Add bpf security fixes
This commit is contained in:
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0b841b071c
commit
405645d788
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@ -7,6 +7,9 @@ linux (4.5.2-2) UNRELEASED; urgency=medium
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* bug control: Update list of related firmware packages
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* Revert "sp5100_tco: fix the device check for SB800 and later chipsets"
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(Closes: #823146; probably fixes #822651)
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* bpf: fix double-fdput in replace_map_fd_with_map_ptr() (CVE-2016-XXXX)
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* bpf: fix refcnt overflow (CVE-2016-XXXX)
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* bpf: fix check_map_func_compatibility logic (CVE-2016-XXXX)
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-- Uwe Kleine-König <ukleinek@debian.org> Sun, 01 May 2016 16:13:04 +0200
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@ -0,0 +1,94 @@
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From: Alexei Starovoitov <ast@fb.com>
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Date: Wed, 27 Apr 2016 18:56:21 -0700
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Subject: [3/3] bpf: fix check_map_func_compatibility logic
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Origin: https://git.kernel.org/linus/6aff67c85c9e5a4bc99e5211c1bac547936626ca
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The commit 35578d798400 ("bpf: Implement function bpf_perf_event_read() that get the selected hardware PMU conuter")
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introduced clever way to check bpf_helper<->map_type compatibility.
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Later on commit a43eec304259 ("bpf: introduce bpf_perf_event_output() helper") adjusted
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the logic and inadvertently broke it.
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Get rid of the clever bool compare and go back to two-way check
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from map and from helper perspective.
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Fixes: a43eec304259 ("bpf: introduce bpf_perf_event_output() helper")
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Reported-by: Jann Horn <jannh@google.com>
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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[bwh: Backported to 4.5:
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- Drop the STACK_TRACE case
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- No verbose() logging]
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---
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--- a/kernel/bpf/verifier.c
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+++ b/kernel/bpf/verifier.c
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@@ -239,15 +239,6 @@ static const char * const reg_type_str[]
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[CONST_IMM] = "imm",
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};
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-static const struct {
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- int map_type;
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- int func_id;
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-} func_limit[] = {
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- {BPF_MAP_TYPE_PROG_ARRAY, BPF_FUNC_tail_call},
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- {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_read},
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- {BPF_MAP_TYPE_PERF_EVENT_ARRAY, BPF_FUNC_perf_event_output},
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-};
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-
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static void print_verifier_state(struct verifier_env *env)
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{
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enum bpf_reg_type t;
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@@ -898,24 +889,42 @@ static int check_func_arg(struct verifie
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static int check_map_func_compatibility(struct bpf_map *map, int func_id)
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{
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- bool bool_map, bool_func;
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- int i;
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-
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if (!map)
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return 0;
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- for (i = 0; i < ARRAY_SIZE(func_limit); i++) {
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- bool_map = (map->map_type == func_limit[i].map_type);
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- bool_func = (func_id == func_limit[i].func_id);
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- /* only when map & func pair match it can continue.
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- * don't allow any other map type to be passed into
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- * the special func;
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- */
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- if (bool_func && bool_map != bool_func)
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- return -EINVAL;
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+ /* We need a two way check, first is from map perspective ... */
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+ switch (map->map_type) {
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+ case BPF_MAP_TYPE_PROG_ARRAY:
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+ if (func_id != BPF_FUNC_tail_call)
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+ goto error;
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+ break;
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+ case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
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+ if (func_id != BPF_FUNC_perf_event_read &&
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+ func_id != BPF_FUNC_perf_event_output)
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+ goto error;
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+ break;
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+ default:
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+ break;
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+ }
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+
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+ /* ... and second from the function itself. */
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+ switch (func_id) {
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+ case BPF_FUNC_tail_call:
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+ if (map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
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+ goto error;
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+ break;
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+ case BPF_FUNC_perf_event_read:
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+ case BPF_FUNC_perf_event_output:
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+ if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
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+ goto error;
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+ break;
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+ default:
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+ break;
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}
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return 0;
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+error:
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+ return -EINVAL;
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}
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static int check_call(struct verifier_env *env, int func_id)
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41
debian/patches/bugfix/all/bpf-fix-double-fdput-in-replace_map_fd_with_map_ptr.patch
vendored
Normal file
41
debian/patches/bugfix/all/bpf-fix-double-fdput-in-replace_map_fd_with_map_ptr.patch
vendored
Normal file
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@ -0,0 +1,41 @@
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From: Jann Horn <jannh@google.com>
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Date: Tue, 26 Apr 2016 22:26:26 +0200
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Subject: [1/3] bpf: fix double-fdput in replace_map_fd_with_map_ptr()
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Origin: https://git.kernel.org/linus/8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7
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When bpf(BPF_PROG_LOAD, ...) was invoked with a BPF program whose bytecode
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references a non-map file descriptor as a map file descriptor, the error
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handling code called fdput() twice instead of once (in __bpf_map_get() and
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in replace_map_fd_with_map_ptr()). If the file descriptor table of the
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current task is shared, this causes f_count to be decremented too much,
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allowing the struct file to be freed while it is still in use
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(use-after-free). This can be exploited to gain root privileges by an
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unprivileged user.
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This bug was introduced in
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commit 0246e64d9a5f ("bpf: handle pseudo BPF_LD_IMM64 insn"), but is only
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exploitable since
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commit 1be7f75d1668 ("bpf: enable non-root eBPF programs") because
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previously, CAP_SYS_ADMIN was required to reach the vulnerable code.
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(posted publicly according to request by maintainer)
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Signed-off-by: Jann Horn <jannh@google.com>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Acked-by: Alexei Starovoitov <ast@kernel.org>
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Acked-by: Daniel Borkmann <daniel@iogearbox.net>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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kernel/bpf/verifier.c | 1 -
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1 file changed, 1 deletion(-)
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--- a/kernel/bpf/verifier.c
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+++ b/kernel/bpf/verifier.c
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@@ -2003,7 +2003,6 @@ static int replace_map_fd_with_map_ptr(s
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if (IS_ERR(map)) {
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verbose("fd %d is not pointing to valid bpf_map\n",
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insn->imm);
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- fdput(f);
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return PTR_ERR(map);
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}
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@ -0,0 +1,147 @@
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From: Alexei Starovoitov <ast@fb.com>
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Date: Wed, 27 Apr 2016 18:56:20 -0700
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Subject: [2/3] bpf: fix refcnt overflow
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Origin: https://git.kernel.org/linus/92117d8443bc5afacc8d5ba82e541946310f106e
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On a system with >32Gbyte of phyiscal memory and infinite RLIMIT_MEMLOCK,
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the malicious application may overflow 32-bit bpf program refcnt.
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It's also possible to overflow map refcnt on 1Tb system.
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Impose 32k hard limit which means that the same bpf program or
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map cannot be shared by more than 32k processes.
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Fixes: 1be7f75d1668 ("bpf: enable non-root eBPF programs")
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Reported-by: Jann Horn <jannh@google.com>
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Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Acked-by: Daniel Borkmann <daniel@iogearbox.net>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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include/linux/bpf.h | 3 ++-
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kernel/bpf/inode.c | 7 ++++---
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kernel/bpf/syscall.c | 24 ++++++++++++++++++++----
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kernel/bpf/verifier.c | 11 +++++++----
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4 files changed, 33 insertions(+), 12 deletions(-)
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--- a/include/linux/bpf.h
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+++ b/include/linux/bpf.h
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@@ -165,12 +165,13 @@ void bpf_register_prog_type(struct bpf_p
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void bpf_register_map_type(struct bpf_map_type_list *tl);
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struct bpf_prog *bpf_prog_get(u32 ufd);
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+struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog);
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void bpf_prog_put(struct bpf_prog *prog);
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void bpf_prog_put_rcu(struct bpf_prog *prog);
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struct bpf_map *bpf_map_get_with_uref(u32 ufd);
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struct bpf_map *__bpf_map_get(struct fd f);
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-void bpf_map_inc(struct bpf_map *map, bool uref);
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+struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref);
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void bpf_map_put_with_uref(struct bpf_map *map);
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void bpf_map_put(struct bpf_map *map);
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--- a/kernel/bpf/inode.c
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+++ b/kernel/bpf/inode.c
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@@ -31,10 +31,10 @@ static void *bpf_any_get(void *raw, enum
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{
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switch (type) {
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case BPF_TYPE_PROG:
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- atomic_inc(&((struct bpf_prog *)raw)->aux->refcnt);
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+ raw = bpf_prog_inc(raw);
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break;
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case BPF_TYPE_MAP:
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- bpf_map_inc(raw, true);
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+ raw = bpf_map_inc(raw, true);
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break;
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default:
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WARN_ON_ONCE(1);
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@@ -297,7 +297,8 @@ static void *bpf_obj_do_get(const struct
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goto out;
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raw = bpf_any_get(inode->i_private, *type);
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- touch_atime(&path);
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+ if (!IS_ERR(raw))
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+ touch_atime(&path);
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path_put(&path);
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return raw;
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--- a/kernel/bpf/syscall.c
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+++ b/kernel/bpf/syscall.c
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@@ -201,11 +201,18 @@ struct bpf_map *__bpf_map_get(struct fd
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return f.file->private_data;
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}
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-void bpf_map_inc(struct bpf_map *map, bool uref)
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+/* prog's and map's refcnt limit */
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+#define BPF_MAX_REFCNT 32768
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+
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+struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref)
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{
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- atomic_inc(&map->refcnt);
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+ if (atomic_inc_return(&map->refcnt) > BPF_MAX_REFCNT) {
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+ atomic_dec(&map->refcnt);
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+ return ERR_PTR(-EBUSY);
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+ }
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if (uref)
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atomic_inc(&map->usercnt);
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+ return map;
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}
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struct bpf_map *bpf_map_get_with_uref(u32 ufd)
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@@ -217,7 +224,7 @@ struct bpf_map *bpf_map_get_with_uref(u3
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if (IS_ERR(map))
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return map;
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- bpf_map_inc(map, true);
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+ map = bpf_map_inc(map, true);
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fdput(f);
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return map;
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@@ -600,6 +607,15 @@ static struct bpf_prog *__bpf_prog_get(s
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return f.file->private_data;
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}
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+struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog)
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+{
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+ if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) {
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+ atomic_dec(&prog->aux->refcnt);
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+ return ERR_PTR(-EBUSY);
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+ }
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+ return prog;
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+}
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+
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/* called by sockets/tracing/seccomp before attaching program to an event
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* pairs with bpf_prog_put()
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*/
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@@ -612,7 +628,7 @@ struct bpf_prog *bpf_prog_get(u32 ufd)
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if (IS_ERR(prog))
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return prog;
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- atomic_inc(&prog->aux->refcnt);
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+ prog = bpf_prog_inc(prog);
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fdput(f);
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return prog;
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--- a/kernel/bpf/verifier.c
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+++ b/kernel/bpf/verifier.c
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@@ -2022,15 +2022,18 @@ static int replace_map_fd_with_map_ptr(s
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return -E2BIG;
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}
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- /* remember this map */
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- env->used_maps[env->used_map_cnt++] = map;
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-
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/* hold the map. If the program is rejected by verifier,
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* the map will be released by release_maps() or it
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* will be used by the valid program until it's unloaded
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* and all maps are released in free_bpf_prog_info()
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*/
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- bpf_map_inc(map, false);
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+ map = bpf_map_inc(map, false);
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+ if (IS_ERR(map)) {
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+ fdput(f);
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+ return PTR_ERR(map);
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+ }
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+ env->used_maps[env->used_map_cnt++] = map;
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+
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fdput(f);
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next_insn:
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insn++;
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@ -155,3 +155,6 @@ bugfix/all/power-cpupower-fix-manpages-NAME.patch
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bugfix/all/tools-lib-traceevent-fix-use-of-uninitialized-variables.patch
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bugfix/all/scripts-fix-x.509-pem-support-in-sign-file.patch
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bugfix/x86/revert-sp5100_tco-fix-the-device-check-for-SB800-and.patch
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bugfix/all/bpf-fix-double-fdput-in-replace_map_fd_with_map_ptr.patch
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bugfix/all/bpf-fix-refcnt-overflow.patch
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bugfix/all/bpf-fix-check_map_func_compatibility-logic.patch
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