On AIX, access(X_OK) may succeed when run as root even if the
execution isn't possible. This behavior is allowed by POSIX
which says:
... for a process with appropriate privileges, an implementation
may indicate success for X_OK even if execute permission is not
granted to any user.
It can lead hook programs to have their execution refused:
git commit -m content
fatal: cannot exec '.git/hooks/pre-commit': Permission denied
Add NEED_ACCESS_ROOT_HANDLER in order to use an access helper function.
It checks with stat if any executable flags is set when the current user
is root.
Signed-off-by: Clément Chigot <clement.chigot@xxxxxxxx>
Message-ID: <AM6PR02MB4950ED66291B16F35BE61A26EA3C0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>
---
Makefile | 8 ++++++++
compat/access.c | 31 +++++++++++++++++++++++++++++++
compat/fileno.c | 2 +-
config.mak.uname | 1 +
git-compat-util.h | 12 +++++++++++-
5 files changed, 52 insertions(+), 2 deletions(-)
create mode 100644 compat/access.c
diff --git a/Makefile b/Makefile
index 9f1b6e8926..6ac7218106 100644
--- a/Makefile
+++ b/Makefile
@@ -439,6 +439,9 @@ all::
#
# Define FILENO_IS_A_MACRO if fileno() is a macro, not a real function.
#
+# Define NEED_ACCESS_ROOT_HANDLER if access() under root may success for X_OK
+# even if execution permission isn't granted for any user.
+#
# Define PAGER_ENV to a SP separated VAR=VAL pairs to define
# default environment variables to be passed when a pager is spawned, e.g.
#
@@ -1833,6 +1836,11 @@ ifdef FILENO_IS_A_MACRO
COMPAT_OBJS += compat/fileno.o
endif
+ifdef NEED_ACCESS_ROOT_HANDLER
+ COMPAT_CFLAGS += -DNEED_ACCESS_ROOT_HANDLER
+ COMPAT_OBJS += compat/access.o
+endif
+
ifeq ($(TCLTK_PATH),)
NO_TCLTK = NoThanks
endif
diff --git a/compat/access.c b/compat/access.c
new file mode 100644
index 0000000000..19fda3e877
--- /dev/null
+++ b/compat/access.c
@@ -0,0 +1,31 @@
+#define COMPAT_CODE_ACCESS
+#include "../git-compat-util.h"
+
+/* Do the same thing access(2) does, but use the effective uid,
+ * and don't make the mistake of telling root that any file is
+ * executable. This version uses stat(2).
+ */
+int git_access(const char *path, int mode)
+{
+ struct stat st;
+
+ /* do not interfere a normal user */
+ if (geteuid())
+ return access(path, mode);
+
+ if (stat(path, &st) < 0)
+ return -1;
+
+ /* Root can read or write any file. */
+ if (!(mode & X_OK))
+ return 0;
+
+ /* Root can execute any file that has any one of the execute
+ * bits set.
+ */
+ if (st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH))
+ return 0;
+
+ errno = EACCES;
+ return -1;
+}
diff --git a/compat/fileno.c b/compat/fileno.c
index 7b105f4cd7..8e80ef335d 100644
--- a/compat/fileno.c
+++ b/compat/fileno.c
@@ -1,4 +1,4 @@
-#define COMPAT_CODE
+#define COMPAT_CODE_FILENO
#include "../git-compat-util.h"
int git_fileno(FILE *stream)
diff --git a/config.mak.uname b/config.mak.uname
index 86cbe47627..ce13ab8295 100644
--- a/config.mak.uname
+++ b/config.mak.uname
@@ -270,6 +270,7 @@ ifeq ($(uname_S),AIX)
NEEDS_LIBICONV = YesPlease
BASIC_CFLAGS += -D_LARGE_FILES
FILENO_IS_A_MACRO = UnfortunatelyYes
+ NEED_ACCESS_ROOT_HANDLER = UnfortunatelyYes
ifeq ($(shell expr "$(uname_V)" : '[1234]'),1)
NO_PTHREADS = YesPlease
else
diff --git a/git-compat-util.h b/git-compat-util.h
index 31b47932bd..bdca50e64d 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1236,12 +1236,22 @@ struct tm *git_gmtime_r(const time_t *, struct tm *);
#ifdef FILENO_IS_A_MACRO
int git_fileno(FILE *stream);
-# ifndef COMPAT_CODE
+# ifndef COMPAT_CODE_FILENO
# undef fileno
# define fileno(p) git_fileno(p)
# endif
#endif
+#ifdef NEED_ACCESS_ROOT_HANDLER
+int git_access(const char *path, int mode);
+# ifndef COMPAT_CODE_ACCESS
+# ifdef access
+# undef access
+# endif
+# define access(path, mode) git_access(path, mode)
+# endif
+#endif
+
/*
* Our code often opens a path to an optional file, to work on its
* contents when we can successfully open it. We can ignore a failure
--
2.17.1
Clément Chigot
ATOS Bull SAS
1 rue de Provence - 38432 Échirolles - France
