Re: [PATCH v4 2/3] audit: add support for the openat2 syscall

From: Christian Brauner <hidden>
Date: 2021-05-20 07:58:52
Also in: linux-alpha, linux-fsdevel, linuxppc-dev, lkml, sparclinux

On Wed, May 19, 2021 at 04:00:21PM -0400, Richard Guy Briggs wrote:

quoted hunk ↗ jump to hunk

The openat2(2) syscall was added in kernel v5.6 with commit fddb5d430ad9
("open: introduce openat2(2) syscall")

Add the openat2(2) syscall to the audit syscall classifier.

Link: https://github.com/linux-audit/audit-kernel/issues/67
Signed-off-by: Richard Guy Briggs <redacted>
Link: https://lore.kernel.org/r/f5f1a4d8699613f8c02ce762807228c841c2e26f.1621363275.git.rgb@redhat.com (local)
---
 arch/alpha/kernel/audit.c           | 2 ++
 arch/ia64/kernel/audit.c            | 2 ++
 arch/parisc/kernel/audit.c          | 2 ++
 arch/parisc/kernel/compat_audit.c   | 2 ++
 arch/powerpc/kernel/audit.c         | 2 ++
 arch/powerpc/kernel/compat_audit.c  | 2 ++
 arch/s390/kernel/audit.c            | 2 ++
 arch/s390/kernel/compat_audit.c     | 2 ++
 arch/sparc/kernel/audit.c           | 2 ++
 arch/sparc/kernel/compat_audit.c    | 2 ++
 arch/x86/ia32/audit.c               | 2 ++
 arch/x86/kernel/audit_64.c          | 2 ++
 include/linux/auditsc_classmacros.h | 1 +
 kernel/auditsc.c                    | 3 +++
 lib/audit.c                         | 4 ++++
 lib/compat_audit.c                  | 4 ++++
 16 files changed, 36 insertions(+)

diff --git a/arch/alpha/kernel/audit.c b/arch/alpha/kernel/audit.c
index 81cbd804e375..3ab04709784a 100644
--- a/arch/alpha/kernel/audit.c
+++ b/arch/alpha/kernel/audit.c

@@ -42,6 +42,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 		return AUDITSC_OPENAT;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/ia64/kernel/audit.c b/arch/ia64/kernel/audit.c
index dba6a74c9ab3..ec61f20ca61f 100644
--- a/arch/ia64/kernel/audit.c
+++ b/arch/ia64/kernel/audit.c

@@ -43,6 +43,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 		return AUDITSC_OPENAT;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/parisc/kernel/audit.c b/arch/parisc/kernel/audit.c
index 14244e83db75..f420b5552140 100644
--- a/arch/parisc/kernel/audit.c
+++ b/arch/parisc/kernel/audit.c

@@ -52,6 +52,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 		return AUDITSC_OPENAT;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/parisc/kernel/compat_audit.c b/arch/parisc/kernel/compat_audit.c
index 1d6347d37d92..3ec490c28656 100644
--- a/arch/parisc/kernel/compat_audit.c
+++ b/arch/parisc/kernel/compat_audit.c

@@ -36,6 +36,8 @@ int parisc32_classify_syscall(unsigned syscall)
 		return AUDITSC_OPENAT;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_COMPAT;
 	}

diff --git a/arch/powerpc/kernel/audit.c b/arch/powerpc/kernel/audit.c
index 6eb18ef77dff..1bcfca5fdf67 100644
--- a/arch/powerpc/kernel/audit.c
+++ b/arch/powerpc/kernel/audit.c

@@ -54,6 +54,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/powerpc/kernel/compat_audit.c b/arch/powerpc/kernel/compat_audit.c
index b1dc2d1c4bad..251abf79d536 100644
--- a/arch/powerpc/kernel/compat_audit.c
+++ b/arch/powerpc/kernel/compat_audit.c

@@ -39,6 +39,8 @@ int ppc32_classify_syscall(unsigned syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_COMPAT;
 	}

diff --git a/arch/s390/kernel/audit.c b/arch/s390/kernel/audit.c
index 7e331e1831d4..02051a596b87 100644
--- a/arch/s390/kernel/audit.c
+++ b/arch/s390/kernel/audit.c

@@ -54,6 +54,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/s390/kernel/compat_audit.c b/arch/s390/kernel/compat_audit.c
index fc3d1c7ad21c..4b3d463e7d97 100644
--- a/arch/s390/kernel/compat_audit.c
+++ b/arch/s390/kernel/compat_audit.c

@@ -40,6 +40,8 @@ int s390_classify_syscall(unsigned syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_COMPAT;
 	}

diff --git a/arch/sparc/kernel/audit.c b/arch/sparc/kernel/audit.c
index 50fab35bdaba..b092274eca79 100644
--- a/arch/sparc/kernel/audit.c
+++ b/arch/sparc/kernel/audit.c

@@ -55,6 +55,8 @@ int audit_classify_syscall(int abi, unsigned int syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/arch/sparc/kernel/compat_audit.c b/arch/sparc/kernel/compat_audit.c
index 1c1b6d075421..2a3f71206fc5 100644
--- a/arch/sparc/kernel/compat_audit.c
+++ b/arch/sparc/kernel/compat_audit.c

@@ -40,6 +40,8 @@ int sparc32_classify_syscall(unsigned int syscall)
 		return AUDITSC_SOCKETCALL;
 	case __NR_execve:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_COMPAT;
 	}

diff --git a/arch/x86/ia32/audit.c b/arch/x86/ia32/audit.c
index eedc37a1ee13..efc7d832fefb 100644
--- a/arch/x86/ia32/audit.c
+++ b/arch/x86/ia32/audit.c

@@ -40,6 +40,8 @@ int ia32_classify_syscall(unsigned syscall)
 	case __NR_execve:
 	case __NR_execveat:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_COMPAT;
 	}

diff --git a/arch/x86/kernel/audit_64.c b/arch/x86/kernel/audit_64.c
index 2a6cc9c9c881..44c3601cfdc4 100644
--- a/arch/x86/kernel/audit_64.c
+++ b/arch/x86/kernel/audit_64.c

@@ -53,6 +53,8 @@ int audit_classify_syscall(int abi, unsigned syscall)
 	case __NR_execve:
 	case __NR_execveat:
 		return AUDITSC_EXECVE;
+	case __NR_openat2:
+		return AUDITSC_OPENAT2;
 	default:
 		return AUDITSC_NATIVE;
 	}

diff --git a/include/linux/auditsc_classmacros.h b/include/linux/auditsc_classmacros.h
index 18757d270961..dc8e72536dbd 100644
--- a/include/linux/auditsc_classmacros.h
+++ b/include/linux/auditsc_classmacros.h

@@ -16,6 +16,7 @@ enum auditsc_class_t {
 	AUDITSC_OPENAT,
 	AUDITSC_SOCKETCALL,
 	AUDITSC_EXECVE,
+	AUDITSC_OPENAT2,
 
 	AUDITSC_NVALS /* count */
 };

diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index d775ea16505b..3f59ab209dfd 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c

@@ -76,6 +76,7 @@
 #include <linux/fsnotify_backend.h>
 #include <uapi/linux/limits.h>
 #include <uapi/linux/netfilter/nf_tables.h>
+#include <uapi/linux/openat2.h>
 
 #include "audit.h"

@@ -196,6 +197,8 @@ static int audit_match_perm(struct audit_context *ctx, int mask)
 		return ((mask & AUDIT_PERM_WRITE) && ctx->argv[0] == SYS_BIND);
 	case AUDITSC_EXECVE:
 		return mask & AUDIT_PERM_EXEC;
+	case AUDITSC_OPENAT2:
+		return mask & ACC_MODE((u32)((struct open_how *)ctx->argv[2])->flags);

That's a lot of dereferncing, casting and masking all at once. Maybe a
small static inline helper would be good for the sake of legibility? Sm
like:

static inline u32 audit_openat2_acc(struct open_how *how, int mask)
{
	u32 flags = how->flags;
	return mask & ACC_MODE(flags);
}

but not sure. Just seems more legible to me.
Otherwise.
Acked-by: Christian Brauner <redacted>

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