diff options
| author | Artem Savkov <asavkov@redhat.com> | 2022-08-10 08:59:03 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-08-10 09:22:18 -0700 |
| commit | 4dd48c6f1f83290d4bc61b43e61d86f8bc6c310e (patch) | |
| tree | 9c01d2a53dac7963116e41142333f73b27d1aa79 | |
| parent | 3143d10b094596f3e5d5964b2660375e586652a3 (diff) | |
bpf: add destructive kfunc flag
Add KF_DESTRUCTIVE flag for destructive functions. Functions with this
flag set will require CAP_SYS_BOOT capabilities.
Signed-off-by: Artem Savkov <asavkov@redhat.com>
Link: https://lore.kernel.org/r/20220810065905.475418-2-asavkov@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
| -rw-r--r-- | Documentation/bpf/kfuncs.rst | 9 | ||||
| -rw-r--r-- | include/linux/btf.h | 3 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
3 files changed, 16 insertions, 1 deletions
diff --git a/Documentation/bpf/kfuncs.rst b/Documentation/bpf/kfuncs.rst index c8b21de1c772..781731749e55 100644 --- a/Documentation/bpf/kfuncs.rst +++ b/Documentation/bpf/kfuncs.rst @@ -152,6 +152,15 @@ ensure the integrity of the operation being performed on the expected object. The KF_SLEEPABLE flag is used for kfuncs that may sleep. Such kfuncs can only be called by sleepable BPF programs (BPF_F_SLEEPABLE). +2.4.7 KF_DESTRUCTIVE flag +-------------------------- + +The KF_DESTRUCTIVE flag is used to indicate functions calling which is +destructive to the system. For example such a call can result in system +rebooting or panicking. Due to this additional restrictions apply to these +calls. At the moment they only require CAP_SYS_BOOT capability, but more can be +added later. + 2.5 Registering the kfuncs -------------------------- diff --git a/include/linux/btf.h b/include/linux/btf.h index 976cbdd2981f..ad93c2d9cc1c 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -49,7 +49,8 @@ * for this case. */ #define KF_TRUSTED_ARGS (1 << 4) /* kfunc only takes trusted pointer arguments */ -#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ +#define KF_SLEEPABLE (1 << 5) /* kfunc may sleep */ +#define KF_DESTRUCTIVE (1 << 6) /* kfunc performs destructive actions */ struct btf; struct btf_member; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 28b02dc67a2a..2c1f8069f7b7 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -7584,6 +7584,11 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, func_name); return -EACCES; } + if (*kfunc_flags & KF_DESTRUCTIVE && !capable(CAP_SYS_BOOT)) { + verbose(env, "destructive kfunc calls require CAP_SYS_BOOT capabilities\n"); + return -EACCES; + } + acq = *kfunc_flags & KF_ACQUIRE; /* Check the arguments */ |