Merge tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next

Alexei Starovoitov says:

====================
pull-request: bpf-next 2023-12-18

This PR is larger than usual and contains changes in various parts
of the kernel.

The main changes are:

1) Fix kCFI bugs in BPF, from Peter Zijlstra.

End result: all forms of indirect calls from BPF into kernel
and from kernel into BPF work with CFI enabled. This allows BPF
to work with CONFIG_FINEIBT=y.

2) Introduce BPF token object, from Andrii Nakryiko.

It adds an ability to delegate a subset of BPF features from privileged
daemon (e.g., systemd) through special mount options for userns-bound
BPF FS to a trusted unprivileged application. The design accommodates
suggestions from Christian Brauner and Paul Moore.

Example:
$ sudo mkdir -p /sys/fs/bpf/token
$ sudo mount -t bpf bpffs /sys/fs/bpf/token \
             -o delegate_cmds=prog_load:MAP_CREATE \
             -o delegate_progs=kprobe \
             -o delegate_attachs=xdp

3) Various verifier improvements and fixes, from Andrii Nakryiko, Andrei Matei.

 - Complete precision tracking support for register spills
 - Fix verification of possibly-zero-sized stack accesses
 - Fix access to uninit stack slots
 - Track aligned STACK_ZERO cases as imprecise spilled registers.
   It improves the verifier "instructions processed" metric from single
   digit to 50-60% for some programs.
 - Fix verifier retval logic

4) Support for VLAN tag in XDP hints, from Larysa Zaremba.

5) Allocate BPF trampoline via bpf_prog_pack mechanism, from Song Liu.

End result: better memory utilization and lower I$ miss for calls to BPF
via BPF trampoline.

6) Fix race between BPF prog accessing inner map and parallel delete,
from Hou Tao.

7) Add bpf_xdp_get_xfrm_state() kfunc, from Daniel Xu.

It allows BPF interact with IPSEC infra. The intent is to support
software RSS (via XDP) for the upcoming ipsec pcpu work.
Experiments on AWS demonstrate single tunnel pcpu ipsec reaching
line rate on 100G ENA nics.

8) Expand bpf_cgrp_storage to support cgroup1 non-attach, from Yafang Shao.

9) BPF file verification via fsverity, from Song Liu.

It allows BPF progs get fsverity digest.

* tag 'for-netdev' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (164 commits)
  bpf: Ensure precise is reset to false in __mark_reg_const_zero()
  selftests/bpf: Add more uprobe multi fail tests
  bpf: Fail uprobe multi link with negative offset
  selftests/bpf: Test the release of map btf
  s390/bpf: Fix indirect trampoline generation
  selftests/bpf: Temporarily disable dummy_struct_ops test on s390
  x86/cfi,bpf: Fix bpf_exception_cb() signature
  bpf: Fix dtor CFI
  cfi: Add CFI_NOSEAL()
  x86/cfi,bpf: Fix bpf_struct_ops CFI
  x86/cfi,bpf: Fix bpf_callback_t CFI
  x86/cfi,bpf: Fix BPF JIT call
  cfi: Flip headers
  selftests/bpf: Add test for abnormal cnt during multi-kprobe attachment
  selftests/bpf: Don't use libbpf_get_error() in kprobe_multi_test
  selftests/bpf: Add test for abnormal cnt during multi-uprobe attachment
  bpf: Limit the number of kprobes when attaching program to multiple kprobes
  bpf: Limit the number of uprobes when attaching program to multiple uprobes
  bpf: xdp: Register generic_kfunc_set with XDP programs
  selftests/bpf: utilize string values for delegate_xxx mount options
  ...
====================

Link: https://lore.kernel.org/r/20231219000520.34178-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 80 insertions, 11 deletions

diff --git a/tools/testing/selftests/bpf/progs/verifier_var_off.c b/tools/testing/selftests/bpf/progs/verifier_var_off.c
index 83a90afba785..c810f4f6f479 100644
--- a/tools/testing/selftests/bpf/progs/verifier_var_off.c
+++ b/tools/testing/selftests/bpf/progs/verifier_var_off.c
@@ -59,9 +59,10 @@ __naked void stack_read_priv_vs_unpriv(void)
 "	::: __clobber_all);
 }
 
-SEC("lwt_in")
+SEC("cgroup/skb")
 __description("variable-offset stack read, uninitialized")
-__failure __msg("invalid variable-offset read from stack R2")
+__success
+__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root")
 __naked void variable_offset_stack_read_uninitialized(void)
 {
 	asm volatile ("					\
@@ -83,13 +84,56 @@ __naked void variable_offset_stack_read_uninitialized(void)
 
 SEC("socket")
 __description("variable-offset stack write, priv vs unpriv")
-__success __failure_unpriv
+__success
+/* Check that the maximum stack depth is correctly maintained according to the
+ * maximum possible variable offset.
+ */
+__log_level(4) __msg("stack depth 16")
+__failure_unpriv
 /* Variable stack access is rejected for unprivileged.
  */
 __msg_unpriv("R2 variable stack access prohibited for !root")
 __retval(0)
 __naked void stack_write_priv_vs_unpriv(void)
 {
+	asm volatile ("                               \
+	/* Get an unknown value */                    \
+	r2 = *(u32*)(r1 + 0);                         \
+	/* Make it small and 8-byte aligned */        \
+	r2 &= 8;                                      \
+	r2 -= 16;                                     \
+	/* Add it to fp. We now have either fp-8 or   \
+	 * fp-16, but we don't know which             \
+	 */                                           \
+	r2 += r10;                                    \
+	/* Dereference it for a stack write */        \
+	r0 = 0;                                       \
+	*(u64*)(r2 + 0) = r0;                         \
+	exit;                                         \
+"	::: __clobber_all);
+}
+
+/* Similar to the previous test, but this time also perform a read from the
+ * address written to with a variable offset. The read is allowed, showing that,
+ * after a variable-offset write, a priviledged program can read the slots that
+ * were in the range of that write (even if the verifier doesn't actually know if
+ * the slot being read was really written to or not.
+ *
+ * Despite this test being mostly a superset, the previous test is also kept for
+ * the sake of it checking the stack depth in the case where there is no read.
+ */
+SEC("socket")
+__description("variable-offset stack write followed by read")
+__success
+/* Check that the maximum stack depth is correctly maintained according to the
+ * maximum possible variable offset.
+ */
+__log_level(4) __msg("stack depth 16")
+__failure_unpriv
+__msg_unpriv("R2 variable stack access prohibited for !root")
+__retval(0)
+__naked void stack_write_followed_by_read(void)
+{
 	asm volatile ("					\
 	/* Get an unknown value */			\
 	r2 = *(u32*)(r1 + 0);				\
@@ -103,12 +147,7 @@ __naked void stack_write_priv_vs_unpriv(void)
 	/* Dereference it for a stack write */		\
 	r0 = 0;						\
 	*(u64*)(r2 + 0) = r0;				\
-	/* Now read from the address we just wrote. This shows\
-	 * that, after a variable-offset write, a priviledged\
-	 * program can read the slots that were in the range of\
-	 * that write (even if the verifier doesn't actually know\
-	 * if the slot being read was really written to or not.\
-	 */						\
+	/* Now read from the address we just wrote. */ \
 	r3 = *(u64*)(r2 + 0);				\
 	r0 = 0;						\
 	exit;						\
@@ -224,6 +263,35 @@ __naked void access_max_out_of_bound(void)
 	: __clobber_all);
 }
 
+/* Similar to the test above, but this time check the special case of a
+ * zero-sized stack access. We used to have a bug causing crashes for zero-sized
+ * out-of-bounds accesses.
+ */
+SEC("socket")
+__description("indirect variable-offset stack access, zero-sized, max out of bound")
+__failure __msg("invalid variable-offset indirect access to stack R1")
+__naked void zero_sized_access_max_out_of_bound(void)
+{
+	asm volatile ("                      \
+	r0 = 0;                              \
+	/* Fill some stack */                \
+	*(u64*)(r10 - 16) = r0;              \
+	*(u64*)(r10 - 8) = r0;               \
+	/* Get an unknown value */           \
+	r1 = *(u32*)(r1 + 0);                \
+	r1 &= 63;                            \
+	r1 += -16;                           \
+	/* r1 is now anywhere in [-16,48) */ \
+	r1 += r10;                           \
+	r2 = 0;                              \
+	r3 = 0;                              \
+	call %[bpf_probe_read_kernel];       \
+	exit;                                \
+"	:
+	: __imm(bpf_probe_read_kernel)
+	: __clobber_all);
+}
+
 SEC("lwt_in")
 __description("indirect variable-offset stack access, min out of bound")
 __failure __msg("invalid variable-offset indirect access to stack R2")
@@ -253,9 +321,10 @@ __naked void access_min_out_of_bound(void)
 	: __clobber_all);
 }
 
-SEC("lwt_in")
+SEC("cgroup/skb")
 __description("indirect variable-offset stack access, min_off < min_initialized")
-__failure __msg("invalid indirect read from stack R2 var_off")
+__success
+__failure_unpriv __msg_unpriv("R2 variable stack access prohibited for !root")
 __naked void access_min_off_min_initialized(void)
 {
 	asm volatile ("					\