Merge patch series "coredump: further cleanups"

Christian Brauner <brauner@kernel.org> says:

Continue reworking the coredump code so it's easier to follow and modify
in the future.

* Each method is moved into a separate helper.
* The cleanup code is simplified and unified.
* Entangle the dependency between the pipe coredump rate limiting and
  the common exit path.

It's likely that there'll be more.

* patches from https://lore.kernel.org/20250612-work-coredump-massage-v1-0-315c0c34ba94@kernel.org: (24 commits)
  coredump: add coredump_skip() helper
  coredump: avoid pointless variable
  coredump: order auto cleanup variables at the top
  coredump: add coredump_cleanup()
  coredump: auto cleanup prepare_creds()
  cred: add auto cleanup method
  coredump: directly return
  coredump: auto cleanup argv
  coredump: add coredump_write()
  coredump: use a single helper for the socket
  coredump: move pipe specific file check into coredump_pipe()
  coredump: split pipe coredumping into coredump_pipe()
  coredump: move core_pipe_count to global variable
  coredump: prepare to simplify exit paths
  coredump: split file coredumping into coredump_file()
  coredump: rename do_coredump() to vfs_coredump()
  selftests/coredump: make sure invalid paths are rejected
  coredump: validate socket path in coredump_parse()
  coredump: don't allow ".." in coredump socket path
  fs: move name_contains_dotdot() to header
  ...

Link: https://lore.kernel.org/20250612-work-coredump-massage-v1-0-315c0c34ba94@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>

3 files changed, 20 insertions, 2 deletions

diff --git a/include/linux/coredump.h b/include/linux/coredump.h
index 76e41805b92d..96e8a66da133 100644
--- a/include/linux/coredump.h
+++ b/include/linux/coredump.h
@@ -43,7 +43,7 @@ extern int dump_emit(struct coredump_params *cprm, const void *addr, int nr);
 extern int dump_align(struct coredump_params *cprm, int align);
 int dump_user_range(struct coredump_params *cprm, unsigned long start,
 		    unsigned long len);
-extern void do_coredump(const kernel_siginfo_t *siginfo);
+extern void vfs_coredump(const kernel_siginfo_t *siginfo);
 
 /*
  * Logging for the coredump code, ratelimited.
@@ -63,7 +63,7 @@ extern void do_coredump(const kernel_siginfo_t *siginfo);
 #define coredump_report_failure(fmt, ...) __COREDUMP_PRINTK(KERN_WARNING, fmt, ##__VA_ARGS__)
 
 #else
-static inline void do_coredump(const kernel_siginfo_t *siginfo) {}
+static inline void vfs_coredump(const kernel_siginfo_t *siginfo) {}
 
 #define coredump_report(...)
 #define coredump_report_failure(...)
diff --git a/include/linux/cred.h b/include/linux/cred.h
index 5658a3bfe803..a102a10f833f 100644
--- a/include/linux/cred.h
+++ b/include/linux/cred.h
@@ -263,6 +263,8 @@ static inline void put_cred(const struct cred *cred)
 	put_cred_many(cred, 1);
 }
 
+DEFINE_FREE(put_cred, struct cred *, if (!IS_ERR_OR_NULL(_T)) put_cred(_T))
+
 /**
  * current_cred - Access the current task's subjective credentials
  *
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 96c7925a6551..18fdbd184eea 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3264,6 +3264,22 @@ static inline bool is_dot_dotdot(const char *name, size_t len)
 		(len == 1 || (len == 2 && name[1] == '.'));
 }
 
+/**
+ * name_contains_dotdot - check if a file name contains ".." path components
+ *
+ * Search for ".." surrounded by either '/' or start/end of string.
+ */
+static inline bool name_contains_dotdot(const char *name)
+{
+	size_t name_len;
+
+	name_len = strlen(name);
+	return strcmp(name, "..") == 0 ||
+	       strncmp(name, "../", 3) == 0 ||
+	       strstr(name, "/../") != NULL ||
+	       (name_len >= 3 && strcmp(name + name_len - 3, "/..") == 0);
+}
+
 #include <linux/err.h>
 
 /* needed for stackable file system support */