* [PATCH bpf-next v3 1/3] tools: bpftool: for "feature probe" define "full_mode" bool as global
2020-04-29 14:45 [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users Quentin Monnet
@ 2020-04-29 14:45 ` Quentin Monnet
2020-04-29 14:45 ` [PATCH bpf-next v3 2/3] tools: bpftool: allow unprivileged users to probe features Quentin Monnet
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Quentin Monnet @ 2020-04-29 14:45 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann
Cc: bpf, netdev, Quentin Monnet, Richard Palethorpe, Michael Kerrisk
The "full_mode" variable used for switching between full or partial
feature probing (i.e. with or without probing helpers that will log
warnings in kernel logs) was piped from the main do_probe() function
down to probe_helpers_for_progtype(), where it is needed.
Define it as a global variable: the calls will be more readable, and if
other similar flags were to be used in the future, we could use global
variables as well instead of extending again the list of arguments with
new flags.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
tools/bpf/bpftool/feature.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index 88718ee6a438..59e4cb44efbc 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -35,6 +35,8 @@ static const char * const helper_name[] = {
#undef BPF_HELPER_MAKE_ENTRY
+static bool full_mode;
+
/* Miscellaneous utility functions */
static bool check_procfs(void)
@@ -540,8 +542,7 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
static void
probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
- const char *define_prefix, bool full_mode,
- __u32 ifindex)
+ const char *define_prefix, __u32 ifindex)
{
const char *ptype_name = prog_type_name[prog_type];
char feat_name[128];
@@ -678,8 +679,7 @@ static void section_map_types(const char *define_prefix, __u32 ifindex)
}
static void
-section_helpers(bool *supported_types, const char *define_prefix,
- bool full_mode, __u32 ifindex)
+section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
{
unsigned int i;
@@ -704,8 +704,8 @@ section_helpers(bool *supported_types, const char *define_prefix,
define_prefix, define_prefix, define_prefix,
define_prefix);
for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++)
- probe_helpers_for_progtype(i, supported_types[i],
- define_prefix, full_mode, ifindex);
+ probe_helpers_for_progtype(i, supported_types[i], define_prefix,
+ ifindex);
print_end_section();
}
@@ -725,7 +725,6 @@ static int do_probe(int argc, char **argv)
enum probe_component target = COMPONENT_UNSPEC;
const char *define_prefix = NULL;
bool supported_types[128] = {};
- bool full_mode = false;
__u32 ifindex = 0;
char *ifname;
@@ -803,7 +802,7 @@ static int do_probe(int argc, char **argv)
goto exit_close_json;
section_program_types(supported_types, define_prefix, ifindex);
section_map_types(define_prefix, ifindex);
- section_helpers(supported_types, define_prefix, full_mode, ifindex);
+ section_helpers(supported_types, define_prefix, ifindex);
section_misc(define_prefix, ifindex);
exit_close_json:
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH bpf-next v3 2/3] tools: bpftool: allow unprivileged users to probe features
2020-04-29 14:45 [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users Quentin Monnet
2020-04-29 14:45 ` [PATCH bpf-next v3 1/3] tools: bpftool: for "feature probe" define "full_mode" bool as global Quentin Monnet
@ 2020-04-29 14:45 ` Quentin Monnet
2020-04-29 14:45 ` [PATCH bpf-next v3 3/3] tools: bpftool: make libcap dependency optional Quentin Monnet
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Quentin Monnet @ 2020-04-29 14:45 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann
Cc: bpf, netdev, Quentin Monnet, Richard Palethorpe, Michael Kerrisk
There is demand for a way to identify what BPF helper functions are
available to unprivileged users. To do so, allow unprivileged users to
run "bpftool feature probe" to list BPF-related features. This will only
show features accessible to those users, and may not reflect the full
list of features available (to administrators) on the system.
To avoid the case where bpftool is inadvertently run as non-root and
would list only a subset of the features supported by the system when it
would be expected to list all of them, running as unprivileged is gated
behind the "unprivileged" keyword passed to the command line. When used
by a privileged user, this keyword allows to drop the CAP_SYS_ADMIN and
to list the features available to unprivileged users. Note that this
addsd a dependency on libpcap for compiling bpftool.
Note that there is no particular reason why the probes were restricted
to root, other than the fact I did not need them for unprivileged and
did not bother with the additional checks at the time probes were added.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
.../bpftool/Documentation/bpftool-feature.rst | 10 +-
tools/bpf/bpftool/Makefile | 2 +-
tools/bpf/bpftool/bash-completion/bpftool | 2 +-
tools/bpf/bpftool/feature.c | 102 +++++++++++++++---
4 files changed, 100 insertions(+), 16 deletions(-)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-feature.rst b/tools/bpf/bpftool/Documentation/bpftool-feature.rst
index b04156cfd7a3..ca085944e4cf 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-feature.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-feature.rst
@@ -19,7 +19,7 @@ SYNOPSIS
FEATURE COMMANDS
================
-| **bpftool** **feature probe** [*COMPONENT*] [**full**] [**macros** [**prefix** *PREFIX*]]
+| **bpftool** **feature probe** [*COMPONENT*] [**full**] [**unprivileged**] [**macros** [**prefix** *PREFIX*]]
| **bpftool** **feature help**
|
| *COMPONENT* := { **kernel** | **dev** *NAME* }
@@ -49,6 +49,14 @@ DESCRIPTION
Keyword **kernel** can be omitted. If no probe target is
specified, probing the kernel is the default behaviour.
+ When the **unprivileged** keyword is used, bpftool will dump
+ only the features available to a user who does not have the
+ **CAP_SYS_ADMIN** capability set. The features available in
+ that case usually represent a small subset of the parameters
+ supported by the system. Unprivileged users MUST use the
+ **unprivileged** keyword: This is to avoid misdetection if
+ bpftool is inadvertently run as non-root, for example.
+
**bpftool feature probe dev** *NAME* [**full**] [**macros** [**prefix** *PREFIX*]]
Probe network device for supported eBPF features and dump
results to the console.
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index f584d1fdfc64..89d7962a4a44 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -55,7 +55,7 @@ ifneq ($(EXTRA_LDFLAGS),)
LDFLAGS += $(EXTRA_LDFLAGS)
endif
-LIBS = $(LIBBPF) -lelf -lz
+LIBS = $(LIBBPF) -lelf -lz -lcap
INSTALL ?= install
RM ?= rm -f
diff --git a/tools/bpf/bpftool/bash-completion/bpftool b/tools/bpf/bpftool/bash-completion/bpftool
index c033c3329f73..fc989ead7313 100644
--- a/tools/bpf/bpftool/bash-completion/bpftool
+++ b/tools/bpf/bpftool/bash-completion/bpftool
@@ -1079,7 +1079,7 @@ _bpftool()
COMPREPLY+=( $( compgen -W 'macros' -- "$cur" ) )
fi
_bpftool_one_of_list 'kernel dev'
- _bpftool_once_attr 'full'
+ _bpftool_once_attr 'full unprivileged'
return 0
;;
*)
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index 59e4cb44efbc..952f4b1987c0 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -6,6 +6,7 @@
#include <string.h>
#include <unistd.h>
#include <net/if.h>
+#include <sys/capability.h>
#include <sys/utsname.h>
#include <sys/vfs.h>
@@ -36,6 +37,7 @@ static const char * const helper_name[] = {
#undef BPF_HELPER_MAKE_ENTRY
static bool full_mode;
+static bool run_as_unprivileged;
/* Miscellaneous utility functions */
@@ -473,6 +475,11 @@ probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types,
}
res = bpf_probe_prog_type(prog_type, ifindex);
+ /* Probe may succeed even if program load fails, for unprivileged users
+ * check that we did not fail because of insufficient permissions
+ */
+ if (run_as_unprivileged && errno == EPERM)
+ res = false;
supported_types[prog_type] |= res;
@@ -501,6 +508,10 @@ probe_map_type(enum bpf_map_type map_type, const char *define_prefix,
res = bpf_probe_map_type(map_type, ifindex);
+ /* Probe result depends on the success of map creation, no additional
+ * check required for unprivileged users
+ */
+
maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
if (strlen(map_type_name[map_type]) > maxlen) {
p_info("map type name too long");
@@ -520,12 +531,17 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
const char *define_prefix, unsigned int id,
const char *ptype_name, __u32 ifindex)
{
- bool res;
+ bool res = false;
- if (!supported_type)
- res = false;
- else
+ if (supported_type) {
res = bpf_probe_helper(id, prog_type, ifindex);
+ /* Probe may succeed even if program load fails, for
+ * unprivileged users check that we did not fail because of
+ * insufficient permissions
+ */
+ if (run_as_unprivileged && errno == EPERM)
+ res = false;
+ }
if (json_output) {
if (res)
@@ -720,6 +736,65 @@ static void section_misc(const char *define_prefix, __u32 ifindex)
print_end_section();
}
+static int handle_perms(void)
+{
+ cap_value_t cap_list[1] = { CAP_SYS_ADMIN };
+ bool has_sys_admin_cap = false;
+ cap_flag_value_t val;
+ int res = -1;
+ cap_t caps;
+
+ caps = cap_get_proc();
+ if (!caps) {
+ p_err("failed to get capabilities for process: %s",
+ strerror(errno));
+ return -1;
+ }
+
+ if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &val)) {
+ p_err("bug: failed to retrieve CAP_SYS_ADMIN status");
+ goto exit_free;
+ }
+ if (val == CAP_SET)
+ has_sys_admin_cap = true;
+
+ if (!run_as_unprivileged && !has_sys_admin_cap) {
+ p_err("full feature probing requires CAP_SYS_ADMIN, run as root or use 'unprivileged'");
+ goto exit_free;
+ }
+
+ if ((run_as_unprivileged && !has_sys_admin_cap) ||
+ (!run_as_unprivileged && has_sys_admin_cap)) {
+ /* We are all good, exit now */
+ res = 0;
+ goto exit_free;
+ }
+
+ /* if (run_as_unprivileged && has_sys_admin_cap), drop CAP_SYS_ADMIN */
+
+ if (cap_set_flag(caps, CAP_EFFECTIVE, ARRAY_SIZE(cap_list), cap_list,
+ CAP_CLEAR)) {
+ p_err("bug: failed to clear CAP_SYS_ADMIN from capabilities");
+ goto exit_free;
+ }
+
+ if (cap_set_proc(caps)) {
+ p_err("failed to drop CAP_SYS_ADMIN: %s", strerror(errno));
+ goto exit_free;
+ }
+
+ res = 0;
+
+exit_free:
+ if (cap_free(caps) && !res) {
+ p_err("failed to clear storage object for capabilities: %s",
+ strerror(errno));
+ res = -1;
+ }
+
+ return res;
+}
+
static int do_probe(int argc, char **argv)
{
enum probe_component target = COMPONENT_UNSPEC;
@@ -728,14 +803,6 @@ static int do_probe(int argc, char **argv)
__u32 ifindex = 0;
char *ifname;
- /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN).
- * Let's approximate, and restrict usage to root user only.
- */
- if (geteuid()) {
- p_err("please run this command as root user");
- return -1;
- }
-
set_max_rlimit();
while (argc) {
@@ -784,6 +851,9 @@ static int do_probe(int argc, char **argv)
if (!REQ_ARGS(1))
return -1;
define_prefix = GET_ARG();
+ } else if (is_prefix(*argv, "unprivileged")) {
+ run_as_unprivileged = true;
+ NEXT_ARG();
} else {
p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?",
*argv);
@@ -791,6 +861,12 @@ static int do_probe(int argc, char **argv)
}
}
+ /* Full feature detection requires CAP_SYS_ADMIN privilege.
+ * Let's approximate, and warn if user is not root.
+ */
+ if (handle_perms())
+ return -1;
+
if (json_output) {
define_prefix = NULL;
jsonw_start_object(json_wtr);
@@ -821,7 +897,7 @@ static int do_help(int argc, char **argv)
}
fprintf(stderr,
- "Usage: %s %s probe [COMPONENT] [full] [macros [prefix PREFIX]]\n"
+ "Usage: %s %s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n"
" %s %s help\n"
"\n"
" COMPONENT := { kernel | dev NAME }\n"
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH bpf-next v3 3/3] tools: bpftool: make libcap dependency optional
2020-04-29 14:45 [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users Quentin Monnet
2020-04-29 14:45 ` [PATCH bpf-next v3 1/3] tools: bpftool: for "feature probe" define "full_mode" bool as global Quentin Monnet
2020-04-29 14:45 ` [PATCH bpf-next v3 2/3] tools: bpftool: allow unprivileged users to probe features Quentin Monnet
@ 2020-04-29 14:45 ` Quentin Monnet
2020-04-29 20:10 ` [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users John Fastabend
2020-04-29 23:14 ` Daniel Borkmann
4 siblings, 0 replies; 6+ messages in thread
From: Quentin Monnet @ 2020-04-29 14:45 UTC (permalink / raw)
To: Alexei Starovoitov, Daniel Borkmann
Cc: bpf, netdev, Quentin Monnet, Richard Palethorpe, Michael Kerrisk
The new libcap dependency is not used for an essential feature of
bpftool, and we could imagine building the tool without checks on
CAP_SYS_ADMIN by disabling probing features as an unprivileged users.
Make it so, in order to avoid a hard dependency on libcap, and to ease
packaging/embedding of bpftool.
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
---
.../bpftool/Documentation/bpftool-feature.rst | 4 ++-
tools/bpf/bpftool/Makefile | 13 +++++++---
tools/bpf/bpftool/feature.c | 26 +++++++++++++++++++
3 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-feature.rst b/tools/bpf/bpftool/Documentation/bpftool-feature.rst
index ca085944e4cf..1fa755f55e0c 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-feature.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-feature.rst
@@ -55,7 +55,9 @@ DESCRIPTION
that case usually represent a small subset of the parameters
supported by the system. Unprivileged users MUST use the
**unprivileged** keyword: This is to avoid misdetection if
- bpftool is inadvertently run as non-root, for example.
+ bpftool is inadvertently run as non-root, for example. This
+ keyword is unavailable if bpftool was compiled without
+ libcap.
**bpftool feature probe dev** *NAME* [**full**] [**macros** [**prefix** *PREFIX*]]
Probe network device for supported eBPF features and dump
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile
index 89d7962a4a44..2759f9cc3289 100644
--- a/tools/bpf/bpftool/Makefile
+++ b/tools/bpf/bpftool/Makefile
@@ -55,16 +55,15 @@ ifneq ($(EXTRA_LDFLAGS),)
LDFLAGS += $(EXTRA_LDFLAGS)
endif
-LIBS = $(LIBBPF) -lelf -lz -lcap
-
INSTALL ?= install
RM ?= rm -f
CLANG ?= clang
FEATURE_USER = .bpftool
-FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib \
+FEATURE_TESTS = libbfd disassembler-four-args reallocarray zlib libcap \
+ clang-bpf-global-var
+FEATURE_DISPLAY = libbfd disassembler-four-args zlib libcap \
clang-bpf-global-var
-FEATURE_DISPLAY = libbfd disassembler-four-args zlib clang-bpf-global-var
check_feat := 1
NON_CHECK_FEAT_TARGETS := clean uninstall doc doc-clean doc-install doc-uninstall
@@ -90,6 +89,12 @@ ifeq ($(feature-reallocarray), 0)
CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
endif
+LIBS = $(LIBBPF) -lelf -lz
+ifeq ($(feature-libcap), 1)
+CFLAGS += -DUSE_LIBCAP
+LIBS += -lcap
+endif
+
include $(wildcard $(OUTPUT)*.d)
all: $(OUTPUT)bpftool
diff --git a/tools/bpf/bpftool/feature.c b/tools/bpf/bpftool/feature.c
index 952f4b1987c0..f54347f55ee0 100644
--- a/tools/bpf/bpftool/feature.c
+++ b/tools/bpf/bpftool/feature.c
@@ -6,7 +6,9 @@
#include <string.h>
#include <unistd.h>
#include <net/if.h>
+#ifdef USE_LIBCAP
#include <sys/capability.h>
+#endif
#include <sys/utsname.h>
#include <sys/vfs.h>
@@ -37,7 +39,9 @@ static const char * const helper_name[] = {
#undef BPF_HELPER_MAKE_ENTRY
static bool full_mode;
+#ifdef USE_LIBCAP
static bool run_as_unprivileged;
+#endif
/* Miscellaneous utility functions */
@@ -475,11 +479,13 @@ probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types,
}
res = bpf_probe_prog_type(prog_type, ifindex);
+#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for unprivileged users
* check that we did not fail because of insufficient permissions
*/
if (run_as_unprivileged && errno == EPERM)
res = false;
+#endif
supported_types[prog_type] |= res;
@@ -535,12 +541,14 @@ probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
if (supported_type) {
res = bpf_probe_helper(id, prog_type, ifindex);
+#ifdef USE_LIBCAP
/* Probe may succeed even if program load fails, for
* unprivileged users check that we did not fail because of
* insufficient permissions
*/
if (run_as_unprivileged && errno == EPERM)
res = false;
+#endif
}
if (json_output) {
@@ -738,6 +746,7 @@ static void section_misc(const char *define_prefix, __u32 ifindex)
static int handle_perms(void)
{
+#ifdef USE_LIBCAP
cap_value_t cap_list[1] = { CAP_SYS_ADMIN };
bool has_sys_admin_cap = false;
cap_flag_value_t val;
@@ -793,6 +802,18 @@ static int handle_perms(void)
}
return res;
+#else
+ /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN).
+ * We do not use libpcap so let's approximate, and restrict usage to
+ * root user only.
+ */
+ if (geteuid()) {
+ p_err("full feature probing requires root privileges");
+ return -1;
+ }
+
+ return 0;
+#endif /* USE_LIBCAP */
}
static int do_probe(int argc, char **argv)
@@ -852,8 +873,13 @@ static int do_probe(int argc, char **argv)
return -1;
define_prefix = GET_ARG();
} else if (is_prefix(*argv, "unprivileged")) {
+#ifdef USE_LIBCAP
run_as_unprivileged = true;
NEXT_ARG();
+#else
+ p_err("unprivileged run not supported, recompile bpftool with libcap");
+ return -1;
+#endif
} else {
p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?",
*argv);
--
2.20.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* RE: [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users
2020-04-29 14:45 [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users Quentin Monnet
` (2 preceding siblings ...)
2020-04-29 14:45 ` [PATCH bpf-next v3 3/3] tools: bpftool: make libcap dependency optional Quentin Monnet
@ 2020-04-29 20:10 ` John Fastabend
2020-04-29 23:14 ` Daniel Borkmann
4 siblings, 0 replies; 6+ messages in thread
From: John Fastabend @ 2020-04-29 20:10 UTC (permalink / raw)
To: Quentin Monnet, Alexei Starovoitov, Daniel Borkmann
Cc: bpf, netdev, Quentin Monnet, Richard Palethorpe, Michael Kerrisk
Quentin Monnet wrote:
> This set allows unprivileged users to probe available features with
> bpftool. On Daniel's suggestion, the "unprivileged" keyword must be passed
> on the command line to avoid accidentally dumping a subset of the features
> supported by the system. When used by root, this keyword makes bpftool drop
> the CAP_SYS_ADMIN capability and print the features available to
> unprivileged users only.
>
> The first patch makes a variable global in feature.c to avoid piping too
> many booleans through the different functions. The second patch introduces
> the unprivileged probing, adding a dependency to libcap. Then the third
> patch makes this dependency optional, by restoring the initial behaviour
> (root only can probe features) if the library is not available.
>
> Cc: Richard Palethorpe <rpalethorpe@suse.com>
> Cc: Michael Kerrisk <mtk.manpages@gmail.com>
>
> v3: Update help message for bpftool feature probe ("unprivileged").
>
> v2: Add "unprivileged" keyword, libcap check (patches 1 and 3 are new).
>
> Quentin Monnet (3):
> tools: bpftool: for "feature probe" define "full_mode" bool as global
> tools: bpftool: allow unprivileged users to probe features
> tools: bpftool: make libcap dependency optional
>
> .../bpftool/Documentation/bpftool-feature.rst | 12 +-
> tools/bpf/bpftool/Makefile | 13 +-
> tools/bpf/bpftool/bash-completion/bpftool | 2 +-
> tools/bpf/bpftool/feature.c | 143 +++++++++++++++---
> 4 files changed, 143 insertions(+), 27 deletions(-)
>
> --
> 2.20.1
>
For the series,
Acked-by: John Fastabend <john.fastabend@gmail.com>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users
2020-04-29 14:45 [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users Quentin Monnet
` (3 preceding siblings ...)
2020-04-29 20:10 ` [PATCH bpf-next v3 0/3] tools: bpftool: probe features for unprivileged users John Fastabend
@ 2020-04-29 23:14 ` Daniel Borkmann
4 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2020-04-29 23:14 UTC (permalink / raw)
To: Quentin Monnet, Alexei Starovoitov
Cc: bpf, netdev, Richard Palethorpe, Michael Kerrisk
On 4/29/20 4:45 PM, Quentin Monnet wrote:
> This set allows unprivileged users to probe available features with
> bpftool. On Daniel's suggestion, the "unprivileged" keyword must be passed
> on the command line to avoid accidentally dumping a subset of the features
> supported by the system. When used by root, this keyword makes bpftool drop
> the CAP_SYS_ADMIN capability and print the features available to
> unprivileged users only.
>
> The first patch makes a variable global in feature.c to avoid piping too
> many booleans through the different functions. The second patch introduces
> the unprivileged probing, adding a dependency to libcap. Then the third
> patch makes this dependency optional, by restoring the initial behaviour
> (root only can probe features) if the library is not available.
>
> Cc: Richard Palethorpe <rpalethorpe@suse.com>
> Cc: Michael Kerrisk <mtk.manpages@gmail.com>
>
> v3: Update help message for bpftool feature probe ("unprivileged").
>
> v2: Add "unprivileged" keyword, libcap check (patches 1 and 3 are new).
>
> Quentin Monnet (3):
> tools: bpftool: for "feature probe" define "full_mode" bool as global
> tools: bpftool: allow unprivileged users to probe features
> tools: bpftool: make libcap dependency optional
>
> .../bpftool/Documentation/bpftool-feature.rst | 12 +-
> tools/bpf/bpftool/Makefile | 13 +-
> tools/bpf/bpftool/bash-completion/bpftool | 2 +-
> tools/bpf/bpftool/feature.c | 143 +++++++++++++++---
> 4 files changed, 143 insertions(+), 27 deletions(-)
>
Applied, thanks!
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