linux-kernel - [PATCH 1/2] fscontext: add custom-prefix log helpers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250806-errorfc-mount-too-revealing-v1-1-536540f51560@cyphar.com>
Date: Wed, 06 Aug 2025 14:48:29 +1000
From: Aleksa Sarai <cyphar@...har.com>
To: Alexander Viro <viro@...iv.linux.org.uk>, 
 Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>
Cc: David Howells <dhowells@...hat.com>, linux-api@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
 Aleksa Sarai <cyphar@...har.com>
Subject: [PATCH 1/2] fscontext: add custom-prefix log helpers

Sometimes, errors associated with an fscontext come from the VFS or
otherwise outside of the filesystem driver itself. However, the default
logging of errorfc will always prefix the message with the filesystem
name.

So, add some *fcp() wrappers that allow for custom prefixes to be used
when emitting information to the fscontext log.

Signed-off-by: Aleksa Sarai <cyphar@...har.com>
---
 include/linux/fs_context.h | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/include/linux/fs_context.h b/include/linux/fs_context.h
index 7773eb870039..671f031be173 100644
--- a/include/linux/fs_context.h
+++ b/include/linux/fs_context.h
@@ -186,10 +186,12 @@ struct fc_log {
 extern __attribute__((format(printf, 4, 5)))
 void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt, ...);
 
-#define __logfc(fc, l, fmt, ...) logfc((fc)->log.log, NULL, \
-					l, fmt, ## __VA_ARGS__)
-#define __plog(p, l, fmt, ...) logfc((p)->log, (p)->prefix, \
-					l, fmt, ## __VA_ARGS__)
+#define __logfc(fc, l, fmt, ...) \
+	logfc((fc)->log.log, NULL, (l), (fmt), ## __VA_ARGS__)
+#define __plogp(p, prefix, l, fmt, ...) \
+	logfc((p)->log, (prefix), (l), (fmt), ## __VA_ARGS__)
+#define __plog(p, l, fmt, ...) __plogp(p, (p)->prefix, l, fmt, ## __VA_ARGS__)
+
 /**
  * infof - Store supplementary informational message
  * @fc: The context in which to log the informational message
@@ -201,6 +203,8 @@ void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt,
 #define infof(fc, fmt, ...) __logfc(fc, 'i', fmt, ## __VA_ARGS__)
 #define info_plog(p, fmt, ...) __plog(p, 'i', fmt, ## __VA_ARGS__)
 #define infofc(fc, fmt, ...) __plog((&(fc)->log), 'i', fmt, ## __VA_ARGS__)
+#define infofcp(fc, prefix, fmt, ...) \
+	__plogp((&(fc)->log), prefix, 'i', fmt, ## __VA_ARGS__)
 
 /**
  * warnf - Store supplementary warning message
@@ -213,6 +217,8 @@ void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt,
 #define warnf(fc, fmt, ...) __logfc(fc, 'w', fmt, ## __VA_ARGS__)
 #define warn_plog(p, fmt, ...) __plog(p, 'w', fmt, ## __VA_ARGS__)
 #define warnfc(fc, fmt, ...) __plog((&(fc)->log), 'w', fmt, ## __VA_ARGS__)
+#define warnfcp(fc, prefix, fmt, ...) \
+	__plogp((&(fc)->log), prefix, 'w', fmt, ## __VA_ARGS__)
 
 /**
  * errorf - Store supplementary error message
@@ -225,6 +231,8 @@ void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt,
 #define errorf(fc, fmt, ...) __logfc(fc, 'e', fmt, ## __VA_ARGS__)
 #define error_plog(p, fmt, ...) __plog(p, 'e', fmt, ## __VA_ARGS__)
 #define errorfc(fc, fmt, ...) __plog((&(fc)->log), 'e', fmt, ## __VA_ARGS__)
+#define errorfcp(fc, prefix, fmt, ...) \
+	__plogp((&(fc)->log), prefix, 'e', fmt, ## __VA_ARGS__)
 
 /**
  * invalf - Store supplementary invalid argument error message
@@ -237,5 +245,7 @@ void logfc(struct fc_log *log, const char *prefix, char level, const char *fmt,
 #define invalf(fc, fmt, ...) (errorf(fc, fmt, ## __VA_ARGS__), -EINVAL)
 #define inval_plog(p, fmt, ...) (error_plog(p, fmt, ## __VA_ARGS__), -EINVAL)
 #define invalfc(fc, fmt, ...) (errorfc(fc, fmt, ## __VA_ARGS__), -EINVAL)
+#define invalfcp(fc, prefix, fmt, ...) \
+	(errorfcp(fc, prefix, fmt, ## __VA_ARGS__), -EINVAL)
 
 #endif /* _LINUX_FS_CONTEXT_H */

-- 
2.50.1