From ed9d95f691c29748f21bc019de9566b698fdfab7 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 11 Nov 2024 10:09:56 -0500 Subject: fs: add the ability for statmount() to report the fs_subtype /proc/self/mountinfo prints out the sb->s_subtype after the type. This is particularly useful for disambiguating FUSE mounts (at least when the userland driver bothers to set it). Add STATMOUNT_FS_SUBTYPE and claim one of the __spare2 fields to point to the offset into the str[] array. Reviewed-by: Jan Kara Reviewed-by: Ian Kent Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20241111-statmount-v4-2-2eaf35d07a80@kernel.org Acked-by: Miklos Szeredi Signed-off-by: Christian Brauner --- include/uapi/linux/mount.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/uapi/linux/mount.h') diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 225bc366ffcb..2e939dddf9cb 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -173,7 +173,9 @@ struct statmount { __u32 mnt_root; /* [str] Root of mount relative to root of fs */ __u32 mnt_point; /* [str] Mountpoint relative to current root */ __u64 mnt_ns_id; /* ID of the mount namespace */ - __u64 __spare2[49]; + __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ + __u32 __spare1[1]; + __u64 __spare2[48]; char str[]; /* Variable size part containing strings */ }; @@ -207,6 +209,7 @@ struct mnt_id_req { #define STATMOUNT_FS_TYPE 0x00000020U /* Want/got fs_type */ #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ +#define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ /* * Special @mnt_id values that can be passed to listmount -- cgit v1.2.3 From 44010543fc8bedad172aa5b6c43480e5d2124497 Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Mon, 11 Nov 2024 10:09:57 -0500 Subject: fs: add the ability for statmount() to report the sb_source /proc/self/mountinfo displays the source for the mount, but statmount() doesn't yet have a way to return it. Add a new STATMOUNT_SB_SOURCE flag, claim the 32-bit __spare1 field to hold the offset into the str[] array. Reviewed-by: Jan Kara Signed-off-by: Jeff Layton Link: https://lore.kernel.org/r/20241111-statmount-v4-3-2eaf35d07a80@kernel.org Acked-by: Miklos Szeredi Signed-off-by: Christian Brauner --- fs/namespace.c | 36 +++++++++++++++++++++++++++++++++++- include/uapi/linux/mount.h | 3 ++- 2 files changed, 37 insertions(+), 2 deletions(-) (limited to 'include/uapi/linux/mount.h') diff --git a/fs/namespace.c b/fs/namespace.c index dbd89fffd919..d32b5afa99dc 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5012,6 +5012,32 @@ static void statmount_fs_subtype(struct kstatmount *s, struct seq_file *seq) seq_puts(seq, sb->s_subtype); } +static int statmount_sb_source(struct kstatmount *s, struct seq_file *seq) +{ + struct super_block *sb = s->mnt->mnt_sb; + struct mount *r = real_mount(s->mnt); + + if (sb->s_op->show_devname) { + size_t start = seq->count; + int ret; + + ret = sb->s_op->show_devname(seq, s->mnt->mnt_root); + if (ret) + return ret; + + if (unlikely(seq_has_overflowed(seq))) + return -EAGAIN; + + /* Unescape the result */ + seq->buf[seq->count] = '\0'; + seq->count = start; + seq_commit(seq, string_unescape_inplace(seq->buf + start, UNESCAPE_OCTAL)); + } else if (r->mnt_devname) { + seq_puts(seq, r->mnt_devname); + } + return 0; +} + static void statmount_mnt_ns_id(struct kstatmount *s, struct mnt_namespace *ns) { s->sm.mask |= STATMOUNT_MNT_NS_ID; @@ -5075,6 +5101,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->fs_subtype = start; statmount_fs_subtype(s, seq); break; + case STATMOUNT_SB_SOURCE: + sm->sb_source = start; + ret = statmount_sb_source(s, seq); + break; default: WARN_ON_ONCE(true); return -EINVAL; @@ -5223,6 +5253,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_FS_SUBTYPE) err = statmount_string(s, STATMOUNT_FS_SUBTYPE); + if (!err && s->mask & STATMOUNT_SB_SOURCE) + err = statmount_string(s, STATMOUNT_SB_SOURCE); + if (!err && s->mask & STATMOUNT_MNT_NS_ID) statmount_mnt_ns_id(s, ns); @@ -5244,7 +5277,8 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) } #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ - STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | STATMOUNT_FS_SUBTYPE) + STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | \ + STATMOUNT_FS_SUBTYPE | STATMOUNT_SB_SOURCE) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 2e939dddf9cb..2b49e9131d77 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -174,7 +174,7 @@ struct statmount { __u32 mnt_point; /* [str] Mountpoint relative to current root */ __u64 mnt_ns_id; /* ID of the mount namespace */ __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ - __u32 __spare1[1]; + __u32 sb_source; /* [str] Source string of the mount */ __u64 __spare2[48]; char str[]; /* Variable size part containing strings */ }; @@ -210,6 +210,7 @@ struct mnt_id_req { #define STATMOUNT_MNT_NS_ID 0x00000040U /* Want/got mnt_ns_id */ #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ #define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ +#define STATMOUNT_SB_SOURCE 0x00000200U /* Want/got sb_source */ /* * Special @mnt_id values that can be passed to listmount -- cgit v1.2.3 From 2f4d4503e9e5ab765a7948f98bc5deef7850f607 Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Tue, 12 Nov 2024 11:10:04 +0100 Subject: statmount: add flag to retrieve unescaped options Filesystem options can be retrieved with STATMOUNT_MNT_OPTS, which returns a string of comma separated options, where some characters are escaped using the \OOO notation. Add a new flag, STATMOUNT_OPT_ARRAY, which instead returns the raw option values separated with '\0' charaters. Since escaped charaters are rare, this inteface is preferable for non-libmount users which likley don't want to deal with option de-escaping. Example code: if (st->mask & STATMOUNT_OPT_ARRAY) { const char *opt = st->str + st->opt_array; for (unsigned int i = 0; i < st->opt_num; i++) { printf("opt_array[%i]: <%s>\n", i, opt); opt += strlen(opt) + 1; } } Example ouput: (1) mnt_opts: (2) opt_array[0]: opt_array[1]: opt_array[2]: opt_array[3]: opt_array[4]: opt_array[5]: Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20241112101006.30715-1-mszeredi@redhat.com Acked-by: Jeff Layton [brauner: tweak variable naming and parsing add example output] Signed-off-by: Christian Brauner --- fs/namespace.c | 47 +++++++++++++++++++++++++++++++++++++++++++++- include/uapi/linux/mount.h | 7 +++++-- 2 files changed, 51 insertions(+), 3 deletions(-) (limited to 'include/uapi/linux/mount.h') diff --git a/fs/namespace.c b/fs/namespace.c index d32b5afa99dc..4f39c4aba85d 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5072,6 +5072,43 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq) return 0; } +static int statmount_opt_array(struct kstatmount *s, struct seq_file *seq) +{ + struct vfsmount *mnt = s->mnt; + struct super_block *sb = mnt->mnt_sb; + size_t start = seq->count; + char *buf_start, *buf_end, *opt_start, *opt_end; + u32 count = 0; + int err; + + if (!sb->s_op->show_options) + return 0; + + buf_start = seq->buf + start; + err = sb->s_op->show_options(seq, mnt->mnt_root); + if (err) + return err; + + if (unlikely(seq_has_overflowed(seq))) + return -EAGAIN; + + if (seq->count == start) + return 0; + + buf_end = seq->buf + seq->count; + *buf_end = '\0'; + for (opt_start = buf_start + 1; opt_start < buf_end; opt_start = opt_end + 1) { + opt_end = strchrnul(opt_start, ','); + *opt_end = '\0'; + buf_start += string_unescape(opt_start, buf_start, 0, UNESCAPE_OCTAL) + 1; + if (WARN_ON_ONCE(++count == 0)) + return -EOVERFLOW; + } + seq->count = buf_start - 1 - seq->buf; + s->sm.opt_num = count; + return 0; +} + static int statmount_string(struct kstatmount *s, u64 flag) { int ret = 0; @@ -5097,6 +5134,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->mnt_opts = start; ret = statmount_mnt_opts(s, seq); break; + case STATMOUNT_OPT_ARRAY: + sm->opt_array = start; + ret = statmount_opt_array(s, seq); + break; case STATMOUNT_FS_SUBTYPE: sm->fs_subtype = start; statmount_fs_subtype(s, seq); @@ -5250,6 +5291,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_MNT_OPTS) err = statmount_string(s, STATMOUNT_MNT_OPTS); + if (!err && s->mask & STATMOUNT_OPT_ARRAY) + err = statmount_string(s, STATMOUNT_OPT_ARRAY); + if (!err && s->mask & STATMOUNT_FS_SUBTYPE) err = statmount_string(s, STATMOUNT_FS_SUBTYPE); @@ -5278,7 +5322,8 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | \ - STATMOUNT_FS_SUBTYPE | STATMOUNT_SB_SOURCE) + STATMOUNT_FS_SUBTYPE | STATMOUNT_SB_SOURCE | \ + STATMOUNT_OPT_ARRAY) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index 2b49e9131d77..c0fda4604187 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -154,7 +154,7 @@ struct mount_attr { */ struct statmount { __u32 size; /* Total size, including strings */ - __u32 mnt_opts; /* [str] Mount options of the mount */ + __u32 mnt_opts; /* [str] Options (comma separated, escaped) */ __u64 mask; /* What results were written */ __u32 sb_dev_major; /* Device ID */ __u32 sb_dev_minor; @@ -175,7 +175,9 @@ struct statmount { __u64 mnt_ns_id; /* ID of the mount namespace */ __u32 fs_subtype; /* [str] Subtype of fs_type (if any) */ __u32 sb_source; /* [str] Source string of the mount */ - __u64 __spare2[48]; + __u32 opt_num; /* Number of fs options */ + __u32 opt_array; /* [str] Array of nul terminated fs options */ + __u64 __spare2[47]; char str[]; /* Variable size part containing strings */ }; @@ -211,6 +213,7 @@ struct mnt_id_req { #define STATMOUNT_MNT_OPTS 0x00000080U /* Want/got mnt_opts */ #define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ #define STATMOUNT_SB_SOURCE 0x00000200U /* Want/got sb_source */ +#define STATMOUNT_OPT_ARRAY 0x00000400U /* Want/got opt_... */ /* * Special @mnt_id values that can be passed to listmount -- cgit v1.2.3 From aefff51e1c2986e16f2780ca8e4c97b784800ab5 Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Thu, 14 Nov 2024 16:31:27 +0100 Subject: statmount: retrieve security mount options Add the ability to retrieve security mount options. Keep them separate from filesystem specific mount options so it's easy to tell them apart. Also allow to retrieve them separate from other mount options as most of the time users won't be interested in security specific mount options. Link: https://lore.kernel.org/r/20241114-radtour-ofenrohr-ff34b567b40a@brauner Reviewed-by: Jeff Layton Signed-off-by: Christian Brauner --- fs/namespace.c | 74 +++++++++++++++++++++++++++++++++++++--------- include/uapi/linux/mount.h | 5 +++- 2 files changed, 64 insertions(+), 15 deletions(-) (limited to 'include/uapi/linux/mount.h') diff --git a/fs/namespace.c b/fs/namespace.c index 4f39c4aba85d..a9065a9ab971 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -5072,13 +5072,30 @@ static int statmount_mnt_opts(struct kstatmount *s, struct seq_file *seq) return 0; } +static inline int statmount_opt_unescape(struct seq_file *seq, char *buf_start) +{ + char *buf_end, *opt_start, *opt_end; + int count = 0; + + buf_end = seq->buf + seq->count; + *buf_end = '\0'; + for (opt_start = buf_start + 1; opt_start < buf_end; opt_start = opt_end + 1) { + opt_end = strchrnul(opt_start, ','); + *opt_end = '\0'; + buf_start += string_unescape(opt_start, buf_start, 0, UNESCAPE_OCTAL) + 1; + if (WARN_ON_ONCE(++count == INT_MAX)) + return -EOVERFLOW; + } + seq->count = buf_start - 1 - seq->buf; + return count; +} + static int statmount_opt_array(struct kstatmount *s, struct seq_file *seq) { struct vfsmount *mnt = s->mnt; struct super_block *sb = mnt->mnt_sb; size_t start = seq->count; - char *buf_start, *buf_end, *opt_start, *opt_end; - u32 count = 0; + char *buf_start; int err; if (!sb->s_op->show_options) @@ -5095,17 +5112,39 @@ static int statmount_opt_array(struct kstatmount *s, struct seq_file *seq) if (seq->count == start) return 0; - buf_end = seq->buf + seq->count; - *buf_end = '\0'; - for (opt_start = buf_start + 1; opt_start < buf_end; opt_start = opt_end + 1) { - opt_end = strchrnul(opt_start, ','); - *opt_end = '\0'; - buf_start += string_unescape(opt_start, buf_start, 0, UNESCAPE_OCTAL) + 1; - if (WARN_ON_ONCE(++count == 0)) - return -EOVERFLOW; - } - seq->count = buf_start - 1 - seq->buf; - s->sm.opt_num = count; + err = statmount_opt_unescape(seq, buf_start); + if (err < 0) + return err; + + s->sm.opt_num = err; + return 0; +} + +static int statmount_opt_sec_array(struct kstatmount *s, struct seq_file *seq) +{ + struct vfsmount *mnt = s->mnt; + struct super_block *sb = mnt->mnt_sb; + size_t start = seq->count; + char *buf_start; + int err; + + buf_start = seq->buf + start; + + err = security_sb_show_options(seq, sb); + if (!err) + return err; + + if (unlikely(seq_has_overflowed(seq))) + return -EAGAIN; + + if (seq->count == start) + return 0; + + err = statmount_opt_unescape(seq, buf_start); + if (err < 0) + return err; + + s->sm.opt_sec_num = err; return 0; } @@ -5138,6 +5177,10 @@ static int statmount_string(struct kstatmount *s, u64 flag) sm->opt_array = start; ret = statmount_opt_array(s, seq); break; + case STATMOUNT_OPT_SEC_ARRAY: + sm->opt_sec_array = start; + ret = statmount_opt_sec_array(s, seq); + break; case STATMOUNT_FS_SUBTYPE: sm->fs_subtype = start; statmount_fs_subtype(s, seq); @@ -5294,6 +5337,9 @@ static int do_statmount(struct kstatmount *s, u64 mnt_id, u64 mnt_ns_id, if (!err && s->mask & STATMOUNT_OPT_ARRAY) err = statmount_string(s, STATMOUNT_OPT_ARRAY); + if (!err && s->mask & STATMOUNT_OPT_SEC_ARRAY) + err = statmount_string(s, STATMOUNT_OPT_SEC_ARRAY); + if (!err && s->mask & STATMOUNT_FS_SUBTYPE) err = statmount_string(s, STATMOUNT_FS_SUBTYPE); @@ -5323,7 +5369,7 @@ static inline bool retry_statmount(const long ret, size_t *seq_size) #define STATMOUNT_STRING_REQ (STATMOUNT_MNT_ROOT | STATMOUNT_MNT_POINT | \ STATMOUNT_FS_TYPE | STATMOUNT_MNT_OPTS | \ STATMOUNT_FS_SUBTYPE | STATMOUNT_SB_SOURCE | \ - STATMOUNT_OPT_ARRAY) + STATMOUNT_OPT_ARRAY | STATMOUNT_OPT_SEC_ARRAY) static int prepare_kstatmount(struct kstatmount *ks, struct mnt_id_req *kreq, struct statmount __user *buf, size_t bufsize, diff --git a/include/uapi/linux/mount.h b/include/uapi/linux/mount.h index c0fda4604187..c07008816aca 100644 --- a/include/uapi/linux/mount.h +++ b/include/uapi/linux/mount.h @@ -177,7 +177,9 @@ struct statmount { __u32 sb_source; /* [str] Source string of the mount */ __u32 opt_num; /* Number of fs options */ __u32 opt_array; /* [str] Array of nul terminated fs options */ - __u64 __spare2[47]; + __u32 opt_sec_num; /* Number of security options */ + __u32 opt_sec_array; /* [str] Array of nul terminated security options */ + __u64 __spare2[46]; char str[]; /* Variable size part containing strings */ }; @@ -214,6 +216,7 @@ struct mnt_id_req { #define STATMOUNT_FS_SUBTYPE 0x00000100U /* Want/got fs_subtype */ #define STATMOUNT_SB_SOURCE 0x00000200U /* Want/got sb_source */ #define STATMOUNT_OPT_ARRAY 0x00000400U /* Want/got opt_... */ +#define STATMOUNT_OPT_SEC_ARRAY 0x00000800U /* Want/got opt_sec... */ /* * Special @mnt_id values that can be passed to listmount -- cgit v1.2.3