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Date: Mon, 2 Feb 2015 18:05:09 +0100
From: Alexander Holler <holler@...oftware.de>
To: linux-fsdevel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
Alexander Holler <holler@...oftware.de>
Subject: [PATCH 1/5] WIP: Add syscall unlinkat_s (currently x86* only)
Signed-off-by: Alexander Holler <holler@...oftware.de>
---
arch/x86/syscalls/syscall_32.tbl | 1 +
arch/x86/syscalls/syscall_64.tbl | 1 +
fs/namei.c | 38 ++++++++++++++++++++++++++++++-----
include/asm-generic/audit_dir_write.h | 1 +
include/linux/fs.h | 1 +
include/linux/syscalls.h | 1 +
include/uapi/asm-generic/unistd.h | 4 +++-
tools/perf/builtin-trace.c | 2 ++
8 files changed, 43 insertions(+), 6 deletions(-)
diff --git a/arch/x86/syscalls/syscall_32.tbl b/arch/x86/syscalls/syscall_32.tbl
index 9fe1b5d..7a3d530 100644
--- a/arch/x86/syscalls/syscall_32.tbl
+++ b/arch/x86/syscalls/syscall_32.tbl
@@ -364,3 +364,4 @@
355 i386 getrandom sys_getrandom
356 i386 memfd_create sys_memfd_create
357 i386 bpf sys_bpf
+359 i386 unlinkat_s sys_unlinkat_s
diff --git a/arch/x86/syscalls/syscall_64.tbl b/arch/x86/syscalls/syscall_64.tbl
index 281150b..97eaf01 100644
--- a/arch/x86/syscalls/syscall_64.tbl
+++ b/arch/x86/syscalls/syscall_64.tbl
@@ -328,6 +328,7 @@
319 common memfd_create sys_memfd_create
320 common kexec_file_load sys_kexec_file_load
321 common bpf sys_bpf
+322 common unlinkat_s sys_unlinkat_s
#
# x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/namei.c b/fs/namei.c
index db5fe86..1ad3724 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3717,7 +3717,7 @@ EXPORT_SYMBOL(vfs_unlink);
* writeout happening, and we don't want to prevent access to the directory
* while waiting on the I/O.
*/
-static long do_unlinkat(int dfd, const char __user *pathname)
+static long do_unlinkat(int dfd, const char __user *pathname, bool secure)
{
int error;
struct filename *name;
@@ -3759,8 +3759,25 @@ exit2:
dput(dentry);
}
mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
- if (inode)
- iput(inode); /* truncate the inode here */
+ if (inode) {
+ // TODO:
+ // if (inode is file and 's' flag is set)
+ // secure = true;
+ if (!secure)
+ iput(inode); /* truncate the inode here */
+ else {
+ struct super_block *sb = inode->i_sb;
+ if (sb->s_op->set_secure_delete)
+ sb->s_op->set_secure_delete(sb, true);
+ // TODO: We should fail if secure isn't supported,
+ // look up how that's possible here.
+ iput(inode); /* truncate the inode here */
+ // TODO: check if sb is still valid after the inode is gone
+ sync_filesystem(sb);
+ if (sb->s_op->set_secure_delete)
+ sb->s_op->set_secure_delete(sb, false);
+ }
+ }
inode = NULL;
if (delegated_inode) {
error = break_deleg_wait(&delegated_inode);
@@ -3796,12 +3813,23 @@ SYSCALL_DEFINE3(unlinkat, int, dfd, const char __user *, pathname, int, flag)
if (flag & AT_REMOVEDIR)
return do_rmdir(dfd, pathname);
- return do_unlinkat(dfd, pathname);
+ return do_unlinkat(dfd, pathname, false);
}
SYSCALL_DEFINE1(unlink, const char __user *, pathname)
{
- return do_unlinkat(AT_FDCWD, pathname);
+ return do_unlinkat(AT_FDCWD, pathname, false);
+}
+
+SYSCALL_DEFINE3(unlinkat_s, int, dfd, const char __user *, pathname, int, flag)
+{
+ if ((flag & ~AT_REMOVEDIR) != 0)
+ return -EINVAL;
+
+ if (flag & AT_REMOVEDIR)
+ return do_rmdir(dfd, pathname);
+
+ return do_unlinkat(dfd, pathname, true);
}
int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
diff --git a/include/asm-generic/audit_dir_write.h b/include/asm-generic/audit_dir_write.h
index 7b61db4..5282aba 100644
--- a/include/asm-generic/audit_dir_write.h
+++ b/include/asm-generic/audit_dir_write.h
@@ -29,4 +29,5 @@ __NR_unlinkat,
__NR_renameat,
__NR_linkat,
__NR_symlinkat,
+__NR_unlinkat_s,
#endif
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9ab779e..039e969 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1594,6 +1594,7 @@ struct super_operations {
int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
long (*nr_cached_objects)(struct super_block *, int);
long (*free_cached_objects)(struct super_block *, long, int);
+ void (*set_secure_delete) (struct super_block *, bool);
};
/*
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index bda9b81..b88019b 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -877,4 +877,5 @@ asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
asmlinkage long sys_getrandom(char __user *buf, size_t count,
unsigned int flags);
asmlinkage long sys_bpf(int cmd, union bpf_attr *attr, unsigned int size);
+asmlinkage long sys_unlinkat_s(int dfd, const char __user * pathname, int flag);
#endif
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 22749c1..2ba072e 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -707,9 +707,11 @@ __SYSCALL(__NR_getrandom, sys_getrandom)
__SYSCALL(__NR_memfd_create, sys_memfd_create)
#define __NR_bpf 280
__SYSCALL(__NR_bpf, sys_bpf)
+#define __NR_unlinkat_s 281
+__SYSCALL(__NR_unlinkat_s, sys_unlinkat_s)
#undef __NR_syscalls
-#define __NR_syscalls 281
+#define __NR_syscalls 282
/*
* All syscalls below here should go away really,
diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index fb12645..1507335 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1110,6 +1110,8 @@ static struct syscall_fmt {
{ .name = "uname", .errmsg = true, .alias = "newuname", },
{ .name = "unlinkat", .errmsg = true,
.arg_scnprintf = { [0] = SCA_FDAT, /* dfd */ }, },
+ { .name = "unlinkat_s", .errmsg = true,
+ .arg_scnprintf = { [0] = SCA_FDAT, /* dfd */ }, },
{ .name = "utimensat", .errmsg = true,
.arg_scnprintf = { [0] = SCA_FDAT, /* dirfd */ }, },
{ .name = "write", .errmsg = true,
--
2.1.0
--
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