diff mbox series

[RFC,bpf-next,1/2] bpf: add signature to eBPF instructions

Message ID 20211012190028.54828-2-mcroce@linux.microsoft.com (mailing list archive)
State RFC
Delegated to: BPF
Headers show
Series bpf: sign bpf programs | expand

Checks

Context Check Description
bpf/vmtest-bpf-next fail VM_Test
bpf/vmtest-bpf-next-PR fail PR summary
netdev/cover_letter success Series has a cover letter
netdev/fixes_present success Fixes tag not required for -next series
netdev/patch_count success Link
netdev/tree_selection success Clearly marked for bpf-next
netdev/subject_prefix success Link
netdev/cc_maintainers warning 6 maintainers not CCed: songliubraving@fb.com yhs@fb.com john.fastabend@gmail.com kafai@fb.com netdev@vger.kernel.org kpsingh@kernel.org
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/module_param success Was 0 now: 0
netdev/build_32bit fail Errors and warnings before: 11790 this patch: 11793
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success No Fixes tag
netdev/checkpatch fail ERROR: "(foo*)" should be "(foo *)" WARNING: line length of 81 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns WARNING: printk() should include KERN_<LEVEL> facility level
netdev/build_allmodconfig_warn fail Errors and warnings before: 11421 this patch: 11422
netdev/header_inline success No static functions without inline keyword in header files

Commit Message

Matteo Croce Oct. 12, 2021, 7 p.m. UTC 
From: Matteo Croce <mcroce@microsoft.com>

When loading a BPF program, pass a signature which is used to validate
the instructions.
The signature type is the same used to validate the kernel modules.

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
---
 include/uapi/linux/bpf.h |  2 ++
 kernel/bpf/syscall.c     | 33 ++++++++++++++++++++++++++++++++-
 2 files changed, 34 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index c2b8857b8a1c..b9d259f26e92 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1336,6 +1336,8 @@  union bpf_attr {
 		};
 		__u32		:32;		/* pad */
 		__aligned_u64	fd_array;	/* array of FDs */
+		__aligned_u64	signature;	/* instruction's signature */
+		__u32		sig_len;	/* signature size */
 	};
 
 	struct { /* anonymous struct used by BPF_OBJ_* commands */
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 3c349b244a28..5589f655033d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -31,6 +31,8 @@ 
 #include <linux/bpf-netns.h>
 #include <linux/rcupdate_trace.h>
 #include <linux/memcontrol.h>
+#include <linux/verification.h>
+#include <linux/module_signature.h>
 
 #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
 			  (map)->map_type == BPF_MAP_TYPE_CGROUP_ARRAY || \
@@ -2156,7 +2158,7 @@  static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
 }
 
 /* last field in 'union bpf_attr' used by this command */
-#define	BPF_PROG_LOAD_LAST_FIELD fd_array
+#define	BPF_PROG_LOAD_LAST_FIELD sig_len
 
 static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 {
@@ -2274,6 +2276,35 @@  static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
 			     bpf_prog_insn_size(prog)) != 0)
 		goto free_prog_sec;
 
+	if (attr->sig_len) {
+		char *signature;
+
+		signature = kmalloc(attr->sig_len, GFP_USER);
+		if (!signature) {
+			err = -ENOMEM;
+			goto free_prog_sec;
+		}
+
+		if (copy_from_user(signature, (char *)attr->signature, attr->sig_len)) {
+			err = -EFAULT;
+			kfree(signature);
+			goto free_prog_sec;
+		}
+
+		err = verify_pkcs7_signature(prog->insns,
+					     prog->len * sizeof(struct bpf_insn),
+					     signature, attr->sig_len,
+					     VERIFY_USE_SECONDARY_KEYRING,
+					     VERIFYING_MODULE_SIGNATURE,
+					     NULL, NULL);
+		kfree(signature);
+
+		if (err) {
+			printk("verify_pkcs7_signature(): %pe\n", (void*)(uintptr_t)err);
+			goto free_prog_sec;
+		}
+	}
+
 	prog->orig_prog = NULL;
 	prog->jited = 0;