amazon.com: backported to 5.4]
+Signed-off-by: Frank van der Linden <fllinden@amazon.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ Documentation/admin-guide/sysctl/kernel.rst |   21 ++++++++++++++++++++
+ init/Kconfig                                |   10 +++++++++
+ kernel/bpf/syscall.c                        |    3 +-
+ kernel/sysctl.c                             |   29 ++++++++++++++++++++++++----
+ 4 files changed, 58 insertions(+), 5 deletions(-)
+
+--- a/Documentation/admin-guide/sysctl/kernel.rst
++++ b/Documentation/admin-guide/sysctl/kernel.rst
+@@ -1125,6 +1125,27 @@ NMI switch that most IA32 servers have f
+ example.  If a system hangs up, try pressing the NMI switch.
+ 
+ 
++unprivileged_bpf_disabled:
++==========================
++
++Writing 1 to this entry will disable unprivileged calls to ``bpf()``;
++once disabled, calling ``bpf()`` without ``CAP_SYS_ADMIN`` will return
++``-EPERM``. Once set to 1, this can't be cleared from the running kernel
++anymore.
++
++Writing 2 to this entry will also disable unprivileged calls to ``bpf()``,
++however, an admin can still change this setting later on, if needed, by
++writing 0 or 1 to this entry.
++
++If ``BPF_UNPRIV_DEFAULT_OFF`` is enabled in the kernel config, then this
++entry will default to 2 instead of 0.
++
++= =============================================================
++0 Unprivileged calls to ``bpf()`` are enabled
++1 Unprivileged calls to ``bpf()`` are disabled without recovery
++2 Unprivileged calls to ``bpf()`` are disabled
++= =============================================================
++
+ watchdog:
+ =========
+ 
+--- a/init/Kconfig
++++ b/init/Kconfig
+@@ -1609,6 +1609,16 @@ config BPF_JIT_ALWAYS_ON
+         Enables BPF JIT and removes BPF interpreter to avoid
+         speculative execution of BPF instructions by the interpreter
+ 
++config BPF_UNPRIV_DEFAULT_OFF
++      bool "Disable unprivileged BPF by default"
++      depends on BPF_SYSCALL
++      help
++        Disables unprivileged BPF by default by setting the corresponding
++        /proc/sys/kernel/unprivileged_bpf_disabled knob to 2. An admin can
++        still reenable it by setting it to 0 later on, or permanently
++        disable it by setting it to 1 (from which no other transition to
++        0 is possible anymore).
++
+ config USERFAULTFD
+       bool "Enable userfaultfd() system call"
+       depends on MMU
+--- a/kernel/bpf/syscall.c
++++ b/kernel/bpf/syscall.c
+@@ -39,7 +39,8 @@ static DEFINE_SPINLOCK(prog_idr_lock);
+ static DEFINE_IDR(map_idr);
+ static DEFINE_SPINLOCK(map_idr_lock);
+ 
+-int sysctl_unprivileged_bpf_disabled __read_mostly;
++int sysctl_unprivileged_bpf_disabled __read_mostly =
++      IS_BUILTIN(CONFIG_BPF_UNPRIV_DEFAULT_OFF) ? 2 : 0;
+ 
+ static const struct bpf_map_ops * const bpf_map_types[] = {
+ #define BPF_PROG_TYPE(_id, _ops)
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -250,6 +250,28 @@ static int sysrq_sysctl_handler(struct c
+ 
+ #endif
+ 
++#ifdef CONFIG_BPF_SYSCALL
++static int bpf_unpriv_handler(struct ctl_table *table, int write,
++                             void *buffer, size_t *lenp, loff_t *ppos)
++{
++      int ret, unpriv_enable = *(int *)table->data;
++      bool locked_state = unpriv_enable == 1;
++      struct ctl_table tmp = *table;
++
++      if (write && !capable(CAP_SYS_ADMIN))
++              return -EPERM;
++
++      tmp.data = &unpriv_enable;
++      ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
++      if (write && !ret) {
++              if (locked_state && unpriv_enable != 1)
++                      return -EPERM;
++              *(int *)table->data = unpriv_enable;
++      }
++      return ret;
++}
++#endif
++
+ static struct ctl_table kern_table[];
+ static struct ctl_table vm_table[];
+ static struct ctl_table fs_table[];
+@@ -1255,10 +1277,9 @@ static struct ctl_table kern_table[] = {
+               .data           = &sysctl_unprivileged_bpf_disabled,
+               .maxlen         = sizeof(sysctl_unprivileged_bpf_disabled),
+               .mode           = 0644,
+-              /* only handle a transition from default "0" to "1" */
+-              .proc_handler   = proc_dointvec_minmax,
+-              .extra1         = SYSCTL_ONE,
+-              .extra2         = SYSCTL_ONE,
++              .proc_handler   = bpf_unpriv_handler,
++              .extra1         = SYSCTL_ZERO,
++              .extra2         = &two,
+       },
+       {
+               .procname       = "bpf_stats_enabled",

diff --git a/queue-5.4/series b/queue-5.4/series
index 302257277bdc5bb641feddc95c1c857f2a79dbbf..0d26f21dc86893a242dcb3271bb681e5d0b7c9e9 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -23,3 +23,4 @@ pm-hibernate-remove-register_nosave_region_late.patch
 usb-dwc2-gadget-don-t-try-to-disable-ep0-in-dwc2_hso.patch
 net-stmmac-dwmac-sun8i-use-return-val-of-readl_poll_.patch
 kvm-nvmx-evmcs-filter-out-vm_exit_save_vmx_preemptio.patch
+bpf-add-kconfig-knob-for-disabling-unpriv-bpf-by-default.patch